LTC4009_15 Datasheet, PDF (1/28 Pages) Linear Technology – High Efficiency, Multi-Chemistry Battery Charger

Features
n _{General Purpose Battery Charger Controller}
n _{Efficient 550kHz Synchronous Buck PWM Topology}
n _{±0.5% Output Float Voltage Accuracy}
n _{Programmable Charge Current: 4% Accuracy}
n _{Programmable AC Adapter Current Limit:}
3% Accuracy
n _{No Audible Noise with Ceramic Capacitors}
n _{Wide Input Voltage Range: 6V to 28V}
n _{Wide Output Voltage Range: 2V to 28V}
n _{Indicator Outputs for AC Adapter Present, Charging,}
C/10 Current Detection and Input Current Limiting
n _{Analog Charge Current Monitor}
n _{Micropower Shutdown}
n _{Thermally Enhanced 20-Pin 4mm × 4mm × 0.75mm}
QFN Package
Applications
n _{Notebook Computers}
n _{Portable Instruments}
n _{Battery Backup Systems}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents including 5723970.
LTC4009
LTC4009-1/LTC4009-2
High Efficiency,
Multi-Chemistry
Battery Charger
Description
The LTC^®4009 is a constant-current/constant-voltage
battery charger controller. It uses a synchronous quasi-
constant frequency PWM control architecture that will
not generate audible noise with ceramic bulk capacitors.
Charge current is set by the combination of external
sense, input and programming resistors. With no built-in
termination, the LTC4009 family charges a wide range of
batteries under external control.
The LTC4009 features a fully adjustable output voltage, while
the LTC4009-1 and LTC4009-2 can be pin-programmed for
lithium-ion/polymer battery packs of 1-, 2-, 3- or 4-series
cells. The LTC4009-1 provides output voltage of 4.1V/cell,
and the LTC4009-2 is a 4.2V/cell version.
The device includes AC adapter input current limiting which
maximizes the charge rate for a fixed input power level. An
external sense resistor programs the input current limit, and
the ICL status pin indicates when the battery charge current
is being reduced as a result of AC adapter current limiting.
The CHRG status pin is active during all charging modes,
including special indication for low charge current.
Typical Application
FROM
ADAPTER
13V TO 20V
0.1µF
CHARGE
CURRENT
MONITOR
14.3k
1.5k
TO/FROM
MCU
DCIN
CLP
CLN
DCDIV BOOST
LTC4009
TGATE
CHRG
ACP
SW
INTV_DD
ICL
BGATE
SHDN GND
ITH
CSP
6.04k
0.1µF
PROG
4.7nF 26.7k
CSN
BAT
FBDIV
V_FB
33mΩ
0.1µF
5.1k
0.1µF
2µF
3.01k
3.01k
20µF
301k
32.8k
POWER TO
20µF
SYSTEM
6.8µH
33mΩ
+ _12.3V
Li-Ion
BATTERY
4009 TA01a
Efficiency at DCIN = 20V
100
10000
95
90
85
80
75
70
0
EFFICIENCY
POWER LOSS
1000
V_OUT = 12.3V
R_SENSE = 33mΩ
R_IN = 3.01k
R_PROG = 26.7k
D_IN = SSB44
L = IHLP-2525CZ 6.8µH
100
0.5 1.0 1.5 2.0 2.5 3.0
CHARGE CURRENT (A)
4009 TA01b
4009fd