LT3653 Datasheet, PDF (1/12 Pages) Linear Technology – 1.2A, HV Input Regulator with Output Current Limit for Battery Charger Applications

LT3653
FEATURES
1.2A, HV Input Regulator
with Output Current Limit for
Battery Charger Applications
DESCRIPTION
n _{Wide Input Range:}
– Operation from 7.5V to 30V
– Overvoltage Lockout Protects Circuit Through 60V
Transients
n _{Operates with LTC Bat-Track™ Li-Ion Battery}
Chargers to Maximize Efficiency
n _{No Reverse Discharge Path from VOUT to VIN}
n _{Programmable Output Current Limit}
n _{Integrated BOOST Diode}
n _{Thermal Protection}
n _{Small Application Size}
n _{Thermally Enhanced 2mm × 3mm DFN Package}
APPLICATIONS
n _{Battery Powered Equipment}
n _{Portable USB Devices – Cameras, MP3 Players,}
PDAs
n _{Automotive Battery Regulation}
n _{Multiple-Source Battery Chargers}
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Bat-Track is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
The LT^®3653 is a monolithic current mode PWM step-down
regulator with programmable output current limit. Typically,
it is used with battery charger power path controllers to
pre-regulate the output and optimize the battery charger
efficiency. Output current limit provides accurate control
over system power dissipation.
The wide operating input voltage range of 7.5V to 30V
suits the LT3653 to a variety of input sources, including
unregulated 12V wall adapters, 24V industrial supplies,
Firewire and automotive power. Input overvoltage protec-
tion allows the LT3653 to handle 60V input transients.
The LT3653 control pin, V_C, is available for external battery
tracking control, Bat-Track. The LT3653 will block output
discharge during an open or shorted input.
The HVOK pin indicates that the internal bias supplies
are present and no faults have occurred (i.e., overtem-
perature and input overvoltage and undervoltage). The
LT3653 includes a 1.5MHz frequency oscillator, internal
compensation, and an internal boost diode to minimize the
number of external components. The LT3653 is available
in an 8-lead (2mm × 3mm) package with exposed pads
for low thermal resistance.
TYPICAL APPLICATION
High Voltage Single-Cell Battery Charger Application
V_IN
7.5V TO 30V
TRANSIENT
TO 60V
V_IN
4.7μF
I_LIM
27.4k
0.1μF
BOOST
SW
LT3653
I_SENSE
V_OUT
GND
HVOK
V_C
3653 TA01a
4.7μH
1.2A
SYSTEM
LOAD
10μF
OUT
WALL
LTC4098
V_C BAT
+ _SINGLE-CELL
Li-Ion
Efficiency vs Load Current
100
90
V_IN = 8V
80
V_IN = 24V
70
V_IN = 12V
60
50
40
0.1
0.3 0.5 0.7 0.9
OUTPUT CURRENT(A)
1.1 1.3
3653 TA01a
3653f
1