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BQ24725A: why we use a PMOS at page 36 typical application for BATFET?

Part Number: BQ24725A

Hi,

in the datasheet page 36 Figure 26.

Why we leave BATDRV unconnected and use a PMOS for BATFET? Unlike other Figure we use NMOS and connect the gate side to BATDRV.

Are there any benefit for configure in this way?

Besides, is this configuration only applicable for 5V Input 1S battery?

  • Hi Howard,

    For most applications, we recommend using the BATDRV signal to drive an NMOS BATFET, as shown in Figure 25. However, for single-cell battery applications, VBAT may be below UVLO, in which case BATDRV may not be able to drive the BATFET, as shown in the tables below.

    The PMOS solution shown in Figure 26 is a workaround that can be used to avoid this issue for single-cell charging. However, if you're charging a single-cell battery, then we recommend using a dedicated single-cell charger instead of the BQ24725A.

    To summarize:
    1) multi-cell applications: use the BATDRV signal to drive an NMOS BATFET
    2) single-cell applications: We recommend using a dedicated single-cell charger. However, if you want to use the BQ24725A, then you can use the PMOS solution shown in Figure 26.

    Best regards,

    Angelo