BQ24751RHDRG4 Datasheet, PDF (2/38 Pages) Texas Instruments – Host-controlled Multi-chemistry Battery Charger

bq24751
SLUS734D – DECEMBER 2006 – REVISED MARCH 2009............................................................................................................................................... www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (CONTINUED)
The bq24751 controls external switches to prevent battery discharge back to the input, connect the adapter to
the system, and to connect the battery to the system using 6-V gate drives for better system efficiency. For
maximum system safety, inrush-power limiting provides instantaneous response to high input voltage multiplied
by current. This AC Over-Power protection (ACOP) feature limits the input-switch power to the programmed level
on the ACOP pin, and latches off if the high-power condition persists to prevent overheating.
The bq24751 features Dynamic Power Management (DPM) and input power limiting. These features reduce
battery charge current when the input power limit is reached to avoid overloading the AC adapter when supplying
the load and the battery charger simultaneously. A highly-accurate current-sense amplifier enables precise
measurement of input current from the AC adapter to monitor the overall system power.
ADAPTER +
ADAPTER -
ACGOOD
R10
2Ω
C1
2.2 µF
P
Q1 (ACFET)
SI4435
P
Q2 (ACFET)
SI4435
C2
0.1 µF
RAC
0.010 Ω
C3
0.1 µF
R1
432 kΩ
1%
R3
422 kΩ
1%
DAC
R2
66.5 kΩ
1%
VREF
R5
10 kΩ
R4
71 kΩ
1%
HOST
C4
1 µF
GPIO
DAC
ADC
C5
100 pF
ACN
PVCC
ACP
ACDRV
ACDET
AGND
BATDRV
HIDRV
bq24751
/ACGOOD
OVPSET
PH
BTST
REGN
SRSET
ACSET
VREF
LEARN
CELLS
CHGEN
VDAC
VADJ
IADAPT
LODRV
PGND
SRP
SRN
BAT
ACOP
PowerPad
C6 C7
10 µF 10 µF
SYSTEM
C8
0.1 µF
Q4
FDS6680A
L1
8.2 µH
P
RSR
0.010 Ω
D1
BAT54
C10
1 µF
C9
0.1 µF
C11
10 µF
C13
Q5 ^{0.1 µF}
FDS6680A
C14
0.1 µF
Q3(BATFET)
SI4435
C12
10 µF
PACK+
PACK-
C16
0.47 µF
C15
0.1 µF
V_IN = 20 V, V_BAT = 3-cell Li-Ion, I_charge = 3 A, I_{adapter_limit} = 4 A
Figure 1. Typical System Schematic, Voltage, and Current Programmed by DAC
2
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