384X-based burst mode PWM controller

1. A 384X-based burst mode PWM controller, comprising:

an oscillator for generating a pulse signal of a constant frequency;

an output circuit for generating an output signal based on the pulse signal and sending the output signal to an external circuit;

an error amplifier for receiving a voltage feedback signal from the external circuit and generating an amplified error signal;

a comparator having a current sense input on one end to receive a voltage of a current sense signal from the external circuit and another end to receive the amplified error signal, and comparing the voltage of the current sense signal with the voltage of the amplified error signal to generate a comparison signal; and

a PWM latch for responding the pulse signal and generating a pulse control signal based on the comparison signal to control the output circuit on and off;

wherein the output circuit turns on when the voltage of the current sense signal is smaller than the voltage of the error signal; the output circuit turns off when the voltage of the current sense signal is greater than the voltage of the error signal;

wherein the burst mode PWM controller further including a logic control current source which has an output end connecting to the current sense input of the comparator;

wherein the pulse control signal generated by the PWM latch controls the logic control current source and the output circuit in opposite conditions of turning on and off.

2. The burst mode PWM controller of claim 1 further including:

an automatic circuit which has a power supply input end and a ground end to receive input of an external power supply;

a voltage reference circuit which has a reference voltage output end, the voltage reference circuit receiving power supply from the automatic circuit to generate a reference voltage which is the output to the external circuit through the reference voltage output end; and

a logic control current circuit to receive the reference voltage of the voltage reference circuit to generate a logic control signal which is sent to the output circuit to control the output signal;

wherein the voltage reference circuit further sends the reference voltage to the error amplifier, the oscillator having a control input end to receive a control signal from the external circuit to generate the pulse signal, the output circuit having a power supply input end to receive input from an external power supply, a ground end and a signal output end to output an output signal to the external circuit, the error amplifier having a voltage feedback input to receive a voltage feedback signal from the external circuit and a compensation output connecting to the external circuit to compensate gain and frequency for the error amplifier.

3. The burst mode PWM controller of claim 1 , further including a RC filter circuit which includes a resistor and a capacitor, the resistor bridging the output of the logic control current source and the current sense input of the comparator, the capacitor bridging the current sense input of the comparator and the ground.

4. The burst mode PWM controller of claim 1 , wherein the PWM controller is a RS trigger.

5. The burst mode PWM controller of claim 1 , further including a temperature protection device to protect the oscillator from overheating.