DC-DC circuit with controllable current limiting point and power supply circuit

Abstract

The invention relates to a DC-DC circuit with a controllable current limiting point and a power supply circuit. The DC-DC circuit with the controllable current limiting point comprises a power supply voltage input end VIN, an input filter capacitor C2, a current limiting circuit, a DC-DC main circuit, a frequency setting capacitor C3, a voltage feedback circuit, an output filter circuit and a converted voltage output end VOUT. The current limiting circuit comprises a current limiting enabling control loop for controlling generation of a bias voltage, the current limiting enabling control loop is provided with an MCU chip with an enabling pin EN and a voltage dividing device, and one end of the current limiting enabling control loop is connected with a second parallel end (namely the output end) in an original current limiting circuit. Therefore, the turn-off or turn-on of the whole DC-DC circuit can be intervened and controlled manually by using the chip N1, the requirement for a multi-gear current output function is met, and the requirement for various variable loads at the rear end of the DC-DC circuit is met.

Description

technical field [0001] The invention relates to the field of DC-to-DC circuits, in particular to a DC-DC circuit and a power supply circuit with a controllable current limiting point. Background technique [0002] A DC-to-DC circuit, also known as a DC-DC circuit, can convert a DC power into another DC power with a fixed voltage or an adjustable voltage, and it can also be called a DC-DC converter (DC-DC converter). In actual use, considering the conversion efficiency of the circuit, the DC-DC circuit is usually used to realize DC step-down. [0003] see figure 1 As shown, the commonly used DC-DC circuit mainly includes the power supply voltage input terminal V IN (such as supply voltage input V IN set to 16V), input filter capacitor C2, current limiting circuit (including resistors R1, R2 and R3), DC-DC main circuit (including chip N1 responsible for controlling DC to DC, inductor L1 and diode VD1), output filter circuit ( Including patch capacitor CE1 and capacitor C1)...

AI Technical Summary

Problems solved by technology

[0010] However, the current DC-DC circuit also has deficiencies: First, the current DC-DC circuit does not have an enabling function, and it cannot realize human intervention to shut down or open the DCDC circuit, and cannot meet the short-term power failure of the DC-DC circuit back-end load. and reset function

Secondly, when the resistance values ​​of the current limiting resistors R1, R2 and R3 in the current limiting circuit are all fixed parameters, the current limiting point of the current DC-DC circuit will be fixed, resulting in the inability of the DC-DC circuit to achieve multi-level current output function, unable to meet the various changing load requirements at the back end of the DC-DC circuit

Images