Isolated high frequency DC/DC switching regulator

• US 10,090,769 B2
• Filed: 11/29/2016
• Issued: 10/02/2018
• Est. Priority Date: 11/29/2016
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Baranwal, Shailendra Kumar, Granato, Maurizio, Frattini, Giovanni
• Primary Examiner(s): NASH, GARY A
• Application Number:
  US15/363,188
• Publication Number:
  US 20180152109A1
• Time in Patent Office: 672 Days
• Field of Search: 363 78, 363 79, 363 84, 363 89, 363127
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 1/083 for the ignition at the zero crossing of the voltage or the current
• CPC Class Codes: H02M 3/33515 with digital control
• CPC Class Codes: H02M 3/33553 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H02M 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

An electronic device, which includes an H-bridge circuit and a miniaturized transformer that is coupled to operate at VHF frequency, and a driver circuit for an n-type power transistor of the H-bridge circuit are disclosed. The driver circuit includes a first p-type transistor and an n-type transistor coupled between an upper rail and a lower rail, with an output taken between the drains of the first p-type transistor and the n-type transistor being coupled to a gate of the n-type power transistor. The driver circuit also includes a sample-and-hold capacitor coupled to capture a drain voltage for the first n-type power transistor on a first edge of a control signal for the first n-type power transistor and a comparator coupled to compare the captured drain voltage to a lower rail on a given edge of a clock signal and to provide a comparator value. The driver circuit also includes an up/down counter, which is coupled to receive the comparator value, to adjust a counter value responsive to receiving the comparator value and to output the counter value, and a first timing circuit that is coupled to receive the counter value and to send an adjustable pulse towards a gate of the first p-type transistor and a gate of the n-type transistor.

Claims

1. A driver circuit for a first n-type power transistor in an H-bridge circuit, the H-bridge circuit comprising the first n-type power transistor and a second n-type power transistor, the H-bridge circuit coupled to first and second terminals of a miniaturized transformer that is coupled to operate at a very high frequency (VHF), the driver circuit comprising:

a first p-type transistor and an n-type transistor coupled between an upper rail and a lower rail, an output taken between the drains of the first p-type transistor and the n-type transistor being coupled to a gate of the first n-type power transistor;

a sample-and-hold capacitor coupled to capture a drain voltage for the first n-type power transistor on a first edge of a control signal for the first n-type power transistor;

a comparator coupled to compare the captured drain voltage to a lower rail on a given edge of a clock signal and to provide a comparator value;

an up/down counter coupled to receive the comparator value, to adjust a counter value responsive to receiving the comparator value and to output the counter value; and

a first timing circuit coupled to receive the counter value and to send an adjustable pulse towards a gate of the first p-type transistor and a gate of the n-type transistor.

2. The driver circuit as recited in claim 1 wherein the first timing circuit comprises:

a digital-to-analog converter coupled to receive the counter value and to provide a ramp threshold; and

a pulse wave modulator coupled to receive the ramp threshold and the clock signal, to reset a ramping voltage on the given edge of the clock signal and to turn ON the adjustable pulse only while the ramping voltage is greater than the threshold.

3. The driver circuit as recited in claim 2 wherein the clock signal is received from a clock.

4. The driver circuit as recited in claim 1 further comprising:

a second p-type transistor and a third p-type transistor coupled in series between the upper rail and the gate of the n-type power transistor, the second p-type transistor having a gate coupled to the drain of the n-type power transistor and the third p-type transistor having a gate controlled by an enable signal from an edge trigger circuit.

5. The driver circuit as recited in claim 4 wherein the edge trigger circuit is coupled to receive a first control signal from the first timing circuit and a second control signal from a second driver circuit coupled to the second n-type power transistor and to turn the enable signal ON when the second n-type power transistor is turned OFF and to turn the enable signal OFF when the first p-type transistor is turned ON.

6. The driver circuit as recited in claim 5 further comprising a logic gate coupled to turn ON the n-type transistor only when the enable signal is OFF and the adjustable pulse is OFF.

7. The driver circuit as recited in claim 6 wherein the first timing circuit is further coupled to receive the clock signal, to turn OFF the adjustable pulse based on the given edge of the clock signal and to adjust the length of the adjustable pulse responsive to the counter value.

8. The driver circuit as recited in claim 7 wherein the clock signal is recovered from zero crossings of the current on the first terminal of the miniaturized transformer.

9. An electronic device comprising:

a miniaturized transformer configured to operate at a very high frequency (VHF) and having a first side and a second side, each of the first and second sides having a first terminal and a second terminal;

a first H-bridge circuit on the first side of the transformer, the first H-bridge circuit comprising a first n-type power transistor having a drain coupled to the first terminal on the first side and a second n-type power transistor having a drain coupled to the second terminal on the first side;

a first adaptive timing control circuit coupled to drive the first n-type power transistor; and

a second adaptive timing control circuit coupled to drive the second n-type power transistor;

the first adaptive timing control circuit comprising;

a first p-type transistor and an n-type transistor coupled between an upper rail and a lower rail, an output taken between the drains of the first p-type transistor and the n-type transistor being coupled to a gate of the first n-type power transistor;

a sample-and-hold capacitor coupled to capture a drain voltage for the first n-type power transistor when the first n-type power transistor is turned OFF;

a comparator coupled to compare the captured drain voltage to a lower rail on a given edge of a clock signal and to provide a comparator value;

an up/down counter coupled to receive the comparator value, to adjust a counter value responsive to receiving the comparator value and to output the counter value; and

a first timing circuit coupled to receive the counter value and to send an adjustable pulse towards a gate of the first p-type transistor and a gate of the n-type transistor.

10. The electronic device as recited in claim 9 further comprising:

a second H-bridge circuit on the second side of the transformer, the second H-bridge circuit comprising a third n-type power transistor having a drain coupled to the first terminal on the second side and a fourth n-type power transistor having a drain coupled to the second terminal on the second side;

a third adaptive timing control circuit coupled to drive the third n-type power transistor; and

a fourth adaptive timing control circuit coupled to drive the fourth n-type power transistor.

11. The electronic device as recited in claim 9 wherein the first timing circuit comprises:

a digital-to-analog converter coupled to receive the counter value and to provide a ramp threshold; and

a pulse wave modulator coupled to receive the ramp threshold and the clock signal, to reset a ramping voltage on the given edge of the clock signal and to turn ON the adjustable pulse only while the ramping voltage is greater than the threshold.

12. The electronic device as recited in claim 11 wherein the clock signal is received from a clock.

13. The electronic device as recited in claim 9 wherein the first adaptive timing control circuit further comprises:

a second p-type transistor and a third p-type transistor coupled in series between the upper rail and the gate of the n-type power transistor, the second p-type transistor having a gate coupled to the drain of the n-type power transistor and the third p-type transistor having a gate controlled by an enable signal from an edge trigger circuit.

14. The electronic device as recited in claim 13 further wherein the edge trigger circuit is coupled to receive a first control signal from the first timing circuit and a second control signal from the second adaptive timing control circuit coupled to the second n-type power transistor and to turn the enable signal ON when the second n-type power transistor is turned OFF and to turn the enable signal OFF when the first p-type transistor is turned ON.

15. The electronic device as recited in claim 14 further comprising a logic gate coupled to turn ON the n-type transistor only when the enable signal is OFF and the adjustable pulse is OFF.

16. The electronic device as recited in claim 15 wherein the first timing circuit is further coupled to receive the clock signal, to turn OFF the adjustable pulse based on the given edge of the clock signal and to adjust the length of the adjustable pulse responsive to the counter value.

17. The electronic device as recited in claim 16 wherein the clock signal is recovered from zero crossings of the current on the first terminal of the miniaturized transformer.

18. The electronic device as recited in claim 9 wherein the first H-bridge circuit is a full bridge circuit.

19. The electronic device as recited in claim 9 wherein the electronic device is a DC-DC converter.