Switch constant current controller and switch constant current power supply drive circuit

Abstract

The invention provides a switching constant-current controller and a switching constant-current power driving circuit. The switching constant-current controller comprises an output voltage detection pin, a grounding pin, a grid pin, a drain pin, an electrostatic discharge device and a driving module, wherein the grid pin is connected with a grid of an external power switching tube. The drain pin is connected with the drain electrode of the power switching tube; the electrostatic discharge device comprises an NMOS tube, the source electrode of the NMOS tube is grounded, and the drain electrodeof the NMOS tube is connected with the output voltage detection pin. The driving module is connected with the grid electrode and the grid electrode pin of the NMOS tube, and is used for controlling the power switching tube and the NMOS tube to be switched on or off in the same time period, so as to ensure that a parasitic reverse body diode of the NMOS tube is not switched on when the voltage at the output voltage detection pin is a negative voltage. According to the invention, the risk that the controller triggers the latch-up effect can be effectively reduced, and the offset of reference voltage and reference current can be reduced.

Description

technical field [0001] The invention relates to the field of switching power supply control, in particular to a switching constant current controller and a switching constant current power supply drive circuit. Background technique [0002] Switching constant current power supply is widely used in lighting LED driving power supply, which provides a constant driving current for the load LED light string to keep the brightness of the LED light continuously and stable. Non-isolated step-down conversion (non-isolated Buck) circuit structure is a common structure for lighting LED switch constant current drive power supply. When the power switch tube in the existing non-isolated Buck circuit structure is turned on, the power supply V at the switch terminal SW approximately equal to the input voltage V IN , that is, the voltage at the controller ground (GND) pin is approximately equal to the input voltage V IN , and the voltage detection divider resistor is connected to the OUT+...

AI Technical Summary

Problems solved by technology

When the controller is in the working state, the negative pressure introduced by its DET pin can easily lead to the leakage of parasitic bipolar devices in the controller. The opening of the parasitic devices not only greatly increases the possibility of the controller triggering the latch effect and failing, It is more likely that the internal reference voltage and current of the controller will shift due to leakage, resulting in a decrease in the constant current performance of the entire system

Images