Output short-circuit soft-restoration control circuit and application thereof in DC-DC converter

Abstract

The invention provides an output short-circuit soft-restoration control circuit and an application thereof in a DC-DC converter. In an initial electrification process, before an output voltage of an FB port does not exceed a given reference voltage V9, a soft-restoration control module of the soft-restoration control circuit has no effect on a switch module. After the output voltage of the FB portis back to normal, if the output voltage of the FB port is lower than the given reference voltage V9, the soft-restoration control module outputs a switch-off signal to a switch control module of thesoft-restoration control circuit, and the switch control module turns off the switch module. The soft-restoration control module continues to detect the output voltage and a load current of the FB port and compares the load current with a threshold current. When the load current is lower than the threshold current of the soft-restoration control module, the soft-restoration control module opens the switch control module, and the output voltage of the FB port restores the normal state. The output short-circuit soft-restoration control circuit can reduce the chip power consumption during the output short circuit and control and output the time for restoration from the short circuit.

Description

technical field [0001] The invention relates to power management technology, in particular to power short circuit protection technology. Background technique [0002] At present, power management circuits are widely used. Most circuits that supply power to loads through switching tubes, such as switching power supplies and low-dropout voltage regulators, need to have output short-circuit protection. When the output is overloaded or short-circuited, the output will be turned on. Short circuit protection function to avoid damage to the circuit itself and the load due to high current. Such as figure 1 The short-circuit protection module (13) of the shown output short-circuit protection circuit judges whether there is a short circuit according to the output voltage value of the load terminal, and then outputs a control signal to the switch control module (12) to completely or intermittently close the switch module (11). For switching power supplies, when the output is short-ci...

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Problems solved by technology

[0022] The disadvantage of the above-mentioned DC-DC converter output short-circuit protection is that: when the output is short-circuited, the switching action continues, and a large power consumption is lost, as shown in formula (3); and when the output recovers from the short-circuit state, there is no Strictly control the recovery threshold point of the output current, as long as the load current is reduced to less than the maximum load Iload of formula (4) max , the output voltage can be fully restored to normal

[0024] figure 1 The output short-circuit protection circuit shown has similar disadvantages: when the output is overloaded or short-circuited to ground, if the switch module is directly turned off, it must be re-powered when the short circuit recovers; if the switch module is turned off intermittently (the so-called "hiccup" " mode, periodically detect the output voltage state during short circuit), which will inevitably lead to an increase in power loss during short circuit

[0025] Summarize the above two shortcomings of the traditional output short-circuit protection circuit: one is that unnecessary energy loss is increased when the output is short-circuited; threshold, and there is no process control of short-circuit recovery

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