Product Info

LTE Module Series
EG61-NA Hardware Design
EG61-NA_Hardware_Design 32 / 77
3.6.2. Decrease Voltage Drop
The power supply range of the module is from 3.3Vto4.3V. Please make sure thatthe input voltage will
never drop below 3.3V. The following figure shows the voltage drop during burst transmission in 2G
network.The voltage drop will be less in 3G and 4G networks.
VBAT
Min.3.3V
Ripple
Drop
Burst
Transmission
Burst
Transmission
Figure 7: Power Supply Limits during Burst Transmission
To decrease voltage drop, a bypass capacitor of about 100µF with low ESR(ESR=0.7Ω) should be used,
and amulti-layer ceramic chip (MLCC) capacitor array should also be reserved due to its ultra-low ESR. It
is recommended to usethree ceramic capacitors (100nF, 33pF, 10pF)for composing the MLCC array, and
place these capacitors close to VBAT_BB/VBAT_RF pins. The main power supply from an external
application has to be a single voltage source and can be expanded to two sub paths with star structure.
The width of VBAT_BB trace should be no less than 1mm, andthe width of VBAT_RF trace should be no
less than 2mm.In principle, the longerthe VBAT trace is, the wider it will be.
In addition, in order to get a stable power source,it is recommended to use a TVS diode of Model
WS4.5D3HV. The following figure shows the star structure of the power supply.
Module
VBAT_RF
VBAT_BB
VBAT
C1
100uF
C6
100nF
C7
33pF
C8
10pF
+
+
C2
100nF
C5
100uF
C3
33pF
C4
10pF
D1
Figure 8: Star Structure of the Power Supply