Undervoltage lock-out circuit having dynamic filtering function

Abstract

The invention provides an undervoltage lock-out circuit having a dynamic filtering function. The undervoltage lock-out circuit comprises a reference circuit, a power supply sampling circuit, a comparator and a filter circuit. A filter circuit in the prior art is replaced by a dynamic filter circuit. The two paths of output signals of the power supply sampling circuit are output to one input end ofthe comparator and one input end of the dynamic filter circuit; the two paths of output signals of the reference circuit are output to the other input end of the comparator and the second input end of the dynamic filter circuit; and the output of the comparator is output to the third input end of the dynamic filter circuit. The filtering time of the dynamic filter circuit is controlled by the three paths of output signals simultaneously, and the filtering time changes with the power supply voltage, that is, the larger the drop amplitude of the power supply voltage is, the smaller the filtering time is, thereby realizing dynamic filtering; and the dynamic filter circuit outputs a feedforward signal to the power supply sampling circuit, and thus the output of the dynamic filter circuit is updated continuously.

Description

technical field [0001] The invention relates to an undervoltage lockout circuit, in particular to an undervoltage lockout circuit with a dynamic filtering function, and belongs to the technical field of integrated circuits. Background technique [0002] In chips with large fluctuations in working power supply voltage, an undervoltage lockout circuit is usually required to ensure stable and normal operation of the system. Such as figure 1 As shown, the traditional undervoltage lockout circuit generally consists of three parts, which are power sampling circuit, reference circuit and comparator. In order to prevent circuit oscillation caused by power supply voltage fluctuations, the undervoltage lockout circuit has a positive undervoltage threshold (V CCUV+ ) and the negative undervoltage threshold (V CCUV- ), and the positive undervoltage threshold is higher than the negative undervoltage threshold. When the supply voltage is higher than the positive undervoltage threshold ...

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Problems solved by technology

[0005] In the above prior art, the filtering function under different power supply voltages can be realized, but the filtering time does not change significantly with the power supply voltage, so when the power supply voltage drops too much, it will seriously increase the response time of the circuit, which may cause the circuit to fail. malfunction of control

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