BQ25792: why input current limit is 3.3A only ?

Anderson Cheng

Part Number: BQ25792
Other Parts Discussed in Thread: BQ25720

Hi team,

BQ25792 input current is 3.3A, so is this means when customer used 4s battery with 16.8V max battery voltage can't get 5A charge current?

assume input voltage is 20V, battery is 4s with max voltage 16.8V, charging efficiency is 90%, then the input current need 16.8V*5A/0.9/20V=4.7A, obvious exceed the input current limit.

Thanks.

Anderson

over 2 years ago

0 Jeff F over 2 years ago

TI__Guru**** 167146 points

HI Anderson,

The charger was designed assuming a USB type C based source. Until recently, USB sources were limited to 3A.

If higher input and output power is desired, I recommend moving to a controller with external FETs like BQ25720/30 family.

Regards,

Jeff

0 Anderson Cheng over 2 years ago in reply to Jeff F

TI__Intellectual 1270 points

HI Jeff,

Type C PD have 20V-5A source, so the BQ25792 is not suitable on this application?

Thanks.

Anderson

0 Jeff F over 2 years ago in reply to Anderson Cheng

TI__Guru**** 167146 points

Hi Anderson,

The charger can still take the Type C PD 20V-5A input source but only be able to draw 3.3A of the 5A.

Regards,

Jeff

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BQ25792: why input current limit is 3.3A only ?