Granted Patent B2

US 7,330,364 · App. 10/969,665 · Granted Feb 12, 2008

Abstract

Claims (45)

1. A method for converting high voltage AC to low voltage DC using a switched power supply comprising:

suppression of falling edge conduction;

closing a switch of the switched power supply to cause conduction only on rising edge when a rectified AC voltage is less then an output voltage; and

opening the switch when the output voltage is approximately equal to a regulation voltage.

2. A method for converting high voltage AC to low voltage DC using a switched power supply comprising:

suppression of falling edge conduction; and

opening and closing a switch of the switched power supply only during rising edge conduction, wherein the switch is opened when an output voltage is approximately equal to a regulation voltage and the switch is closed to cause conduction only on rising edge when a rectified AC voltage is less then an output voltage.

3. The method of claim 2 further comprising:

sensing when an input voltage falls below an output voltage; and

closing the switch only when the input voltage falls below an output voltage.

4. The method of claim 2 further comprising:

sensing when an input voltage is slightly above the output voltage; and

closing the switch after a predetermined delay to allow the input voltage falls below an output voltage.

5. The method of claim 2 further comprising:

sensing a rate of change of an input voltage; and

closing the switch when the rate of change changes from a negative value to a positive value.

6. The method of claim 2 further comprising:

sensing when an input voltage falls below a predetermined value, the predetermined value being a lowest anticipated output voltage; and

closing the switch only when the input voltage falls below the predetermined value.

7. The method of claim 2 further comprising opening the switch when an output voltage reaches a regulation voltage.

8. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction comprising:

a rectifier coupled to an Alternating Current (AC) power source;

a switching device coupled to the rectifier, wherein opening and closing of the switching device is done only during rising edge conduction;

control circuitry coupled to the switching device for suppression of falling edge conduction, the control circuitry opening of the switching device when an output voltage reaches a regulation voltage and will close the switching device when a rectified AC voltage from the AC power source is less than the output voltage; and

a storage capacitive element coupled to the switching device.

9. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 8 further comprising a floating gate drive supply referenced to the output voltage and coupled to the rectifier to power the control circuitry.

10. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 8 wherein the switching device is an N-channel transistor.

11. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 10 wherein the switching device is an N-channel MOSFET.

12. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 10 wherein the switching device is an N-channel IGBT.

13. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 9 wherein the floating gate drive supply is a zener shunt regulator.

14. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 9 wherein the floating gate drive supply comprises:

a zener diode;

a resistor having a first terminal coupled to the rectifier and a second terminal coupled to a first terminal of the zener diode; and

a capacitor having a first terminal coupled to a first terminal of the zener diode and a second terminal coupled to a second terminal of the zener diode.

15. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 8 wherein the control circuitry comprises:

control logic having a first input coupled to the rectifier and an output coupled to the switching device; and

a voltage divider circuit having an output coupled to a second input of the control logic.

16. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 15 wherein the control logic comprises:

a first comparator having a first input coupled to the rectifier and a second input coupled to the storage capacitive element;

a second comparator having a first input coupled to the voltage divider circuit and a second input coupled to a voltage source; and

a flip flop having a first input coupled to an output of the first comparator, a second input coupled to an output of the second comparator, and an output coupled to the switching device.

17. A circuit for converting high voltage AC to low voltage DC using a switched power supply and rising edge conduction in accordance with claim 15 wherein the voltage divider circuit comprises:

a first resistor;

a second resistor coupled in series with the first resistor; and

a comparator having a first input coupled to the first and second resistors, a second input coupled to a regulation voltage, and an output coupled to the control logic.

Assignments (16)