LTC4007_15 Datasheet, PDF (1/24 Pages) Linear Technology – 4A, High Effi ciency, Standalone Li-Ion Battery Charger

LTC4007
4A, High Efficiency,
Standalone Li-Ion Battery Charger
FEATURES
DESCRIPTION
n Complete Charger Controller for 3- or 4-Cell
Lithium-Ion Batteries
n High Conversion Efficiency: Up to 96%
n Output Currents Exceeding 4A
n ±0.8% Charging Voltage Accuracy
n Built-In Charge Termination for Li-Ion Batteries
n AC Adapter Current Limiting Maximizes Charge Rate*
n Thermistor Input for Temperature Qualified Charging
n Wide Input Voltage Range: 6V to 28V
n 0.5V Dropout Voltage; Maximum Duty Cycle: 98%
n Programmable Charge Current: ±4% Accuracy
n Indicator Outputs for Charging, C/10 Current Detection,
AC Adapter Present, Low Battery, Input Current
Limiting and Faults
n Charging Current Monitor Output
n Available in a 24-Pin Narrow SSOP Package
APPLICATIONS
n _{Notebook Computers}
n _{Portable Instruments}
n _{Battery-Backup Systems}
n _{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 ±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 charge
termination 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 current
to safely charge depleted batteries. The FAULT pin is also
asserted and charging terminates if the low-battery con-
dition persists for more than 1/4 of the total charge time.
L, LT, LTC, LTM, Linear Technology and the Linear logo 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 APPLICATION
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
LOBAT
INFET
CLP
I_CL LTC4007 CLN
ACP
TGATE
SHDN
FAULT
CHG
FLAG
BGATE
PGND
CSP
BAT
NTC
PROG
R_T
ITH
GND
309k
TIMING RESISTOR
(~2 HOURS)
INPUT SWITCH
0.1μF
4.99k
15nF 0.025Ω
20μF
Q1
10μH _0.025Ω
Q2
SYSTEM
LOAD
Li-Ion
20μF
BATTERY
3.01k
3.01k
6.04k
0.0047μF
0.12μF
26.7k
Q1: Si4431DY
Q2: FDC6459
CHARGING
CURRENT
MONITOR
4007 TA01
4007fc
1