Patent ID: 9263937
Filing Date: 2016-02-16
CPC Classification: H02M,H03K

Claim Text:
1. A short protection circuit for protecting a power switch, the power switch having a first end, a second end and a control end, the short protection circuit having a first input, a second input and an output, wherein the first input of the short protection circuit is coupled to the first end of the power switch, the second input of the short protection circuit is coupled to the second end of the power switch, and the output of the short protection circuit is configured to provide a short protection signal, the short protection circuit comprising a transistor, and wherein: the transistor has a threshold voltage; the short protection circuit is configured to compare a differential voltage between the first end of the power switch and the second end of the power switch to the threshold voltage of the transistor only when the power switch is in an ON state; wherein when the differential voltage is higher than the threshold voltage, the short protection signal transits in an effective state configured to turn off the power switch; further comprising an enable circuit having a first input, a second input and an output, wherein the first input of the enable circuit is coupled to the control end of the power switch configured to receive a gate control signal, the second input of the enable circuit is configured to receive an on-control signal and the output of the enable circuit is configured to provide an enable signal, wherein the enable signal transits into an effective state with a blanking time after the gate control signal transits into an effective state and the enable signal transits into an ineffective state different from the effective state of the enable signal when either the on-control signal transits into an ineffective state or the gate control signal transits into an ineffective state, further wherein the effective state of the gate control signal is configured to turn on the power switch, and each of the ineffective state of the on-control signal and the ineffective state of the gate control signal are configured to turn off the power switch; a comparator comprising an enable switch and the transistor, the comparator having a first input, a second input, a third input and an output, wherein the first input of the comparator is coupled to the first end of the power switch, the second input of the comparator is coupled to the second end of the power switch, the third input of the comparator is coupled to the output of the enable circuit configured to receive the enable signal, and the output of the comparator is configured to provide a comparing signal, and wherein when the enable signal is in the effective state of the enable signal, the enable switch is turned on and the comparator is configured to compare the differential voltage of the power switch to the threshold voltage of the transistor, and wherein when the differential voltage is higher than the threshold voltage, the comparing signal is in an effective state, and when the differential voltage is lower than the threshold voltage, the comparing signal is in an ineffective state, and further wherein when the enable signal is in the ineffective state of the enable signal, the enable switch is turned off, and the comparing signal is in the ineffective state of the comparing signal; and a latch having a first input, a second input and an output, wherein the first input of the latch is configured to receive a POR signal, the second input of the latch is coupled to the output of the comparator configured to receive the comparing signal, and the output of the latch is configured to provide the short protection signal, and wherein when the comparing signal transits in the effective state of the comparing signal, the short protection signal transits in the effective state of the short protection signal, and wherein when the POR signal transits in an effective state, the short protection signal transits in an ineffective state different from the effective state of the short protection signal.