The LT3501 is a dual current mode PWM step-down DC/DC converter with two internal 3.5A switches. Independent input voltage, feedback, soft-start and power good pins for each channel simplify complex power supply tracking/sequencing requirements.

Both converters are synchronized to either a common external clock input or a resistor programmable fi xed 250kHz to 1.5MHz internal oscillator. At all frequencies, a 180° phase relationship between channels is maintained, reducing voltage ripple and component size. Programmable frequency allows for optimization between effi ciency and external component size.

Minimum input-to-output voltage ratios are improved by allowing the switch to stay on through multiple clock cycles, only switching off when the boost capacitor needs recharging, resulting in ~95% maximum duty cycle.

Each output can be independently disabled using its own soft-start pin, or by using the SHDN pin the entire part can be placed in a low quiescent current shutdown mode.

The LT3501 is available in a 20-lead TSSOP package with exposed leadframe for low thermal resistance.

Applications

• DSP Power Supplies
• Disc Drives
• DSL/Cable Modems
• Wall Transformer Regulation
• Distributed Power Regulation

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.