NHS31xx: Using POR - PowerOn reset - when attaching Battery Power

[stefanvoß]

Hi,

for my NHS3100 (NXP Demoboard) i like to get a reset (ResetISR) when i attach battery power. 

So far, the result is none, Nothing happens when i attach (sufficient) battery.

When I wait 30 seconds after attaching same Battery and do use either the 'Reset Pin' or move NFC-phone close to the NFC field, the NHS3100 will finally reboot and i get the ResetISR.

My Problem is, that i want that ResetISR after attaching battery without manually doing Reset Pin or NFC phone action.

According to the 'Nxp NHS3100 UM10876.pdf' manual page 4 subsection 'Power control' there is a Power-On Reset (POR) feature.

Thanks in advance

[driesmoors · Accepted solution]

Hi,

Attaching the battery will not start the IC. This is intended behavior. After attaching the battery, the so called 'disconnect circuitry' will block power from propagating through the rest of the IC. The only way to start the IC is to pull the reset line low, or to bring an NFC field nearby.

BR,
Dries.

[stefanvoß]

Hi,

thanks for your reply, this gives me the answer i was looking for. The battery POR i had in mind is not provided

Best regards,

Stefan

[estephania_mart]

Hello,

You can find more information in the datasheet of the device, you can see the figure 7

The PSWBAT is the one of your interest in this case, applying battery power when the PSWBAT switch is closed, or NFC power becomes available, provides the always-on part with a Power-On Reset (POR) signal.

I believe you will find a deeper explanation of this in the chapter 8.4.1 System power architecture where you can see as well some of the power sequences and states changes regarding the power management.

Hope this helps

Regards,

Estephania