Patent ID: 9698677
Date: 2017-07-04
CPC Classifications: H02M,H03K

Claim:
1. A brownout recovery circuit configured for a switch power supply circuit with a first switch, said brownout recovery circuit comprising: a) an under-voltage detection circuit configured to activate a detection signal when a bootstrap capacitor is not in an under-voltage state, and to deactivate said detection signal when said bootstrap capacitor is in said under-voltage state; b) a logic circuit configured to, when said detection signal is active, generate a first control signal according to a main control signal from said switch power supply circuit and a switch state of a second switch, wherein an active duration of said first control signal is less than a first predetermined time when said detection signal is active, and said active duration of said first control signal is controlled to be said first predetermined time when said detection signal is inactive; c) a first control circuit configured to generate a first switch signal according to said detection signal and having a same state as said first control signal, wherein said first switch signal is configured to control said first switch to be turned on or off when said detection signal is active, and to turn off said first switch when said detection signal is inactive; and d) a second control circuit configured to receive said first control signal, and to generate a second switch signal configured to turn off said second switch when said detection signal is active, and to turn on said second switch when said first control signal changes from active to inactive and said detection signal is inactive, wherein an on time of said second switch is controlled to be a second predetermined time when said detection signal is inactive.