ST25R3916 datasheet(38/157 Pages) STMICROELECTRONICS

38 / 157 page

Application information

ST25R3916/7

38/157

DS12484 Rev 4

Figure 9. Phase detector inputs and output in case of 90º phase shift

Figure 10. Phase detector inputs and output in case of 135º phase shift

Amplitude detector

Signals from pins RFI1 and RFI2 are used as inputs to the self-mixing stage. The output of

this stage is a DC voltage proportional to the amplitude of signals on pins RFI1 and RFI2.

During execution of direct command Measure amplitude this output is multiplexed to the A/D

converter input.

4.2.10

External field detector

This block is used to detect the presence of an external device generating an RF field. It is

used in NFCIP-1 Active communication and Passive target modes. It is enabled by

en_fd_c<1:0> option bits. The external field detector supports two different detection

thresholds, namely Peer detection and Collision avoidance. The two thresholds can be

independently set by writing the External field detector activation threshold register. The

actual state of the detector output can be checked by reading the Auxiliary display register.

Input to this block is the signal from the RFI1 pin.

For both thresholds there is a possibility to separately set the activation and deactivation

levels.

MS42426V1

VSP_A

VSP_A/2

Input 1

Input 2

Output

MS42427V1

VSP_A

VSP_A/2

Input 1

Input 2

Output

ST25R3916 Datasheet(PDF) 38 Page - STMicroelectronics