Claims
- 1. A DC-DC converter having first and second DC power-supply voltage inputs comprising:
- a transformer having a primary winding with first and second terminals and having a secondary winding, said first terminal of said primary winding being coupled to the first DC power-supply voltage input;
- a switching device coupled between said second terminal of said primary winding and the second DC power-supply voltage input, said switching device having a control input for turning ON/OFF;
- a control circuit for supplying a pulse train to said control input; and
- a snubber circuit, coupled between said first and second terminals of said primary winding, for absorbing energy of fly-back voltage from said secondary winding to said primary winding when said switching device is turned OFF, said snubber circuit providing a voltage output generated by absorbed energy of said fly-back voltage, a voltage of said voltage output of said snubber circuit being stacked onto a voltage of said first DC power-supply voltage input for providing a power source voltage to said control circuit.
- 2. A DC-DC converter according to claim 1, further comprising:
- a low pass filter coupled between said voltage output of said snubber circuit and a DC power-supply voltage input of said control circuit.
- 3. A DC-DC converter according to claim 2, further comprising:
- a rectifier circuit for rectifying AC voltage induced in said secondary winding to provide a rectified DC voltage; and
- a smoothing circuit for smoothing said rectified DC voltage to provide a smoothed DC voltage as a DC power-supply output.
- 4. A DC-DC converter according to claim 3, further comprising:
- an over-voltage protection circuit for forcibly turning said switching device to off when said DC power-supply output exceeds a reference voltage.
- 5. A DC-DC converter according to claim 3 wherein said control circuit controls a duty ratio of said output pulse so that said DC power-supply output becomes constant.
- 6. A DC-DC converter according to claim 2 wherein said low pass filter is a LC low pass filter.
- 7. A DC-DC converter according to claim 1 wherein said snubber circuit comprises:
- a capacitor having first and second terminals, said first terminal of said capacitor being coupled to said first terminal of said primary winding;
- a discharge unit, coupled in parallel to said capacitor, which discharges a portion of electric charge accumulated in said capacitor; and
- a diode connected between said second terminal of said primary winding and said second terminal of said capacitor to limit a current direction in order to stack a voltage of said capacitor onto said voltage of said first DC power-supply voltage input.
- 8. A DC-DC converter according to claim 7 wherein said discharge unit is a resistor.
- 9. A DC-DC converter according to claim 7 wherein said discharge unit is a Zener diode.
- 10. A DC-DC converter according to claim 1, further comprising:
- an over-current protection circuit for forcibly turning said switching device to off when a time-average of current flowing through said switching device exceeds a reference value.
- 11. A display unit comprising:
- a display panel;
- a driver circuit for driving said display panel; and
- a DC-DC converter having first and second DC power-supply voltage inputs, said DC-DC converter comprising:
- a transformer having a primary winding, with first and second terminals, and a secondary winding, said first terminal of said primary winding being coupled to the first DC power-supply voltage input;
- a switching device coupled between said second terminal of said primary winding and the second DC power-supply voltage input, said switching device having a control input for turning ON/OFF;
- a control circuit for supplying a pulse train to said control input; and
- a snubber circuit, coupled between said first and second terminals of said primary winding, for absorbing energy of fly-back voltage from said secondary winding to said primary winding when said switching device is turned OFF, said snubber circuit providing a voltage output generated by absorbed energy of said fly-back voltage, a voltage of said voltage output of said snubber circuit being stacked onto a voltage of said first DC power-supply voltage input for providing a power source voltage to said control circuit.
- 12. A display unit according to claim 11, wherein said display panel is a plasma display panel.
Priority Claims (1)
Number |
Date |
Country |
Kind |
6-008810 |
Jan 1994 |
JPX |
|
CROSS REFERENCE TO RELATED APPLICATION
This is a Continuation-in-Part application of Ser. No. 08/202,558, filed Feb. 28, 1994 abandoned.
US Referenced Citations (6)
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
202558 |
Feb 1994 |
|