BQ24780S: Battery FET type considerations

Wenmin Hua

Part Number: BQ24780S
Other Parts Discussed in Thread: BQ24770, , BQ24610

When comparing Hybrid Boost Power mode charger products with NVDC charger products, it seems the HBP chargers tend to choose N-mos as battery FET while NVDC chargers choose P mos.

BQ24770 and BQ24780s are examples. I wonder whether there are some considerations in choosing the type of FETs. On the other way, why 24770 has a P-type driver for Battery FET but 24780s has a N-type driver?

over 2 years ago

0 Pengzhao Zhu over 2 years ago

TI__Genius 11385 points

Hi Wenmin,

I believe it was a decision made by the analog designers.

Thanks,

Peng

0 Wenmin Hua over 2 years ago in reply to Pengzhao Zhu

TI__Prodigy 450 points

Thank you for your answer. I'm curious about why there is such tendency.

0 Pengzhao Zhu over 2 years ago in reply to Wenmin Hua

TI__Genius 11385 points

Hi Wenmin,

PMOS is not unique to the NVDC chargers. For example, BQ24610, which is an non-NVDC charger, also uses PMOS.

The selection of PMOS vs NMOS is more of a decision based on IC internal resources. NMOS typically needs 2 dedicated pins but PMOS usually only need 1 dedicated pin because the other one can be a shared function pin. NMOS is cheaper and more efficient. It is all about tradeoff.

Thanks and I hope this helps,

Peng

*Please press "This Resolved My Issue" on the thread if my answer is satisfactory

0 Wenmin Hua over 2 years ago in reply to Pengzhao Zhu

TI__Prodigy 450 points

Thanks for your answer. I get it.

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BQ24780S: Battery FET type considerations