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BQ24257 setting D+/D- in Standalone mode

Other Parts Discussed in Thread: BQ24257

Hi,

I want to use the BQ24257 in standalone mode but I don't understand how I must set D+/D- pins on the IC (I don't want to use an USB connector to charge battery but only use an AC source connect to IN pin so D+/D- for me are unnecessary).

Now with a D+ short to GND an D- short to GND the charger only charge at a rate of 100 mA.

How should I set D+ and D- to enter in the mode that the charge current is set by the ISET pin?

Thanks

  • Try D+ tied to D-.
  • Hi

    I tried your suggestion but it still continue to charge at 100mA.

    I post the schematic that I use

    Investigating on all pin I see that PG, when I connect the battery, is in High Impedance, so this can be an issue, but why it reach this state and don't be pulled low?

    Thanks for any help

  • When I short D+/D- on the bq24257EVM-150 EVM, set to 1A charge, I get 1A charge.
    If PG is not asserting, please measure as close to IC IN and GND as possible and see if the VINDPM loop is reducing current.
  • I'll try to short D+/D- with a new PCB design but it still continue to charge at max 100mA..
    Voltage at Vin is correct: ~5,3V and Vdpm is 1.41V with this input voltage of 5.3V so greater than the threshold voltage of 1.2 Volt..
    PG continue to stay HIGH so there is a problem...The output voltage on ISET pin is ~0.1 Volt.

    PG seems to go LOW when I disconnect the battery (the battery charger continue to receive the Vin of 5.3V at input) 

    UPDATE : I solve the problem...there was wrong capacitor on PMID so the charger doesn't work properly...however I see that I can set correctly the current on 1 A but if I set 1.4 the charger don't reach this value.

    Thanks