NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
FXTH87ERM
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© NXP B.V. 2019. All rights reserved.
Reference manual
Rev. 5.0 — 4 February 2019
113 / 183
AMP1
LFA
LFB
BUFF1
AMP2
DATA SLICER
BUFF2
AMP3
BUFF3
Vref_sensitivity
aaa-028019
SENSITIVITY
CARRIER
DETECTOR
CLAMP
R
V
RECTIFIER0
RECTIFIER1
RECTIFIER2
SUMMATOR
AVERAGE
FILTER
RECTIFIER3
LOGIC BLOCK 2
· DATA DECODING
129 kHz
typ
1 kHz_clock typ
LOGIC BLOCK 1
· ON/OFF CYCLING
· CARRIER DETECTION
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.
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