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BQ78350-R1: BQ78350-r1 VAUX, KEYIN And PRES Functions

Adesh Jagtap98
Prodigy 210 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ78350

Hello,

I have faced the difficulty regarding the role of three pins in BQ78350, VAUX, KEYIN and PRES.

In these pins, KEYIN and PRES are active low pins.

Can anyone please explain the functionsof these pins?

It will really help me.

  • 0
    Mastermind 8415 points

    Hi Adesh,

    All three pins are explained in the technical reference manual.

    PRES: Section 6.
    The PRES pin is used to detect whether a "battery" is present. It controls both FETs and is active low. This feature cannot be configured or disabled.

    KEYIN: Section 15.
    The KEYIN input is used to control the DSG FET only. This feature can be enabled/disabled and the polarity can be changed.

    VAUX: Section 2.3.
    The VAUX pin allows measuring an optional auxiliary voltage.

    Regards,

    Michel

  • 0 in reply to Michel Solecki
    Prodigy 210 points
    Thanks Michel.
    I understood operation of these pins. But see I am not able understand the significance of these pins properly. I am not able to imagine the systems where these functions are required.

    VAUX can be used where you need to control(ON/OFF) the battery charging according to some external voltage in the system.
    But Why KEYIN?
    If having any system example, Please explain.
    It will really help me to utilize this device optimally.

    Regards,
    Adesh
  • 0 in reply to Adesh Jagtap98
    Mastermind 8415 points

    Hi Adesh,

    Both VAUX and KEYIN pins are optional. So it's up to you, if you want to use them or not.

    The VAUX pin is an optional pin used to measure some external voltage. This could be anything: the voltage of your charger, or some sensor in your system (ex: temperature, humidity).

    The KEYIN can be used for instance to make sure that only "specific" devices are allowed to connect to the device. This can prevent anybody from connecting a device to your battery and discharging the cells. This is a very basic security, but it can useful if several devices use the same connector. It could also be used to detect a charger to make sure that the cells will not discharge into the charger (in case the voltage is higher in the pack).

    Regards,

    Michel

  • 0 in reply to Michel Solecki
    Prodigy 210 points
    Thank you, Michel!

    Regards,
    Adesh