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IR2110 bootstrap startup and undervoltage lockout

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Blinding_flash_maker

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ir2110 bootstrap capacitor

Given a standard bootstrap circuit as in the IR2110 datasheet "Typical Connection", how does the bootstrap charge pump start up? Reading the datasheet, it seems the IR2110 is in undervoltage lockout if either bias voltage (Vb-Vs, or Vcc-Com) is below its ~8V threshold to avoid frying its MOSFETs.

Is that not the case at power-on? If the IR2110 is shutdown, how can the charge pump function? Since I see no discussion of this in the datasheet or application notes, it is apparently not a problem, but I don't understand why. Does it start in lockout, but somehow emerge and pump up the capacitors? It seems like a Catch 22 problem.
 

under voltage lockout circuit

The bootstrap circuit is not a charge pump. The bootstrap capacitor simply charges up through the bootstrap diode (connected to a positive voltage, typ 12V) when the Vss is LOW. Thus, the circuit will be in UVLO, but the cap charges up. The circuit only starts working when the voltage on the cap is higher than the threshold.
 

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