Wireless MCUのトピックRe: KW45 gpio injection current

KW45 gpio injection current

Lingyinglu — Tue, 11 Jul 2023 06:58:15 GMT

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"

回复： KW45 gpio injection current

Gavin_Jia — Wed, 12 Jul 2023 07:09:04 GMT

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

Re: KW45 gpio injection current

ChristianSchweer — Fri, 30 Aug 2024 11:41:02 GMT

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