NFCのトピックRe: PN7642 DPC

PN7642 DPC

MPEngineering — Tue, 01 Jul 2025 09:54:12 GMT

Hey there,

currently I´m designing a new PCB with the PN7642.

As far as i know, new values for DPC (LUT) control have to be written, when using your own antenna.

But in my case, i want to decrease power consumption. The only goal should be, to detect Mifare DESFire (EV1 - 3) safe, within a distance of 1 - 2 cm.

Should i disable DPC and change the impedance of the Antenna, or is it more useful to calibrate the Antenna with NFC Cockpit, enable DPC and set the Gear Level to a fixed value (Antenna design like suggested in AN´s)?

Thanks for replying.

Best regards

Oliver

Re: PN7642 DPC

EduardoZamora — Tue, 01 Jul 2025 21:09:16 GMT

Hello @MPEngineering,

Hope you are doing well.

If you already performed a symmetric antenna tuning, you can configure the DPC. DPC can operate in current limiting + current reduction mode. Current reduction is achieved by lowering the transmitter supply voltage, allowing the optimization of power transfer.

Also, please take a look at How to use the low-power features of the PN76 family NFC controller. This App Note explains how to use different low-power modes on PN76 family, including LPCD and ULPCD.

Regards,
Eduardo.

Re: PN7642 DPC

MPEngineering — Wed, 02 Jul 2025 11:55:04 GMT

Hey Eduardo,

thanks for replying.

In my case i dont want to use LPCD or ULPCD. The IC should always be sleeping or powered off, till a button is pressed.

Then poll for a card, interact and sleep again without card detection function.

But if there is a current limiting/reduction mode, it should be simple to reduce Transmitter Power to a level, where safe detection (1 - 2cm) is achieved, isnt´t it?

Best regards,

Oliver

Re: PN7642 DPC

EduardoZamora — Wed, 02 Jul 2025 21:21:57 GMT

Hello @MPEngineering

Hope you are doing well.

In addition to a wake-up due to an object detected in the proximity of the reader, ULPCD allows the usage of a GPIO (GPIO 3) to abort ULPCD from an external source. This is described in How to use the low-power features of the PN76 family NFC controller, Section 2.3.2.1. Would you consider this approach?

Regards,
Eduardo.