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BQ40Z60 ESD Ratings

FB
Intellectual 350 points
Other Parts Discussed in Thread: BQ40Z60

Hallo,

for series production we need to make our design ESD safe. Are the IO pins of the evaluation board schematics ESD safe or do we need to add extra parts to protect the BQ40Z60? We also have to protect VSYS, VAC und GND pin as they are connected to the outside of the pack.

Every hint would be nice.

Best wishes.

  • 0
    TI__Guru 73830 points
    We added Zener diodes and spark gaps to the bq40z60EVM to imporve ESD robustness.
  • 0 in reply to ThomasCosby
    Intellectual 350 points
    Do you mean the D2, D4, D5 zener diodes in EVM schematics? And wich traces (signals) do I have to check for spark gaps?

    Thank you very much for your help
  • 0 in reply to FB
    TI__Guru 73830 points
    Yes, the zeners are used for ESD protection. The spark gaps are not shown on the schematic, but they are on the EVM. You can look at the bottom side near the connectors. The spark gaps are the exposed copper regions.
  • 0 in reply to ThomasCosby
    Intellectual 790 points
    Dear Thomas,

    In different posts [p1][p2] and guides [1][2] you comment the purpose to use spark gaps to improve ESD immunity (including the zener and resistor).

    I'm deciding to use include ESD protection in my battery pack (level 4), but it's not clear the reason why to use the spark gaps versus ESD protection diodes.

    Please, can you comment the following questions:

    - The spark gaps would be counterproductive in case of generating fire?
    - Any reason to not choose a ESD protection diode? (i.e. price)

    I'm using the BQ40Z50RSMT-R1.

    Thanks for your help,

    Julio

    [p1] Bq20z95 Layout Query e2e.ti.com/.../588359
    [p2] BQ40Z60 ESD Ratings e2e.ti.com/.../1567699
    [1] Guide "Avoiding ESD and EMI Problems in bq20zxx Battery Pack Electronics"
    [2] Guide "Printed Circuit Board Layout Guide"
  • 0 in reply to Lao Hu
    TI__Guru 73830 points

    The device pins are rated at 2kV, unless noted otherwise. If your ESD requirements are higher than this, then you need to add protection. This is usually in the form of external components such as the zeners and series resistors. The spark gaps help, if your protection requirements exceed 8kV. You will see and hear arcing for higher ESD strikes, but there will usually be an arc somewhere else, if the spark gap is not present. The spark gap helps to localize the arc and shunt the ESD away from the sensitive circuits.