Feed-forward circuit for adjustable output voltage controller circuits

• US 7,595,619 B2
• Filed: 08/23/2005
• Issued: 09/29/2009
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Vieira Formenti, Jose Antonio
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US11/210,235
• Publication Number:
  US 20070053212A1
• Time in Patent Office: 1,498 Days
• Field of Search: 323/223, 323/225, 323/268, 323/271, 323/282, 323/285
• US Class Current: 323/282
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

A feedback loop in a variable power supply has an adjustable response speed based on operating conditions of the power supply. The response speed can be increased upon encountering a transient to improve response performance to the transient. A response speed control for the control loop modifies or bypasses a major low frequency pole in a compensation network in the control loop to increase response speed. The control limits fast response duration or impact with respect to the low frequency pole to avoid instability issues. The control may include counters or timers to selectively disable or enable the fast response function. The control can operate based on an error feedback signal and a reference to determine when a fast response should be applied. The resulting power supply system provides robust, well-regulated power, with fast responses to system transients.

Claims

1. A feedback control system for a power supply, comprising:

an error amplifier that is adapted to generate an error signal;

a compensation circuit coupled to the error amplifier to provide a power supply feedback control signal;

a response speed control circuit that receives the error signal, wherein the response speed control circuit includes a switch coupled to the compensation circuit to modify a response speed of the compensation circuit.

2. The system according to claim 1, wherein the response speed control circuit further comprises:

a plurality of comparators, wherein each comparator receives the error signal;

a first logic gate that receives outputs from each comparator and that produces an error detection signal; and

a second logic gate that receives the error detection signal that outputs a signal that closes the switch.

3. The system according to claim 1, wherein the compensation circuit further comprises an amplifier.

4. The system according to claim 1, wherein the system further comprises a plurality of error amplifiers, wherein the outputs of the error amplifiers are combined to generate the error signal.

5. A feedback control system for a power supply, comprising:

an error amplifier that is adapted to generate an error signal;

a compensation circuit coupled to the error amplifier to provide a power supply feedback control signal;

a response speed control circuit that receives the error signal and that is adapted to modify a response speed of the compensation circuit, wherein the response speed control circuit includes a counter that records the number of times the response speed control circuit is active to modify the response speed of the compensation circuit.

6. The system according to claim 5, wherein the response speed control circuit further comprises:

a plurality of comparators, wherein each comparator receives the error signal;

a first logic gate that receives outputs from each comparator and that produces an error detection signal; and

a second logic gate that receives the error detection signal and an output from the counter, wherein the second logic gate outputs a signal that modifies the response speed.

7. The system according to claim 5, wherein the compensation circuit further comprises an amplifier.

8. The system according to claim 5, wherein the system further comprises a plurality of error amplifiers, wherein the outputs of the error amplifiers are combined to generate the error signal.

9. A feedback control system for a power supply, comprising:

an error amplifier;

a first resistor that is coupled to the error amplifier;

a second resistor that is coupled to the error amplifier;

a switch that is coupled to the second resistor and that is coupled to the first resistor;

feed forward logic that is coupled to the error amplifier, wherein the feed forward logic actuates and deactuates the switch based at least in part on an output from the error amplifier;

a compensation amplifier that is coupled to the first resistor and to the switch; and

a resistor-capacitor (RC) feedback network that is coupled to the compensation amplifier.

10. The system according to claim 9, wherein feed forward logic further comprises:

a plurality of comparators, wherein each comparator is coupled to the error amplifier;

an first OR gate that is coupled to each comparator;

a counter;

an first AND gate that is coupled to the counter and the first OR gate, wherein the first AND gate actuates and deactuates the switch;

an inverter that is coupled to the first AND gate;

a second AND gate that is coupled to the first OR gate and to the inverter;

a first timer that is coupled to the first OR gate;

a second timer that is coupled to the second AND gate;

a second OR gate that is coupled to the first and second timers; and

a one shot that is coupled between the second AND gate and the counter.