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Original question:

BQ24074: Schematic review

BQ24074: Question of device operation

na na78
Guru 16770 points
Part Number: BQ24074

Hi

I have two question about bq24074 operation.

Could you please check the following file and please give me feedback?

6175.E2E.xlsx

The followings is extract of the question from upper file.

Question 1.

Is this correct behavior for charger that the voltage at BAT is observed when /CE is high?

Question 2.

The pulse of which the period is 529msec is observed at CH1:BAT.

However, CHG is not changed.

Is it correct behavior?

BestRegards

  • 0
    TI__Mastermind 21590 points
    Hello,
    For question 1, that is the correct behavior. With /CE high, charging is disabled which causes /CHG to be high impedance as shown in table 3 of the datasheet.
    For Question 2, the square wave is expected due to the battery detection routine run y the device charging and discharging the capacitor on the battery pin. In this case the battery is also absent so /CHG will be high impedance which is what the scope capture shows. This is correct behavior.
  • 0 in reply to Raheem
    Guru 16770 points
    Hi Raheem


    Thank you for your reply.
    I have additional questions.

    >For question 1, that is the correct behavior. With /CE high, charging is disabled which
    >causes /CHG to be high impedance as shown in table 3 of the datasheet.

    Why does 0.72V appear at BAT pin (CH1) when charging is disabled?
    Is it offset at BAT pin? Or is it voltage which is charged at capacitor?

    >For Question 2, the square wave is expected due to the battery detection routine
    >run y the device charging and discharging the capacitor on the battery pin.
    >In this case the battery is also absent so /CHG will be high impedance
    > which is what the scope capture shows. This is correct behavior.

    Can we see the explanation that shows battery detection routine is run with T=~500msec on datasheet?

    I appreciate if you could reply.

    BestRegards
  • 0 in reply to na na78
    TI__Mastermind 21590 points
    Hello,
    For question 1, the 0.72V will be voltage on the BAT pin capacitor.
    For Question 2, please take a look at figure 32 and figure 33 of the datasheet.