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BQ25898: IINLIM setting over PSEL status

Sabarish Subramanyan
Prodigy 40 points
Part Number: BQ25898

Hi,

1. If PSEL is externally connected to GND (3.25A IINLIMIT) can changing the IINLIM register setting will take the priority? PSEL is GND and IINLIM = 500mA so actual Input current limit is 500mA?

2. If PSEL is toggled will IINLIM setting overwrites? 

3. Can PSEL be pulled high to VSYS? what is the logical high state for PSEL?

Regards,

--Sabarish

  • 0
    TI__Guru*** 144180 points
    Sabarish,

    Regarding 1, PSEL sets the default value for IINLIM register. PSEL=GND sets the IINLIM register default to 3.25A while PSEL=High sets the IINLIM register to 500mA. Keep in mind that the ILIM pin resistor clamps the actual input current limit. So, even if the IINLIM register is set to 3.25A, if the ILIM pin resistor will set the input current limit to a lower level.

    Regarding 2, once I2C communication is established, the IINLIM register can be changed but will be clamped by the resistor on the ILIM pin.

    Regarding 3, datasheet page 12 shows the PSEL pin logic high minimum as 1.3V. PSEL can be tied to VSYS but most people tie it to REGN.
  • 0 in reply to Jeff F
    Prodigy 40 points
    Hi Jeff,

    Appreciate your quick response.
    4. I am going to tie ILIM to GND externally and PSEL to REGN, this way when in host mode only IINLIMIT should control the final input current limit. Let me know whether this scheme works?
    5. Can ILIM be directly connected to GND or should i use 100Ohms resistor? I reckon there should be internal current clamp so grounding should be fine?

    Regards,
    --Sabarish
  • 0 in reply to Sabarish Subramanyan
    TI__Guru*** 144180 points
    Yes, you can tie ILIM directly to GND and PSEL to REGN. I recommend using a small resistor from ILIM to GND in case you change your mind later.