Hi,
both ST25R95 and CR95HF will properly do the job of reading the UID. For new project, ST25R95 is recommended. Customers using CR95HF in already existing products will continue to be served with CR95HF to avoid them to redo product qualification. I would suggest you contact your local ST sales representative for a quote for ST25R95.
Regarding the field detection, it can be used either through the PollField command or through the Idle command. The main use case is for Card Emulation: you can enter low power sleep mode thanks to the Idle command and then as soon as the field is detected, the device exits the sleep mode and can be set to card emulation mode.
Rgds
BT
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