ISSI IS31LT3350

Description

The IS31LT3350 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 providesan 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 IS31LT3350 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 standby state.

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 750mA outputcurrent application.

Features

• Simple low parts count
• Internal 40V power switch
• Wide input voltage range: 6V to 40V
• Up to 750mA output current（SOT89-5 package）
• High efficiency (up to 95% )
• Typical 1200：1 dimming ratio
• Typical 5% output current accuracy
• Single pin on/off and brightness control using DC voltage or PWM
• Up to 1MHz switching frequency
• Inherent open-circuit LED protection
• Thermal shutdown protection circuitry
• Two packages available for different current

Remarks:

• Recommended inductor values for the IS31LT3350 are in the range of 47μH to 220μH. Refer page num 9.

Typical applications

• Low voltage halogen replacement LEDs
• Illuminated sign
• LED back-up lighting
• Low voltage industrial lighting
• Automotive lighting

More information

• Datasheet