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Can I use darlington-PNP (like TIP127) as my pass element with UC3906?

Bhavesh Gupta
Prodigy 10 points
Other Parts Discussed in Thread: UC3906, BQ24450

Hi there,

 

I'm designing a battery charger using UC3906. I want to charge two 12V batteries in series (24V) of 4.5AH. The Imax (Max charging current) would be 900mA.

Now, my question is: Can I use a darlington-PNP as my pass element? Like TIP127 with hfe of around 1000.

Thanks in advance.

 

  • 0
    TI__Guru**** 150690 points

    You should also look at the bq24450, which is a similar part with a better datasheet.  A true darlington configuration of 2 PNPs (as in the TIP127) simply appears as a single PNP in the circuit configurations on page 13 and 14 of the bq24450 datasheet.  Thus, the common-emitter PNP would be the best option for you.