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BQ25172: EVM is detecting continuously fault

Part Number: BQ25172

Tool/software:

Hello Support Team, 

I'm using a BQ25172EVM and 3 NiMh batteries in series. 

I'm trying to configure the EVM to charge three cells as follows: 

S1 : R2

S2 : R12

JP6 : Fixed

JP7 : Open (No jumper shorted)

JP4 : Fixed

JP1 : Closed

JP5 : Closed

JP3 : Closed

JP2 : IN+ 

After connecting to the charging supply (the USB port of the laptop), the LED is continuously blinking. 

I'm not sure why. 

Please let me know i'm missing anything or any fault conditions to check. 

Thanks,

Regards,

Venkatesha K M

venkatesha@adaptideations.com

  • Hi Venkatesha

    I think the problem may be S1, S2 and JP7 setting

    1.) S1 -- Check the resistance of TP7 to ground should be 24k ohms.  But suspect it is 0 ohm, the S1 switch settings are reversed.

    2.) S2/JP7 -- Check the resistance of TP10 to ground should be 18.2k ohms. S2 switch setting also appear to be reversed.  Install JP7 

  • Hello Bill Johns,

    Below are observations

    1) S1 -- Resistance between the TP7 to GND is 1 Ohm

    2) S2 -- Resistance between the TP10 to GND is 60K Ohm

  • Hi Venkatesha

    1) S1 -- Resistance between the TP7 to GND is 1 Ohm  -- Bill J - Resistance below 3.0k will set a fault at power up, 

    ---Reset S1, place all Actuators in the OPEN position and verify TP7 Resistance is high impedance.  Then set Actuator 2 to CLOSED position and verify 24k.

    2) S2 -- Resistance between the TP10 to GND is 60K Ohm  -- Bill J - Resistance Above 45k will set a fault at power up.

    ---Reset S2, place all Actuators in the OPEN position and verify TP10 Resistance is high impedance.  Then set Actuator 2 to CLOSED position and verify 18k.

  • Hello Bill Johns,

    1) I reset the S1 switch to open and then closed the actuator 2 in S2

    2)I also reset the S2 and closed actuator 2 in S2

    Finally it's working.

    But i have few questions Can you please suggest the configurations for 3S-cell NiMh batteries?(Or above configurations are good to go ahead.)

    Thanks,

    Venkatesha K M

  • Hi Venkatesha

    The above configuration is good.

    VSET - 24k = 3Cell NiMH.  But does not have intermittent charge to recharge when battery voltage drops due to self discharge or use.  VSET - 18k will provide recharge.

    TMR - 18k will provide 10hr charge time, 

  • Hello Bill Johns,

    Below are the configurations of the battery::

    2 packs of 3S cell, and they are connected in parallel to achieve the 4.5V and double the capacity.

    For this pack, I wanted to build a charging circuit.

  • Hi Venkatesha

    The above configuration will work.

    Depending on the application intermittent charge may or not be needed.