IS32LT3953

IS32LT3953 CONSTANT-CURRENT 3-AMPERE PWM DIMMABLE BUCK REGULATOR LED DRIVER Advanced Information December 2013 GENERAL DESCRIPTION The IS32LT3953 is a DC-to-DC switching converter with an integrated N-channel MOSFET operating in a buck configuration. The device is connected to a voltage higher than the LED voltage; between 6V and 48V and provides a constant current of up to 3.0A for driving a single LED or multiple series connected LEDs. The LED output current is set by an external current sense resistor, allowing the output voltage to be automatically adjusted for a variety of LED configurations. The IS32LT3953 operates in a fixed frequency mode during switching. The on-time (switching frequency) is programmed using an external resistor connected between the VIN and TON pins. LED dimming is accomplished by applying a logic input PWM (pulse-width-modulation) signal to the enable (EN) pin. The resulting LED brightness is proportional to the duty cycle of the PWM signal. True average current is output using cycle-by-cycle, controlled on-time method. The IS32LT3953 is offered in an SOP-8-EP package with an exposed pad for enhanced thermal dissipation. The operating temperature range is from -40°C to +125°C. FEATURES  Supply voltage 6V ~ 48V  True average output current control  3.0A maximum output over operating temperature range  Cycle-by-cycle current limit  Integrated MOSFET switch  Dimming via direct logic input or power supply voltage  Internal control loop compen...