BQ24742 Datasheet, PDF (3/35 Pages) Texas Instruments – Li-Ion or Li-Polymer Battery Charger with Low Iq and Accurate Trickle Charge

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ADAPTER +
ADAPTER -
R11
2Ω
C1
2.2 µF
P
P
Q1 (ACFET) Q2 (ACFET)
SI4435
SI4435
Controlled by
HOST
C2
R1
432 kΩ
0.1 µF
1%
R_AC
0.010 Ω
C3
0.1 µF
EXTPWR
R2
66.5 kΩ
1%
VREF
R3
10 kΩ
R4
10 kΩ
R5
10 kΩ
C4
1 µF
GPIO
HOST
ISET _PWM
(D = 0.72, V_peak = VDAC)
DAC
ADC
R15
10 kΩ
120 kΩ
R14
C13
100 nF
C5
100 pF
bq24741, bq24742
SLUS875B – MARCH 2009 – REVISED OCTOBER 2009
R16
10 Ω
D2
BAT54
C6
C7
10 µF 10 µF
SYSTEM
ACN
ACP
PVCC
ACDET _bq24741/2
AGND
HIDRV
EXTPWR
VREF
SW
BTST
REGN
TRICKLE
DPMDET
LPMOD
CELLS
CE
VDAC
ISET
LODRV
PGND
CSP
CSN
BAT
ACSET
VADJ
IADAPT PowerPad
LPREF
FSET
C8
0.1 µF
C9
D1 BAT54 _{0.1 µF}
C10
1 µF
Q3 (BATFET)
SI4435
Controlled by
HOST
Q4_A
FDS8978
L1
P
RSR
0.020 Ω
4.7 µH
C11
10 µF
C13
0.1 µF
Q4_B
FDS8978
C14
0.1 µF
R6
56.2 kΩ
VREF
R7
73.2 kΩ
1%
R8
26.7 kΩ
1%
C15
0.1 µF
C12
10 µF
PACK+
PACK-
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(1) Pull-up rail could be either VREF or other system rail.
(2) SRSET/ACSET could come from either DAC or resistor dividers.
F_S = 650 kHz, 90 W Adapter, V_ADAPTER = 19 V, V_BAT = 3-cell Li-Ion (4.2V/cell), I_charge = 3.6 A, I_{adapter_limit} = 4.0 A
Figure 2. Typical System Schematic, Voltage and Current Programmed by DAC
Part number
bq24741
bq24742
ORDERING INFORMATION
Package
Ordering Number
(Tape and Reel)
28-PIN 5 x 5 mm² QFN
bq24741RHDR
bq24741RHDT
28-PIN 5 x 5 mm² QFN
bq24742RHDR
bq24742RHDT
Quantity
3000
250
3000
250
PACKAGE THERMAL DATA
PACKAGE
QFN – RHD^{(1) (2)}
θ_JA
39°C/W
T_A = 25°C POWER RATING
2.36 W
DERATING FACTOR ABOVE T_A = 25°C
0.028 W/°C
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
Web site at www.ti.com.
(2) This data is based on using the JEDEC High-K board and the exposed die pad is connected to a Cu pad on the board. This is
connected to the ground plane by a 2x3 via matrix.
Copyright © 2009, Texas Instruments Incorporated
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