Power regulator with prevention of inductor current reversal

Patent metadata

Field	Value
Publication number	US-10243464-B2
Application number	US-201715854061-A
Country	US
Kind code	B2
Filing date	Dec 26, 2017
Priority date	Apr 6, 2017
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A controller including a voltage synthesizer for a switching regulator includes a synthesizer input to be coupled to an input of the regulator. First and second replica switching transistors are connected at a first node. A resistor couples between the first node and a second node, and a capacitor couples between the second node and ground. A transconductance stage compares a voltage sampled onto the capacitor to the output voltage of the regulator and generates an output signal in response to the comparison. A first switch couples between first and second inputs of the transconductance stage. The first switch is turned on during each cycle of operation of the voltage synthesizer to reset the capacitor voltage to the output voltage of the regulator.

First claim

What is claimed is:

1. A converter for use in a switching regulator system that includes an inductor coupled at an output voltage node to a load, the converter to convert an input voltage to an output voltage at the output voltage node, the converter comprising:
a first power switch coupled between an input voltage node and a first switch node;
a second power switch coupled between the first switch node and a ground;
the first switch node to couple to the inductor; and
a controller including
an output voltage synthesizer including:
a transconductance stage with a third switch coupled between first and second inputs of the transconductance stage, and
a synthesizer control circuit;

the output voltage synthesizer to synthesize the output voltage to produce a synthesized output voltage;
the first input of the transconductance stage to receive the synthesized output voltage and the second input to receive the output voltage from the output voltage node; and
the synthesizer control circuit to close the third switch to reset the synthesized output voltage in each cycle of operation of the converter.

2. The converter of claim 1 , wherein the output voltage synthesizer further includes:
a fourth replica switch coupled between the input voltage node and a second switch node, the fourth replica switch being a replica of the first power switch;
a fifth replica switch coupled between the second switch node and the ground, the fifth replica switch being a replica of the second power switch;
a resistor coupled to the second switch node;
a sixth switch coupled between the second switch node and the first input of the transconductance stage; and
a first capacitor coupled between the first input of the transconductance stage and the ground.

3. The converter of claim 2 , wherein the output voltage synthesizer further includes:
an off time control circuit;
a seventh switch coupled between an output of the transconductance stage and the off time control circuit; and
a second capacitor coupled between the ground and a node interconnecting the seventh switch and the transconductance stage;
wherein, during each cycle of operation of the converter, the control circuit generates control signals to:
turn on the sixth switch during the time in which at least one of first and second power switches is on;
turn on the seventh switch during the time in which neither the first or second power switch is on to thereby use the output of the transconductance stage to charge the third capacitor; and
turn on the third switch to short the first and second inputs of the transconductance stage after a voltage on the second capacitor has been received by the off time control circuit.

4. The converter of claim 2 , wherein the synthesizer control circuit asserts control signals to cause the time period during which the second power switch and the fifth replica switch are on to decrease in response to an output signal of the transconductance stage indicating that the synthesized output voltage is less than the output voltage on the output voltage node.

5. The converter of claim 2 , wherein the controller asserts control signals to cause the time period during which the second power switch and fifth replica switch are on to increase in response to an output signal of the transconductance stage indicating that the synthesized output voltage is greater than the output voltage.

6. The converter of claim 1 , further comprising:
an off time control circuit and a fourth switch coupled between an output of the transconductance stage and the off time control circuit; and
a first capacitor coupled between the ground and a node interconnecting the fourth switch and the transconductance stage;
wherein, responsive to a voltage on the first capacitor, the off time control circuit generates an output signal to the synthesizer control circuit to cause the synthesizer control circuit to adjust the off time of the period of time that the second switch is on.

7. A system including a switching regulator to convert an input voltage to an output voltage supplied to a load, comprising:
a first power transistor coupled between an input voltage node and a first switch node;
a second power transistor coupled between the first switch node and a ground;
an inductor coupled between the first switch node and an output voltage node;
a first capacitor coupled between the output voltage node and the ground;
a controller to control switching of the first and second power transistors; and
an output voltage synthesizer, including
a third replica transistor coupled between the input voltage node and a second switch node, the third replica transistor being a replica of the first power transistor;
a fourth replica transistor coupled between the second switch node and the ground, the fourth replica transistor being a replica of the first power transistor;
a resistor coupled to the second switch node;
a transconductance stage including a first input coupled to the resistor and a second input coupled to the output voltage node; and
a fifth switch coupled between the first and second inputs of the transconductance stage.

8. The system of claim 7 , further comprising a sixth switch coupled between the resistor and the first input of the transconductance stage.

9. The system of claim 8 , further comprising a seventh switch coupled to an output of the transconductance stage.

10. The system of claim 9 , further comprising a synthesizer control circuit including the resistor and a second capacitor coupled between the resistor and the ground, and an off-time control circuit coupled to the seventh switch, wherein the off-time control circuit to generate a signal to the synthesizer control circuit responsive to an error signal sampled across the second capacitor to cause the synthesizer control circuit to adjust the timing of the second power transistor and the fourth replica transistor.

11. The system of claim 7 , further comprising a second capacitor coupled between the first input of the transconductance stage and the ground.

12. The system of claim 11 , further comprising a synthesizer control circuit to turn on the fifth switch to thereby reset a voltage on the second capacitor to the output voltage in each cycle of operation of the switching regulator.

13. The system of claim 7 , further comprising a synthesizer control circuit configured to turn on the fifth switch once during each cycle of operation of the switching regulator.

14. A controller for at least partially controlling a switching regulator that includes first and second power transistors and provides a regulated output voltage, the controller comprising:
control circuit to control switching of the first and second power transistors;
an output voltage synthesizer including:
a synthesizer input coupled to an input of the switching regulator;
a first replica transistor coupled between the synthesizer input and a first node, the first replica transistor being a replica of the first power transistor;
a second replica transistor coupled between the first node and a ground, the second replica transistor being a replica of the second power transistor;
a resistor coupled between the first node and a second node;
a capacitor coupled between the second node and the ground;
a transconductance stage to generate a voltage difference based on a comparison of a voltage on the capacitor received at a first input of the transconductance stage to the regulated output voltage received at a second input of the transconductance stage and to generate an output signal in response to the voltage difference; and
a third switch

Assignees

• Texas Instruments Inc

Inventors

• Mehdi Syed Wasif
• Gibson Neil
• Priego Antonio

Classifications

• H03K17/166

  Soft switching · CPC title

• G05F1/62

  using bucking or boosting DC sources · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02M3/158 Primary

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M3/1582 Primary

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title