18V LED driver with internal switch
The SN3340 is a continuous mode inductive step-down
converter, designed for driving a single LED or multiple
series connected LEDs efficiently from a voltage source
higher than the required LED voltage. The chip operates
from an input supply between 6V and 18V and provides an
externally adjustable output current of up to 750mA.
Depending upon supply voltage and external components,
this can provide up to 12 watts of output power.
The SN3340 includes an integrated switch and a high-side
output current sensing circuit, which uses an external
resistor to set the nominal average output current.
Output current can be adjusted linearly by applying an
external control signal to the ADJ pin. The ADJ pin will
accept either a DC voltage or a PWM waveform. This will
provide either a continuous or a gated output current.
Applying a voltage of 0.2V or lower to the ADJ pin turns
the output off and switches the chip into a low current
The chip is assembled in SOT23-5 and SOT89-5 package.
SOT23-5 is available for 350mA output current application;
SOT89-5 is available for 700mA output current application.
z Simple low parts count
z input voltage range: 6V to 18V ， 30V transient
z Internal 18V power switch
z Up to 750mA output current（SOT89-5 package）
z Single pin on/off and brightness control using DC
voltage or PWM
z High efficiency (up to 95% )
z Up to 1MHz switching frequency
z Inherent open-circuit LED protection
z Thermal shutdown protection circuitry
z High Power LED Driver
z Automotive Lighting
z White LED Lamps
z Constant-Current Source
March 2009 Ver1.0
1 SI-EN Technology