nRF52832 reset IC

[Kenichi Sagara]

Hello, Technical support team

In the past, I contacted you to confirm nRF52832 application.

This time, I have a question for a external reset as follows.

My application is 2.5V input operating, but the rise time for the input voltage is very slow like a transient response.

Therefore, I don't think that the nRF52832 internal power-on reset has a stable operating. So, I am using a exteral reset.

But, I can't see a stable operating even if I use the external reset IC.

The input voltage rise time is about 1 sec untill reaching to 2.5V, and the reset IC works at 2.4V.

But, the nRF52832 starts working at 1.7V . So, I think that the nRF52832 operating is still unstable.

So that, what is the reset voltage and the reset timing?  Otherwaise, if the input voltage rise time is very slow, reset IC is not available.

Could you give me your advaise as soon as possible? 

Please send me if you have any question of my application.

Best regars, K.Sagara

[Kenneth]

Hello,

The slowest allowed rise time on VDD from 0V -> 1.7V is 60ms:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/recommended_op_conditions.html#concept_vng_xls_2q 

We do not guarantee that the chip will start with slower rise than this, the pin reset may not work if the initial rise time was slower than this. The internal SoC require a valid POR signal to start operating as specified, and the POR signal may not trigger if VDD ramp up is slower than 60ms.

You will have to redesign your board, e.g. by using a voltage detector to only feed VDD to the nRF52832 only after VDD are above 1.7V.

Best regards,
Kenneth