DC/DC power input overvoltage and under-voltage protection device composed of voltage-stabilizing tube

Abstract

The invention discloses a DC / DC power input overvoltage and under-voltage protection device composed of a voltage-stabilizing tube, and the device comprises a low threshold circuit, a high threshold circuit, a first switching circuit, and a second switching circuit. An input voltage is inputted to the low threshold circuit and the high threshold circuit, and is compared with the threshold values of the low and high threshold circuits, thereby achieving the respective control of the on / off of the first and second switching circuits. When the input voltage is within the range between the two threshold values of the low and high threshold circuits, an isolation switch power supply works normally. When the input voltage is outside the range between the two threshold values of the low and high threshold circuits, the power Vdd of a power controller is lowered to be less than a starting voltage of the power controller, and the isolation switch power supply does not work. Through the arrangement of two voltage-stabilizing values, the input overvoltage and under-voltage protection thresholds of the isolation switch power supply are arranged, thereby saving the cost, and facilitating the miniature integration of a DC-DC power supply. The device irons out the defect that the range of the input voltage is limited, and is wider in the range of a design voltage.

Description

technical field [0001] The invention relates to a DC / DC power supply input overvoltage and undervoltage protection device composed of a voltage stabilizing tube, which belongs to the technical field of circuits. Background technique [0002] The input overvoltage and undervoltage protection devices for isolated DC-DC power supplies in the prior art are generally composed of a reference source, a comparator, and a MOS switch. Both the comparator and the reference source require two circuits, and require power supply, and the structure is complex. higher cost. [0003] There are also output overvoltage protection devices that turn off the primary side controller, and are divided into two protection forms: permanently shutting off the output when a fault occurs and oscillating output pulses when a fault occurs. Oscillating output pulses will continuously cause the power supply to restart, which will have an impact on the reliability of the power supply itself, and cannot check...

AI Technical Summary

Problems solved by technology

Oscillating output pulses will continuously cause the power supply to restart, which will have an impact on the reliability of the power supply itself, and cannot check the load fault online

[0004] There are also circuits that use two TL431s to form an overvoltage and undervoltage protection device. The disadvantage is that the gate voltage range of the PMOS switch is 0-20V, which determines that the range of the input voltage is limited.

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