BQ24725A_17 Datasheet, PDF (36/47 Pages) Texas Instruments – 1-4 Cell Li+ Battery SMBus Charge Controller with N-Channel Power MOSFET Selector and Advanced Circuit Protection

bq24725A
SLUSAL0A – SEPTEMBER 2011 – REVISED AUGUST 2014
System Examples (continued)
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Adapter +
Adapter -
Din _*
BAT54A
Q1 (ACFET)
FDS6680A
C17
2200pF
C16
0.047µF
Q2 (RBFET)
FDS6680A ^{RAC 10 mW}
C1
0.1 µF
C3
0.1µF
R10
4.02 kW
R11
4.02 kW
C2
0.1µF
ACN
ACP
VCC
BATDRV
R1
430 kW
R2
487 kW
+3.3V
HOST SMBus
Dig I/O
CMSRC
REGN
ACDRV
ACDET
BTST
R8
100 kW
ILIM
R7
549 kW
HIDRV
U1
bq24725A ^PHASE
R3
R4
10 kW 10 kW
R5
10 kW
SDA
LODRV
GND
SCL
ACOK
SRP
ADC
C4
100 pF
IOUT
PowerPad ^SRN
R9
4.7 W
C5
1µF
C6
1µF
D1
BAT54
C7
0.047µF
R6
4.02 kW
R12
100 kW
* ^Total
Csys
220 µF
Q5 (BATFET)
Si4435DDY
D2
SL42
SYSTEM
C8
10uF
Q3
Sis412DN
C9
10uF
RSR
10 mW
L1
4.7µH
Q4
Sis412DN
C10 C11
10 µF 10 µF
Pack +
Pack -
R14 _*
10 W
R15 _*
7.5 W
C13
0.1µF
C14
0.1µF
F_s = 750kHz, I_ADPT = 2.048A, I_CHRG = 1.984A, I_LIM = 2.54A, V_CHRG = 4.200V, 12W adapter and 1S2P battery pack
Use 0Ω for better current sensing accuracy, use 10Ω/7.5Ω resistor for reversely battery connection protection. See
application information about negative output voltage protection for hard shorts on battery to ground or battery
reversely connection.
The total Csys is the total lump sum of system capacitance. It is not required by charger IC. Use Din for reverse input
voltage protection. See application information about reverse input voltage protection.
Figure 26. Typical System Schematic for 5V Input 1S Battery
10 Power Supply Recommendations
When adapter is attached, and ACOK goes HIGH, the system is connected to adapter through ACFET/RBFET.
An external resistor voltage divider attenuates the adapter voltage before it goes to ACDET. The adapter detect
threshold should typically be programmed to a value greater than the maximum battery voltage, but lower than
the IC maximum allowed input voltage and system maximum allowed voltage.
When adapter is removed, the system is connected to battery through BATFET. Typically the battery depletion
threshold should be greater than the minimum system voltage so that the battery capacity can be fully utilized for
maximum battery life.
36
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