# Patent

## Title
System for controlling and monitoring an array of point-of-load regulators by a host

## Abstract

A power control system comprises a plurality of POL regulators, at least one serial data bus operatively connecting the plurality of POL regulators, and a system controller connected to the serial data bus and adapted to send and receive digital data to and from the plurality of POL regulators. The serial data bus further comprises a first data bus carrying programming and control information between the system controller and the plurality of POL regulators. The serial data bus may also include a second data bus carrying fault management information between the system controller and the plurality of POL regulators. The power control may also include a front-end regulator providing an intermediate voltage to the plurality of POL regulators on an intermediate voltage bus.

## Background
RELATED APPLICATION DATA
This application claims priority as a continuation-in-part pursuant to 35 U.S.C. § 120 to patent application Ser. No. 10/326,222, filed Dec. 21, 2002 now U.S. Pat. No. 7,000,125, and patent application Ser. No. 10/293,001, filed Nov. 13, 2002 now U.S. Pat. No. 7,049,798.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to power control systems, or more particularly, to a method and system to control and monitor an array of point-of-load regulators.
2. Description of Related Art
With the increasing complexity of electronic systems, it is common for an electronic system to require power provided at several different discrete voltage and current levels. For example, electronic systems may include discrete circuits that require voltages such as 3v, 5v, 9v, etc. Further, many of these circuits require a relatively low voltage (e.g., 1v), but with relatively high current (e.g., 100 A). It is undesirable to deliver relatively high current at low voltages over a relatively long distance through an electronic device for a number of reasons. First, the relatively long physical run of low voltage, high current lines consumes significant circuit board area and congests the routing of signal lines on the circuit board. Second, the impedance of the lines carrying the high current tends to dissipate a lot of power and complicate load regulation. Third, it is difficult to tailor the voltage/current characteristics to accommodate changes in load requirements.
In order to satisfy these power requirements, it is known to distribute an intermediate bus voltage throughout the electronic system, and include an individual point-of-load (“POL”) regulator, i.e., DC/DC converter, at the point of power consumption within the electronic system. Particularly, a POL regulator would be included with each respective electronic circuit to convert the intermediate bus voltage to the level required by the electronic circuit. An electronic system may include multiple POL regulators to convert the intermediate bus voltage into each of the multiple voltage levels. Ideally, the POL regulator would be physically located adjacent to the corresponding electronic circuit so as to minimize the length of the low voltage, high current lines through the electronic system. The intermediate bus voltage can be delivered to the multiple POL regulators using low current lines that minimize loss.
With this distributed approach, there is a need to coordinate the control and monitoring of the POL regulators of the power system. The POL regulators generally operate in conjunction with a power supply controller that activates, programs, and monitors the individual POL regulators. It is known in the art for the controller to use a multi-connection parallel bus to activate and program each POL regulator. For example, the parallel bus may communicate an enable/disable bit for turning each POL regulator on and off, and voltage identification (VID) code bits for programming the output voltage set-point of the POL regulators. The controller may further use additional connections to monitor the voltage/current that is delivered by each POL regulator so as to detect fault conditions of the POL regulators. A drawback with such a control system is that it adds complexity and size to the overall electronic system.
Thus, it would be advantageous to have a system and method for controlling and monitoring POL regulators within a distributed power system.
SUMMARY OF THE INVENTION
The present invention provides a system and method for controlling and monitoring POL regulators within a distributed power system.
In an embodiment of the invention, the power control system comprises a plurality of POL regulators, at least one serial data bus operatively connecting the plurality of POL regulators, and a system controller connected to the serial data bus and adapted to send and receive digital data to and from the plurality of POL regulators. The serial data bus further comprises a first data bus carrying programming, control and monitoring information between the system controller and the plurality of POL regulators. The serial data bus may also include a second data bus carrying fault management information between the system controller and the plurality of POL regulators. The power control may also include a front-end regulator providing an intermediate voltage to the plurality of POL regulators on an intermediate voltage bus.
The POL control system enables four different modes of operation. In the first operational mode, the POL regulators function independently in the absence of a system controller and without interaction with other POL regulators. In the second operational mode, the POL regulators interoperate for the purpose of current sharing or interleaving in the absence of a system controller. In the third operational mode, the POL regulators operate as an array in which the behavior of each POL regulator and the array as a whole are coordinated by a system controller. Lastly, the fourth operational mode includes both central control using the system controller and local control over certain functionality. This way, the POL regulators operate as an array coordinated by a system controller and also interoperate with each other to perform functions such as current sharing.
A more complete understanding of the method and system for controlling and monitoring a plurality of POL regulators will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings, which will first be described briefly.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a prior art distributed power delivery system;
FIG. 2 depicts a prior art POL control system using a parallel control bus;
FIG. 3 depicts an exemplary POL control system constructed in accordance with an embodiment of the present invention;
FIG. 4 depicts an exemplary POL regulator of the POL control system;
FIG. 5 depicts an exemplary system controller of the POL control system;
FIG. 6 depicts an exemplary method of communicating with a POL regulator over a serial bus;
FIG. 7 depicts an exemplary method of providing/utilizing fault-monitoring data in a POL control system;
FIG. 8 depicts an exemplary communication cycle that may be transmitted to/from a POL regulator;
FIG. 9 depicts an alternative embodiment of a POL control system;
FIG. 10 depicts another alternative embodiment of a POL control system;
FIG. 11 depicts an exemplary method for programming parameters for operating a POL control system;
FIGS. 12A-12D depict an exemplary POL control system being programmed in accordance with the method of FIG. 11; and
FIG. 13 depicts an exemplary communication cycle for transmitting information between a system controller and at least one POL regulator.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention provides a system and method for controlling and monitoring POL regulators within a distributed power system. In the detailed description that follows, like element numerals are used to describe like elements illustrated in one or more figures.
Referring first to FIG. 1, a prior art distributed power delivery system is shown. The prior art distributed power deliver system includes an AC/DC converter 12 that converts the available AC power into a primary DC power source, e.g., 48 volts. The primary DC power source is connected to a primary power bus that distributes DC power to plural electronic systems, such as printed circuit board 14. The bus may be further coupled to a battery 18 providing a back-up power source for the electronic systems connected to the primary power bus. When the AC/DC converter 12 is delivering DC power into the primary power bus, the battery 18 is maintained in a fully charged state. In the event of loss of AC power or fault with the AC/DC converter 12, the battery 18 will continue to deliver DC power to the primary power bus for a limited period of time defined by the capacity of the battery 18.
The printed circuit board 14 may further include a DC/DC converter that reduces the primary bus voltage to an intermediate voltage level, such as 5 or 12 volts. The intermediate voltage is then distributed over an intermediate power bus provided to plural circuits on the printed circuit board 14. Each circuit has an associated point-of-load (“POL”) regulator located closely thereby, such as POLs 22, 24, and 26. Each POL regulator converts the intermediate bus voltage to a low voltage, high current level demanded by the electronic circuit, such as 1.8 volts, 2.5 volts, and 3.3 volts provided by POLs 22, 24, and 26, respectively. It should be appreciated that the voltage levels described herein are entirely exemplary, and that other voltage levels could be selected to suit the particular needs of electronic circuits on the printed circuit board 14. By locating the POLs 22, 24, 26 close to their corresponding electronic circuits, the length of the low voltage, high current lines on the printed circuit board 14 are minimized. Moreover, the intermediate power bus can be adapted to carry relatively low current, thereby minimizing power loss due to the line impedance. But, this distributed power delivery system does not provide a way to monitor and control the performance of the POLs 22, 24, 26.
FIG. 2 illustrates a prior art DC/DC converter control system having a power supply controller 32 and a plurality of DC/DC converters 34, 36, 38, and 42. The DC/DC converters 34, 36, 38, and 42 are each connected to a power bus (as described above with respect to FIG. 1), which provides an input voltage. The DC/DC converters 34, 36, 38, and 42 each provide a low voltage, high current output that passes through respective sensing resistors 46, 52, 56, and 62 and respective switches 48, 54, 58, and 64. The controller 32 provides control signals to the DC/DC converters 34, 36, 38, and 42 via a plurality of six-bit parallel buses that each carry an enable/disable bit and five VID code bits. The VID code bits program the DC/DC converters for a desired output voltage/current level. The controller 32 also monitors the performance of the DC/DC converters 34, 36, 38, and 42 using the sensing resistors 46, 52, 56, and 62. Particularly, the controller 32 monitors the output voltage of each DC/DC converter by detecting the voltage at the output side of the sensing resistor, and monitors the output current through the sensing resistor by detecting the voltage across the sensing resistor. The voltage and current sensing for each DC/DC converter requires two separate lines, so eight separate lines are needed to sense the voltage and current condition of the exemplary four-converter system. Moreover, the controller 32 has a switch enable line connected to the gate terminals of switches 48, 54, 58, and 64, by which the controller 32 can shut off the output from any of the DC/DC controllers 34, 36, 38, and 42.
In an exemplary operation, the controller 32 provides control parameters (e.g., output voltage set-point) to the DC/DC converter 34 via the VID code portion of the six-bit parallel bus. The controller 32 then activates the DC/DC converter 34 via the enable/disable portion of the six-bit parallel bus. Once activated, the DC/DC converter 34 converts the power bus voltage (e.g., 48 volts) into a selected output voltage. The controller 32 then verifies that the output voltage is the desired voltage by measuring the voltage via the voltage monitoring line. If the output voltage is within an acceptable range, it is provided to the load (not shown) by activating the switch 48 via the switch enable line. The controller 32 can then continuously monitor the output voltage and the output current produced by the DC/DC converter 34 by measuring the output voltage via the voltage monitoring line and measuring the voltage drop across the sensing resistor (i.e., the voltage differential between the current monitoring line and the voltage monitoring line). If the controller 32 detects a fault condition of the DC/DC converter 34 (e.g., output voltage drops below a specific threshold), the controller 32 can disable and reset the DC/DC converter. The controller 32 communicates with the other DC/DC converters 36, 38, and 42 in the same manner.
A disadvantage with the control system of FIG. 2 is that it adds complexity and size to the overall electronic system by using a six-bit parallel bus to control each DC/DC converter and a separate three-line output connection to monitor the performance of each DC/DC converter. In other words, the controller 32 utilizes thirty-six separate connections in order to communicate with four DC/DC converters 34, 36, 38, and 42. As the complexity and power requirements of electronic systems increase, the number of connections to the controller will also increase in a linear manner.
Referring now to FIG. 3, a POL control system 100 is shown in accordance with an embodiment of the present invention. Specifically, the POL control system 100 includes a system controller 102, a front-end regulator 104, and a plurality of POL regulators 106, 108, 110, 112, and 114 arranged in an array. The POL regulators depicted herein include, but are not limited to, point-of-load regulators, power-on-load regulators, DC/DC converters, voltage regulators, and all other programmable voltage or current regulating devices generally known to those skilled in the art. An intra-device interface is provided between individual ones of the POL regulators to control specific interactions, such as current share or paralleling, e.g., current share interface (CS1) provided between POL0 106 and POL1 108, and CS2 provided between POL4 112 and POLn 114. In the exemplary configuration shown in FIG. 3, POL0 106 and POL1 108 operate in parallel mode to produce output voltage VO1 with increased current capability, POL2 110 produces output voltage VO2, and POL4 112 and POLn 114 operate in parallel mode to produce output voltage VO3, though it should be appreciate that other combinations and other numbers of POL regulators could be advantageously utilized.
The front-end regulator 104 provides an intermediate voltage to the plurality of POL regulators over an intermediate voltage bus, and may simply comprise another POL regulator. The system controller 102 and front-end regulator 104 may be integrated together in a single unit, or may be provided as separate devices. Alternatively, the front-end regulator 104 may provide a plurality of intermediate voltages to the POL regulators over a plurality of intermediate voltage buses. The system controller 102 may draw its power from the intermediate voltage bus.
The system controller 102 communicates with the plurality of POL regulators by writing and/or reading digital data (either synchronously or asynchronous) via a uni-directional or bi-directional serial bus, illustrated in FIG. 3 as the synch/data bus. The synch/data bus may comprise a two-wire serial bus (e.g., I2C) that allows data to be transmitted asynchronously or a single-wire serial bus that allows data to be transmitted synchronously (i.e., synchronized to a clock signal). In order to address any specific POL in the array, each POL is identified with a unique address, which may be hardwired into the POL or set by other methods. The system controller 102 also communicates with the plurality of POL regulators for fault management over a second uni-directional or bi-directional serial bus, illustrated in FIG. 3 as the OK/fault bus. By grouping plural POL regulators together by connecting them to a common OK/fault bus allows the POL regulators have the same behavior in the case of a fault condition. Also, the system controller 102 communicates with a user system via a user interface bus for programming, setting, and monitoring of the POL control system 10. Lastly, the system controller 102 communicates with the front-end regulator 104 over a separate line to disable operation of the front-end regulator.
An exemplary POL regulator 106 of the POL control system 10 is illustrated in greater detail in FIG. 4. The other POL regulators of FIG. 3 have substantially identical configuration. The POL regulator 106 includes a power conversion circuit 142, a serial interface 144, a POL controller 146, default configuration memory 148, and hardwired settings interface 150. The power conversion circuit 142 transforms an input voltage (Vi) to the desired output voltage (VO) according to settings received through the serial interface 144, the hardwired settings 150 or default settings. The power conversion circuit 142 may also include monitoring sensors for output voltage, current, temperature and other parameters that are used for local control and also communicated back to the system controller through the serial interface 144. The power conversion circuit 142 may also generate a Power Good (PG) output signal for stand-alone applications in order to provide a simplified monitoring function. The serial interface 144 receives and sends commands and messages to the system controller 102 via the synch/data and OK/fault serial buses. The default configuration memory 148 stores the default configuration for the POL regulator 106 in cases where no programming signals are received through the serial interface 144 or hardwired settings interface 150. The default configuration is selected such that the POL regulator 106 will operate in a “safe” condition in the absence of programming signals.
The hardwired settings interface 150 communicates with external connections to program the POL regulator without using the serial interface 144. The hardwired settings interface 150 may include as inputs the address setting (Addr) of the POL to alter or set some of the settings as a function of the address (i.e., the identifier or the POL), e.g., phase displacement, enable/disable bit (En), trim, and VID code bits. Further, the address identifies the POL regulator during communication operations through the serial interface 144. The trim input allows the connection of one or more external resistors to define an output voltage level for the POL regulator. Similarly, the VID code bits can be used to program the POL regulator for a desired output voltage/current level. The enable/disable bit allows the POL regulator to be turned on/off by toggling a digital high/low signal.
The POL controller 146 receives and prioritizes the settings of the POL regulator. If no settings information is received via either the hardwired settings interface 150 or the serial interface 144, the POL controller 146 accesses the parameters stored in the default configuration memory 148. Alternatively, if settings information is received via the hardwired settings interface 150, then the POL controller 146 will apply those parameters. Thus, the default settings apply to all of the parameters that cannot be or are not set through hard wiring. The settings received by the hardwired settings interface 150 can be overwritten by information received via the serial interface 144. The POL regulator can therefore operate in a stand-alone mode, a fully programmable mode, or a combination thereof. This programming flexibility enables a plurality of different power applications to be satisfied with a single generic POL regulator, thereby reducing the cost and simplifying the manufacture of POL regulators.
An exemplary system controller 102 of the POL control system 100 is illustrated in FIG. 5. The system controller 102 includes a user interface 122, a POL interface 124, a controller 126, and a memory 128. The user interface 122 sends and receives messages to/from the user via the user interface bus. The user interface bus may be provided by a serial or parallel bi-directional interface using standard interface protocols, e.g., an I2C interface. User information such as monitoring values or new system settings would be transmitted through the user interface 122. The POL interface 124 transforms data to/from the POL regulators via the synch/data and OK/fault serial buses. The POL interface 124 communicates over the synch/data serial bus to transmit setting data and receive monitoring data, and communicates over the OK/fault serial bus to receive interrupt signals indicating a fault condition in at least one of the connected POL regulators. The memory 128 comprises a non-volatile memory storage device used to store the system set-up parameters (e.g., output voltage, current limitation set-point, timing data, etc.) for the POL regulators connected to the system controller 102. Optionally, a secondary, external memory 132 may also be connected to the user interface 122 to provide increased memory capacity for monitoring data or setting data.
The controller 126 is operably connected to the user interface 122, the POL interface 124, and the memory 128. The controller 126 has an external port for communication a disable signal (FE DIS) to the front-end regulator 104. At start-up of the POL control system 100, the controller 126 reads from the internal memory 128 (and/or the external memory 132) the system settings and programs the POL regulators accordingly via the POL interface 124. Each of the POL regulators is then set up and started in a prescribed manner based on the system programming. During normal operation, the controller 126 decodes and executes any command or message coming from the user or the POL regulators. The controller 126 monitors the performance of the POL regulators and reports this information back to the user through the user interface 122. The POL regulators may also be programmed by the user through the controller 126 to execute specific, autonomous reactions to faults, such as over current or over voltage conditions. Alternatively, the POL regulators may be programmed to only report fault conditions to the system controller 102, which will then determine the appropriate corrective action in accordance with predefined settings, e.g., shut down the front-end regulator via the FE DIS control line.
A monitoring block 130 may optionally be provided to monitor the state of one or more voltage or current levels of other power systems not operably connected to the controller 102 via the synch/data or OK/fault buses. The monitoring block 130 may provide this information to the controller 126 for reporting to the user through the user interface in the same manner as other information concerning the POL control system 10. This way, the POL control system 10 can provide some backward compatibility with power systems that are already present in an electronic system.
Returning to FIG. 3, the system controller 102 is adapted to provide initial-configuration data to each POL regulator (i.e., 106, 108, 110, 112, 114). It should be appreciated that the initial-configuration data may include, but is not limited to, one or more of the following types of data: output-voltage-set-point-data (i.e., a desired output voltage); output-current-set-point data (i.e., the highest desired output current); low-voltage-limit data (i.e., the lowest desired output voltage); high-voltage-limit data (i.e., the highest desired output voltage); output-voltage-slew-rate data (i.e., the desired-output slew rate); enable/disable data (i.e., turning on/off the POL regulator output); timing data (e.g., turn-on delay, turn-off delay, fault recovery time, etc.) and/or all other types of POL programming data generally known to those skilled in the art. Once the initial-configuration data is received, the POL controller 146 (see FIG. 4) is adapted to store at least a portion of the initial-configuration data in memory. At least a portion of the stored initial-configuration data is then used to produce a desired output. For example, an output may be produced to include a particular voltage level, a particular slew rate, etc., depending on the type of initial-configuration data received/stored.
After the output has been produced, the POL controller 146 is adapted to receive fault-monitoring data (e.g., from an external device, a sense circuit, etc.). The fault-monitoring data, which contains information on the POL regulator or its output, is then stored in the memory. The POL controller 146, in response to a condition (e.g., receiving a request, exceeding a known parameter, having a register's contents change, etc.), is then adapted to provide at least a portion of the fault-monitoring data to the system controller 102. It should be appreciated that the fault-monitoring data may include, but is not limited to, one or more of the following types of data: output-voltage data, which may include actual-output-voltage data (i.e., the measured output voltage) or voltage-comparison data (e.g., whether the measured output voltage is above or below the highest desired output voltage, whether the measured output voltage is above or below the lowest desired output voltage, etc.); output-current data, which may include actual-output-current data (i.e., the measured output current) or current-comparison data (e.g., whether the measured output current is above or below the highest desired output current); temperature-status data, which may include actual-temperature data (i.e., the measured temperature of a POL regulator, or more particularly its heat generating components) or temperature-comparison data (e.g., whether the temperature of the POL regulator (or its components) is above or below a known value, etc.), and/or all other types of POL fault monitoring data generally known to those skilled in the art. It should also be appreciated that fault-monitoring data is not limited to data representing the existence of a faulty condition. For example, fault-monitoring data that indicates that the POL regulator is operating within acceptable parameters (e.g., within an acceptable temperature range) is considered to be within the spirit and scope of the present invention.
The fault-monitoring data can be used by either the system controller 102 or the POL controller 146 to monitor and/or control the POL regulator. In other words, the POL controller 146 can use the fault-monitoring data to either provide POL status information (i.e., data corresponding to a particular POL regulator or its output) to the system controller 102 or disable the POL regulator if a particular condition is met (e.g., the status register changes, the temperature limit has been exceeded, etc.). Alternatively, the system controller 102 can use the fault-monitoring data to either provide POL status information to an administrator, disable a particular POL regulator, or store the fault-monitoring data for future use. For example, in one embodiment of the present invention, each POL regulator includes unique ID data (e.g., serial number, date of manufacture, etc.) stored in an ID register. This enables the system controller 102 to provide POL status information and unique ID data to an administrator.
In another embodiment of the present invention, each POL regulator further includes at least one sensor circuit. The sensor circuit is used to produce either the fault-monitoring data, or data that can be used (e.g., together with information stored in the memory) to produce the fault-monitoring data. It should be appreciated that the sensor circuit, as described herein, will vary (e.g., as to circuitry, location, inputs, etc.) depending upon the type of information that is being detected. For example, a sensor circuit that detects current may include different circuitry, have different inputs, and be placed in a different location than a sensor circuit that detects temperature.
FIG. 8 illustrates a signal adapted to be communicated over the synch/data bus. Specifically, a transmission line is created by propagating a clock signal 800 over the bus. The clock signal 800 can be generated by the system controller 102, a particular POL regulator (e.g., the POL regulator with the least significant address), or an external device. The clock signal 800 synchronizes the various communicating devices (i.e., the POL regulators and the controller) and creates a series of clock cycles 810, each one including at least one data bit. This allows the various communicating devices to transmit a single bit of data for every clock cycle 810. In other words, each communicating device transmits data by leaving/pulling the data bit high or low (i.e., binary one or zero).
FIG. 13 illustrates an exemplary communication cycle 50 for transmitting information between the system controller 102 and at least one POL regulator. Specifically, the communication cycle 50 can be used to transmit initial-configuration data, fault-monitoring data, unique ID data, or any other type of data. As shown in FIG. 13, an exemplary forty-two bit transmission cycle 50 includes a start sequence 510 (e.g., four bits), an address 520, a command set 530, a first acknowledgement bit 540, a data set 560, and a second acknowledge bit 570. An additional bit 550 has been added to ensure that the command set 540 is executed before the data set 560 is provided.
The first and second acknowledgement bits 540, 570 are used to acknowledge the reception of the command set 530 and the data set 560, respectively. It should be appreciated that the device responsible for the providing the first and second acknowledgement bits 540, 570 varies depending upon whether the information is being sent to or from the POL regulator (i.e., whether the information is being written, read, or provided).
The command set 530, data set 560, and address set 520 enable the system controller 102 and the POL regulators to write, read and provide data. Specifically, (i) the command set 530 is used to identify whether and what the controller is writing (e.g., writing to the status register), the controller is reading (e.g., reading the status register), or the POL regulator is providing (e.g., providing status register information), (ii) the address set 520 is used to identify the POL regulator(s) that is being written to or read, or the POL regulator that is providing information, and (iii) the data set 560 is used to identify the actual data that is being written, read, or provided.
The start sequence 510 and address set 520 are used, in part, to identify the sender of the information. For example, the system controller 102 may use a different start sequence 510 than the individual POL regulators. Thus, the system controller 102 can determine, by reading the start sequence 510 of the communication cycle 50 being transmitted, whether a POL regulator is also attempting to send a communication cycle 50 at the same time. Similarly, each POL regulator may have a different address set 520. Thus, a POL regulator can determine, by reading the start sequence 510 and address set 520 of the communication cycle 50 being transmitted, whether another POL regulator or the controller is also attempting to send a communication cycle 50 at the same time. If multiple devices are attempting to send a communication cycle 50, sequencing data is used to allocate or arbitrate bus use. It should be appreciated that the sequence data can either be stored (or hard wired) as a default value or provided as initial-configuration data and stored in the storage device (e.g., a sequencing configuration register).
One method of providing/utilizing initial-communication data is illustrated in FIG. 6, starting at step 610. Specifically, at step 620, the POL control unit begins by receiving initial-configuration data (e.g., output-voltage-set-point, output-current-set-point, etc.). The initial-configuration data is then stored in memory at step 630. At step 640, the POL control unit uses at least a portion of the initial-configuration data to determine at least one output parameter (e.g., voltage level, slew rate, etc.) of the POL regulator. The POL control unit then generates an output including the output parameter(s) at step 650, ending the process at step 660.
One method of providing/utilizing fault-monitoring data is illustrated in FIG. 7, starting at step 710. Specifically, at step 720, the POL regulator, or more particularly a sensor circuit (either alone or together with information stored in the storage device) detects fault-monitoring data (e.g., output-voltage data, output-current data, etc.). The fault-monitoring data is then stored in memory at step 730. At step 740, the system controller 102 sends (and the POL controller 146 receives) a request for at least a portion of the fault-monitoring data. At step 750, the POL controller 146 provides the requested portion of the fault-monitoring data to the system controller 102. The system controller 102, at step 760, uses the requested portion of the fault-monitoring data to monitor at least one parameter of the POL regulator.
At step 770, the system controller 102 determines whether the monitored parameter violates a known parameter. For example, if the monitored parameter is output voltage, the output voltage could be compared to a maximum output voltage value. If a violation occurs (e.g., the output voltage exceeds a maximum output voltage value), then the POL regulator would be disabled at step 780. Alternatively, if a violation does not occur, the system controller 102 continues monitoring the POL regulator by again requesting at least a portion of fault-monitoring data at step 740. It should be appreciated that while it may be advantageous to disable a POL regulator in light of a violation, the present invention is not limited to such a result. For example, the system controller 102 or a POL regulator may be programmed to perform a different action (e.g., closely monitor the faulty POL regulator, notify the administrator, store fault-monitoring data, etc.) if a particular parameter violation occurs.
In another embodiment of the invention, the fault-monitoring data itself indicates whether a monitored parameter violates a known parameter. For example, if output-current-set-point data (i.e., the highest desired output current) is received as initial-configuration data and stored in the storage device, the POL regulator (or more particular the POL controller 146) can provide the system controller 102 with fault-monitoring data that indicates whether the measured output current is over or under the stored maximum current value. In this instance, if the received fault-monitoring data indicates that the output current is below the maximum value, the system controller 102 can continue to monitor the POL regulator as previously described. Alternatively, if the received fault-monitoring data indicates that the output current is above the maximum value, the system controller 102 (without making any additional calculations) can disable the POL regulator.
The POL control system 10 enables four different modes of operation. In the first operational mode, the POL regulators function independently in the absence of a system controller and without interaction with other POL regulators. The POL regulators each include local feedback and control systems to regulate their own performance as well as control interfaces to enable local programming. The POL regulators further include default settings in which they can revert to in the absence of local programming or data from the system controller. In other words, each of the POL regulators can operate as a standalone device without the need for a system controller or interactions with another POL regulator.
In the second operational mode, the POL regulators interoperate for the purpose of current sharing or interleaving in the absence of a system controller. The POL regulators communicate with each other over the current share interface. The synch/data line may be used to communicate synchronization information to permit phase interleaving of the POL regulators, in which the phase is programmed locally by entering an address through hardwired connections. In either the first or second modes of operation, there would generally be information communicated between the POL regulators except for synchronization; there would be no need to communicate programming information.
In the third operational mode, the POL regulators operate as an array in which the behavior of each POL regulator and the array as a whole are coordinated by a system controller. The system controller programs the operation of each of the POL regulators over the synch/data serial bus, and thereby overrides the predetermined settings of the POL regulators. The synch/data serial bus is further used to communicate synchronization information to permit synchronization and interleaving of the POL regulators. This operational mode would not include interdevice communications over the current share interface.
Lastly, the fourth operational mode includes both central control using the system controller and local control over certain functionality. This way, the POL regulators operate as an array coordinated by a system controller and also interoperate with each other to perform functions such as current sharing.
It should be appreciated that the POL control system of the present invention provides a great deal of flexibility in the manner in which it implemented to regulate power for a host system. FIG. 9 illustrates an exemplary embodiment of a POL control system implemented with a host system. The host system may be a specialized master that provides the main interface to the user system CPU. Alternatively, the host system may be provided directly by the user system CPU or any other control system dedicated to manage the power management subsystems.
One such embodiment would include a host system, a system controller and an array of POL regulators. An advantage of this embodiment is that the host is relieved of the overhead of continuous communication with the POL regulators. Instead, the system controller provides the supervisory level communications with the POL regulators, and the host may only be provided with high level interactions, such as monitoring and status information. The system controller also provides memory for storage of POL array programming parameters, thereby relieving the host of this responsibility. Another embodiment could include a system controller and array of POL regulators, without a host system. The system controllers would independently manage the operation of the POL control systems without need for interaction with a host. Alternatively, the host system could be adapted to provide the function of the system controller, and thereby would communicate directly with the array of POL regulators. While this would place substantial overhead requirements on the host, it may be desirable in certain applications.
Specifically, the POL control system includes two separate POL control systems similar to that described above with respect to FIG. 3. The first POL control system 220 (i.e., System A) includes a system controller 225 coupled to a plurality of POL regulators 222, 224, 226, 228. The second POL control system 210 has a similar structure, including a system controller and plurality of POL regulators. The POL control systems may each be associated with different aspects of a host system. For example, System A may provide regulated power to a first rack of circuit boards, and System B may provide regulated power to a second rack of circuit boards. Alternatively, Systems A and B may each provide regulated power to different circuit boards within one rack. In either case, by each having their own system controller, the POL control systems can operate autonomously from each other, and would therefore be best suited for large host systems. It should be appreciated that additional POL control systems could be coupled to the host system, and that two POL control systems are illustrated merely for convenience and simplicity.
The system controllers from each the POL control systems would communicate with a host controller 240 via the user interface serial bus. As described above, the link with the host controller 240 enables the communication of monitoring, control and programming data. The host controller 240 may additionally be coupled to a local area network (LAN) or wide area network (WAN). A user would then have several options for accessing the POL control systems for purposes of monitoring, controlling and/or programming the POL control systems. In a first embodiment, a user system 266 (i.e., computer) equipped with a suitable application programming interface (API) may be coupled directly to the user interface bus for receiving communicating with the system controllers of the Systems A and B. The user system would likely include a user interface, such as a graphical user interface (GUI), that enables the display of status information regarding the POL control systems. The GUI may also serve as a diagnostic tool to enable troubleshooting of fault conditions within the POL control system.
Alternatively, in a second embodiment, the user system 264 may instead be coupled directly to the host controller 240. This might enable the same level of access to the POL control systems, or the host controller 240 may limit the extent of access (e.g., monitoring only, without ability to control or program). In yet another alternative, the user system 262 may be coupled to the host controller 240 through a LAN/WAN, thereby enabling the user to access the POL control systems from a remote location. As in the preceding embodiment, the host controller 240 may limit the extent of access to the POL control systems.
FIG. 10 illustrates another exemplary embodiment of a POL control system implemented with a host system. The POL control system includes two separate POL control systems similar to that described above with respect to FIG. 3. Unlike the embodiment of FIG. 9, the two POL control system 320, 310 each include a plurality of POL regulators without separate system controllers. Specifically, POL control system 320 includes a plurality of POL regulators 322, 324, 326, 328. The second POL control system 310 has a similar structure. A system controller 330 and front end regulator 332 may be included in a host system and provide control and intermediate bus voltage to each of the POL control systems. The system controller 330 may receive interrupt signals from each of the POL control systems to thereby determine which system has control of the synch/data bus. As before, the POL control systems may each be associated with different aspects of a host system. For example, the POL control systems A and B may each provide regulated power to different circuit boards within a common rack. Since the POL control systems share a system controller, the POL control systems can be made to operate cooperatively with other, and would therefore be best suited for small host systems. It should be appreciated that additional POL control systems could be coupled to the host system, and that two POL control systems are illustrated merely for convenience and simplicity.
In this exemplary embodiment, the system controller 330 would communicate with a host via the user interface serial bus. The communication with the host may be direct or via a local area network (LAN) or wide area network (WAN). A user may access the POL control systems for purposes of monitoring, controlling and/or programming the POL control systems by coupling directly to the user interface bus. As above, the user system would likely include a user interface, such as a graphical user interface (GUI), that enables the display of status information regarding the POL control systems.
A POL control system may be designed for a particular application, with certain parameters and values selected to achieve desired performance requirements. Once a set of desired parameters is achieved, these parameters may be programmed into the system controller to enable mass production of the POL array for use in a production level application. FIG. 11 shows an exemplary method of programming a POL array in accordance with an embodiment of the invention, and FIGS. 12A-12D illustrate a corresponding system implementing the exemplary method.
Specifically, in FIG. 12A, a prototype POL control system 830 includes a POL array 832 and a system controller (unprogrammed) 834. A proxy host 836 may also be provided to emulate interactions of the POL control system with an actual host. An operator communicates with the prototype POL control system using a suitable graphical user interface 838. As shown in step 812, an initial arrangement of the POL array is defined by the operator using the GUI 838. For example, the operator may designate the number of POL regulators of the array, the output voltage parameters of the POL regulators, the fault monitoring characteristics, and other such parameters generally described above. In step 814, the operator will optimize the system by adjusting parameter values until a desired configuration is achieved. For example, the GUI 838 may enable the operator to simulate various operational loads, faults and other conditions unique to the particular host environment, and can thereby select operational parameters that are best suited to achieve performance requirements of the host environment. When the operator is satisfied with the selected operational parameters, the GUI 838 would write these parameters to a suitable configuration file 840, as shown in FIG. 12B and in step 816.
Thereafter, the configuration file 84 would be used to program a final system controller 852, as shown in FIG. 12C and step 818. This step may be repeated many times to fabricate a production run of system controller devices to be used in a production level application. Then, a production level POL control system 870 is produced including a POL array 872 and a programmed system controller 852, for use with the actual host system 836, as shown in FIG. 12D. In step 820, the pre-programmed system controller devices are installed in an actual production system. Finally, at step 822, the POL control system including the POL array 872 and system controller 852 are implemented in the production system, and the system controller operates as described above to mange the operation of the POL array.
It should be appreciated that the POL control system of the present invention provides certain advantages over prior art distributed power distribution systems. The present POL control system requires much less complexity or “glue” components (e.g., mediating devices) in order to provide communication and control of a plurality of POL regulators, thereby reducing the amount of circuit board space for the POL control system and number of control lines needed for communication, control and monitoring. The POL control system is easily scalable by adding POL regulators to the array in order to support additional power requirements, without increasing the overhead requirements.
Having thus described a preferred embodiment of a method and system to control and monitor an array of DC/DC power converters, it should be apparent to those skilled in the art that certain advantages of the system have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is further defined by the following claims.

## Claims

1. A power control system for a host, comprising:
a plurality of point-of-load (POL) regulators providing regulated power to corresponding loads of the host;
at least one serial data bus operatively connected to said plurality of POL regulators; and
a system controller connected to said at least one serial data bus and adapted to send and receive digital data to and from said plurality of POL regulators, the system controller having a host interface adapted for communications with the host via a communication channel that is separate from said at least one serial data bus;
wherein, programming, control and monitoring information is carried on said at least one serial data bus between said system controller and said plurality of POL regulators, the programming, control and monitoring information being selectively communicated between the system controller and the host via the host interface.

2. The power control system of claim 1, wherein at least one of the plurality of POL regulators comprises a DC-to-DC converter.

3. The power control system of claim 1, wherein said at least one serial data bus further comprises a first data bus carrying said programming, control and monitoring information between said system controller and said plurality of POL regulators.

4. The power control system of claim 3, wherein said at least one serial data bus further comprises a second data bus carrying fault management information between said system controller and said plurality of POL regulators.

5. The power control system of claim 1, further comprising a front-end regulator providing an intermediate voltage to said plurality of POL regulators on an intermediate voltage bus.

6. The power control system of claim 5, wherein said front-end regulator is combined with said system controller in a single device.

7. The power control system of claim 5, wherein said plurality of POL regulators each further comprise a power conversion circuit adapted to transform said intermediate voltage to a desired output voltage.

8. The power control system of claim 1, wherein each of said plurality of POL regulators further comprise an intradevice interface adapted to communicate interaction information with at least one other one of said plurality of POL regulators.

9. The power control system of claim 8, wherein said interaction information further comprises current sharing information for a parallel operation between respective ones of said plurality of POL regulators.

10. The power control system of claim 1, wherein said plurality of POL regulators each further comprise at least one serial interface adapted to communicate with said at least one serial data bus.

11. The power control system of claim 10, wherein said plurality of POL regulators each further comprises a hardwired interface permitting programming in the absence of data received from said system controller via said serial interface.

12. The power control system of claim 11, wherein said hardwired interface further comprises an input enabling connection of at least one external resistor thereto to define an operating characteristic of a corresponding one of said plurality of POL regulators.

13. The power control system of claim 11, wherein said hardwired interface further comprises an address interface adapted to receive a unique identification address for each said POL regulator.

14. The power control system of claim 11, wherein said hardwired interface further comprises a VID interface adapted to receive VID codes.

15. The power control system of claim 1, wherein said plurality of POL regulators each further comprises a memory containing default configuration settings to revert to in the absence of data received from said system controller.

16. The power control system of claim 1, wherein the programming information comprises initial-configuration data defining desired operating parameters for at least one of the plurality of POL regulators.

17. The power control system of claim 16, wherein said plurality of POL regulators each further comprises a memory adapted to store the initial-configuration data, each POL regulator thereby operating in accordance with the stored initial-configuration data.

18. The power control system of claim 16, wherein the initial-configuration data includes at least output voltage set point data.

19. The power control system of claim 16, wherein the initial-configuration data includes at least low-voltage limit data.

20. The power control system of claim 16, wherein the initial-configuration data includes at least high-voltage limit data.

21. The power control system of claim 16, wherein the initial-configuration data includes at least output voltage slew rate data.

22. The power control system of claim 16, wherein the initial-configuration data includes at least enable/disable data.

23. The power control system of claim 16, wherein the initial-configuration data includes at least timing data.

24. The power control system of claim 1, wherein the monitoring information comprises fault-monitoring data defining status of at least one of the plurality of POL regulators.

25. The power control system of claim 24, wherein said plurality of POL regulators each further comprises a memory adapted to store the fault-monitoring data for a respective one of the POL regulators.

26. The power control system of claim 24, wherein said fault-monitoring data comprises at least output voltage data.

27. The power control system of claim 24, wherein said fault-monitoring data comprises at least output current data.

28. The power control system of claim 24, wherein said fault-monitoring data comprises at least temperature data.

29. The power control system of claim 1, wherein the system controller further comprises a memory adapted to store the monitoring information.

30. The power control system of claim 1, wherein the system controller sends the command information in response to the monitoring information.

31. The power control system of claim 30, wherein the command information includes a command to disable a particular one of the plurality of POL regulators.

32. The power control system of claim 1, wherein the system controller notifies the host in response to the monitoring information.

33. The power control system of claim 1, wherein the system controller compares the monitoring information to predetermined parameters to determine whether corrective action is needed.

34. The power control system of claim 1, wherein each one of the plurality of POL regulators includes a unique ID.

35. The power control system of claim 1, wherein the system controller sends a clock signal on the serial data bus to synchronize communication of the programming, control and monitoring information.

36. The power control system of claim 1, wherein at least one of the programming, control and monitoring information is communicated on the serial data bus in the form of a message having a command set, a data set, and an address set.

37. The power control system of claim 1, further comprising a user interface operable from the host for receiving communications from the system controller.

38. The power control system of claim 37, wherein the user interface further comprises a graphical user interface.

39. The power control system of claim 38, wherein the graphical user interface provides status information regarding the plurality of POL regulators.

40. The power control system of claim 38, wherein the graphical user interface provides a diagnostic tool for evaluating a fault condition of at least one of the plurality of POL regulators.

41. The power control system of claim 37, wherein the user interface communicates with the host interface through a local area network.

42. The power control system of claim 37, wherein the user interface communicates with the host interface through a wide area network.

43. The power control system of claim 1, wherein at least one of the plurality of POL regulators communicate the monitoring information with at least one other one of the POL regulators.

44. The power control system of claim 1, wherein at least one of the plurality of POL regulators comprises a voltage regulator.

45. A power control system for a host, comprising:
at least one point-of-load (POL) regulator providing regulated power to at least one corresponding load, said at least one POL regulator comprising a POL controller and a POL memory device for storing initial configuration data;
at least one serial data bus operatively connected to said at least one POL regulator; and
a system controller comprising a memory device for storing said initial configuration data and a host interface adapted for communications with said host, said system controller being connected to said at least one serial data bus and adapted to send said initial configuration data to said at least one POL regulator at a start-up of said system controller;
wherein, said POL controller is adapted to use at least a portion of said initial configuration data to determine at least one parameter of said regulated power, and digital data concerning said at least one POL regulator is selectively communicated between said system controller and said host via said host interface.

46. The power control system of claim 45, further comprising a user interface operable from the host for receiving communications from the system controller.

47. The power control system of claim 45, wherein said POL controller if further adapted to use at least a portion of said initial configuration data to regulate said at least one parameter of said regulated power.

48. The power control system of claim 45, wherein said initial configuration data comprises at least one of output-voltage-set-point data, output-current-set-point data, low-voltage-limit data, high-voltage-limit data, output-voltage-slew-rate data, enable/disable data, and timing data.

49. The power control system of claim 45, wherein said initial configuration data comprises at least two of output-voltage-set-point data, output-current-set-point data, low-voltage-limit data, high-voltage-limit data, output-voltage-slew-rate data, enable/disable data, and timing data.

50. The power control system of claim 45, wherein said initial configuration data comprises at least output-voltage-set-point data and enable/disable data.

51. The power control system of claim 45, wherein said at least one serial data bus further comprises a first data bus carrying said initial configuration data between said system controller and said at least one POL regulator.

52. The power control system of claim 51, wherein said at least one serial data bus further comprises a second data bus carrying fault management information between said system controller and said at least one POL regulator.

53. The power control system of claim 45, further comprising a front-end regulator providing an intermediate voltage to said at least one POL regulator on an intermediate voltage bus.

54. The power control system of claim 53, wherein said front-end regulator is combined with said system controller in a single device.

55. The power control system of claim 45, wherein said at least one POL regulator further comprises a serial interface adapted to communicate with said at least one serial data bus.

56. The power control system of claim 55, wherein said at least one POL regulator further comprises a hardwired interface permitting programming in the absence of data received from said system controller via said serial interface.

57. The power control system of claim 56, wherein said hardwired interface further comprises an address interface adapted to receive a unique identification address for each said POL regulator.

58. The power control system of claim 45, wherein said POL memory device is further adapted to store fault-monitoring data for said at least one POL regulator.

59. The power control system of claim 58, wherein said fault-monitoring data comprises at least output voltage data.

60. The power control system of claim 58, wherein said fault-monitoring data comprises at least output current data.

61. The power control system of claim 58, wherein said fault-monitoring data comprises at least temperature data.

62. The power control system of claim 45, wherein said POL memory device is further adapted to store a unique POL ID.

63. The power control system of claim 45, wherein said initial configuration data is communicated on said serial data bus in the form of a message having a command set, a data set, and an address set.

64. The power control system of claim 45, wherein said user interface further comprises a graphical user interface.

65. The power control system of claim 64, wherein said user interface communicates with said host interface through a wide area network.

66. The power control system of claim 64, wherein said graphical user interface provides status information regarding said at least one POL regulator.

67. The power control system of claim 64, wherein said graphical user interface provides a diagnostic tool for evaluating a fault condition of said at least one POL regulator.

68. The power control system of claim 64, wherein said user interface communicates with said host interface through a local area network.