40V LED driver with internal switch
The SN3350 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 LED voltage. The chip operates from an
input supply between 6V and 40V and provides an
externally adjustable output current of up to 750mA.
Depending upon supply voltage and external components,
this can provide up to 30 watts of output power.
The SN3350 includes an integrated output 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 Internal 40V power switch
z Wide input voltage range: 6V to 40V
z Up to 750mA output current（SOT89-5 package）
z High efficiency (up to 95% )
z Typical 1200：1 dimming rate
z Typical 5% output current accuracy
z Single pin on/off and brightness control using DC
voltage or PWM
z Up to 1MHz switching frequency
z Inherent open-circuit LED protection
z Thermal shutdown protection circuitry
z Two packages available for different current
z Low voltage halogen replacement LEDs
z Automotive lighting
z Low voltage industrial lighting
z LED back-up lighting
z Illuminated sign
March 2009 Ver1.0
1 SI-EN Technology