Datasheet

PN532_C1 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.6 — 28 November 2017
115436 113 of 222
NXP Semiconductors
PN532/C1
Near Field Communication (NFC) controller
8.6.7 Transmitter control
The signals delivered by the transmitter are on pins TX1 and pin TX2. The supply and
grounds of the transmitter drivers are TVDD, TVSS1 and TVSS2.
The signals delivered are the 13.56 MHz energy carrier modulated by an envelope signal.
It can be used to drive an antenna directly, using a few passive components for matching
and filtering, see Section 13 “
Application information” on page 212. The signals on TX1
and TX2 can be configured by the register CIU_TxControl, see Table 212 on page 160
.
The modulation index can be set by adjusting the impedance of the drivers. The
impedance of the p-driver can be configured by the registers CIU_CWGsP and
CIU_ModGsP. The impedance of the n-driver can be configured by the registers
CIU_GsNOn and CIU_GsNOff. Furthermore, the modulation index depends on the
antenna design and tuning.
Remark: It is recommended to use a modulation index in the range of 8% for the FeliCa
and NFCIP-1 communication scheme at 212 and 424 kbit/s.
The registers CIU_TxMode and CIU_TxAuto control the data rate and framing during the
transmission and the setting of the antenna driver to support the different requirements at
the different modes and transfer speeds.
In the following tables, these abbreviations are used:
• RF: 13. 56 MHz clock derived from 27.12 MHz quartz divided by 2
• RF_n: inverted 13.56 MHz clock
• GsPMos: Conductance of the transmitter PMOS
• GsNMos: Conductance of the transmitter NMOS
• CWGsP: PMOS conductance value for Continuous Wave (see Table 249 on
page 177)
• ModGsP: refers to ModGsP[5:0], PMOS conductance value for Modulation (see
Table 250 on page 177
)
• CWGsNOn: refers to CWGsP[5:0], NMOS conductance value for Continuous Wave
(see Table 247 on page 176
)
• ModGsNOn: NMOS conductance value for Modulation when generating RF field (see
Table 247 on page 176
)
• CWGsNOff: NMOS conductance value for Continuous Wave when no RF is
generated by the PN532 itself (see Table 239 on page 172
)
• ModGsNOff: NMOS conductance value for modulation when load Modulation (see
Table 239 on page 172
)
Remark: If only 1 driver is switched on, the values for ModGsNOn and CWGsNOn are
used for both drivers.