LTC4012_15 Datasheet, PDF (1/28 Pages) Linear Technology – High Efficiency, Multi-Chemistry Battery Charger with PowerPath Control

LTC4012/
LTC4012-1/LTC4012-2
Features
High Efficiency,
Multi-Chemistry Battery Charger
with PowerPath Control
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 AC Adapter Present, 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 LTC4012 is a constant-current /constant-volt-
age 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 resis-
tors and can be monitored as an output voltage.
With no built-in termination, the LTC4012 family charges
a wide range of batteries under external control.
The LTC4012 features fully adjustable output voltage, while
the LTC4012-1 and LTC4012-2 can be pin-programmed for
Lithium-Ion/Polymer battery packs of 1-, 2-, 3- or 4-series
cells. The LTC4012-1 provides output voltage of 4.1V/cell
and the LTC4012-2 is a 4.2V/cell version.
The device includes AC adapter input current limiting, which
maximizes 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 28V
0.1µF
TO/FROM
MCU
6.04k
0.1µF
26.7k
4.7nF
INFET
DCIN
CLP
CLN
BOOST
TGATE
ACP
CHRG
SW
INTV_DD
ICL
BGATE
SHDN GND
ITH
CSP
LTC4012
PROG
CSN
BAT
FBDIV
V_FB
0.1µF
25mΩ
5.1k
0.1µF
POWER TO
20µF
SYSTEM
2µF
3.01k
3.01k
301k
32.8k
6.8µH
33mΩ
20µF
+
12.3V
Li-Ion
BATTERY
4012 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
0.5 1
1.5 2
100
2.5 3
CHARGE CURRENT (A)
PIN NAME
PART INFET DCDIV
LTC4009
X
LTC4012 X
4012 TA02
4012fa