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BQ2057T: Control method of BQ2057T

user6251399
Prodigy 140 points
Part Number: BQ2057T
Other Parts Discussed in Thread: BQ24004

Hi.

Refer to the circuit shown in Fig.1 of SLUS025F and change to the following parts.
・ Q1: 2SA2097
・ C1: 10uF × 2
・ RT1: 10kΩ
・ RT2: 39kΩ
・ Rsns, R1, C2 unchanged
・ Battery
　Rated capacity: 2800mAh
　Nominal voltage: 7.2V
　Charging voltage: 8.2V
　Charging current: MAX.1400mA

1. What are the conditions for turning off Q1?
2. Does Q1 fit this mechanism?
3.I am trying to change Rsns to 0.1Ω. Does Q1 work properly?

please tell me!

  • 0
    TI__Guru* 75656 points

    Hello

    The BQ2057T is and older device with a large number of external parts.  Can you change to another device?

    A more integrated device to consider is the BQ24004, 05, or 06.

  • 0 in reply to Bill Johns
    Prodigy 140 points

    I can't change the device.
    Please answer my question on this device.

  • 0 in reply to user6251399
    TI__Guru* 75656 points

    Hello

    TS input -- Battery Temp

    ・ RT1: 10kΩ
    ・ RT2: 39kΩ

    Voltage at TS needs to be between 30% and 60% of VCC for normal operation.  The RT1 and RT2 value alone will be a little high of this point. 

    1. What are the conditions for turning off Q1?---This would be any conditions that disables charge or charge complete.
    2. Does Q1 fit this mechanism?---We have not evaluated the 2SA2097, it look similar to FZT788B.  But you will need to evaluate performance.
    3.I am trying to change Rsns to 0.1Ω. Does Q1 work properly?---With Rsns at 0.2 ohms the charge current is 500mA, 0.1 ohm will be 1A.  this should work.  The device is a linear regulator and will have high power dissipation in Q1.  Increasing charge current will increase power dissipation.  This needs to be take into consideration.