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
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Mobile devices such as mobile phones and handheld POS systems are powered by batteries. When
different batteries are utilized, the charging and discharging curve has to be modified correspondingly so
as to achieve the best effect.
If thermistor is not available in the battery, or adapter is utilized for powering module, then there is only
need for VBAT and GND connection. In this case, the system may mistakenly judge that the battery
temperature is abnormal, which will cause battery charging failure. In order to avoid this, VBAT_THERM
should be connected to GND via a 47KΩ resistor. If VBAT_THERM is unconnected, the system will be
unable to detect the battery, making battery cannot be charged.
VBAT_SNS pin must be connected. Otherwise, the module will have abnormalities in voltage detection,
as well as associated power on/off and battery charging and discharging issues.
3.9. USB Interface
SC20 contains one integrated Universal Serial Bus (USB) interface which complies with the USB 2.0
specification and supports high speed (480Mbps) and full speed (12Mbps) modes. The USB interface is
used for AT command communication, data transmission, software debugging and firmware upgrade.
The following table shows the pin definition of USB interface.
Table 10: Pin Definition of USB Interface
Pin Name
Pin No.
I/O
Description
Comment
USB_VBUS
141, 142
PI
USB power supply
4.35V~6.3V.
Typical 5.0V.
USB_DM
13
IO
USB differential data bus (minus)
Require differential
impedance of 90Ω
USB_DP
14
IO
USB differential data bus (plus)
USB_ID
16
AI
USB ID detection
High level by default
USB_VBUS can be powered by USB power or adapter. It can also be used for detecting USB connection,
as well as for battery charging via the internal PMU. The input voltage of power supply ranges from 4.35
to 6.3V, and the typical value is 5V. SC20 module supports charging management for a single Li-ion
battery, but varied charging parameters should be set for batteries with varied models or capacities. The
module is available a built-in linear-charging circuit which supports maximally 1.44A charging current.
The following are two USB interface reference designs for customers to choose from.