CONVERTER CONTROL CIRCUIT

• US 20100072967A1
• Filed: 05/12/2009
• Published: 03/25/2010
• Est. Priority Date: 09/19/2008
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kamishinbara, Takashi, Yoshikawa, Noriaki
• Application Number:
  US12/464,172
• Publication Number:
  US 20100072967A1
• Time in Patent Office: Days
• US Class Current: 323/284
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• 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

There is provided a converter control circuit including: a high-side switching element connected between an input voltage terminal and an inductive load; a low-side switching element connected between the inductive load and a reference potential; a drive circuit configured to drive a gate of the switching elements; a drive switch connected to the gate of at least one of the switching elements in parallel with the drive circuit; and a drive switch control circuit switching the drive switch from ON to OFF when the gate voltage of the switching element with the gate connected to the drive switch reaches a prescribed threshold while the switching element is driven by the drive circuit.

Claims

1. A converter control circuit comprising:

a high-side switching element connected between an input voltage terminal and an inductive load;

a low-side switching element connected between the inductive load and a reference potential;

a drive circuit configured to drive a gate of the switching elements;

a drive switch connected to the gate of at least one of the switching elements in parallel with the drive circuit; and

a drive switch control circuit switching the drive switch from ON to OFF when the gate voltage of the switching element with the gate connected to the drive switch reaches a prescribed threshold while the switching element is driven by the drive circuit.

2. The converter control circuit according to claim 1, wherein the drive switch is connected to a gate of the high-side switching element in parallel with a high-side drive circuit to drive the gate of the high-side switching element.

3. The converter control circuit according to claim 2, wherein the prescribed threshold is an on-detection threshold at which the high-side switching element is turned on.

4. The converter control circuit according to claim 3, further comprising:

an output current detective circuit sensing an output current of the converter,

the on-detection threshold being configured in accordance with the output current.

5. The converter control circuit according to claim 4, wherein the output current detective circuit includes a sense resistor connected in series with the inductive load.

6. The converter control circuit according to claim 4, wherein the output current detective circuit senses the output current as voltage across on-resistance of the high-side switching element.

7. The converter control circuit according to claim 4, wherein the on-detection threshold increases as the output current is relatively high, and the on-detection threshold decreases as the output current is relatively low.

8. The converter control circuit according to claim 3, wherein the on-detection threshold is configured by an external signal supplied to the drive switch control circuit.

9. The converter control circuit according to claim 1, wherein the drive switch is connected to a gate of the low-side switching element in parallel with the low-side drive circuit to drive the gate of the low-side switching element.

10. The converter control circuit according to claim 9, wherein the prescribed threshold is an on-detection threshold at which the low-side switching element is turned on.

11. The converter control circuit according to claim 10, further comprising:

an output current detective circuit sensing an output current of the converter,

the on-detection threshold being configured in accordance with the output current.

12. The converter control circuit according to claim 11, wherein the output current detective circuit includes a sense resistor connected in series with the inductive load.

13. The converter control circuit according to claim 11, wherein the output current detective circuit senses the output current as voltage across on-resistance of the low-side switching element.

14. The converter control circuit according to claim 11, wherein the on-detection threshold increases as the output current is relatively high, and the on-detection threshold decreases as the output current is relatively low.

15. The converter control circuit according to claim 10, wherein the on-detection threshold is externally configured for the drive switch control circuit configured to switch the low-side drive switch.

16. The converter control circuit according to claim 1, wherein

the drive circuit comprises a high-side drive circuit to drive the gate of the high-side switching element, and a low-side drive circuit to drive the gate of the low-side switching element,

the drive switch comprises a high-side drive switch connected to the gate of the high-side switching element in parallel with the high-side drive circuit, and a low-side drive switch connected to the gate of the low-side switching element in parallel with the low-side drive circuit, and

the drive switch control circuit comprises a high-side drive switch control circuit to switch the high-side drive switch from ON to OFF when a gate voltage of the high-side switching element reaches a first threshold while the high-side switching element is driven, and a low-side drive switch control circuit to switch the low-side drive switch from ON to OFF when a gate voltage of the low-side switching element reaches a second threshold while the low-side switching element is driven.

17. The converter control circuit according to claim 16, wherein the high-side switching element is turned on at the first threshold, and the low-side switching element is turned on at the second threshold.

18. The converter control circuit according to claim 17, further comprising:

an output current detective circuit sensing an output current of the converter,

the on-detection threshold being configured in accordance with the output current.

19. The converter control circuit according to claim 18, wherein the on-detection threshold is increased when the output current is relatively high, and the on-detection threshold is decreased when the output current is relatively low.

20. The converter control circuit according to claim 17, wherein the on-detection threshold is configured by an external signal supplied to the drive switch control circuit.