NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
COMP
VOLT
Comp
Voltage
COMP_VOLTAGE
Input Raw Voltage
Raw
RAW
VOLT
READ_VOLTAGE
Voltage
COMP
TEMP
Comp
Temperature
COMP_TEMPERATURE
Input Raw Temperature
Raw
RAW
TEMP
READ_TEMPERATURE
READ_PRESSURE
Temperature
COMP
PRESS
Comp
Pressure
COMP_PRESSURE
Input Raw Pressure
Input Raw Voltage
RAW
PRESS
Input Raw Temperature
Raw
Pressure
Comp Z
Acceleration
COMP Z
ACCEL
COMP_Z_ACCELERATION
Input Raw Z Acceleration
Input Raw Voltage
RAW Z
ACCEL
READ_Z_ACCELERATION
Input Raw Temperature
Raw Z
Acceleration
Universal Uncompensated
Measurement Array (UUMA)
CALL
RESULTS
0 - Voltage (16-bit)
1 - Temperature (16-bit)
2 - Pressure (16-bit)
3 - Z Acceleration (16-bit)
aaa-026795
Figure 22.ꢀData flow for measurements
12.7 Thermal shutdown
When the package temperature becomes too low or too high the MCU can be placed
into a STOP mode to suspend operation and prevent transmission of RF signals which
may be corrupted at the temperature extremes. Return to normal operation after the
temperature falls back within the recovery temperature range. The presence of either the
low or high temperature shutdown will disable the PWU from causing either a periodic
wakeup or a periodic reset. The MCU, temperature sensor and ADC10 are all functional
over the full temperature range from TL to TH.
12.7.1 Low temperature shutdown
Low temperature shutdown is achieved using temperature readings taken by the ADC10
as described in Section 12.2 "Temperature measurements" and enabling the thermal
restart circuit by setting the TRE bit and selecting the low temperature threshold by
clearing the TRH bit. When the software programmed low temperature is reached the
MCU will turn off all operating functions and enter the STOP1 mode.
12.7.2 High temperature shutdown
The high temperature shutdown level is determined from a measurement of the
temperature sensor by the ADC10 as described in Section 12.2 "Temperature
measurements" and enabling the thermal restart circuit by setting the TRE bit and
selecting the high temperature threshold by setting the TRH bit. When the software
FXTH87ERM
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© NXP B.V. 2019. All rights reserved.
Reference manual
Rev. 5.0 — 4 February 2019
104 / 183
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