Linear unveil 36V step-down switching regulator

The LT3514’s unique design includes an onboard boost regulator, enabling each channel to operate at 100% duty cycle, even with input voltage as low as 3.2V. This architecture makes the LT3514 well suited for applications requiring continuous output regulation such as automotive cold-crank and stop-start scenarios.

The LT3514’s switching frequency is user-programmable from 250kHz to 2.2MHz and is synchronizable throughout the range, enabling the designer to optimize efficiency while avoiding critical noise-sensitive frequency bands. The combination of its 28-lead 4mm x 5mm QFN package and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint for multiple output applications.

The LT3514 utilizes one internal 3A switch and two 1.45A switches for the step-down conversion and a 220mA switch for the internal boost circuit, with the necessary oscillator, control and logic circuitry integrated into a single die. Special design techniques deliver efficiencies up to 88% over a wide input voltage range, and the LT3514’s current mode topology enables fast transient response and excellent loop stability. Anti-phase switching reduces input ripple and robust short-circuit protection enhances system reliability. Other features include output voltage tracking, programmable undervoltage lockout and a power good pin to indicate when all outputs are in regulation.

The LT3514 is available in thermally enhanced 4mm x 5mm QFN-28 and TSSOP-24 packages. The LT3514E is priced starting at $3.50 each for 1,000-piece quantities. The LT3514I is tested and guaranteed to operate from a -40°C to 125°C junction temperature range and is priced starting at $3.85 each for 1,000-piece quantities. Both versions are available from stock.

LT3514 key features:

• Wide Input Range: 3.2V to 36V (40VMAX),
• One 2A Output & Two 1A Outputs,
• 100% Duty Cycle Operation,
• Resistor-Programmed Constant Frequency,
• Short-Circuit Robust,
• Wide SYNC Range: 250kHz to 2.2MHz,
• Anti-Phase Switching Reduces Ripple,
• 800mV FB Voltage,
• Independent Run/Soft-Start Pins,
• Shutdown with UVLO,
• Internal Compensation,
• Thermal Shutdown,
• Tiny 28-Lead (4mm × 5mm) Thermally Enhanced QFN & TSSOP-24 Packages.