LTC4007-1_15 Datasheet, PDF (1/24 Pages) Linear Technology – 4A, High Efficiency, Li-Ion Battery Charger

LTC4007-1
4A, High Efficiency,
Li-Ion Battery Charger
FEATURES
DESCRIPTIO
■ _{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 4mm × 5mm QFN Package}
U
APPLICATIO S
■ _{Notebook Computers}
■ _{Portable Instruments}
■ _{Battery-Backup Systems}
■ _{Li-Ion Chargers}
The LTC^®4007-1 is a 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 capaci-
tors. Charging current is programmable to ±4% accuracy
using a programming resistor. Charging current can also
be monitored as a voltage across the programming
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.
The LTC4007-1 includes a thermistor input, which sus-
pends charging if an unsafe temperature condition is de-
tected. If the cell voltage is less than 3.25V, a low-battery
indicator asserts and can be used to program a trickle charge
current 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.
, LTC and LT 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
DCIN
0V TO 28V
V_LOGIC
100k 100k 100k
3C4C
CHEM
DCIN
INFET
LOBAT
LOBAT
CLP
I_CL
I_CL LTC4007-1 CLN
ACP
ACP
TGATE
SHDN
SHDN
BGATE
FAULT
FAULT
PGND
CHG
CHG
CSP
FLAG
32.4k
FLAG
NTC
BAT
PROG
THERMISTOR
10k
NTC
R_T
ITH
0.47µF
GND
309k
TIMING RESISTOR
(~2 HOURS)
12.6V, 4A Li-Ion Battery Charger
INPUT SWITCH
0.1µF
4.99k
15nF 0.025Ω
20µF
Q1
10µH
SYSTEM
LOAD
0.025Ω
Q2
3.01k
3.01k
6.04k
0.0047µF
0.12µF
26.7k
Q1: Si4431BDY
Q2: FDC645N
20µF
CHARGING
CURRENT
MONITOR
40071 TA01
PART
LOW BATTERY
AUTO THRESHOLD (Per Cell)
RESTART
(4.2V/4.1V)
LTC4007-1 NO
3.25V/3.173V
LTC4007
YES
2.5V/2.44V
Li-Ion
BATTERY
40071f
1