LSP3312
1A LED Driver with Internal Switch
Features
Simple low parts count
Internal 40V NDMOS switch
1A output current
Single pin on/off and brightness control
Using DC voltage or PWM
Soft-start
High efficiency (up to 97%)
Wide input voltage range
：6V
to 40V
Output shutdown
Up to 1MHz switching frequency
Inherent open-circuit LED protection
Typical 5% output current accuracy
Package
：
SOT23-5L,ESOP-8L
General Description
The LSP3312 is a continuous mode
inductive step-down converter, designed for
driving single or multiple series connected
LEDs efficiently from a voltage source higher
than the LED voltage. The device operates
from an input supply between 6V and 40V
and provides and externally adjustable
output current of up to 1A. Depending upon
supply voltage and external components,
this can provide up to 30 watts of output
power.
The LSP3312 includes the output switch and
a high-side output current sensing circuit,
which uses and external resistor to set the
nominal average output current.
Output current can be adjusted below the set
values, bye applying an external control
signal to the VSET pin.
The VSET pin will accept either a DC
voltage or a PWM waveform.
The soft-start time can be increased using
an external capacitor from the VSET pin to
ground.
Applying a voltage of 0.2V or lower to the
VSET pin turns the output off and switches
the device into a low current standby state.
Applications
Low voltage halogen replacement LEDs
Automotive lighting
Low voltage industrial lighting
LED back-up lighting
Typical Application Circuit
D1
Rs
0.3
Ω
VIN (6V -40V )
V IN
IS EN SE
LSP3312
V S ET
C1
10uF
Floating
L1
100uH
LX
LSP3312 Rev. Preliminary 0.1
1 of 12
www.liteon-semi.com
2010/08/23
LITEON [ LITE-ON TECHNOLOGY CORPORATION ]
