LT3652
Power Tracking 2A Battery
Charger for Solar Power
FEATURES
DESCRIPTION
The LT®3652 is a complete monolithic step-down bat-
tery charger that operates over a 4.95V to 32V input
voltage range. The LT3652 provides a constant-current/
constant-voltage charge characteristic, with maximum
charge current externally programmable up to 2A. The
charger employs a 3.3V float voltage feedback reference,
so any desired battery float voltage up to 14.4V can be
programmed with a resistor divider.
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Input Supply Voltage Regulation Loop for Peak
Power Tracking in (MPPT) Solar Applications
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Wide Input Voltage Range: 4.95V to 32V (40V Abs Max)
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Programmable Charge Rate Up to 2A
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User Selectable Termination: C/10 or On-Board
Termination Timer
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Resistor Programmable Float Voltage Up to 14.4V
Accommodates Li-Ion/Polymer, LiFePO , SLA,
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NiMH/NiCd Chemistries
TheLT3652employsaninputvoltageregulationloop,which
reduces charge current if the input voltage falls below a
programmed level, set with a resistor divider. When the
LT3652 is powered by a solar panel, the input regulation
loop is used to maintain the panel at peak output power.
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No V Blocking Diode Required for Battery
IN
Voltages ≤ 4.2V
1MHz Fixed Frequency
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0.5% Float Voltage Reference Accuracy
5% Charge Current Accuracy
2.5% C/10 Detection Accuracy
Binary-Coded Open-Collector Status Pins
3mm × 3mm DFN12 or MSOP-12 Packages
The LT3652 can be configured to terminate charging
when charge current falls below 1/10 of the programmed
maximum(C/10).Oncechargingisterminated,theLT3652
enters a low-current (85μA) standby mode. An auto-re-
charge feature starts a new charging cycle if the battery
voltage falls 2.5% below the programmed float voltage.
The LT3652 also contains a programmable safety timer,
used to terminate charging after a desired time is reached.
This allows top-off charging at currents less than C/10.
APPLICATIONS
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Solar Powered Applications
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Remote Monitoring Stations
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LiFePO (Lithium Phosphate) Applications
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Portable Handheld Instruments
12V to 24V Automotive Systems
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.
Solar Panel Input Voltage
Regulation, Tracks Max Power
Point to Greater Than 98%
TYPICAL APPLICATION
2A Solar Panel Power Manager With 7.2V LiFePO4 Battery
and 17V Peak Power Tracking
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CMSH1-40MA
T
= 25°C
A
SOLAR PANEL INPUT
(<40V OC VOLTAGE)
SYSTEM LOAD
CMSH3-40MA
20
18
16
14
12
10
CMSH3-40MA
10μF
530k
100% TO 98% PEAK POWER
98% TO 95% PEAK POWER
SW
V
IN
LT3652
IN_REG
1μF
10μH
0.05
V
BOOST
SENSE
BAT
SHDN
CHRG
FAULT
TIMER
100k
10μF
542k
NTC
V
FB
459k
+
10k
B = 3380
0.2
0.6 0.8
1
1.2 1.4 1.6 1.8
2
0.4
CHARGER OUTPUT CURRENT (A)
3652 TA01b
2-CELL LiFePO (2 × 3.6V) BATTERY PACK
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3652 TA01a
3652fb
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