Product Info
Table Of Contents
- About the Document
- Contents
- Table Index
- Figure Index
- 1Introduction
- 2Product Concept
- 3Application Interfaces
- 3.1.General Description
- 3.2.Pin Assignment
- 3.3.Pin Description
- 3.4.Power Supply
- 3.5.Turn on and off Scenarios
- 3.6.VRTC Interface
- 3.7.Power Output
- 3.8.Battery Charge and Management
- 3.9.USB Interface
- 3.10.UART Interfaces
- 3.11.(U)SIM Interfaces
- 3.12.SD Card Interface
- 3.13.GPIO Interfaces
- 3.14.I2C Interfaces
- 3.15.ADC Interfaces
- 3.16.Motor Drive Interface
- 3.17.LCM Interface
- 3.18.Touch Panel Interface
- 3.19.Camera Interfaces
- 3.20.Sensor Interfaces
- 3.21.Audio Interfaces
- 3.22.Emergency Download Interface
- 4Wi-Fi and BT
- 5GNSS
- 6Antenna Interface
- 7Electrical, Reliability and Radio Characteristics
- 8Mechanical Dimensions
- 9Storage, Manufacturing and Packaging
- 10Appendix A References
- 11Appendix B GPRS Coding Schemes
- 12Appendix C GPRS Multi-slot Classes
- 13Appendix D EDGE Modulation and Coding Schemes
Smart LTE Module Series
SC20 Hardware Design
SC20_Hardware_Design Confidential / Released
3-40
/ 122
USIM2_VDD
1.750~3.337
1.80/2.95
50
3.8. Battery Charge and Management
SC20 module can recharge batteries. The battery charger in SC20 module supports trickle charging,
constant current charging and constant voltage charging modes, which optimize the charging procedure
for Li-ion batteries.
Trickle charging: There are two steps in this mode. When the battery voltage is below 2.8V, a 90mA
trickle charging current is applied to the battery. When the battery voltage is charged up and is
between 2.8V and 3.2V, the charging current can be set to 450mA maximally.
Constant current mode (CC mode): When the battery is increased to between 3.2V and 4.2V, the
system will switch to CC mode. The maximum charging current is 1.44A when adapter is used for
battery charging; and the maximum charging current is 450mA while USB charging.
Constant voltage mode (CV mode): When the battery voltage reaches the final value 4.2V, the
system will switch to CV mode and the charging current will decrease gradually. When the battery
level reaches 100%, the charging is completed.
SC20 module supports battery temperature detection in the condition that the battery integrates a
thermistor (47K 1% NTC thermistor with B-constant of 4050K by default; SDNT1608X473F4050FTF of
SUNLORD is recommended) and the thermistor is connected to VBAT_THERM pin. The default battery
temperature range is -3.0°C~48.5°C. If VBAT_THERM pin is not connected, there will be malfunctions
such as battery charging failure, battery level display error, etc.
A reference design for battery charging circuit is shown as below.
Figure 12: Reference Design for Battery Charging Circuit