Smart LTE Module Series
SC66 Hardware Design
SC66_Hardware_Design 51 / 139
GND
BAT_THERM
VBAT
100uF
NTC
VBAT
33pF
1uF
ESD
USB _VBUS
Adapter or USB
Module
Battery
C1
C2
C3
D1
D2
BAT_PLUS
ESD
BAT_MINUS
GND
NM
GND
BAT_THERM
VBAT
100 uF
NTC
VBAT
33pF
1uF
ESD
USB _ VBUS
Adapter or USB
Module
Battery
C1
C2
C3
D1
D 2
BAT_PLUS
ESD
BAT_MINUS
GND
NM
Figure 12: Reference Design for Battery Charging Circuit
SC66 offers a fuel gauge algorithm that is able to accurately estimate the battery’s state by current and
voltage monitor techniques. Using precise measurements of battery voltage, current, and temperature,
the fuel gauge provides a dependable state of charge estimate throughout the entire life of the battery and
across a broad range of operating conditions. It effectively protects the battery from over-discharging, and
also allows users to estimate the battery life based on the battery level so as to timely save important data
before completely power-down.
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 the module, then there is only
a need for VBAT and GND connection. In this case, the system may be unable to detect the battery,
which will cause power-on failure. In order to avoid this, VBAT_THERM should be connected to GND with
a 47KΩ resistor. BAT_PLUS and BAT_MINUS must be connected, otherwise there may be abnormalities
