IS31LT3360 40V/1.2A LED DRIVER WITH INTERNAL SWITCH January 2014 GENERAL DESCRIPTION FEATURES The IS31LT3360 is a continuous mode inductive Up to 1.2A output current step-down converter, designed for driving a single High efficiency (up to 98%) LED or multiple series connected LEDs efficiently Wide input voltage range: 6V ~ 40V from a voltage source higher than the LED voltage. Internal 40V power switch The chip operates from an input supply between 6V Simple low parts count and 40V and provides an externally adjustable output current of up to 1.2A. Typical 3% output current accuracy (-40C to +105C, IS31LT3360-SDLS3-TR) The IS31LT3360 includes an integrated output Typical 5% output current accuracy (-40C to switch and a high-side output current sensing circuit, +125C, IS31LT3360-SDLS4-TR) which uses an external resistor to set the nominal Single pin on/off and brightness control using average output current. DC voltage or PWM Output current can be adjusted linearly by applying Up to 1MHz switching frequency an external control signal to the ADJ pin. The ADJ Inherent LED open-circuit/short-circuit pin will accept either a DC voltage or a PWM protection waveform. This will provide either a continuous or a gated output current. Thermal shutdown protection circuitry Up to 1200: 1 dimming ratio Applying a voltage less than 0.2V to the ADJ pin turns the output off and switches the chip into a low APPLICATIONS current standby state. Automotive and avionic lighting The chip is assembled in SOT89-5 package. It LED MR16, MR11 spot light operates from 6V to 40V over two temperature LED street light ranges of -40C to +105C and -40C to +125C. PAR light Industrial lighting Refrigeration lights Other LED lighting TYPICAL APPLICATION CIRCUIT Figure 1 Typical Application Circuit Note: The capacitor, C , cant be removed. And it should be placed as close as possible to the VIN and GND pins, otherwise the operation 2 might be abnormal. Lumissil Microsystems www.lumissil.com 1 Rev. C, 12/22/2013 IS31LT3360 PIN CONFIGURATION Package Pin Configuration LX 1 5 VIN SOT89-5 GND Thermal Pad 2 ADJ 34 ISENSE PIN DESCRIPTION No. Pin Description 1 LX Drain of power switch. 2 GND Ground (0V). Multi-function On/Off and brightness control pin: * Leave floating for normal operation.(V = V = 1.2V giving ADJ REF nominal average output current I =0.1/R ) OUT(NOM) S * Drive to voltage below 0.2V to turn off output current 3 ADJ * Drive with DC voltage (0.3V<V <1.2V) to adjust output ADJ current from 25% to 100% of I OUT NOM * Drive with PWM signal to adjust output current. * When driving the ADJ pin above 1.2V, the current will be clamped to 100% brightness automatically. Connect resistor R from this pin to V to define nominal S IN 4 ISENSE average output current I =0.1/R OUT NOM S Input voltage (6V ~ 40V). Decouple to ground with 0.1F X7R 5 VIN ceramic capacitor as close to device as possible. Thermal Pad Connect to GND. Lumissil Microsystems www.lumissil.com 2 Rev. C, 12/22/2013