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bq24618 Safety timer (cont.)

PAN-M
Mastermind 8375 points

Hi

Our customer set a TTC capacitor to 8.9nF.
Iｔ worked as follows actually;

48 minute worked -> 2 sec. stop -> Recharge -> 96 minute work -> stop

Is this working right?

Regards,
PAN-M

  • 0
    TI__Expert 5565 points
    With a 8.9nF TTC capacitor, the timer should be set to 50 minutes. Therefore, it seems the 48 minutes the customer is measuring is correct.

    Could you elaborate more on the next set of events? Does the battery voltage fall to the recharge threshold in the 2 seconds it's not charging, and then recharges for 96 minutes? The timer could be reset at any time if one of the following event occurs:
    1. Battery voltage falls below the recharge threshold
    2. Power on reset event occurs
    3. CE pin is toggled

    Also, what is the termination current set to? Are you sure no fault occurs during the second recharge cycle? Is the customer measuring the time by monitoring the STAT1/2 pins?
  • 0 in reply to Smriti B
    Mastermind 8375 points

    Thank you for support, Smriti-san

    Our customer feedback are;
    1) termination current setting = 0.75A
        A charge will be termination current in 70 minutes, but a charge is continued until 90 minutes.
        That time's current is 0.35A.
    2) There are no errors in any charge times.

    Our customer said the CE may do a toggle by MCU, but they don't have enough evaluation time now.
    They would check this issue later.

    Thanks and Regards,
    PAN-M

  • 0 in reply to PAN-M
    TI__Expert 5565 points
    If the termination current is set to 0.75A, then the device shouldn't keep charging until the current is 0.35A. The only way this can happen is if the TTC pin is taken low. Taking the TTC pin low disables the safety timer and termination. Is there anything else connected to the TTC pin?