NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
• nVOLT = Total number of voltage measurements over lifetime
18.3 Transmission events
The overall charge consumed by the transmissions is:
(15)
where:
• QXMT = Transmit charge over lifetime, tTOT, in mA-hr
• QFRM = Transmit charge per frame of data in μA-sec
• nXMT = Number of transmissions over lifetime
• F = Frames transmitted during each datagram
18.4 Total consumption
The overall charge consumed is:
(16)
where:
• QTOT = Total charge over lifetime, tTOT, in mA-hr
• QSTDBY = Standby charge over lifetime in mA-hr
• QMEAS = Measurement charge over lifetime in mA-hr
• QXMT = Transmit charge over lifetime in mA-hr
• Y = Lifetime in years
• SD = Battery self-discharge rate in %/year
Additional margin in battery capacity can be added to the calculated value of QTOT
.
FXTH87ERM
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Reference manual
Rev. 5.0 — 4 February 2019
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