BQ24747 Datasheet, PDF (2/36 Pages) Texas Instruments – SMBus-Controlled Level 2 Multi-Chemistry Battery Charger With Input Current Detect Comparator and Charge Enable Pin

bq24747
SLUS988 – OCTOBER 2009 ............................................................................................................................................................................................. www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
DESCRIPTION (CONTINUED)
The bq24747 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 adaptor 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, allowing monitoring 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
performance to the power available from the adapter. An integrated comparator monitors the input current
through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold
limit.
TYPICAL APPLICATIONS
V_IN = 20 V, V_BAT = 4-cell Li-Ion, I_CHARGE = 4.5 A
ADAPTER +
R10
2
ADAPTER -
C1
2.2 uF
R1
309k
1%
R10
10
P
Q1 (ACFET)
SI4835BDY
P
Q2 (DFET)
SI4835BDY
Controlled by
HOST
C4
C3
0.1uF
0.1uF
RAC
0.010
C5 0.1uF
27 CSSN
28 CSSP
22 DCIN
C9
2x10uF
Controlled by
HOST
Q5
(BATFET)
SI4835BDY
CHRG_IN
R2
49.9k
1%
+3 .3V _ALWAYS
OR
+5V_ALWAYS
DISCRETE
LOGIC
R3
10k
R4 R5
10k 10k
2 ACIN
12 GND
bq24747
11 VDDSMB
C6 1uF
13 ACOK
3 VREF
C7 1uF
UGATE 24
PHASE 23
BOOT 25
D1
VDDP 21
C11
C10
0.1uF
BAT54
1uF
LGATE 20
PGND 19
Q3
FDS6680A
L1
5.6uH
C12
0.1uF
Q4
FDS6680A
RSR
0.010
C14
3x10uF
C13
0.1uF
PACK+
PACK-
26 ICOUT
CSOP 18
HOST
(EC)
Dig I/O
SMBus
DISCRETE
LOGIC
R6
10k
C8 100pF
7 _CE
9 SDA
10 SCL
8 _VICM
14 NC
16 NC
CSON 17
VFB 15
ICREF ¹
EAO 4
EAI 5
FBO 6
R11
100
C15
0.1u
R7
7.5k
C16
51pF
C17
2000pF
R8
4.7k
R9
200k
C18
130pF
Pull-up rail could be either VREF or other system rail.
Figure 1. Typical System Schematic: Using External Input Current Comparator (discrete logic) Instead of
Internal Comparator
2
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