User Guide

LM960 HW Design Guide
1VV0301485 Rev. 15 Page 36 of 88 2020-08-13
4.3.1.1. + 5V Input Source Power Supply – Design Guidelines
 The desired output for the power supply is 3.3V. Being the difference between the
input source and the desired output moderate, a linear regulator can be used. A
switching power supply is preferred to reduce power consumption.
 When using a linear regulator, a proper heat sink must be provided to dissipate the
power generated.
 A bypass low ESR capacitor of adequate capacity must be provided to cut the
current absorption peaks close to the LM960 module. A 100 μF tantalum capacitor
is usually suitable on VBATT.
 Make sure that the low ESR capacitor on the power supply output (usually a
tantalum one) is rated at least 10V.
 A protection diode must be inserted close to the power input to protect the LM960
module from power polarity inversion.
4.3.2. 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 LM960
as shown in Section 4.2, Power Consumption table.
Information – The average consumption during transmission depends
on the power level at which the device is requested to transmit via the
network.
Therefore, the average current consumption varies significantly.
Information – The thermal design for the power supply must be made
keeping an average consumption at the maximum transmitting level
during calls of LTE/HSPA.
Considering the very low current during Idle, especially if the Power Saving function is
enabled, it is possible to consider from the thermal point of view that the device absorbs
significant current only during Data transfer sessions.