KW45 gpio injection current

[Lingyinglu]

Hi Guys

Here is a quetion for the KW45 gpio injection current.I want to know why the KW45 injection current

is limit to zero.I've used the othe chipset like KW35/36/38, and I've never seen its injectioncurrent is zero.

I ues one ADC PIN of KW45 to detect the input voltage of Automotive Battery,the Volatage may exceed 3.3v+0.3v=3.6V,this will cause the injection current ＞0mA.Is any suggestion?

KW45datasheetREV.9.datasheet "page13"

[ChristianSchweer]

Hello @Gavin_Jia ,

Unfortunately, the answer about the injection current is not enough for me. The KW45 data sheet clearly states that no injection current is permitted. Even if a resistor is used, there will always be an injection current through the clampling diodes.

Can you please tell me the relevant passages in the KW45 that confirm safe operation despite the injection current.

Thanks in advance,

Christian

[Gavin_Jia]

Hi @Lingyinglu ,

Thanks for contacting NXP support.

Judging from this datasheet, if the I/O pins can observe the limit, then is no need to provide current limiting resistors at the pads, otherwise current limiting resistors is needed. For details on how to select the current limiting resistor and injection current, you can refer to this AN: AN4731 Understanding Injection Current on NXP Automotive Microcontrollers

Best regards,

Gavin