Hi Team
Our customer have a MeanWell AC-DC power converter running 15V 20W 1.4A running into a board built to TI specs. Charging a 3 cell Li-ion battery pack, the cells are 16850 type. The customer that built it wanted it to charge in under 3 hours. The question is what would cause the converter and the BQ24105 chip to run at 86 degrees C?
I hope you can help.
Regards,
Marvin
Hi Marvin,
The datasheet doesn't show 3-cell efficiency data but a reasonable, slightly pessimistic assumption is 90%. eff=Pout/Pin and Pin-Ploss=Pout so Ploss = Pin-Pout =Pin - eff*Pin=Pin(1-eff) so Ploss =15V*1.4A(1- 0.9) = 2.1W. Using the thermal data below (which assumes a very specific board that might not match customer board) for a rough estimate, the Junction to top case temp rise could be as much as 2.1W*39.3 C/W = 82.53C.
The measured temp sounds reasonable.
Regards,
Jeff
