LT3651-4.1_15 Datasheet, PDF (1/22 Pages) Linear Technology – Monolithic 4A Wide Input 1 Cell Li-Ion Battery Charger

FEATURES
n _{Wide Input Voltage Range: Up to 32V}
(40V Absolute Maximum)
n _{Programmable Charge Current Up to 4A}
n _{Selectable C/10 or Onboard Timer Termination}
n _{Dynamic Charge Rate Programming/Soft-Start}
n _{Programmable Input Current Limit}
n _{0.5% Float Voltage Accuracy}
n _{7.5% Charge Current Accuracy}
n _{4% C/10 Detection Accuracy}
n _{NTC Resistor Temperature Monitor}
n _{Auto-Recharge at 97.5% Float Voltage}
n _{Auto-Precondition <70% Float Voltage}
n _{Bad Battery Detection with Auto-Reset}
n _{Average Current Mode, Synchronous Switcher}
n _{User Programmable Frequency}
n _{Low Profile (0.75mm) 5mm × 6mm 36-Pin}
QFN Package
APPLICATIONS
n _{Industrial Handheld Instruments}
n _{12V to 24V Automotive and Heavy Equipment}
n _{Desktop Cradle Chargers}
n _{Notebook Computers}
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property of their respective owners.
LT3651-4.1/LT3651-4.2
Monolithic 4A Wide Input
1 Cell Li-Ion Battery Charger
DESCRIPTION
The LT^®3651 is a 1 cell 4A Li-Ion/Polymer battery charger
that operates with input voltages up to 32V. An efficient
monolithic average current mode synchronous switching
regulator provides constant current, constant voltage
charging with programmable maximum charge current.
A charging cycle starts with battery insertion or when
the battery voltage drops 2.5% below the float voltage.
Charger termination is selectable as either charge current
or internal safety timer timeout. Charge current termina-
tion occurs when the charge current falls to one-tenth
the programmed maximum current (C/10). Timer based
termination is typically set to three hours and is user pro-
grammable (charging continues below C/10 until timeout).
Once charging is terminated, the LT3651 supply current
drops to 85µA into a standby mode.
The LT3651 offers several safety features. A discharged
battery is preconditioned with a small trickle charge and
generates a signal if unresponsive. A thermistor monitors
battery temperature, halting charging if out of range. Ex-
cessive die temperature reduces charge current. Charge
current is also reduced to maintain constant input current
to prevent excessive input loading.
The LT3651 is available in a 5mm × 6mm 36-pin QFN
package.
TYPICAL APPLICATION
6.5V to 32V Single Cell 4A Charger
DC_IN
6.5V TO 32V
Si7611DN
100k _10V
100k
301k
CLP CLN V_IN
SHDN
SW
ACPR
FAULT
CHRG
BOOST
LT3651-4.2
SENSE
RT
TIMER
BAT
NTC
I_LIM RNG/SS GND
TO
SYSTEM
22µF ^LOAD
1µF
1N5819
6.5µH
WÜRTH 744314650
24mΩ
100µF ⁺ BATTERY
365142 TA01a
Efficiency, Power Loss vs DC_IN
86
E_FF
85
4.4
V_BAT = 3.9
4.0
84
3.6
83
3.2
82
2.8
81
80
5
P_LOSS
10 15 20
DC_IN (V)
2.4
2.0
25 30
365142 TA01b
For more information www.linear.com/LT3651-4.1
365142ff
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