Power supply monitoring circuit and switching power supply

Abstract

The invention discloses a power supply monitoring circuit and a switching power supply, and the power supply monitoring circuit comprises a core sampling control module which is used for outputting a first control signal with a first logic level according to the level state of a power supply voltage; the charge pump is used for generating corresponding reference voltages according to the effective level states of different reset indication signals; the logic level conversion module is used for converting the logic level of the first control signal according to the reference voltage so as to output a second control signal with a second logic level; and the output module comprises at least one switch tube, a grid electrode receives the second control signal, the switch tube is used for outputting an effective reset indication signal at a drain electrode when the switch tube is switched on, and the switch tube is a depletion type transistor. The circuit can work normally when the power supply voltage is 0V, and is small in occupied area and high in stability and accuracy.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a power supply monitoring circuit and a switching power supply. Background technique [0002] For circuits such as power monitoring chips, the output pins are required to have the ability to provide a correct indication voltage even at the lowest possible power supply voltage, and to provide a sufficiently low output impedance. In order to prevent power failure, in most circuit systems, the power supply monitoring chip is used to monitor the system power supply voltage. When the power supply voltage is lower than the system operating voltage, the power supply monitoring chip outputs a logic high level or a logic low level to the core circuit. circuit reset. This requires that the power monitoring chip can provide a correct reset indication to the post-stage chip of the system under a very low power supply voltage, which requires the reset chip to work under a very low ...

AI Technical Summary

Problems solved by technology

For this solution, adding an external resistor R will increase the overall power consumption of the system

Increasing the width-to-length ratio of the transistor M10 and the transistor M11 in the output circuit 11 not only increases the chip area, but this circuit does not completely solve the problem of low voltage operation, and it usually requires the core circuit to be able to work at low voltage

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