Overheat detection protection circuit for power device

Abstract

The invention discloses an overheat detection protection circuit for a power device. The overheat detection protection circuit comprises a resistor R2, a resistor R4, a resistor R6, a triode Q2, an MOS transistor Q3 and a temperature sensor R5, wherein the resistor R2 is connected in series with the resistor R6; the other end of the resistor R2 is used for connecting a reference voltage output endof a PWM (Pulse Width Modulation) control chip; the other end of the resistor R6 is grounded; the resistor R4 is connected in series with the temperature sensor R5; the other end of the resistor R4 is used for connecting the reference voltage output end of the PWM control chip; the other end of the temperature sensor R5 is grounded; a temperature contact of the temperature sensor R5 is in contactwith the power device; a base electrode of a triode Q2 is connected between the resistor R4 and the temperature sensor R5; an emitting electrode of the triode Q2 is grounded; a collecting electrode of the triode Q2 is connected between the resistor R2 and the resistor R6; a grid electrode of the MOS transistor Q3 is connected between the resistor R2 and the resistor R6; a source electrode of theMOS transistor is grounded; and a drain electrode of the MOS transistor is used for connecting a soft start control end of the PWM control chip. The simple protection circuit is designed by flexible use of the pin characteristic of the PWM control chip, and has the advantages of simple structure, low cost and high portability.

Description

technical field [0001] The invention belongs to the technical field of circuit protection, and in particular relates to a power device overheat detection and protection circuit. Background technique [0002] With the development of modern computer and automation technology, as a functional device for the perception, collection, conversion, transmission and processing of various information, the role of temperature sensors has become increasingly prominent, and has become an indispensable part of automatic detection, automatic control systems and measurement tests. Technical tools are used in various fields of industrial R&D, production and daily life. For example, the power density of devices in the standard instrument industry continues to increase, and the devices operate under high-power conditions. How to ensure that the power transformers and switching devices in the instruments will not cause system collapse due to overheating is particularly important. [0003] At pr...

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Problems solved by technology

Although this method can achieve better results, it uses more circuits, and there are problems such as sampling circuit power supply, isolation, occupying CPU resources, and increasing costs.

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