Granted Patent B2

US 12,749,964 · App. 18/196,667 · Granted Sep 29, 2026

Inventors: Xiuhong Zhang (Shanghai, CN); Lieyi Fang (Shanghai, CN)

Assignee: ON-BRIGHT ELECTRONICS (SHANGHAI) CO., LTD.

H02M1/088H02M1/0087

Abstract

Claims (23)

1 . A controller for a power converter, the controller comprising:

a first controller terminal connected to a first base of a first bipolar transistor, the first bipolar transistor further including a first collector and a first emitter;

a second controller terminal connected to the first emitter of the first bipolar transistor and a second base of a second bipolar transistor, the second bipolar transistor further including a second collector and a second emitter, the second collector being connected to the first collector; and

a third controller terminal connected to the second emitter of the second bipolar transistor and a resistor, the resistor being configured to generate a sensing voltage received by the third controller terminal;

wherein:

if the sensing voltage is smaller than a predetermined threshold, the first controller terminal is configured to output a first current to the first base to generate a second current at the first emitter, the second current flowing to the second base to turn on the second bipolar transistor; and

if the sensing voltage reaches the predetermined threshold, the second controller terminal is configured to output a third current to the second base before the second bipolar transistor becomes turned off;

wherein the third current is smaller than the second current in magnitude.

2 . The controller of claim 1 wherein:

the first current is equal to the third current in magnitude; and

the first current is smaller than the second current in magnitude.

3 . The controller of claim 1 wherein, if the sensing voltage reaches the predetermined threshold, the first controller terminal is configured to reduce the first current to zero to turn off the first bipolar transistor and also reduce the second current to zero.

4 . A method for a power converter, the method comprising:

receiving a sensing voltage from a resistor;

if the sensing voltage is smaller than a predetermined threshold, outputting a first current to a first base of a first bipolar transistor to generate a second current at a first emitter of the first bipolar transistor, the first emitter of the first bipolar transistor being connected to a second base of a second bipolar transistor, the second current flowing to the second base to turn on the second bipolar transistor, the first bipolar transistor further including a first collector, the second bipolar transistor further including a second collector and a second emitter, the second collector being connected to the first collector, the second emitter being connected to the resistor; and

if the sensing voltage reaches the predetermined threshold, outputting a third current to the second base of the second bipolar transistor before the second bipolar transistor becomes turned off;

wherein the third current is smaller than the second current in magnitude.

5 . The method of claim 4 wherein:

the first current is equal to the third current in magnitude; and

the first current is smaller than the second current in magnitude.

6 . The method of claim 4 , and further comprising, if the sensing voltage reaches the predetermined threshold:

reducing the first current to zero to turn off the first bipolar transistor; and

reducing the second current to zero.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (82)