A boost dc/dc converter

Abstract

The invention provides a step-up DC / DC converter, which includes a step-up output circuit, a feedback control circuit and an overvoltage protection circuit. The boost output circuit includes an inductor, a first switch device, a second switch device and a capacitor; the connection node between the second switch device and the capacitor serves as the output terminal VOUT of the boost output circuit. The first input terminal of the feedback control circuit is connected to the output terminal VOUT, the first output terminal is connected to the control terminal of the first switching device, and the second output terminal is connected to the control terminal of the second switching device. The overvoltage protection circuit includes a third switching device and an overvoltage detection circuit, the third switching device is connected in parallel with the inductor; the overvoltage detection circuit is used to detect whether the output voltage of the output terminal VOUT is overvoltage, and when it is detected that the output voltage is not overvoltage, The overvoltage detection circuit controls the third switch device to be turned off; when the output voltage overvoltage is detected, the overvoltage detection circuit controls the third switch device to be turned on. Compared with the prior art, the step-up DC / DC converter in the present invention can prevent the output voltage from overvoltage.

Description

[0001] 【Technical field】 [0002] The invention relates to the technical field of step-up DC / DC converters, in particular to a step-up DC / DC converter with an overvoltage protection function. [0003] 【Background technique】 [0004] Boost DC-DC converter (Boost DC / DC Converter) is a common and widely used power management circuit, which can not only realize the conversion from low voltage source to high voltage source, but also has small size, simple High efficiency and other advantages. Please refer to figure 1 As shown, it is a schematic circuit diagram of a commonly used step-up DC / DC converter. figure 1 The step-up DC / DC converter includes a step-up output circuit 110 and a feedback control circuit 120 . The feedback control circuit 120 controls the first switching device SW1 and the second switching device SW2 to be turned on alternately based on the output voltage VOUT of the boost output circuit 110 . First, the first switching device SW1 is turned on, the second swi...

AI Technical Summary

Problems solved by technology

[0005] However, there is a common problem in the existing step-up DC / DC converters, that is, when the load jumps, it may cause the output voltage VOUT to overvoltage, especially when the load suddenly changes from heavy load to light load, the output voltage VOUT will occur. Overvoltage, the feedback control circuit 120 will turn off the first switching device SW1 and turn on the second switching device SW2, but because the current on the inductor L1 cannot change abruptly, the energy on the inductor L1 will still be transmitted to the output terminal VOUT, This will make the output voltage VOUT overshoot more severe

In addition, in the actual circuit, due to loop adjustment lag and logic delay, the overshoot of the output voltage VOUT will be even worse. If it is not handled in time, it will cause great damage to the subsequent circuit. burnt circuit

Images