LTC4012-3
High Efficiency,
Multi-Chemistry Battery Charger
with PowerPath Control
FeaTures
DescripTion
The LTC®4012-3 is a constant-current/constant-voltage
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General Purpose Battery Charger Controller
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Efficient 550kHz Synchronous Buck PWM Topology
0ꢀ5ꢁ ꢂutput ꢃloat ꢄoltage Accuracy
Programmable Charge Current: 4ꢁ Accuracy
Programmable AC Adapter Current Limit:
3ꢁ Accuracy
No Audible Noise with Ceramic Capacitors
INꢃET Low Loss Ideal Diode PowerPath™ Control
Wide Input Voltage Range: 6V to 28V
Wide Output Voltage Range: 2V to 28V
Indicator Outputs for Charging, C/10 Current
Detection and Input Current Limiting
Analog Charge Current Monitor
battery charger controller. It uses a synchronous quasi-
constant frequency PWM control architecture that will not
generateaudiblenoisewithceramicbulkcapacitors.Charge
current is set by external resistors and can be monitored
as an output voltage across the programming resistor.
With no built-in termination, the LTC4012-3 charges a
wide range of batteries under external control.
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TheLTC4012-3featuresfullyadjustableoutputvoltage.For
charge management and safety, the IC includes an input
P-channelMOSFETidealdiodecontroller,battery(output)
overvoltageprotection,reversechargecurrentprotection,
PWM soft-start and robust non-overlap control for an all
N-channel MOSFET PWM power stage.
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Micropower Shutdown
20-Pin 4mm × 4mm × 0.75mm QFN Package
ThedeviceincludesACadapterinputcurrentlimiting,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 reduced charge current as
a result of AC adapter current limiting. Ideal diode control
at the adaptor input improves charger efficiency.
applicaTions
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Notebook Computers
Portable Instruments
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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.
The CHRG status pin is active during all charging modes,
including special indication for low charge current.
Typical applicaTion
FROM
ADAPTER
25mΩ
POWER TO
SYSTEM
Efficiency at DCIN = 20ꢄ
0.1µF
13V TO 20V
20µF
5.1k
100
95
90
85
80
75
70
10000
1000
100
INFET
DCIN
CLP
CLN
BOOST
EFFICIENCY
0.1µF
0.1µF
TGATE
SW
POWER LOSS
CHRG INTV
DD
2µF
TO/FROM
MCU
6.8µH
33mΩ
ICL
BGATE
GND
V
= 12.3V
OUT
SHDN
ITH
R
R
R
= 33mΩ
SENSE
= 3.01k
3.01k
3.01k
IN
PROG
CSP
= 26.7k
2.5
6.04k
LTC4012-3
0
1
1.5
2
3
0.5
0.1µF
CSN
CHARGE CURRENT (A)
BAT
FBDIV
PIN 5 NAME
PROG
20µF
PART
LTC4012
LTC4012-3
GND
ACP
301k
+
26.7k
4.7nF
X
12.3V
V
FB
X
4012-3 TA02
Li-Ion
32.8k
BATTERY
4012-3 TA01
40123fb
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