Service Guide
Table Of Contents
- Safety Information
- About the Document
- Contents
- Table Index
- Figure Index
- 1 Introduction
- 2 Product Overview
- 3 Operating Characteristics
- 4 Application Interfaces
- 5 Antenna Interfaces
- 6 Reliability, Radio, and Electrical Characteristics
- 7 Mechanical Information
- 8 Storage, Manufacturing, and Packaging
- 9 Appendix References
LTE Standard Module Series
EG915U_Series_Hardware_Design 34 / 90
VBAT
Burst
Transmission
Ripple
Drop
Burst
Transmission
Figure 8: Power Supply Limits during Burst Transmission
To decrease the voltage drop, use bypass capacitors of about 100 µF with low ESR (ESR = 0.7 Ω) and
reserve a multi-layer ceramic chip (MLCC) capacitor array due to their ultra-low ESR. It is recommended
to use three ceramic capacitors (100 nF, 33 pF, 10 pF) for composing the MLCC array, and place these
capacitors close to the VBAT_BB and VBAT_RF pins. When the external power supply is connected to
the module, VBAT_BB and VBAT_RF need to be routed in star structure. The width of the VBAT_BB trace
should not be less than 2 mm and VBAT_RF trace should not be less than 2.5 mm.
In addition, to avoid the surge, use a TVS diode of which reverse working voltage is 4.7 V and peak pulse
power is up to 2550 W. The reference circuit is shown as below.
Module
VBAT_RF
VBAT_BB
VBAT
C1
100 µF
C6
100 nF
C7
33 pF
C8
10 pF
+
+
C2
100 nF
C5
100
µ
F
C3
33 pF
C4
10 pF
D1
WS4.5D3HV
Figure 9: Power Supply