The LM3409, LM3409-Q1, LM3409HV, and LM3409HV-Q1 are P-channel MOSFET (PFET) controllersfor step-down (buck) current regulators. They offer wide input voltage range, high-sidedifferential current sense with low adjustable threshold voltage and fast output enable/disablefunction and a thermally enhanced 10-pin, HVSSOP package. These features combine to make the LM3409 family of devices ideal for use as constant current sources for driving LEDs where forward currentsup to 5 A are easily achievable. The LM3409 devices use constant off-time (COFT) control to regulate an accurate constantcurrent without the need for external control loop compensation. Analog and PWM dimming are easy toimplement and result in a highly linear dimming range with excellent achievable contrast ratios. Programmable UVLO, low-power shutdown, and thermal shutdown complete the feature set. For all available packages, see the orderable addendum at the end of the data sheet.