Smart Module Series
SC690A_Series_Hardware_Design 37 / 105
The module supports battery temperature detection in the condition that the battery integrates a
thermistor (10 k
Ω 1 % NTC thermistor with a B-constant of 4050 by default; and the thermistor is
connected to BAT_THERM pin, or there will be malfunctions such as battery charging failure, battery
level display error, etc.
A reference design for the battery charging circuit is shown below.
GND
BAT_P
BAT_THERM
VBAT
TEMP
VBAT
1
2
3
USB_VBUS
Adapter or USB
Module
Battery
GND
C1
C2
C3
R1
D1
D2
BAT_M
0 R
0 R
R2
33 pF
R3
N
M
_
1
0
K
22
μ
F
1
μ
F
Figure 3: 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 must be modified correspondingly to
achieve the best effect.
If the thermistor is not available in the battery, or an adapter is utilized for powering the module, then
there is only a need for connecting VBAT and GND. In this case, the system may mistakenly judge that
VBAT
36, 37,
38
PIO
Power supply for the
module
It must be able to provide sufficient
current up to 3.0 A.
It is suggested to use a TVS to
increase voltage surge withstand
capability.
BAT_P
27
AI
Battery voltage detect (+)
Cannot be kept open.
BAT_M
28
AI
Battery voltage detect (-)
Cannot be kept open.
BAT_THERM
29
AI
Battery temperature detect
Internally pulled up.
Externally connected to GND via a
10 k
Ω NTC resistor.
Maximum input voltage: 1.875 V.
BAT_ID
17
AI
Battery type detect
Maximum input voltage: 1.875 V.
If unused, keep this pin open.
