Dropout recovery with overshoot and inrush current reduction

Patent metadata

Field	Value
Publication number	US-10180695-B1
Application number	US-201815956047-A
Country	US
Kind code	B1
Filing date	Apr 18, 2018
Priority date	Dec 29, 2017
Publication date	Jan 15, 2019
Grant date	Jan 15, 2019

Abstract

In a power management device, a hiccup mode is implemented by using, for example, a counter to count the number of cycles for which a current limiting event has occurred and forcing the power management device to hiccup when a certain number of current limiting events have been counted. A soft start circuit is typically employed to ramp up the output voltage when the power management device is turned back on. By resetting the soft start voltage to the feedback voltage of the load of the power management device upon the first detection of a current limiting event, hiccup can be avoided because resetting the soft start voltage to the feedback voltage will reduce the current in proceeding cycles thereby avoiding additional current limiting events.

First claim

What is claimed is:

1. An apparatus comprising:
a clock signal generating circuit configured to generate a clock stretch signal in an absence of a reset signal;
an under voltage detection circuit configured to determine an under voltage condition and to output an under voltage signal in response to determining that the under voltage condition has occurred;
a current limit detection circuit configured to determine a current limit condition and to output a current limit signal in response to determining that the current limit condition has occurred; and
a dropout recovery circuit configured to set a soft start voltage of a soft start circuit upon receiving the clock stretch signal from the clock signal generating circuit, the under voltage signal from the under voltage detection circuit, and the current limit signal from the current limit detection circuit.

2. The apparatus of claim 1 , further comprising: a feedback circuit configured to output a feedback voltage corresponding to an output voltage of the apparatus, wherein the under voltage detection circuit is configured to compare the feedback voltage to an under voltage input value to determine the under voltage condition.

3. The apparatus of claim 2 , wherein the dropout recovery circuit is configured to reset a voltage of the soft start circuit to the feedback voltage upon receiving the clock stretch signal from the clock signal generating circuit, the under voltage signal from the under voltage detection circuit, and the current limit signal from the current limit detection circuit.

4. The apparatus of claim 1 , further comprising a voltage regulator circuit comprising an input terminal and a resistive load, wherein the under voltage detection circuit is configured to detect the under voltage condition across the resistive load of the voltage regulator circuit, and wherein the current limit detection circuit is configured to determine the current limit condition at the input terminal of the voltage regulator circuit.

5. The apparatus of claim 2 wherein the dropout recovery circuit is configured to cause the soft start circuit to sample the feedback voltage when the clock stretch signal is generated after the under voltage condition is determined to have occurred.

6. The apparatus of claim 2 wherein the dropout recovery circuit is configured to set the soft start voltage to the feedback voltage upon the dropout recovery circuit receiving the clock stretch signal from the clock signal generating circuit, the under voltage signal from the under voltage detection circuit, and the current limit signal from the current limit detection circuit.

7. A method for dropout recovery using a soft start circuit, the method comprising:
determining, by an under voltage determining circuit, an under voltage condition;
generating, by a clock signal generating circuit, a clock stretch signal in an absence of receiving a reset signal at the clock signal generating circuit;
determining, by a current limit determining circuit, a current limit condition; and
resetting, by a dropout recovery circuit, a soft start voltage of the soft start circuit when the clock stretch signal has been generated and each of the current and under voltage conditions have been detected.

8. The method of claim 7 , wherein the determining an under voltage condition comprises:
comparing, by the under voltage detection circuit, a feedback voltage of a feedback circuit to an under voltage input value to determine the under voltage condition.

9. The method of claim 7 , wherein the resetting the soft start circuit further comprises:
resetting, by the dropout recovery circuit, a voltage of the soft start circuit to match a feedback voltage of a feedback circuit upon receiving, at the dropout recovery circuit, the clock stretch signal from the clock signal generating circuit, the under voltage signal from the under voltage detection circuit, and the current limit signal from the current limit detection circuit.

10. The method claim 9 further comprising: causing, by the dropout recovery circuit, the soft start circuit to sample the feedback voltage when a clock stretch signal is generated after the under voltage condition has been determined.

11. The method claim 9 , further comprising resetting the soft start voltage, by the dropout recovery circuit, to the feedback voltage when the clock stretch signal has been generated and both the current limit condition and the under voltage condition have been detected.

12. A power management device comprising:
a soft start circuit;
a clock signal generating circuit configured to generate a clock stretch signal in an absence of a reset signal;
an under voltage detection circuit configured to determine an under voltage condition across a load of the voltage regulator circuit and to output an under voltage signal in response to determining occurrence of the under voltage condition;
a current limit detection circuit configured to determine a current limit condition and to output a current limit signal in response to determining occurrence of the current limit condition at an input of the voltage regulator circuit; and
a dropout recovery circuit configured to reset a soft start voltage of the soft start circuit to a feedback voltage of the feedback circuit upon the dropout recovery circuit receiving the clock stretch signal from the clock signal generating circuit, the under voltage signal from the under voltage detection circuit, and the current limit signal from the current limit detection circuit.

13. The power management device of claim 12 further comprising:
a feedback circuit configured to output a feedback voltage corresponding to an output voltage of the power management device, wherein the under voltage detection circuit is configured to compare the feedback voltage to an under voltage input value to determine the under voltage condition.

14. The power management device of claim 13 , wherein the dropout recovery circuit is configured to reset a voltage of the soft start circuit to the feedback voltage upon receiving the clock stretch signal from the clock signal generating circuit, the under voltage signal from the under voltage detection circuit, and the current limit signal from the current limit detection circuit.

15. The power management device claim 13 wherein the dropout recovery circuit is configured to cause the soft start circuit to sample the feedback voltage when the clock stretch signal is generated after the under voltage condition is determined to have occurred.

Assignees

• Texas Instruments Inc

Inventors

• Bikulcius Simon M

Classifications

• G05F1/468

  characterised by reference voltage circuitry, e.g. soft start, remote shutdown · CPC title

• G05F1/575 Primary

  characterised by the feedback circuit · CPC title

• G05F1/62

  using bucking or boosting DC sources · CPC title

• H02M3/156 Primary

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title