User's Guide

LE920A4 HW User Guide Power Supply
Doc#: 1VV0301261 General Design Rules
Rev. 4.7.1 Page 59 of 124 2019-11-21
6.2.1.3. Battery Source Power Supply Design Guidelines
 The desired nominal output of the power supply is 3.8V, and the maximum allowed
voltage is 4.2V. Hence, a single 3.7V Li-Ion cell battery type is suitable for
powering the module.
WARNING:
Do not use any Ni-Cd, Ni-MH, and Pb battery types directly connected to the
module. Their use can lead to overvoltage on the module and damage it.
Use only Li-Ion battery types.
 A bypass low ESR capacitor of adequate capacity must be provided to cut the
current absorption peaks; a 100μF tantalum capacitor is usually suitable (on both
VBATT and VBATT_PA together).
 Make sure the low ESR capacitor (usually a tantalum one) is rated at least 10V.
 A protection diode must be inserted close to the power input to protect the module
from power polarity inversion. Otherwise, the battery connector must be designed
to avoid polarity inversions when connecting the battery.
 The battery capacity must be at least 500mAh to withstand the current peaks of
2A.
6.2.2. Thermal Design Guidelines
The thermal design for the power supply heat sink must be done with the following
specifications:
 Average current consumption during RF transmission @PWR level max in the
module as shown in Section 6.1, Power Supply Requirements
 Average current consumption during Class12 GPRS transmission for LE920A4-EU
and LE920A4-CN variants / Class10 GPRS transmission for LE920A4-NA @PWR
level max as shown in Section 6.1, Power Supply Requirements
 Average GPS current during GPS ON (Power Saving disabled) : 45 mA
NOTE:
The average consumption during transmissions depends on the power level
at which the device has to transmit via the network. The average current
consumption hence varies significantly.