CONTROL CIRCUIT AND ELECTRONIC DEVICE

• US 20130127518A1
• Filed: 09/21/2012
• Published: 05/23/2013
• Est. Priority Date: 11/18/2011
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Nakao, Hiroshi
• Granted Patent: US 8,698,547 B2
• Time in Patent Office: Days
• US Class Current: 327/434
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/7787 with wide bandgap charge-carrier supplying layer, e.g. direct single heterostructure MODFET
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H03K 17/0412 by measures taken in the control circuit
• CPC Class Codes: H03K 17/06 Modifications for ensuring a fully conducting state
• 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

A control circuit includes: a first switching element having a source, a gate, and a drain; a battery configured to supply a voltage to the gate through a second switching element; a PWM signal generator circuit configured to supply a PWM signal to the gate through a third switching element; and a gate control circuit configured to, under a power-off condition, turn on the second switching element to supply the voltage of the battery to the gate and turns off the third switching element, and configured to under a power-on condition, turn on the third switching element to supply the PWM signal voltage to the gate and turns off the second switching element.

Claims

1. A control circuit comprising:

a first switching element having a source, a gate, and a drain;

a battery configured to supply a voltage to the gate through a second switching element;

a PWM signal generator circuit configured to supply a PWM signal to the gate through a third switching element; and

a gate control circuit configured to, under a power-off condition, turn on the second switching element to supply the voltage of the battery to the gate and turns off the third switching element, and configured to under a power-on condition, turn on the third switching element to supply the PWM signal voltage to the gate and turns off the second switching element.

2. The control circuit according to claim 1,

wherein the first switching element is a GaN-HEMT rendered normally-off from a normally-off state.

3. The control circuit according to claim 2,

wherein the voltage of the battery is higher than a threshold voltage of the GaN-HEMT rendered normally-off.

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

a detector circuit configured to compare the voltage of the battery,

wherein, when the voltage of the battery is lower than the threshold voltage of the GaN-HEMT rendered normally-off, the detector circuit turns off the power.

5. The control circuit according to claim 1, further comprising:

a threshold voltage measurement circuit configured to measure the threshold voltage of the first switching element,

wherein, when the threshold voltage of the first switching element is lower than a predetermined voltage, the threshold voltage measurement circuit turns off the power.

6. The control circuit according to claim 1,

wherein the PWM signal generator circuit outputs a first PWM signal having a first frequency, and a second PWM signal having a second frequency that is lower than the first frequency.

7. The control circuit according to claim 6, further comprising:

a threshold voltage measurement circuit configured to measure the threshold voltage of the first switching element,

wherein the threshold voltage measurement circuit supplies the second PWM signal to the gate when the threshold voltage of the first switching element is lower than a predetermined voltage, and the threshold voltage measurement circuit supplies the first PWM signal to the gate when the threshold voltage of the first switching element reaches or exceeds the predetermined voltage.

8. The control circuit according to claim 1,

wherein the second switching element is a PMOS-FET, and the third switching element is an NMOS-FET.

9. The control circuit according to claim 1, further comprising:

an inrush current blocking circuit on the drain side of the first switching element,

wherein the inrush current blocking circuit includes a triac and a resistor connected in series, and a relay connected in parallel with the triac and the resistor.

10. An electronic device comprising:

a converter circuit configured to include a first switching element having a source, a gate, and a drain;

a battery configured to supply a voltage to the gate through a second switching element;

a PWM signal generator circuit configured to supply a PWM signal to the gate through a third switching element; and

a gate control circuit configured to, under a power-off condition, turn on the second switching element to supply the voltage of the battery to the gate and turns off the third switching element, and configured to, under a power-on condition, turn on the third switching element to supply the PWM signal voltage to the gate and turns off the second switching element.