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BQ24070: CE pin

Shota Mago
Expert 7260 points
Part Number: BQ24070
Other Parts Discussed in Thread: BQ24075

Hi all, 

My customer considers to use BQ24070 for his end product and provided a question.

[Question]

Is it ok to apply 3~4.2V when VIN=0V?

(Does the device stay sleep mode since VIN=0V and device will not be damaged?)

[Background of this question]

When BQ24070 is operating and battery is absent, the BAT pin cycles between charge done (VO(REG)) and charging as described in 8.4.3.5 Battery Voltage Regulation.

In such a case, if STAT pin is connected to LED, LED blinks.

In order to prevent this situation, the customer attempts to connect CE pin to battery and add pull down resistor so that device can operate only in case that VIN and battery exist and the device can't operate if Vin exists and battery is absent.

Best regards,

Shota Mago

  • 0
    TI__Mastermind 23220 points

    Hi Shota,

    Just to clarify, the customer is asking if it is ok to apply the 3-4.2V on the CE pin? I

    f there is only the battery present, the CE will be pulled to BAT or is there a pull down to GND in that case?

    If the requested operation is to operating in the following conditions by connecting the CE pin and the BAT pin by means of a pulldown resistor:

    VIN

    VBAT

    Desired Behavior

    Present

    Present

    Output ON

    Present

    Absent

    Output OFF

    Absent

    Present

    Output OFF

    There should be no concern on the CE pin as the pin is has a maximum absolute rating of 7V. 

    If there is no input, the output will be powered by the battery as the Q2 FET is still on as the device is in sleep mode. I believe a more suitable device is the BQ24075. This device will have the SYSOFF pin which controls the Q2 FET connecting BAT and OUT which will work for eliminating standby mode. 

  • 0 in reply to Anthony P Pham
    TI__Expert 7260 points

    Hi Anthony,

    Thanks for your quick reply.

    Sorry, I forgot to add "CE pin"  at original question "Is it ok to apply 3~4.2V when VIN=0".

    Your understanding is correct as you summarized on the table.

    I understood that CE pin has tolerance for 3~4.2V even if Vin=0V since abs max is 7V.

    Best regards,

    Shota Mago