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UCC27523: Driving Low-Side NMOS for Battery Protection

Peiheng Liu
Prodigy 620 points
Part Number: UCC27523
Other Parts Discussed in Thread: BQ76920,

Hi,

I'm looking for a TI solution that could drive a low-side back-to-back NMOS pair (e.g. 2* IRFS4010) commonly seen in battery packs. The UCC2752x family seems to be fitting in right. The application specified in datasheet normally points to SMPS.

Could you please help to tell the additional considerations when using UCC2752x driving NMOS for battery protection? I think adding a few components to the drive path would work for battery over current protection.

  • 0
    TI__Guru**** 189399 points
    Hi Peiheng,

    Ni hao!

    Where did you get Figure 7-3 from? I'd like to see more of that document to make the correct recommendation for you.
  • 0 in reply to Don Dapkus
    TI__Prodigy 620 points

    Hi Don,

    Please refer to the bq76920 datasheet page 28 for this circuit cofig. My point here is the negative voltage on PACK- terminal when the NMOS disconnect the power loop. There would be ~100A current to be cut off during a external short event and a negative swing could be seen on PACK- with even small parasitic inductance. This circuit could handle the negative swing rather than stressing the driver. Do you have any better ideas?

    Great thanks for your prompt!

    Peiheng. 

  • 0 in reply to Peiheng Liu
    TI__Guru**** 189399 points
    Hi Peiheng,

    It looks like BQ76920 has built in drivers. What problem are you trying to solve by adding external drivers?
  • 0 in reply to Don Dapkus
    TI__Prodigy 620 points
    Hi Don,
    Getting close. bq76920 is an AFE with complete monitoring and protection driver feature set, but my customer is doing a bit different in their design.
    The monitoring features were implemented on a MCU and opamp elsewhere, so some external driver for low-side protection NMOS could help to finish the jigsaw.
    Hardware engineers usually do this driver thing by totem pole. Customer is looking for a simple driver this time because the power is huge and schedule is tight. Do you think UCC27523 could fit in this application?
    Thanks for your prompt!
    Peiheng.
  • 0 in reply to Peiheng Liu
    TI__Guru**** 189399 points
    Hi Peiheng,

    Gotcha!!! Now it's clear! Thank you.

    A low-side driver can certainly drive the fet connected to DSG.

    I'm not sure about the CHG FET though as the source is connected to the battery pack and I'm not sure what voltage it will see. We need to run some simulations to verify the voltages will be within acceptable ranges.

    I'll drop you an email so we can get more information.