BQ24740_14 Datasheet, PDF (2/33 Pages) Texas Instruments – Host-Controlled Multi-Chemistry Battery Charger

bq24740
SLUS736C – 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 bq24740 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 current-sense amplifier enables precise measurement of input
current from the ac adapter to monitor the overall system power. If the adapter current is above the programmed
low-power threshold, a signal is sent to host so that the system optimizes its power performance according to
what is available from the adapter.
TYPICAL APPLICATION
ADAPTER+
ADAPTER-
R10
2Ω
C1
2.2 µF
P
P
Q1 (ACFET) Q2 (ACFET )
SI4435
SI4435
Controlled by
HOST
C2
R1
0.1 µF
432 kΩ
1%
RAC
0.010 Ω
C3
0.1 µF
EXTPWR
R2
66.5 kΩ
1%
VREF
R3
10k Ω
DAC
HOST
R4
R5
C4
10k Ω 10k Ω
1 µF
DAC
ADC
C5
100 pF
D2
BAT54
C6 ^C7
10 µF ^{10 µF}
SYSTEM
ACN
ACP
ACDET
AGND
bq24740
EXTPWR
SRSET
ACSET
VREF
IADSLP
DPMDET
LPMD
CELLS
CHGEN
VDAC
VADJ
IADAPT
PVCC
C8
0.1 µF
Q3(BATFET )
SI4435
Controlled by
HOST
HIDRV
PH
BTST
REGN
LODRV
PGND
C9
D1 BAT 54 _{0.1 µF}
C10
1 µF
Q4
FDS 6680A
L1
8.2 µH
C11
10 µF
C13
0.1 µF
Q5
FDS6680 A
P
RSR
0.010 Ω
C14
0.1 µF
SRP
SRN
BAT
LPREF
ISYNSET
PowerPad
R6
24 kΩ
VREF
R7
200 kΩ
R8
24.9 kΩ
C15
0.1 µF
C12
10 µF
PACK+
PACK-
R9
1.8 MΩ
( 1 ) Pull - up rail could be either VREF or other system rail .
( 2 ) SRSET /ACSET could come from either DAC or resistor dividers .
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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