NXP Semiconductors UM11227 - Battery Charge Consumption Modeling; Standby Current; Measurement Events

NXP Semiconductors
UM11227
NTM88 family of tire pressure monitor sensors
UM11227 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 6 — 24 April 2020
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READ_Z_ACCELERATION
READ_PRESSURE
READ_TEMPERATURE
READ_VOLTAGE
CALL
RESULTS
Universal Uncompensated
Measurement Array (UUMA)
aaa-026795
COMP Z
ACCEL
RAW Z
ACCEL
RAW
TEMP
RAW
VOLT
COMP
PRESS
COMP
TEMP
COMP
VOLT
RAW
PRESS
0 - Voltage (16-bit)
1 - Temperature (16-bit)
2 - Pressure (16-bit)
3 - Z Acceleration (16-bit)
Comp
Temperature
Comp
Pressure
Raw
Pressure
Comp Z
Acceleration
Raw Z
Acceleration
Comp
Voltage
Raw
Voltage
Raw
Temperature
COMP_PRESSURE
Input Raw Pressure
Input Raw Voltage
Input Raw Temperature
COMP_Z_ACCELERATION
Input Raw Z Acceleration
Input Raw Voltage
Input Raw Temperature
COMP_VOLTAGE
Input Raw Voltage
COMP_TEMPERATURE
Input Raw Temperature
Figure 59. Example single axis accelerometer data flow for measurements
10.27 Battery charge consumption modeling
The supply current consumed by the NTM88 can be estimated using the following basic
model.
10.27.1 Standby current
The overall charge consumed by the standby features is:
(11)
Where:
Q
STDBY
= Standby charge over lifetime, t
TOT
, in mA-hr
t
TOT
= Total lifetime in hours
I
STDBY
= General standby current in μA
I
LF
= LFR detector (if used) current in μA
10.27.2 Measurement events
The overall charge consumed by the measurements is:
(12)