The PT4205S is a continuous conduction mode inductive step - down converter

GENERAL DESCRIPTION The PT4205S is a continuous conduction mode inductive step - down converter, designed for d riving single or multiple serie s connected LED s efficiently from a voltage source higher than the total LED chain voltage. The device operates from an input supply between 5 V and 30V and provides an externally adjustable output current of up to 1.2A. Depending upon the supply voltage and external comp onents, the PT4205S can provide more than tens of watts of output power. The PT4205S includes the pow er sw itch and a high side output current sensing circuit, which uses an external resistor to set the nominal average output current, and a dedicated DIM input accepts either a DC voltage or a wide range of pulsed dimming. Applying a voltage of 0.3V or lowe r to the DIM pin turns the output off and switches the device into a low current standby state. The PT4205S is available in SOT89 - 5 and E SOP - 8 packages. F EATURES  Simple low parts count  Wide input voltage range: 5 V to 30V  Up to 1.2A output current  Single pi n on/off and brightness control using DC voltage or PWM  Typical 3 % output current accuracy  Inherent open - circuit LED protection  High efficiency (up to 97%)  Hysteretic Control: No Compensatio n  Adjustable Constant LED Current  Soft over temperature protection  ESOP - 8 package for large output power application  RoHS complian ce A PPLICATIONS  Low voltage halogen replacement LEDs  Automotive lighting  LED back - up lighting  Illuminated signs
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