SC20-W_Manual_R1.0 Confidential / Released 18 / 41
A reference design for battery charging circuit is shown as below.
GND
VBAT_SNS
VBAT_THERM
VBAT
0R
100uF
NTC
VBAT
1uF
ESD
ESD
1
2
3
USB_VBUS
Adapter or USB
Module
Battery
GND
C1
C2
R1
D1
D2
Figure 9: Reference Design for Battery Charging Circuit
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 a
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 with
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/discharging issues.
3.8.
USB Interface
SC20-W contains one integrated Universal Serial Bus (USB) transceiver which complies with the USB 2.0
specification and supports high speed (480 Mbps) and full speed (12 Mbps) modes. The USB interface is
used for AT command communication, data transmission, software debugging and firmware upgrade.