LTC4007_1 Datasheet, PDF (1/24 Pages) Linear Technology – 4A, High Efficiency, Standalone Li-Ion Battery Charger

LTC4007
4A, High Efficiency,
Standalone Li-Ion Battery Charger
FEATURES
DESCRIPTIO
■ _{Complete Charger Controller for 3- or 4-Cell}
Lithium-Ion Batteries
■ _{High Conversion Efficiency: Up to 96%}
■ _{Output Currents Exceeding 4A}
■ _{±0.8% Charging Voltage Accuracy}
■ _{Built-In Charge Termination for Li-Ion Batteries}
■ _{AC Adapter Current Limiting Maximizes Charge Rate*}
■ _{Thermistor Input for Temperature Qualified Charging}
■ _{Wide Input Voltage Range: 6V to 28V}
■ _{0.5V Dropout Voltage; Maximum Duty Cycle: 98%}
■ _{Programmable Charge Current: ±4% Accuracy}
■ _{Indicator Outputs for Charging, C/10 Current}
Detection, AC Adapter Present, Low Battery, Input
Current Limiting and Faults
■ _{Charging Current Monitor Output}
■ _{Available in a 24-Pin Narrow SSOP Package}
U
APPLICATIO S
■ _{Notebook Computers}
■ _{Portable Instruments}
■ _{Battery-Backup Systems}
■ _{Standalone Li-Ion Chargers}
The LTC^®4007 is a complete constant-current/constant-
voltage charger controller for 3- or 4-cell lithium-ion
batteries. The PWM controller uses a synchronous, quasi-
constant frequency, constant off-time architecture that
will not generate audible noise even when using ceramic
capacitors. Charging current is programmable to ±5%
accuracy using a programming resistor. Charging current
can also be monitored as a voltage across the program-
ming resistor.
The output float voltage is pin programmed for cell count
(3 cells or 4 cells) and chemistry (4.2V/4.1V). A timer,
programmed by an external resistor, sets the total charge
time. Charging is automatically restarted when cell voltage
falls below 3.9V/cell.
LTC4007 includes a thermistor input, which suspends
charging if an unsafe temperature condition is detected. If
the cell voltage is less than 2.5V, a low-battery indicator
asserts and can be used to program a trickle charge cur-
rent to safely charge depleted batteries. The FAULT pin is
also asserted and charging terminates if the low-battery
condition persists for more than 1/4 of the total charge time.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 5723970.
TYPICAL APPLICATIO
12.6V, 4A Li-Ion Battery Charger
DCIN
0V TO 28V
V_LOGIC
LOBAT
I_CL
ACP
SHDN
FAULT
CHG
FLAG
100k
THERMISTOR
10k
NTC
100k 100k
32.4k
0.47µF
3C4C
DCIN
CHEM
INFET
LOBAT
CLP
I_CL LTC4007 CLN
ACP
TGATE
SHDN
BGATE
FAULT
PGND
CHG
CSP
FLAG
BAT
NTC
PROG
R_T
ITH
GND
309k
TIMING RESISTOR
(~2 HOURS)
INPUT SWITCH
0.1µF
4.99k
15nF 0.025Ω
20µF
Q1
10µH
Q2
3.01k
3.01k
6.04k
0.0047µF
0.12µF
26.7k
Q1: Si4431DY
Q2: FDC6459
SYSTEM
LOAD
0.025Ω
20µF
CHARGING
CURRENT
MONITOR
4007 TA01
Li-Ion
BATTERY
4007fa
1