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NFC Technology
Hello, I have a question: Is the NFC technology in the iPhone always active, even if the Wallet app is not in use? I mean, is it always emitting RF radiation to read/write?
Ulysses HERNIOSUSBest answer
ST Technical Moderator
September 16, 2024
Hello Jonamleonel,
I think you need to differentiate two scenarios:
- Phone acting as reader writer (poller) to find external cards. In this mode it is periodically emitting pulses to find NFC tags. Constant Carrier is only entered during communication with a card. Typically this polling (also background polling on iPhone) is only entered when the phone is unlocked (on iPhones also when screen is locked but on). To my knowledge no phone is polling in screen-off state.
- When talking about wallet it means phone acting as card. In this mode the phone is by its own not emitting any field. Only when providing an answer to an external NFC field modulated command it will for a short time turn on an own field (Active Load Modulation as opposed to NFC cards which are doing Passive Load Modulation). This field emission is pretty much neglectable. This NFC activity is also active when the phone is in Screen Off state.
About health effects: Due to the low frequency and the low power the consensus is that there is no risk here (even if it would be Constant Carrier.) Constant Carrier is typically avoided to save power.
BR, Ulysses