July 10, 2012 – Linear Technology Korea (CEO Hong Sa-kwak) announced the launch of the LT3504, a quad 1A output 40V step-down switching regulator capable of 100% duty cycle operation. The LT3504, with an input voltage range of 3.2V to 40V, is ideal for automotive and industrial applications requiring multiple outputs. The product's internal 1.5A switch provides continuous output current up to 1A per channel at a low voltage of 0.8V.

A key design feature of the LT3504 is the onboard boost regulator, which enables each channel to operate at 100% duty cycle, even when the input voltage is as low as 3.2V. Based on this architecture characteristic, the LT3504 is ideal for applications requiring continuous output regulation, such as automotive cold crank or stop-start scenarios. The switching frequency is user-programmable in the range of 250kHz to 2.2MHz, and synchronization is possible across the entire range, allowing designers to optimize efficiency while avoiding problematic noise-sensitive frequency bands. Through the 28-pin 4mm x 5mm QFN package and high switching frequency characteristics, extremely compact external inductors and capacitors can be used, providing a compact and thermally efficient footprint for multi-output applications.

The LT3504 integrates four internal 1.5A switches for step-down conversion and a 220mA switch for the internal boost circuit, along with essential oscillator, control, and logic circuits integrated on a single die. Through this unique design technique and new high-voltage process, the LT3504 delivers high efficiency up to 88% across the entire input voltage range. The LT3504's current-mode topology provides fast transient response and excellent loop stability. Anti-phase switching reduces input ripple, and robust short-circuit protection enhances system reliability. Additional features include output voltage tracking, programmable under-voltage lockout, and a power good pin to indicate when all outputs are in regulation.

The LT3504EUFD is supplied in a 4mm x 5mm QFN-28 package, with pricing starting at $3.50 per unit at 1,000-unit quantities. The LT3504IUFD is tested and guaranteed to operate at temperatures from -40°C to 125°C, with pricing at $3.85 per unit at 1,000-unit quantities. All versions are currently available for immediate purchase. For detailed product information, refer to www.linear.com/product/LT3504.

Photo Caption: 40V, Quad 1A (IOUT), 2.2MHz Step-Down DC/DC Converter

Product Features: LT3504

• Wide Input Range: 3.2V to 40V
• 4 x 1A Outputs
• 100% Duty Cycle Operation
• Resistor-Programmable Fixed Frequency
• Robust Short-Circuit Protection
• Wide SYNC Range: 250kHz to 2.2MHz
• Reduced Ripple with Anti-Phase Switching
• 800mV FB Voltage
• Independent RUN/Soft-Start Pin
• Shutdown with UVLO (Under-Voltage Lockout)
• Thermal Shutdown
• Ultra-Compact 28-Pin (4mm × 5mm) Thermally Enhanced QFN Package