Hello everyone,
I was building a circuit that includes a High Side Driver which can be summarized from Capture2. I noticed after construction that the boot strap has a hard time charging because of high load impedance to ground and the long Vgs on times.
I found a way to use an astable oscillation with a charge pump to keep the boot strap continuously charge as seen in Catpure3.
I was playing around and found an alternative as seen in Capture1 that prevents more expensive timers and uses extra IO ports from the main IC. The 200k R1 is for the low side driver leakage, C1 is the normal boot strap, D3/D2/C2 is the charge pump injecting a 12VAC waveform at 20kHz.
I noticed that during initial charge from the boot strap when Vc1 ~ 0, instead of charging through the load path to ground, there is a much smaller impedance through D3->C2->GND when Q3 is on and thus makes the original boot strap time constant much less.
Any reason why I shouldn't try this?
Thanks,
BSECE OSU
I was building a circuit that includes a High Side Driver which can be summarized from Capture2. I noticed after construction that the boot strap has a hard time charging because of high load impedance to ground and the long Vgs on times.
I found a way to use an astable oscillation with a charge pump to keep the boot strap continuously charge as seen in Catpure3.
I was playing around and found an alternative as seen in Capture1 that prevents more expensive timers and uses extra IO ports from the main IC. The 200k R1 is for the low side driver leakage, C1 is the normal boot strap, D3/D2/C2 is the charge pump injecting a 12VAC waveform at 20kHz.
I noticed that during initial charge from the boot strap when Vc1 ~ 0, instead of charging through the load path to ground, there is a much smaller impedance through D3->C2->GND when Q3 is on and thus makes the original boot strap time constant much less.
Any reason why I shouldn't try this?
Thanks,
BSECE OSU
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