Smart Module Series
SC200L_Series(Dual-band Wi-Fi)_Hardware_Design 39 / 111
A reference design for battery charging circuit is shown as below.
GND
BAT_SNS
BAT_THERM
VBAT
0R
22
μ
F
NTC
VBAT
33 pF
1
μ
F
ESD
ESD
1
2
3
USB_VBUS
Adapter or USB
SC200L
Battery
GND
C1
C2
C3
R1
D1
D2
CS_P
CS_M
R2
20 m
Ω
R3
47K 1%
LDO1_1V85
Figure 10: Reference Design for Battery Charging Circuit
Mobile devices such as mobile phones and handheld POS systems are powered by batteries. For
different batteries, you need to modify the charging and discharging curve correspondingly to achieve the
best performance.
If the thermistor is not available in the battery, or an adapter is utilized for powering the module, you must
connect BAT_THERM to GND via a 10 k
Ω resistor. Otherwise, the system may misjudge that the battery
temperature is abnormal, and therefore causes battery charging failure.
BAT_SNS must be connected. Otherwise, the module will have trouble in voltage detection, as well as
associated module power-on/off issues and battery charging/discharging issues.
The module supports current sensing fuel gauge by default, and conducts current sampling through a
20 mΩ sampling resistor R2.
3.8. USB Interfaces
The module contains two integrated Universal Serial Bus interfaces which comply with the USB 2.0
specification. The USB1 interface supports high-speed (480 Mbps) and full-speed (12 Mbps) modes. It
supports USB OTG mode but does not support USB hub. The USB1 interface is used for AT command
communication, data transmission, software debugging and firmware upgrade. The USB2 interface
supports USB host mode only and supports USB hub. The maximum rate is 100 Mbps.