High efficiency DC-DC converter with active shunt to accommodate high input voltage transients

Patent metadata

Field	Value
Publication number	US-9780661-B2
Application number	US-201514926555-A
Country	US
Kind code	B2
Filing date	Oct 29, 2015
Priority date	Oct 29, 2015
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

Switch mode power supplies and integrated circuits are presented to provide a DC output voltage signal using high and low side switches, with a switching control circuit to turn off the high side switch and engage an active shunt circuit to provide a reduced voltage to continue converter operation to accommodate high input voltage transients when the DC input voltage exceeds a threshold voltage without requiring an oversized low side switch for improved efficiency through reduced switching and conduction losses in normal operation.

First claim

The following is claimed:

1. An integrated circuit, comprising:
a DC-DC converter circuit to control an output voltage signal, the DC-DC converter circuit including:
a first switching device coupled between a DC input node and a switching node, the first switching device operative according to a first switching control signal, and
a second switching device coupled between the switching node and a constant voltage node, the second switching device operative according to a second switching control signal;

an active shunt circuit including a shunt circuit input coupled to the DC input node, and a shunt circuit output, the active shunt circuit operative according to a shunt circuit switching control signal to provide a shunt circuit output voltage signal to the shunt circuit output at a shunt circuit voltage level less than the input voltage; and
a detector circuit including an input coupled to the DC input node, and an output to provide a mode control signal in a first state when an input voltage of the DC input node is less than a threshold voltage, the output operative to provide the mode control signal in a different second state when the input voltage of the DC input node is greater than the threshold voltage;
a switching control circuit operative in a first mode when the mode control signal is in the first state to provide the first and second switching control signals to operate the first and second switching devices to regulate the output voltage signal according to a feedback signal, the switching control circuit operative in a second mode when the mode control signal is in the second state to provide the first switching control signal to turn off the first switching device, and to provide the second switching control signal and the shunt circuit switching control signal to operate the active shunt circuit and the second switching device to control the output voltage signal.

2. The integrated circuit of claim 1 , wherein the switching control circuit is operative in the second mode to provide the shunt circuit switching control signal to control the shunt circuit voltage level at approximately half the input voltage.

3. The integrated circuit of claim 1 , wherein the switching control circuit is operative in the second mode to provide the shunt circuit switching control signal to control the shunt circuit voltage level at a voltage less than a rated blocking voltage of the second switching device.

4. The integrated circuit of claim 3 , wherein the threshold voltage is less than a rated blocking voltage of the second switching device.

5. The integrated circuit of claim 1 , wherein the threshold voltage is less than a rated blocking voltage of the second switching device.

6. The integrated circuit of claim 1 ,
wherein the active shunt circuit includes:
a first transistor coupled between the DC input node and a first internal node, the first transistor operative according to a first shunt circuit switching control signal,
a second transistor coupled between the first internal node and the shunt circuit output, the second transistor operative according to a second shunt circuit switching control signal,
a third transistor coupled between the shunt circuit output and a second internal node, the third transistor operative according to a third shunt circuit switching control signal,
a fourth transistor coupled between the second internal node and the constant voltage node, the fourth transistor operative according to a fourth shunt circuit switching control signal, and
a capacitor coupled between the first and second internal nodes; and

wherein the switching control circuit is operative in the first mode to provide the shunt circuit switching control signals to turn off the first, second, third and fourth transistors, and wherein the switching control circuit is operative in the second mode to provide the shunt circuit switching control signals to provide the shunt circuit output voltage signal at the shunt circuit output at the shunt circuit voltage level less than the input voltage.

7. The integrated circuit of claim 6 ,
wherein the switching control circuit is operative in the second mode to provide the shunt circuit switching control signals in a repeating sequence of a first phase, a second phase, and a third phase;
wherein the switching control circuit provides the shunt circuit switching control signals in the first phase to turn on the first and third transistors and turn off the second and fourth transistors to charge the capacitor through the shunt circuit output;
wherein the switching control circuit provides the shunt circuit switching control signals in the second phase to turn off the first, second, third and fourth transistors; and
wherein the switching control circuit provides the shunt circuit switching control signals in the third phase to turn off the first and third transistors and turn on the second and fourth transistors to discharge the capacitor through the shunt circuit output.

8. The integrated circuit of claim 6 , further comprising a third switching device coupled between the shunt circuit output and the switching node, the third switching device operative according to a third switching control signal;
wherein the switching control circuit is operative in the first mode to provide the third switching control signal to turn off the third switching device; and
wherein the switching control circuit is operative in the second mode to provide the second and third switching control signals to control the output voltage signal.

9. The integrated circuit of claim 8 , wherein the active shunt circuit includes a second capacitor coupled between the shunt circuit output and the constant voltage node.

10. The integrated circuit of claim 8 ,
wherein the switching control circuit is operative in the second mode to provide the shunt circuit switching control signals in a repeating sequence of a first phase and a second phase;
wherein the switching control circuit provides the shunt circuit switching control signals in the first phase to turn on the first and third transistors and turn off the second and fourth transistors to charge the capacitor through the shunt circuit output; and
wherein the switching control circuit provides the shunt circuit switching control signals in the second phase to turn off the first and third transistors and turn on the second and fourth transistors to discharge the capacitor through the shunt circuit output.

11. The integrated circuit of claim 10 , wherein the switching control circuit is operative in the second mode to provide the second and third switching control signals as alternating pulse width modulated signals to control the output voltage signal.

12. The integrated circuit of claim 1 , wherein the DC-DC converter circuit is a buck converter to control the output voltage signal.

13. The integrated circuit of claim 1 , wherein the DC-DC converter circuit is a three level converter.

14. The integrated circuit of claim 1 , further comprising a second DC-DC converter circuit to control a second output voltage signal, the second DC-DC converter circuit including:
a third switching device coupled between a DC input node and a switching node, the first switching device operative according to a first switching control signal, and
a second switching device coupled between the switching node and a constant voltage node, the second switching device operative according to a second switching control signal.

15. The integrated circuit of claim 1 , further comprising a second DC-DC converter circuit to control the output voltage signal, the second DC-DC co

Assignees

• Texas Instruments Inc

Inventors

• Chakraborty Sombuddha
• Ramadass Yogesh Kumar

Classifications

• H02M3/158 Primary

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

• H02M3/06

  using resistors or capacitors, e.g. potential divider · CPC title

• H02M1/08

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title

• H02M2003/072

  Electricity · mapped topic

• H02M2001/0009

  Electricity · mapped topic