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FIBOCOM SU806 Series Hardware Guide
Page 28 of 91
VBAT
Module
VBAT
6.
8pF
8.
2pF
18
pF
33
pF
39
pF
100
nF
1uF
220
uF
220
uF
+
+
Figure 3-2 Power supply reference design
Table 3-2 Power supply decoupling capacitor design
Recommended Capacitor
Application
Description
220uF x 2
Voltage stabilizing
capacitor
To reduce power fluctuations during module
operation, it is required to adopt low ESR
capacitor
LDO or DCDC power requires not less than
440uF capacitor
Battery power can be properly reduced to
100 - 220uF capacitor
1uF,100nF
Filter capacitor
Filter clock and digital signal interference
39pF,33pF,18pF,8.2pF,6.8pF
Filter capacitor
Filter high frequency interference
3.1.2 VRTC
VRTC is the power supply of the internal RTC clock of the module. When VBAT no power supply, the real
time clock is not correct, it is recommended to update system clock from network. The VRTC parameters
are as follows:
Table 3-3 VRTC parameters
Parameter
Minimum
Typical
Maximum
Unit
VRTC output voltage
-
3.0
3.35
V
