Hello. I’m designing a power supply unit for high (up to 60°C) ambient temperature application. Vin range is from 8 to 80V. All frequencies will be synchronized to 200kHz clock. It consists of:
- LTC3779: 24Vout, 10A output current at 12Vin (in reality it would never peak above 8-9A), unnecessary loads will be turned off, when Vin drops down to 8V, DRVCC = 10V;
- LTC7801, 6Vout, 5A output current, DRVCC = 10V;
- LT8490, 12.6V 1A LiPo charger, MPPT off, possible modifications for higher voltage batteries
In order to decrease heat on LDOs, I’ve been thinking of switching from LTC3779 to LTC3777, which could potentially provide voltage for EXTVcc for all three cotrollers from its bias supply. I’m not sure, how much current all three devices would consume on average and what safety margin should I add. The LTSpice simulation shows that LTC3779 never draws more than 25mA from 12V source at EXTVCC pin, but in the LTC3777 datasheet I see 38mA current, LTC3779 — 48mA, LTC7801 - 32mA, and LT8490 datasheet doesn't provide any information. I suppose that even LTC3639 might not be enough for this with its 100mA output current. Should I move to LTC3638?