BQ24750_07 Datasheet, PDF (2/38 Pages) Texas Instruments – Host-controlled Multi-chemistry Battery Charger with Integrated System Power Selector and AC Over-Power Protection

bq24750
SLUS735 – DECEMBER 2006
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 bq24750 charges two, three, or four series Li+ cells, supporting up to 10 A of charge current, and is
available in a 28-pin, 5x5-mm QFN package.
The bq24750 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 bq24750 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.
TYPICAL APPLICATION
C17 C18
10 mF 10 mF
C19
10 mF
ADAPTER +
ADAPTER -
C1
10 mF
P
Q1 (ACFET)
SI4435
R1
432 kW
1%
P
Q2 (ACFET)
SI4435
C2
0.1 mF
RAC
0.010 W
C3
0.1 mF
ACGOOD
PACK
THERMISTER
SENSE
R2 ^{66.5 kW}
VREF
VREF
1%
R3
5.6 kW
R5
1%
10 kW
DAC
R4 ^{118 kW}
1%
HOST
R6
10 kW
C4
1 mF
DAC
C6
C7
10 mF 10 mF
SYSTEM
ACN
PVCC
ACP
ACDRV
ACDET
BATDRV
AGND
HIDRV
bq24750 PH
ACGOOD
TS
BTST
REGN
SRSET
ACSET
VREF
LODRV
PGND
C8
1 mF
C9 0.1 mF
D1 BAT54
C10
1 mF
R7 100 kW
Q4
FDS6680A
L1
8.2 mH
C11
10 mF
C13
0.1 mF
Q5
FDS6680A
P
R_SR
0.010 W
C14
0.1 mF
Q3(BATFET)
SI4435
C12
10 mF
PACK +
PACK -
DPMDET
CELLS
CHGEN
VDAC
VADJ
SRP
SRN
BAT
ACOP
C16
0.47 mF
C15
0.1 mF
ADC
C5
100 pF
IADAPT
PowerPad
(1) Pull-up rail could be either VREF or other system rail.
(2) SRSET/ACSET could come from either DAC or resistor dividers.
A. V_IN=20 V, V_BAT = 3-cell Li-Ion, I_CHARGE = 3 A, I_{ADAPTER_LIMIT} = 4 A, T_BAT = 0-45°C
Figure 1. Typical System Schematic, Voltage and Current Programmed by DAC
2
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