Product Info

Smart LTE Module Series
SC20 Hardware Design
SC20_Hardware_Design 41 / 130
Large
Capacitance
Capacitor
Module
RTC
Core
VRTC
C
Figure 11: RTC Powered by Capacitor
If RTC is ineffective, it can be synchronized through network after the module is powered on.
⚫ 2.0V~3.25V input voltage range and 3.0V typical value for VRTC. When VBAT is disconnected, the
average consumption is about 5uA.
⚫ When powered by VBAT, the RTC error is 50ppm. When powered by VRTC, the RTC error is
200ppm.
⚫ If the rechargeable battery is used, the ESR of the battery should be less than 2K, and it is
recommended to use the MS621FE FL11E of SEIKO.
⚫ If large capacitance capacitor is selected, it is recommended to use a 100uF capacitor with low ESR.
The capacitor will be able to power the real-time clock for 45 seconds.
3.7. Power Output
SC20 supports output of regulated voltages for peripheral circuits. During application, it is recommended
to use parallel capacitors (33pF and 10pF) in the circuit to suppress high frequency noise.
Table 9: Power Description
Pin Name
Default Voltage (V)
Driving Current (mA)
IDLE
LDO5_1V8
1.8
20
KEEP
LDO6_1V8
1.8
100
/
LDO17_2V85
2.85
300
/
SD_LDO12
2.95
50
/
SD_LDO11
2.95
600
/
USIM1_VDD
1.80/2.95
50
USIM2_VDD
1.80/2.95
50