Abstract:
In accordance with embodiments of the present disclosure, a power supply unit may include one or more stages including an output stage configured to generate a direct-current output voltage at an output of the power supply, an OR-ing metal-oxide-semiconductor field effect transistor (MOSFET) coupled between the output stage and the output, and a controller. The controller may be configured to measure a signal indicative of a voltage associated with the OR-ing MOSFET and determine an estimated output current of the power supply based on the signal.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates in general to information handling systems, and more particularly to sensing a current associated with a power system in an information handling system. 
       BACKGROUND 
       [0002]    As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
         [0003]    An information handling system may include a power supply in order to convert power (e.g., provided by a public utility) to a desired voltage level and/or current level to power components of the information handling system. Oftentimes, it is desirable to collect telemetry data regarding the power supply, such as an amount of current being delivered by a power supply to components of an information handling system. For example, such monitoring of power supply output current may be used to inform a controller of an information handling system for implementing a power sharing scheme among power supply units, power supply redundancy schemes, over-current warnings, power throttling, and/or other uses. 
         [0004]    A popular existing approach to measure output current is the use of bulky resistor shunts, which may be placed proximate to OR-ing metal-oxide-semiconductor-field-effect-transistors (MOSFETs) at the output of a power system. A voltage across such resistor shunts may be measured, and by knowing the resistance of such resistor shunts, the current may be determined from the voltage based on Ohm&#39;s law. Such shunts may undesirably consume power, are bulky and may take a significant amount of area, cause significant heat output, and may also add financial cost to the manufacturing of an information handling system. 
       SUMMARY 
       [0005]    In accordance with the teachings of the present disclosure, the disadvantages and problems associated with current sensing in a power supply may be reduced or eliminated. 
         [0006]    In accordance with embodiments of the present disclosure, a power supply unit may include one or more stages including an output stage configured to generate a direct-current output voltage at an output of the power supply, an OR-ing metal-oxide-semiconductor field effect transistor (MOSFET) coupled between the output stage and the output, and a controller. The controller may be configured to measure a signal indicative of a voltage associated with the OR-ing MOSFET and determine an estimated output current of the power supply based on the signal. 
         [0007]    In accordance with these and other embodiments of the present disclosure, a method may include measuring a signal indicative of a voltage associated with an OR-ing metal-oxide-semiconductor field effect transistor (MOSFET) coupled between an output of a power supply and an output stage configured to generate a direct-current output voltage at the output and determining an estimated output current of the power supply based on the signal. 
         [0008]    In accordance with these and other embodiments of the present disclosure, an information handling system may include a power supply unit and at least one information handling resource electrically coupled to the power supply unit. The power supply unit may include one or more stages including an output stage configured to generate a direct-current output voltage at an output of the power supply, an OR-ing metal-oxide-semiconductor field effect transistor (MOFET) coupled between the output stage and the output, and a controller. The controller may be configured to measure a signal indicative of a voltage associated with the OR-ing MOSFET and determine an estimated output current of the power supply based on the signal. 
         [0009]    Technical advantages of the present disclosure may be readily apparent to one skilled in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims. 
         [0010]    It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
           [0012]      FIG. 1  illustrates a block diagram of an example information handling system, in accordance with embodiments of the present disclosure; 
           [0013]      FIG. 2  illustrates a block diagram of an example power supply for use in the information handling system depicted in  FIG. 1 , in accordance with embodiments of the present disclosure; 
           [0014]      FIG. 3  illustrates a circuit diagram of an example OR-ing MOSFET and example amplifier for use in the example power supply of  FIG. 2 , in accordance with embodiments of the present disclosure; and 
           [0015]      FIG. 4  illustrates a circuit diagram of another example OR-ing MOSFET and example amplifier for use in the example power supply of  FIG. 2 , in accordance with embodiments of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Preferred embodiments and their advantages are best understood by reference to  FIGS. 1-4 , wherein like numbers are used to indicate like and corresponding parts. 
         [0017]    For the purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a personal data assistant (PDA), a consumer electronic device, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components of the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communication between the various hardware components. 
         [0018]    For the purposes of this disclosure, computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and/or flash memory; as well as communications media such as wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing. 
         [0019]    For the purposes of this disclosure, information handling resources may broadly refer to any component system, device or apparatus of an information handling system, including without limitation processors, service processors, basic input/output systems (BIOSs), buses, memories, I/O devices and/or interfaces, storage resources, network interfaces, motherboards, power supplies, air movers (e.g., fans and blowers) and/or any other components and/or elements of an information handling system. 
         [0020]      FIG. 1  illustrates a block diagram of an example of an information handling system  102  incorporating a power supply  110  in accordance with an embodiment of the present disclosure. As depicted, information handling system  102  may include power supply  110 , a motherboard  101 , and one or more other information handling resources. 
         [0021]    Motherboard  101  may include a circuit board configured to provide structural support for one or more information handling resources of information handling system  102  and/or electrically couple one or more of such information handling resources to each other and/or to other electric or electronic components external to information handling system  102 . As shown in  FIG. 1 , motherboard  101  may include a processor  103 , memory  104 , a management controller  106 , and one or more other information handling resources. 
         [0022]    Processor  103  may comprise any system, device, or apparatus operable to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, processor  103  may interpret and/or execute program instructions and/or process data stored in memory  104  and/or another component of information handling system  102 . Memory  104  may be communicatively coupled to processor  103  and may comprise any system, device, or apparatus operable to retain program instructions or data for a period of time. Memory  104  may comprise random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a PCMCIA card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to information handling system  102  is turned off. 
         [0023]    Management controller  106  may be configured to provide out-of-band management facilities for management of information handling system  102 . Such management may be made by management controller  106  even if information handling system  102  is powered off or powered to a standby state. Management controller  106  may include a processor, memory, out-of-band network interface separate from and physically isolated from an in-band network interface of information handling system  102 , and/or other embedded information handling resources. In certain embodiments, management controller  106  may include or may be an integral part of a baseboard management controller (BMC) or a remote access controller (e.g., a Dell Remote Access Controller of Integrated Dell Remote Access Controller). In other embodiments, management controller  106  may include or may be an integral part of a chassis management controller (CMC). In some embodiments, management controller  106  may be configured to communicate with power supply  110  to communicate control and/or telemetry data between the two. 
         [0024]    Generally speaking, power supply  110  may include any system, device, or apparatus configured to supply electrical current to one or more information handling resources of information handling system  102 . An example of power supply  110  is set forth in  FIG. 2 . 
         [0025]      FIG. 2  illustrates a block diagram of an example power supply  110  for use in information handling system  102  depicted in  FIG. 1 , in accordance with embodiments of the present disclosure. As shown in  FIG. 2 , power supply  110  may comprise a power-factor correction block  202 , a direct-current-to-direct-current (DC-DC) converter  204 , a bulk capacitor  206 , an OR-ing MOSFET  208 , an amplifier  212 , a microcontroller  214 , and a temperature sensor  216 . 
         [0026]    Power factor correction block  202  may comprise any system, device, or apparatus configured to receive an alternating current (AC) power source with voltage V IN  and increase the ratio of the real power (e.g., non-reactive power) to the apparent power (e.g., reactive power plus non-reactive power) delivered from the power source as compared to if power factor correction block  202  were not present. Power factor correction block  202  may be implemented in any suitable manner now or in the future known to provide power factor correction. 
         [0027]    DC-DC converter  204  may be coupled to the output of power factor correction block  202  and may comprise any suitable electronic or electric system, device, or apparatus is an electronic circuit which converts a source of direct current (DC) (e.g., a DC current generated by power factor correction block  202 ) from one voltage level to another voltage level with voltage V DC . Examples of such a DC-DC converter  204  may be a boost converter, buck converter, buck-boost converter, Ćuk-type converter, or any other suitable type of converter. In some embodiments, voltage V DC  may be equal to approximately 12 volts. 
         [0028]    Bulk capacitor  206  may include any passive two-terminal electrical component configured to store energy electrostatically in an electric field. As shown in  FIG. 2 , bulk capacitor  206  may be coupled between output terminals of DC-DC converter  204  and may thus be operable to hold voltage V DC  at a stable level. 
         [0029]    The combination of power factor correction block  202 , DC-DC converter  204  and bulk capacitor  206  may serve to convert an AC voltage source V IN  into a DC voltage supply V DC . However, in embodiments in which a DC voltage source is to be converted into another DC voltage, power factor correction block  202  may not be present, and DC-DC converter  204  may directly convert the DC source voltage into a DC voltage supply V DC . 
         [0030]    OR-ing MOSFET  208  may be coupled via its source terminal to a positive polarity output terminal of DC-DC converter  204  and via its drain terminal to a positive polarity output of power supply  110 . OR-ing MOSFET  208  may comprise any suitable MOSFET, including a typical n-type MOSFET or a current-sensing n-type power MOSFET, having a diode coupled between its source and drain terminals. Example implementations for OR-ing MOSFET  208  are set forth in  FIGS. 3 and 4  described below. In operation, OR-ing MOSFET  208  may protect against reverse current flow should one power supply  110  or another power supply of information handling system  102  develop a catastrophic output short to ground or should a voltage of an individual power supply in information handling system  102  fall significantly below the others. Although only one OR-ing MOSFET  208  is depicted in  FIG. 2  for the purposes of clarity and exposition, in some embodiments, power supply  110  may comprise a plurality of OR-ing MOSFETs  208  coupled in parallel at their respective source and drain terminals. Due to the presence of OR-ing MOSFET  208 , power supply  110  may generate an output supply voltage V SUPPLY  which may be slightly different from but substantially equal to voltage V DC . Power supply  110  may communicate output supply voltage V SUPPLY  to motherboard  101  and/or other information handling resources of information handling system  102 . 
         [0031]    Amplifier  212  may comprise any system, device, or apparatus for increasing power of a signal, for example by taking energy from a power supply and controlling the output of the amplifier to match the input signal shape but with a larger amplitude. Example implementations for amplifier  212  are set forth in  FIGS. 3 and 4  described below. 
         [0032]    Microcontroller  214  may comprise any suitable system, device, or apparatus for processing an amplified voltage signal V SENSE   _   AMP  associated with OR-ing MOSFET  208  and determining a current delivered by power supply  110  based on such amplified voltage signal V SENSE   _   AMP . In some embodiments, microcontroller  214  may include an analog-to-digital converter for converting analog voltage V SENSE   _   AMP  into a corresponding digital signal that may be processed by digital circuitry of microcontroller  214  (e.g., a digital signal processor, application-specific integrated circuit, microprocessor, or other controller). 
         [0033]    Temperature sensor  216  may comprise any system, device, or apparatus (e.g., a thermometer, thermistor, diode, etc.) configured to communicate a signal to microcontroller  214  and/or control logic internal to the microcontroller  214  indicative of a temperature proximate to OR-ing MOSFET  208 . In some embodiments, temperature sensor  216  may comprise a negative temperature coefficient resistor which is typically present in power supplies provided by many vendors to measure temperature. 
         [0034]      FIG. 3  illustrates a circuit diagram of an example OR-ing MOSFET  208 A and example amplifier  212 A for use as OR-ing MOSFET  208  and amplifier  212 , respectively, of example power supply  110  of  FIG. 2 , in accordance with embodiments of the present disclosure. As shown in  FIG. 3 , OR-ing MOSFET  208 A may comprise a typical n-type MOSFET. A control signal CTRL may be applied to a gate terminal of MOSFET  302  in order to control its operation, as is known in the art. The voltage V SENSE  received by amplifier  212 A may be the voltage difference between the drain terminal and the source terminal of MOSFET  302  (e.g., the drain-source voltage of MOSFET  302 ). In the embodiments represented by  FIG. 3 , such voltage V SENSE  may be amplified by a traditional inverting amplifier comprising an operational amplifier  310  and gain resistors  306  and  308 . 
         [0035]      FIG. 4  illustrates a circuit diagram of an example OR-ing MOSFET  208 B and example amplifier  212 B for use as OR-ing MOSFET  208  and amplifier  212 , respectively, of example power supply  110  of  FIG. 2 , in accordance with embodiments of the present disclosure. As shown in  FIG. 4 , OR-ing MOSFET  208 B may comprise a current-sensing n-type power MOSFET  402 . A control signal CTRL may be applied to a gate terminal of MOSFET  402  in order to control its operation, as is known in the art. MOSFET  402  may comprise any suitable MOSFET having an additional terminal, often referred to as a “sense” terminal, for measuring a current associated with MOSFET  402 . In some embodiments, MOSFET  402  may comprise a SENSEFET®. For OR-ing  208 B, the voltage V SENSE  amplified by amplifier  212 B may be the voltage difference between the source terminal and the sense terminal of MOSFET  402  that may develop across sense resistor  405  of amplifier  212 B as a result of the current flowing from the sense terminal of MOSFET  202 . In the embodiments represented by  FIG. 4 , such voltage V SENSE  may be amplified by a traditional inverting amplifier comprising an operational amplifier  410  and gain resistors  406  and  408 . 
         [0036]    To account for temperature, process, or other variations of parameters of OR-ing MOSFET  208  (e.g., a drain-to-source resistance of MOSFET  208 ), calibration and temperature compensation may be undertaken by components of power supply  110 . For the embodiments of power supply  110  which include the OR-ing MOSFET  208 A of  FIG. 3 , calibration may be made part of a factory/production line test plan and performed by automatic test equipment. For example, automatic test equipment may use its own sensors to measure the level of current being supplied by power supply  110  and compare that with the reading from microcontroller  214  to determine an accurate value of the drain-to-source resistance of OR-ing MOSFET  208 A for a given temperature (e.g., 25° C.). With this base value for the drain-to-source resistance derived for a particular temperature, microcontroller  214  may utilize temperature readings from temperature sensor  216  as the temperature of OR-ing MOSFET  208 A. In some embodiments, a difference in temperature between temperature sensor  216  and the junction temperature of MOFET  208 A may also be considered. From the measured temperature of OR-ing MOSFET  208 A, microcontroller  214  may calculate the drain-to-source resistance based on known resistance versus junction temperature characteristics of OR-ing MOSFET  208 A. In some embodiments, such resistance versus junction temperature characteristics may be linearized section-by-section and stored into a computer-readable medium of or accessible to microcontroller  214 . 
         [0037]    Alternatively, for the embodiments of power supply  110  which include the OR-ing MOSFET  208 A of  FIG. 3 , microcontroller  214  may leverage a current transformer (not shown) of DC-DC converter  204  that may be used to provide current limiting protection within DC-DC converter  204 . A measurement of the current of such current transformer may be received by microcontroller  214  and compared to the current for OR-ing MOSFET  208 A sensed by microcontroller  214 . Based on turns ratio and other properties of DC-to-DC converter  206 , the current for OR-ing MOSFET  208 A sensed by microcontroller  214  may be a function of the current transformer within DC-DC converter  204  for stable output loads (e.g., without large transients). Accordingly, calibration may be performed at start up or initialization of power supply  110 , wherein management controller  106  may cause processor  103 , memory  104 , and/or one or more other information handling resources of information handling system  102  to run at a particular steady-state load such that the load to power supply  110  remains substantially constant. By comparing a measured current of a current transformer of DC-DC converter  204  to the reported measured current of OR-ing MOSFET  208 A, microcontroller  214  may determine an accurate value of the drain-to-source resistance of OR-ing MOSFET  208 A for a given temperature (e.g., 25° C.). With this base value for the drain-to-source resistance derived for a particular temperature, microcontroller  214  may utilize temperature readings from temperature sensor  216  as the temperature of OR-ing MOSFET  208 A. In some embodiments, a difference in temperature between temperature sensor  216  and the junction temperature of MOFET  208 A may also be considered. From the measured temperature of OR-ing MOSFET  208 A, microcontroller  214  may calculate the drain-to-source resistance based on known resistance versus junction temperature characteristics of OR-ing MOSFET  208 A. In some embodiments, such resistance versus junction temperature characteristics may be linearized section-by-section and stored into a computer-readable medium of or accessible to microcontroller  214 . 
         [0038]    For embodiments employing OR-ing MOSFET  208 B, a separate calibration step may not be needed because the current output of the sense terminal may be proportional to the current of the main channel, with such ratio being fixed in production. Nonetheless, temperature compensation may still be needed, and may be performed in a manner similar to that discussed above with respect to temperature compensation of OR-ing MOSFET  208 A. 
         [0039]    As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements. 
         [0040]    This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. 
         [0041]    All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure.