NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
DATA SLICER
SUMMATOR
AVERAGE
FILTER
CLAMP
R
RECTIFIER0
RECTIFIER1
RECTIFIER2
RECTIFIER3
V
AMP1
BUFF1
AMP2
BUFF2
AMP3
BUFF3
LFA
LFB
SENSITIVITY
Vref_sensitivity
CARRIER
DETECTOR
LOGIC BLOCK 1
· ON/OFF CYCLING
129 kHz
typ
LOGIC BLOCK 2
· DATA DECODING
· CARRIER DETECTION
1 kHz_clock typ
aaa-028019
Figure 26.ꢀBlock diagram
For definitions of the acronyms and detailed descriptions of the bits and/or byte registers,
please refer to Section 14.17 "LFR register definition".
14.1 Features
Major features of the LFR module include:
• Differential input LF detector (two dedicated pins):
– Selectable sensitivity (two levels: Low Sens (LS) and High Sens (HS)).
– Thresholds trimmed at the factory with trim setting saved in nonvolatile memory.
– LFR has a reference oscillator (LFRO) trimmed at the factory with trim setting saved
in nonvolatile memory.
– Selectable signal sampling time interval and on-time.
– Sample interval and on times controlled by LFR state machine or directly by the
MCU.
• Configurable receive mode:
– Simple LF carrier detection/Telegram decode. (CARMOD)
• Configurable message protocol (telegram structure):
– Various SYNC decoding (SYNC[1:0])
6-bit time SYNC requirements
7.5-bit time SYNC requirements
9-bit time SYNC requirements
– Optional ID (ID[1:0])
8-bit or 16-bit ID
On or off
– 0-n bytes of message data. End-of-data marked by loss of Manchester at a byte
boundary.
FXTH87ERM
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2019. All rights reserved.
Reference manual
Rev. 5.0 — 4 February 2019
113 / 183
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