Delay adjustable circuit and its lithium battery protection circuit

Abstract

The invention discloses an adjustable delay circuit and a lithium battery protection circuit thereof. The adjustable delay circuit includes a voltage-controlled oscillator circuit, a reference circuit, a short-circuit detection circuit, a delay circuit and a switch tube, wherein: the reference circuit is used for Generate a reference voltage source and current source that does not change with the voltage inside the chip; the short circuit detection circuit is used to detect whether the current at both ends of the switch tube exceeds the set current value; the delay circuit is used to set the delay of the short circuit detection circuit; the switch tube is used for Control the opening or closing of the charging and discharging path; the voltage-controlled oscillator circuit is used to control the delay of the oscillator through the voltage of the VM terminal. The invention controls the charging and discharging speed and time of the second capacitor or the third capacitor, so that the protection delay is reduced when the short-circuit current is large, the damage to the switch tube caused by energy accumulation is reduced, and the protection delay is increased when the short-circuit current is small, so as to prevent false triggering Turn off the switch tube to protect the stability and reliability of the lithium battery protection circuit.

Description

technical field [0001] The invention relates to the technical field of lithium battery protection, in particular to a time delay adjustable circuit and a lithium battery protection circuit thereof. Background technique [0002] Due to the increasing capacity of lithium batteries and the production of high-rate lithium batteries, especially in applications such as smart phones and mobile power supplies, the capacity of batteries is as high as several thousand mAH, or even tens of thousands mAH. [0003] In the prior art, when a lithium battery is short-circuited, the short-circuit current can reach tens of A or even hundreds of A, while the current lithium battery protection chip detects that the short-circuit current of the lithium battery reaches or exceeds the set value, and passes After the delay set by the corresponding delay circuit, the discharge path is turned off for protection. Since the fixed delay is used, the protection time of different short-circuit currents i...

AI Technical Summary

Problems solved by technology

Since the fixed delay is used, after the short-circuit current is exceeded, the protection time of different short-circuit currents is the same. If a shorter protection delay is selected, the short-circuit protection function is easily triggered when the system is working, causing the switch to be turned off by mistake. , if a longer protection delay is selected, it is easy to accumulate energy during a large short-circuit current and cause the switch tube to burn out, resulting in the failure of the lithium battery protection chip function, and in severe cases, battery damage

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