Power level control circuit

Abstract

The invention provides a power level control circuit, which comprises a drive circuit, an error amplifying circuit, a current generating circuit and a feedback short circuit checking circuit, wherein the drive circuit receives an error amplifying signal and generates a drive signal according to the error amplifying signal, so as to drive the power level control circuit; the error amplifying circuit receives a feedback voltage, compares the feedback voltage with a reference signal and produces the error amplifying signal according to a comparison result, so as to input the error amplifying signal to the drive circuit; the current generating circuit is coupled with a feedback end and generates a fault detecting current flowing to the feedback end; and when the feedback voltage is smaller than a set feedback short circuit voltage or the fault detecting current is larger than a set feedback short circuit current, the feedback short circuit checking circuit generates a fault signal, so as to input the fault signal to the drive circuit to enable the drive circuit to stop driving the power level control circuit.

Description

technical field [0001] The invention relates to a power stage control circuit, in particular to a power stage control circuit with a short-circuit protection function at a feedback terminal. Background technique [0002] figure 1 A schematic diagram showing a prior art power stage control circuit, such as figure 1 As shown, the power stage 10 receives an input voltage Vin from an input terminal, and converts it to an output voltage Vout at an output terminal (or converts it to an output current, depending on the need for voltage regulation or current regulation of the load circuit). The output terminal is electrically connected to two series resistors Z1 and Z2 to the ground potential, wherein the two ends of the resistor Z2 are connected between the feedback terminal FB of the power stage control circuit 20 and the ground terminal, and the voltage across it is used as the feedback voltage Vfb to input An input end of the error amplifier circuit 22 of the power stage contr...

AI Technical Summary

Problems solved by technology

[0006] However, in actual circuit applications, the input voltage Vin, the output voltage Vout, and the load conditions may be different, resulting in different rising speeds of the feedback voltage Vfb. Therefore, the setting of the blanking interval time Tbk (that is, the setting of the blanking interval signal inv_BL set), it must be long enough to ensure that it can still start normally under the minimum input voltage and maximum load conditions without misjudgment

However if Figure 2B As shown, if there is a maximum input voltage and no load, if the feedback terminal FB is short-circuited, the circuit may be damaged before the feedback terminal FB short-circuit protection mechanism is activated.

In the power stage control circuit of the prior art, in order to ensure the normal start-up of the circuit, it is necessary to temporarily disable the short-circuit protection mechanism of the feedback terminal FB by setting the start-up blanking interval Tbk, which is not ideal

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