NXP Semiconductors
UM11227
NTM88 family of tire pressure monitor sensors
UM11227 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 6 — 24 April 2020
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• VCO Calibration Machine
– Automatic Calibration with every power up sequence
– Possible to override of calibration result by writing directly to sub-band register
• Power Up/Dn state machine
– Automatic power up/down sequencer
– Manual control available
• Register Map
– Fully accessible read/write 8-bit wide register map
– Protected register space for non-user functionality
• TX Buffer
– 32 byte / 256 bit Transmit buffer
– End of transmission Interrupt
– Encodes and assembles data stream for transmission (Manchester, Bi-Phase, NRZ)
CRYSTAL
OSCILLATOR
CONTROL
REGISTERS
AND LOGIC
RF
AMP
VCO
XI
XO
PHASE
DETECTOR
RF
LOW-PASS
FILTER
FRACTIONAL-N
DIVIDER
256-BIT
DATA BUFFER
MODULATION
CONTROL
RF
STATE
MACHINE
MCU
AVDD
aaa-028030
AVSS
VREG
RINT
LFSR
RANDOM
GEN
MFO
DX
500 kHz
VOLT
REG
RF
AVDD
RF
LVD
Figure 29. Radio frequency module block diagram
10.16.1 RF data modes
There are two modes of operation in using the RF output in either the data buffer mode
or MCU direct mode.
10.16.1.1 RF data buffer mode
In the RF data buffer mode the transmissions are sent by dedicated logic hardware while
the MCU can be put into a low power mode until the transmission is completed. This RF
state machine is clocked by the MFO which is enabled when the SEND bit is set and
when any of the LFR, SMI or MCU are operating.
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