NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
by the firmware to the application software as either the raw ADC10 result or further
compensated and scaled for an output between one and the maximum digital value
minus one. The minimum digital value of zero and the maximum digital value are
reserved as error codes.
The signal ranges and their significant data points are shown in Figure 48. In this
definition the signal source would normally output a signal between SINLO and SINHI
.
Due to process, temperature and voltage variations this signal may increase its range
to SINMIN to SINMAX. In all cases the signal will be between the supply rails, so that the
ADC10 will convert it to a range of digital numbers between 0 and 1023. These digital
numbers will have corresponding DINMIN, DINLO, DINHI, DINMAX values. The ADC10 digital
value is taken by the firmware and compensated and scaled to give the required output
code range.
UPPER ERROR CASE
FORCE
OUTPUT
TO 511
OVERFLOW
VDD
1023
511
510
CASE
SINMAX
SINHI
DINMAX
DINHI
NORMAL CASE
VDD/2
512
256
SIGNAL
SOURCE
FIRMWARE
ROUTINE
ADC10
SENSOR
ANALOG
VOLTAGE
ADC10 RAW
DIGITAL
(10-BIT CONVERSION)
CALCULATED
DIGITAL
(9-BIT EXAMPLE)
SINLO
DINLO
SINMIN
DINMIN
1
0
VDD
0
UNDERFLOW
CASE
FORCE
OUTPUT
TO ZERO
LOWER ERROR CASE
aaa-028041
Figure 48.ꢀMeasurement signal range definitions
Digital input values below DINMIN and above DINMAX are immediately flagged as being out
of range and generate error bits and the output is forced to the 0 value.
Digital values below DINLO (but above DINMIN) or above DINHI (but not DINMAX) will most
likely cause an output that would be less than 1 or greater than 510, respectively. These
cases are considered underflow or overflow, respectively. Underflow results will be forced
to a value of 1. Overflow results will be forced to a value of 510.
Digital values between DINLO and DINHI will normally produce an output between 1 to
510 (for a 9-bit result). In some isolated cases due to compensation calculations and
rounding the result may be less than 1 or greater than 510, in which case the underflow
and overflow rule mentioned above is used.
FXTH87ERM
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© NXP B.V. 2019. All rights reserved.
Reference manual
Rev. 5.0 — 4 February 2019
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