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Carrier Board Design Guide for SOM-9X35 Module
70
4.17.2
Gas Gauge Design Notes
•
The Gas gauge sensor and calculation circuit is already included by the PMU on the SOM-9X35
module. If using a lithium-ion battery, an external circuit must be reserved for the battery current
sensor and single battery voltage circuit. The battery voltage must be isolated by the P Channel MOS
FET to prevent power leakage.
VPACK+
VBAT1
EN_MAIN_PWR
[5,16,19]
Q58
SM2313PSAC-TRG
-20V
-3.5A
G
D
S
R629
1M_1%
Q59
LMBT3904TT1G
1
2
3
R631
0/X
R628
470K
Figure 86: SOM-9X35 battery leakage protect reference circuitry
2-Cell Ba
�
ery Wafer
VPACK+
CS_P
[5]
CS_N
[5]
R242
0/X
t
RT1
NCP15WF104F03RC
100K OHM ±1%
NTC
ESD44
TLSD05CBL/X
5V
5pF
1
2
VPACK+1
1
R252
0.01_0.5%
ESD43
AESD24CB
24V
13PF
1
2
NTC_BAT1
1
R253
0
C345
1000pF
50V
X7R
C355
1000pF/X
50V
X7R
J17
2417SJ-07-F3
1
2
3
4
5
6
7
R241
0/X
VPACK-1
1
R250
0
R693
100K_1%
VPACK-
NTC_BAT
NTC1_BAT
NTC_CHG
Figure 87: SOM-9X35 gas gauge current sense reference circuitry