NFC port power consumption

[Andrew Lohmann]

Nordic nRF52832 chipset

If I understand the answers given the NFC port always consumes power even when just listening but otherwise in active?

Am I correct and also is this current 450uA I see commented elsewhere or is the current lower.

I like to avoid adding another IC for NFC in order to resolve this issue because I do not have space but I am using an M24LR?? ST which does resolve this issue plus will not put power back into VCC unless it is desired by circuit design.

[Jørn]

Hello Andrew

If you look at the NFC electrical specification of the nRF52832 product specification it lists a current consumption while in the ACTIVE mode of 480 uA. In addition to this, if you see the overview section the high frequency crystal oscillator (HFXO) must be running while in the ACTIVE mode, which will further increase the current consumption. When the NFC peripheral is running in SENSE mode it has a current consumption of 100nA. As stated in the overview section the HFXO does not need to be running while in this mode. So whenever the peripheral is enabled in either ACTIVE or SENSE mode it will consume power.

The nRF52832 NFC port emulates an NFC tag and cannot be a NFC poller.

The NFC port does not support energy harvesting, so current induced in the tag cannot be used to charge the battery or power the circuit. However do pay note to section 42.10 Battery protection, if you have a strong NFC field you may need a diode to protect your battery from return currents.

Best regards

Jørn Frøysa