资 源 简 介
The SN3340 is a conTInuous mode inducTIve step-down converter, designed for driving single or mulTIple series connected LEDs efficiently from a voltage source higherthan the LED voltage. The device operates from an inputsupply between 5V and 18V and provides an externallyadjustable output current of up to 350mA. Depending uponsupply voltage and external components, this can provide up to 10 watts of output power.The SN3340 includes the output switch and a high-sideoutput current sensing circuit, which uses an externalresistor to set the nominal average output current.Output current can be adjusted above, or below the setvalue, by applying an external control signal to the ADJ pin.The ADJ pin will accept either a DC voltage or a PWMwaveform. Depending upon the control frequency, this willprovide either a conTInuous or a gated output current. ThePWM filter components are contained within the chip.The PWM filter provides a soft-start feature by controllingthe rise of input/output current. The soft-start time can beincreased using an external capacitor from the ADJ pin to ground.Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the device into a low current standby state. The device is assembled in a TSOT23-5 package.
