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BQ24640: BQ24640 ISSUE

Hsu cheng
Expert 1565 points
Part Number: BQ24640
Other Parts Discussed in Thread: CSD17573Q5B, LM5109B

About BQ24640 My customers have the following questions?
1. Can the Sense resistor be changed to 4m ohms to become a 25A fast charge?
2. Can I push two parallel CSD17573Q5B MOS?

  • 0
    TI__Mastermind 24075 points

    Hi Hsu,

       Theoretically you can have 25A charge current by just changing the sense resistor, however we recommend for up to 10A. The reason being at high charge current, higher rated bulkier MOSFETs are required which have high Qg. The internal gate drive strength would most likely not be strong enough to drive these external MOSFETs and result in decreased efficiency due the increased switching losses incurred to turn on and off the HSFET and LSFET. Possible for including an external half bridge gate driver to boost internal gate drive strength (ex: LM5109b), but we have not verified such a solution. Layout is very very critical at 25A charge current.