PN746X Datasheet, PDF (32/86 Pages) NXP Semiconductors – NFC Cortex-M0 microcontroller

NXP Semiconductors
PN746X_736X
NFC Cortex-M0 microcontroller
• Transaction includes initialization, anticollision methods, and data exchange (in a
continuous way means no interruption by another transaction).
In order not to disturb current infrastructure based on 13.56 MHz, the following general
rules to start NFCIP-1 communication are defined:
1. By default, NFCIP-1 device is in target mode. It means that its RF field is switched off.
2. The RF level detector is active.
3. Only if the application requires, the NFCIP-1 device switches to initiator mode.
4. An initiator shall only switch on its RF field if the RF level detector does not detect
external RF field during a time of T_IDT.
5. The initiator performs initialization according to the selected mode.
8.10.2 Low-Power Card Detection (LPCD)
The low-power card detection is an energy saving feature of the PN7462. It detects the
presence of a card without starting a communication. Communication requires more
energy to power the card and takes time, increasing the energy consumption.
It is based on antenna detuning detection. When a card comes close to the reader, it
affects the antenna tuning, which is detected by PN7462.
The sensitivity can be varied for adjusting to various environment and applications
constraints.
Remark: Reader antenna detuning may have multiple sources such as cards and metal
near the antenna. Hence it is important to adjust the sensitivity with care to optimize the
detection and power consumption. As the generated field is limited, distance for card
detection might be reduced compared to normal reader operation. Performances depend
on the antenna and the sensitivity used.
8.10.3 Active Load Modulation (ALM)
When PN7462 is used in card emulation mode or P2P passive target mode, it modulates
the field emitted by the external reader or NFC passive initiator.
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(1) Type A reader or NFC passive initiator generate the RF and sends commands
(2) PN7462 modulates the field of reader for sending its answer
Fig 20. Communication in card emulation of NFC passive target
To modulate the field, PN7462 has two possibilities:
• Passive Load Modulation (PLM): The PN7462 modifies the antenna characteristics,
which is detected by the reader through antenna coupling.
PN746X_736X
Product data sheet
COMPANY PUBLIC
All information provided in this document is subject to legal disclaimers.
Rev. 3.1 — 5 April 2016
369231
© NXP Semiconductors N.V. 2016. All rights reserved.
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