LTC4012-3_15 Datasheet, PDF (1/28 Pages) Linear Technology – High Efficiency, Multi-Chemistry Battery Charger with PowerPath Control

LTC4012-3
High Efficiency,
Multi-Chemistry Battery Charger
with PowerPath Control
Features
Description
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 _{INFET Low Loss Ideal Diode PowerPath™ Control}
n _{Wide Input Voltage Range: 6V to 28V}
n _{Wide Output Voltage Range: 2V to 28V}
n _{Indicator Outputs for Charging, C/10 Current}
Detection and Input Current Limiting
n _{Analog Charge Current Monitor}
n _{Micropower Shutdown}
n _{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.
The LTC^®4012-3 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 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.
The LTC4012-3 features fully adjustable output voltage. For
charge management and safety, the IC includes an input
P-channel MOSFET ideal diode controller, battery (output)
overvoltage protection, reverse charge current protection,
PWM soft-start and robust non-overlap control for an all
N-channel MOSFET PWM power stage.
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 reduced charge current as
a result of AC adapter current limiting. Ideal diode control
at the adaptor input improves charger efficiency.
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
INFET
DCIN
CLP
CLN
BOOST
TGATE
0.1µF
25mΩ
5.1k
0.1µF
POWER TO
20µF
SYSTEM
TO/FROM
MCU
6.04k
0.1µF
26.7k
4.7nF
CHRG
ICL
SW
INTV_DD
BGATE
SHDN GND
ITH
CSP
LTC4012-3
PROG
CSN
BAT
FBDIV
V_FB
2µF
3.01k
3.01k
301k
32.8k
6.8µH
33mΩ
20µF
+
12.3V
Li-Ion
BATTERY
4012-3 TA01
Efficiency at DCIN = 20V
100
10000
95
EFFICIENCY
90
85
POWER LOSS
1000
80
75
70
0
V_OUT = 12.3V
R_SENSE = 33mΩ
R_IN = 3.01k
R_PROG = 26.7k
100
0.5 1 1.5 2 2.5 3
CHARGE CURRENT (A)
PART
LTC4012
LTC4012-3
PIN 5 NAME
GND ACP
X
X
4012-3 TA02
40123fb