Battery protection PCB board parameters defined and part seletion

user5196705

On 10.2.1 &Table 2 of the document 《bq297xx Cost-Effective Voltage and Current Protection Integrated Circuit for Single-Cell Li-Ion and Li-Polymer Batteries (Rev.F) 》 shows the parameters of battery protection board . If Maximum operating discharge current is 7A，the inrush current is about 15A, how to select the MOSFET ?The current criteria of the MOSFET is 7A or 15A？

Thanks~

over 5 years ago

0 Shawn Hinkle over 5 years ago

TI__Expert 7455 points

Hi User,

The criteria for the MOSFET is 7A. See Section 10.2.2 in the datasheet for detailed design procedure and FET selection.

0 user5196705 over 5 years ago in reply to Shawn Hinkle

Prodigy 50 points

Hi Shawn:

If set the criteria for MOSFET 7A ,can the inrush current 15A activate the discharing over current protection?

Thanks~

0 Shawn Hinkle over 5 years ago in reply to user5196705

TI__Expert 7455 points

Hi User,

If the voltage between V- and VSS exceeds the limit for discharge overcurrent protection, then the device will trip that fault. So yes, it is possible.

0 user5196705 over 5 years ago in reply to Shawn Hinkle

Prodigy 50 points

Hi Shawn：

I'm confused about that discharge overcurrent protection needs delay 8 ms normally，but the inrush current duration is only several us. Why it can trigger the discharge overcurrent protection？

Thanks for your reply.

0 Shawn Hinkle over 5 years ago in reply to user5196705

TI__Expert 7455 points

Hi,

I apologize, I forgot to mention the delay. You are correct. The over current protection also requires a delay of at least 8 ms. The fault will not trigger if the current is above the threshold only for several us.

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Battery protection PCB board parameters defined and part seletion