LT3652EDD
1
DESCRIPTION
Demonstration Circuit 1568A is a 2A Monolithic
Multi-Chemistry battery charger for solar power
applications featuring the LT3652EDD. The
LT3652 is a complete mid-power Li-Ion battery
charger that can operate over a wide input volt-
age range. The charger employs a 3.3V float
voltage feedback reference that allows the bat-
tery float voltage to be adjusted up to 14.4V.
R10 and R11, in the demonstration circuit, set
the float voltage and are 0603 resistors to ac-
commodate the use of 0.1% resistors if desired.
The circuit is constructed with 1% resistors
which could introduce as much as a 1.56% error
in the float voltage. Replacing these resistors
with 0.1% resistors would introduce less than a
0.154% error. The LT3652 has an input voltage
regulation loop which reduces charge current if
the input falls below a programmed level, set
with a resistor divider. The charger is a CC/CV
charger with a maximum charge current of 2A. A
precondition feature trickle charges a low-
voltage battery, and bad battery detection pro-
vides a signal if the battery doesn’t respond to
preconditioning.
The LT3652EDD is available in a 12-lead (3mm
× 3mm) DFN surface mount package with an
exposed pad.
Design files for this circuit board are available. Call
the LTC factory.
L
, LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are registered
trademarks of Linear Technology Corporation. Adaptive Power, C-Load, DirectSense, Easy
Drive, FilterCAD, Hot Swap, LinearView, μModule, Micropower SwitcherCAD, Multimode
Dimming, No Latency
ΔΣ
, No Latency Delta-Sigma, No R
SENSE
, Operational Filter, PanelProtect,
PowerPath, PowerSOT, SmartStart, SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT,
UltraFast and VLDO are trademarks of Linear Technology Corporation. Other product names
may be trademarks of the companies that manufacture the products.
Table 1: Typical Specifications (25°C)
HV Input Voltage Range
11.5V to 32V
VOUT
8.04V to 8.36V
Output Float Voltage (constant voltage mode)
8.2V
Output Current Limit ILIM
2A
OPERATING PRINCIPLE
LT3652 is a complete monolithic mid-power Li-Ion bat-
tery charger, addressing high input voltage applications
with solutions that require a minimum of external com-
ponents. The IC uses a 1MHz constant frequency, aver-
age-current mode step-down architecture.
The LT3652 incorporates a 2A switch that is driven by a
bootstrapped supply to maximize efficiency during
charging cycles. A wide input range allows operation to
fully charge from 11.5V (single cell) to 32V. A precision-
threshold shutdown pin allows the incorporation of
UVLO functionality using a simple resistor divider. The
IC can also be put into a low-current shutdown mode, in
which the input supply bias is reduced to only 15uA.
The LT3652 incorporates several degrees of charge cur-
rent control freedom. The overall maximum charge cur-
DEMO CIRCUIT 1568A
QUICK START GUIDE
LT3652EDD
2A Monolithic Multi-
Chemistry Battery Charger
