Gate drive circuit

• US 5,434,527 A
• Filed: 10/25/1993
• Issued: 07/18/1995
• Est. Priority Date: 10/25/1993
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Antone, James A.
• Primary Examiner(s): Cunningham, Terry D.
• Application Number:
  US08/140,934
• Time in Patent Office: 631 Days
• Field of Search: 307/282, 307/299.1, 307/571, 307/572, 307/575, 307/576, 307/581, 307/584, 307/585, 327/190, 327/379, 327/389, 327/391, 327/427, 327/434, 327/435, 327/436, 327/309, 327/310, 327/314
• US Class Current: 327/391
• CPC Class Codes: H03K 17/04123 in field-effect transistor switches
• CPC Class Codes: H03K 17/691 using transformer coupling

Abstract

A circuit includes a high voltage energy source, a power transistor having a drain connected to the energy source and a source connected to a load, and a first capacitor connected between the power transistor gate and source. Also included is a first P-channel transistor connected in parallel with the first capacitor, and a second capacitor connected between the first P-channel transistor gate and drain. A transformer delivers positive voltage to the first capacitor to bias the power transistor ON, and delivers negative voltage to the second capacitor to bias the first P-channel transistor ON, which causes the energy stored in the first capacitor to discharge; thereby biasing the power transistor OFF.

Claims

1. A circuit, comprising:

a high voltage energy source;

a power transistor having a drain connected to the energy source and a source being connected to a load;

a first capacitor being connected between the power transistor gate and source;

a first P-channel transistor being connected in parallel with the first capacitor;

a second capacitor being connected between the first P-channel transistor gate and drain; and

means for delivering positive voltage to the first capacitor to bias the power transistor ON, and delivering negative voltage to the second capacitor to bias the first P-channel transistor ON causing the energy stored in the first capacitor to discharge to bias the power transistor OFF, the means including;

a transformer having a primary and secondary winding;

a first N-channel transistor being connected between the high-side of the secondary transformer winding and the second capacitor, the first N-channel transistor having an internal drain-source body diode; and

a first pair of diodes, one of the first pair being connected between the first N-channel transistor drain and the second capacitor to cancel the effect of the internal drain-source body diode associated with the first N-channel transistor, the other one of the first pair being connected between the first N-channel transistor source and the second capacitor to provide a shunt for the first N-channel transistor.

2. A circuit, as set forth in claim 1, wherein the means further includes:

a second N-channel transistor being connected between the low-side of the secondary transformer winding and the second capacitor, the second N-channel transistor having an internal drain-source body diode; and

a second pair of diodes, one of the second pair being connected between the second N-channel transistor drain and the second capacitor to cancel the effect of the internal drain-source body diode associated with the second N-channel transistor, the other one of the second pair being connected between the second N-channel transistor source and the second capacitor to provide a shunt for the second N-channel transistor.

3. A circuit, as set forth in claim 2, including an RC snubber circuit connected across the secondary transformer winding.

4. A circuit, as set forth in claim 3, including a Zener diode connected in parallel with the first capacitor.

5. A circuit, as set forth in claim 4, wherein the power transistor is a N-channel MOSFET.

6. A circuit, as set forth in claim 5, wherein the first P-channel transistor is a P-channel MOSFET and the first and second N-Channel transistors are N-channel MOSFETs.

7. A circuit, as set forth in claim 6, wherein the load is a piezoelectric actuator.