LT3651-4.1/LT3651-4.2
1
365142ff
For more information www.linear.com/LT3651-4.1
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Monolithic 4A Wide Input
1 Cell Li-Ion Battery Charger
n
Industrial Handheld Instruments
n
12V to 24V Automotive and Heavy Equipment
n
Desktop Cradle Chargers
n
Notebook Computers
6.5V to 32V Single Cell 4A Charger
Efficiency, Power Loss vs DC
IN
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
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.
DC
IN
(V)
5
EFFICIENCY (%)
POWER LOSS (W)
83
84
85
86
15 25
365142 TA01b
82
81
80
3.2
3.6
4.0
4.4
2.8
2.4
2.0
10
20
30
V
BAT
= 3.9
E
FF
P
LOSS
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
RT
TIMER
SW
BOOST
SENSE
BAT
I
LIM
RNG/SS
GND
NTC
CLP
CLN
1µF
100µF
BATTERY
365142 TA01a
6.5µH
WÜRTH 744314650
TO
SYSTEM
LOAD
24mΩ
301k
DC
IN
6.5V TO 32V
1N5819
LT3651-4.2
V
IN
22µF
+
FAULT
CHRG
ACPR
SHDN
10V
Si7611DN
100k
100k