1
dc1362aabfa
DEMO MANUAL DC1362A-A/-B
DESCRIPTION
LT3651EUHE-4.2/-4.1
4A High Voltage Li-Ion
Battery Charger
Demonstration circuit 1362A-A/1362A-B is a 4A high voltage
Li-Ion battery charger featuring the
EUHE-4.2/
LT3651EUHE-4.1. The LT3651 is a complete, high power
Li-Ion battery charger that can operate over a wide input
voltage range. The charger is a constant-current, constant-
voltage type with a maximum charge current of 4A that can
be externally set. A precondition feature trickle charges a
low voltage battery and bad battery detection provides a
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.
PERFORMANCE SUMMARY
signal if the battery doesn’t respond to preconditioning. The
LT3651EUHE is available in a 36-lead (5mm × 6mm) QFN
surface mount package with two exposed thermal pads.
Design files for this circuit board are available at
Input Voltage Range
6.5V to 32V
VOUT
2.9V to 4.24V (–A)/2.7V to 4.14V (–B)
Output Float Voltage (Constant Voltage Mode)
4.2V (–A)/4.1V (–B)
Output Current Limit ILIM
4A
Specifications are at T
A
= 25°C
OPERATING PRINCIPLE
LT3651 is a complete Li-Ion battery charger, addressing
wide input voltage (6.5V to 32V) and high charge current
(up to 4A). High charging efficiency, as shown in Figure 1,
is produced with a constant frequency, average current
mode synchronous step-down switcher architecture.
The charger includes the necessary circuitry to allow for
programming and control of constant-current, constant-
voltage (CC/CV) charging with both current only and
timer termination. High charging efficiency is achieved
by using a bootstrapped supply for low switch drop on
the high side driver and a MOSFET for the low side (syn-
chronous) switch.
Maximum charge current is set with an external sense
resistor in series with the inductor and is adjusted through
the RNG/SS pin. The total system input current is moni-
tored with an input sense resistor and is used to maintain
constant input current by regulating battery charge current.
It is adjusted through the I
LIM
pin.
If the battery voltage is low, charge current automatically
reduces to 15% of the programmed current to provide
safe battery preconditioning. Once the battery voltage
climbs above the battery precondition threshold, the IC
automatically increases the maximum charging current
to the full programmed value.