# Patent

## Title
Method and apparatus for powering electronic circuits

## Abstract

A method and apparatus for powering an electronic circuit use comparators of supply voltages and voltage regulators to facilitate powering the electronic circuit utilizing more than one supply voltage. In one embodiment, power supplies of step-up power units are controlled using comparators of step-down power units and the step-up power units temporarily provide power to accidentally disabled of step-down power units.

## Background
FIELD OF THE INVENTION
The invention relates to the field of electronic circuits and, in particular, to a method and apparatus for powering the electronic circuits.
BACKGROUND OF THE INVENTION
Most of integrated electronic circuits (e.g., microprocessors, memory devices, application specific integrated circuits (ASICS), and the like) require several power supplies, where each power supply provides one or more supply voltages. In operation, such voltages should be applied to and removed from the electronic circuits in pre-determined orders, or sequences. Violation of such sequences may result in damaging an electronic circuit.
Conventionally, banks of pre-charged capacitors are used as emergency sources of energy to protect the electronic circuits from accidental loss of a supply voltage as a result of, e.g., a failure of the respective power supply. Such capacitors temporarily substitute for the loss of a supply voltage for the duration of time needed to execute a pre-determined emergency sequence for powering down the affected electronic circuit. However, in advanced electronic circuits using low supply voltages and consuming high supply currents, the number and dimensions of such capacitors become prohibitively large.
Therefore, there is a need in the art for an improved method and apparatus for powering electronic circuits.
SUMMARY OF THE INVENTION
The present invention is a method and apparatus for powering electronic circuits using more than one supply voltage.
In one aspect of the invention, there is provided a method for powering an electronic circuit using a plurality of power units, each unit providing one of supply voltages and including a power supply, a comparator of the supply voltage (i.e., output voltage of the power supply), and a voltage regulator. In one embodiment, the method includes the steps of (i) controlling the power supply of a step-up power unit using the comparator of a step-down power unit and (ii) using the regulator to selectively convert an output voltage of the step-up power unit in an output voltage of the step-down power unit and provide the converted voltage to an output of the step-down power unit. Such a method protects the electronic circuit from damage during accidental failures of the power supplies.
In another aspect of the invention, there is provided an apparatus for powering an electronic circuit that, in operation, executes the inventive method.



BRIEF DESCRIPTION OF THE DRAWINGS
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
FIG. 1 depicts a schematic diagram of an apparatus for powering an electronic circuit in accordance with one embodiment of the present invention; and
FIG. 2 depicts a flow diagram of a method for powering an electronic circuit using the apparatus of FIG. 1 in accordance with one embodiment of the present invention.



To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
DETAILED DESCRIPTION OF THE INVENTION
The present invention facilitates powering electronic circuits that are using more than one supply voltage and advantageously protects the electronic circuits from damage at accidental losses of power.
FIG. 1 depicts a schematic diagram of an apparatus 100 for powering an electronic circuit 150 in accordance with one embodiment of the present invention. In one embodiment, the apparatus 100 comprises a plurality of power units 101K, where K is an integer from 1 to N, and N is equal to the number of supply voltages VK that are provided to the electronic circuit 150 using the apparatus 100. Herein, similar devices, signals, and properties (e.g., voltages, currents, and the like) are identified using same numeric and alphabetic references, except that the suffixes may be added, when appropriate, to differentiate between the specific devices, signals, and properties. Illustratively, for an example and without limitation, in the depicted embodiment N=3 and V1<V2<V3.
In one embodiment, the power unit 101N having the highest output voltage VN comprises a power supply 110N, a comparator 112N, and an optional bank 113N of energy-storing capacitors. In the depicted embodiment, a power unit 1013 is such power unit having the highest output voltage (i.e., voltage V3).
Each of the power units 110K, other than the power unit 101N, generally comprises a power supply 110, a comparator 112, a voltage regulator 114, and the optional bank 113 of energy-storing capacitors.
The power units 101 are powered and controlled by a power controller 102 of an electronic system (not shown) that encompasses the electronic circuit 150. Generally, the power controller 102 includes a control module 104, at least one primary power source 106, and at least one auxiliary power source 108. Illustratively, for an example and without limitation, in the depicted embodiment the power controller 102, components of the power units 101, and the electronic circuit 150 are coupled to a common ground terminal 103 of the electronic system.
In operation, the control module 104 facilitates execution of pre-determined sequences for routine and emergency powering up and powering down the apparatus 100 and the electronic circuit 150, as well as monitors if the supply voltages of the power units 101 are within operational limits. Hereafter, the terms “supply voltage” in reference to the electronic circuit 150 and “output voltage” in reference to a power supply 110 or a power unit 101 are used interchangeably. The primary power source(s) 106 and the auxiliary power source(s) 108 (e.g., DC/DC converters, AC/DC converter, and the like) provide power to the power supplies 110 (source 106) and power and references signals (e.g., reference voltages) to comparators 112 and regulators 114 (source 108), respectively.
The power supply 110 is typically a DC/DC converter having a power input terminal 120, a power output terminal 122 coupled to an output rail 107, and an ON/OFF terminal 124. The power input terminal 120 and the output rail 107 are coupled to a respective output 142 of the power controller 102 and a respective input 152 of the electronic circuit 150.
The comparator 112K monitors if the output voltage VK is within operational limits. A first input of the comparator 112K is coupled to the output rail 107 K of the power supply 11OK and a second input of the comparator 112K is generally provided with a reference voltage VK—MIN from the auxiliary power source 108 of the power controller 102. An output of the comparator 110K of a step-down power supply 112K is coupled to the ON/OFF terminal 124K+1 of a step-up power supply 110K+1, as well as to terminals 140K of the power controller 102 that are monitored by the control module 104. An output of the comparator of the power supply having the highest output voltage (i.e., power supply 1103) and the ON/OFF terminal of the power supply having the smallest output voltage (i.e., power supply 1103) are coupled only to the power controller 102.
Herein, the terms “step-down power supply” and “step-up power supply” refer to the power supplies 110K and 110K+1 having most close output voltages, while the step-down power supply 110K has a smaller output voltage VK (e.g., V1 or V2) and the step-up power supply 110K+1 has a greater output voltage VK+1 VK (e.g., V2 or V3, respectively).
The voltage VK-MIN corresponds to the minimal output voltage of the power unit 101K that is acceptable for powering the electronic circuit 150. Depending on the value of the output voltage VK relative to the reference voltage VK—MIN (i.e., if VK>VK—MIN or VK≦VK—MIN), an output signal of the comparator 112 asserts one of two distinct (i.e., binary) states. In one embodiment, such binary states correspond to logic levels “0” and “1” of control circuits of the power supply 110 and the module 104. Specifically, when VK>VK—MIN, the comparator 112K sets the step-up power supply to an ON state and, when VK≦VK—MIN, the comparator 112K sets the step-up power supply to an OFF state.
The voltage regulator 114 may selectively draw power from the step-up power supply 110K+1 by coupling to the output of the step-up power supply, converting output voltage VK+1 of the power supply 110K+1 in the voltage VK-MIN, and providing that voltage to the output rail 107K of the step-down power supply 110K and, as such, to the terminal 152K of the electronic circuit 150.
In the depicted embodiment, the voltage regulator 1141 may selectively draw power from the power supply 1102 and convert the output voltage V2 in the voltage V1—MIN that is then provided to the terminal 1521. Accordingly, the regulator 1142 may selectively draw power from the power supply 1103 and the convert output voltage V3 in the voltage V2—MIN that is then provided to the terminal 1522.
In one embodiment, the regulator 114 comprises a voltage comparator 116 and an electronically controlled voltage converter 118 (e.g., field effect transistor (FET) based voltage converter, and the like).
The comparator 116K monitors if the output voltage VK exceeds a pre-determined limit voltage VK—LIM. The limit voltage VK—LIM is smaller than the reference voltage VK—MIN and is greater than or at least equal to a minimal output voltage that may cause malfunctioning of or damage to the electronic circuit 150.
A first input of the comparator 116K is coupled to the output rail 107K of the power supply 110K and a second input of the comparator 116K is generally provided with a reference voltage VK—LIM from the auxiliary power source 108K of the power controller 102. Depending on the value of the output voltage VK relative to the reference voltage VK—LIM (i.e., if VK>VK—LIM or VK≦VK—LIM), an output signal of the comparator 116 asserts one of two distinct (i.e., binary) states. In one embodiment, such binary states correspond to logic levels “0” and “1” of a control circuit of the voltage converter 118K.
An output of the comparator 116K is coupled to control input of the voltage converter 118K. Specifically, when VK>VK—LIM, the comparator 116K sets the converter 118K to an open (i.e., non-conducting) state and, when VK≦VK—LIM, the comparator 116K sets the converter 118K to convert the output voltage VK+1 in the voltage VK-MIN provided to the output rail 107K.
A typical powering up sequence for the electronic circuit 150 requires that supply voltages VK are applied sequentially, starting with the smaller voltages. In the depicted embodiment, such a sequence corresponds to turning ON the power supplies 110 in the following order: (1) turn ON the power supply 1101, (2) turn ON the power supply 1102, and (3) turn ON the power supply 1103.
In the apparatus 100 during the powering up sequence, when the comparator 1121 detects that the output voltage V1 of the power supply 1101 has reached the minimal operational voltage V1-MIN, the comparator turns ON the power supply 1102. Similarly, when the comparator 1122 detects that the output voltage V2 of the power supply 1102 has reached the minimal operational voltage V2-MIN, the comparator turns ON the power supply 1103. 
A typical powering down sequence for the electronic circuit 150 requires that the supply voltages VK are removed sequentially, starting with the highest applied voltage. In the depicted embodiment, such a sequence corresponds to turning OFF the power supplies in the following order: (1) turn OFF the power supply 1103, (2) turn OFF the power supply 1102, and (3) turn OFF the power supply 1101.
When, in operation, a power supply 110M accidentally turns OFF or becomes disabled, the voltage regulator 114M selectively draws power from the step-up power supply 110M+1, converts the output voltage VM+1 of the power supply 110M+1 in the voltage VM-MIN, and provides that voltage to the output rail of the power supply 110M, where M is an integer from 1 to N−1. When both power supplies 110M and 110M+1 accidentally turn OFF or become disabled, the voltage regulators 114M and 114M+1 similarly provide conversions of the power of the power supply having a higher voltage VM+2 (in the depicted embodiment, voltage V3) in the minimal operational voltages of the power supplies 110M and 110M+1.
In the case that the voltage converters 118 are step-down or linear (i.e., drop-down) regulators, it is beneficial to keep their drop voltages low in order to maintain, at the terminals 152K, output voltages close to the defined minimal values VK—LIM.
Such power conversion continues for a duration of time that is sufficient for the power controller 102 to detect the loss of power by a respective power supply and activate emergency powering down sequences and procedures that assure operability of the electronic circuit 150. Alternatively, the comparators 112 and voltage regulators 114 of the apparatus 100 may facilitate disabling of the step-up power supplies before the power controller 102 activates such emergency sequences and procedures.
FIG. 2 depicts a flow diagram of one embodiment of the inventive method for powering electronic circuits using the apparatus of FIG. 1 as a process 200. For best understanding of this embodiment of the invention, the reader should refer simultaneously to FIGS. 1-2.
The process 200 starts at step 202 and proceeds to step 204. At step 204, the apparatus 100 comprising a plurality of the power units 101 is provided. At step 206, the power units 101 are coupled to the power controller 102 and the electronic circuit 150 is powered using the apparatus 100.
At step 208, the powering up sequence is facilitated by controlling the step-up power supplies using comparators 112 of the step-down power supplies, as discussed above in reference to FIG. 1. Specifically, a step-up power supply is enabled (i.e., turned ON) when the output voltage of the step-down power supply exceeds the minimal operational limit for the output voltage of that step-down power supply.
At step 210, the apparatus 100 powers the electronic circuit 150. During accidental loss of power by a power supply other than the power supply having the highest output voltage (i.e., power supply 110N), the voltage regulator 114 of the affected power supply (e.g., power supply 1101) draws power from the step-up power supply (e.g., power supply 1102) to maintain the limit voltage of the affected power supply (e.g., limit voltage V1—LIM). In one embodiment, step 210 may continue until the power controller 102 activates the emergency recovery sequences and procedures. In an alternate embodiment, the apparatus 100 facilitates disabling of the power supplies that have output voltages greater than the output voltage of the affected power supply before the power controller 102 activates the such sequences and procedures. At step 212, the process 200 ends.
The invention is described above as using specific functions and devices. It will be appreciated by those skilled in the art that a large number of functions and devices that may alternatively be employed, either individually or in combination, to achieve the objects of the invention described herein are within the scope of the invention.
While the forgoing is directed to various embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. As such, the appropriate scope of the invention is to be determined according to the claims, which follow.

## Claims

1. A method for powering an electronic circuit, comprising:
(a) providing a plurality of power units, each power unit supplying an output voltage to the electronic circuit, the plurality including:
a power unit having the highest output voltage, comprising:
a power supply; and
a comparator of an output voltage of the power supply; and

voltage step-up and step-down power units, each comprising:
a power supply;
a comparator of an output voltage of the power supply; and
a voltage regulator;


(b) controlling the power supply of the step-up power unit using the comparator of the step-down power unit; and
(c) selectively converting an output voltage of the step-up power unit into an output voltage of the step-down power unit using the regulator of the step-down power unit and providing the converted voltage to an output of the step-down power unit.

2. The method of claim 1 wherein the electronic circuit is a digital, analog, or mixed signal electronic circuit using more than one supply voltage.

3. The method of claim 1 wherein the step (b) further comprises:
applying to a first input of the comparator of the step-down power unit an output voltage of the step-down power unit;
applying to a second input of the comparator of the step-down power unit a first reference voltage that is equal to or greater than a minimal operational output voltage of the step-down power unit;
coupling an output of the comparator of the step-down power unit to an ON/OFF terminal of the power supply of the step-up power unit; and
switching off the power supply of the step-up power unit when the output voltage of the step-down power unit is smaller than the minimal operational output voltage of the step-down power unit.

4. The method of claim 1 wherein the respective voltage regulators of the step-up power unit and the step-down power unit each comprise a network including a voltage comparator and a voltage converter.

5. The method of claim 4 further comprising for at least one of the step-up power unit and the step-down power unit:
applying to a first input of the voltage comparator of the power unit an output voltage of the power unit;
applying to a second input of the voltage comparator of the power unit a second reference voltage that is smaller by a predetermined margin than a minimal operational output voltage of the power unit;
coupling an output of the voltage comparator of the power unit to a control input of the voltage converter of the power unit; and
enabling the voltage converter when the second reference voltage is greater than the output voltage.

6. The method of claim 1 wherein at least one of the power supplies is a DC/DC converter.

7. The method of claim 1 wherein at least one of the power units further comprises at least one capacitor coupled to an output of the power unit.

8. An apparatus for powering an electronic circuit, comprising:
a plurality of power units, each power unit supplying an output voltage to the electronic circuit, the plurality including:
a power unit having the highest output voltage, comprising:
a power supply; and
a comparator of an output voltage of the power supply; and

voltage step-up and step-down power units, each comprising:
a power supply;
a comparator of an output voltage of the power supply; and
a voltage regulator,


wherein the comparator of the step-down power unit controls the power supply of the step-up power unit; and the regulator of the step-down power unit selectively converts an output voltage of the step-up power unit into an output voltage of the step-down power unit and provides the converted voltage to an output of the step-down power unit.

9. The apparatus of claim 8 wherein the electronic circuit is a digital, analog, or mixed signal electronic circuit using more than one supply voltage.

10. The apparatus of claim 9 wherein at least one of the power supplies is a DC/DC converter.

11. The apparatus of claim 8 wherein:
a first input of the comparator of the step-down power unit is coupled to an output of the step-down power unit;
a second input of the comparator of the step-down power unit is coupled to a source of a first reference voltage; and
an output of the comparator of the step-down power unit is coupled to an ON/OFF terminal of the power supply of the step-up power unit.

12. The apparatus of claim 11 wherein the first reference voltage is equal to or greater than a minimal operational output voltage of the step-down power unit.

13. The apparatus of claim 8 wherein the comparator of the step-down power unit switches off the power supply of the step-up power unit when the output voltage of the step-down power unit is smaller than a minimal operational output voltage of the step-down power unit.

14. The apparatus of claim 8 wherein the voltage regulators of the step-up power unit and the step-down power unit each comprise a network including a voltage comparator and a voltage converter.

15. The apparatus of claim 14 wherein for at least one of the step-up power unit and the step-down power unit:
a first input of the voltage comparator of the power unit is coupled to an output of the power unit;
a second input of the voltage comparator of the power unit is coupled to a source of a second reference voltage; and
an output of the voltage comparator is coupled to a control input of the voltage converter of the power unit.

16. The apparatus of claim 15 wherein the second reference voltage is smaller by a predetermined margin than a minimal operational output voltage of the power unit.

17. The apparatus of claim 15 wherein the voltage provided by the regulator of the power unit is equal to or greater than the minimal operational voltage of the step-down power unit.

18. The apparatus of claim 8 wherein at least one of the power units further comprises at least one capacitor coupled to an output of the power unit.