Brief Description
The KTD251 is a versatile constant current LED driver with a high efficiency DC-DC step up “boost” converter architecture. The low-side power MOSFET is integrated in the device, minimizing the total number of external components. Unique technology and high 800mA current limit allow KTD251 to drive up to 36V output (10 LEDs in series), up to 24V using KTD251B (6 LEDs in series) or up to 19V using KTD251C (5 LEDs in series). Alternatively, KTD251 can deliver 160mA total current with 3 series LEDs per string. It can also maximize the current capability while achieving high conversion efficiency. The optimized 0.9MHz and 1.1MHz switching frequencies result in small external component size. The driver allows a wide range of PWM dimming frequencies through the EN pin.

FEATUREs
• Wide output range: up to 10 series LEDs
• Integrated 40V high current switch (800mA
   limit)
• High efficiency PWM converter (up to 90%)
• Low 200mV feedback voltage
• High accuracy across full load range
• VIN range: 2.7V to 5.5V
• LED open-circuit (OVP) protection
   − KTD251: 36V
   − KTD251B: 24V
   − KTD251C: 19V
• High switching frequency
   − KTD251: 900kHz
   − KTD251B/C: 1.1MHz
• PWM dimming frequency: 100Hz to 200kHz
• Simple, small solution size
• Integrated Soft-start
• Shutdown Current less than 1µA
• Small TSOT23-6 Package
• RoHS and Green compliant
• -40°C to +85°C Temperature Range

APPLICATIONs
• LED backlighting
• Mobile Phones
• Handheld Devices
• Digital Photo Frames
• Automotive Navigation