Features up to 95% efficiency and 2MHz operating frequency

January 19, 2012 – Linear Technology Korea (CEO Hong Sa-kwak) announced the release of the High-Frequency Controlled On-Time Single Output Dual-Phase Synchronous Step-Down DC/DC Controller (Product Name: LTC3839). This product can achieve up to 92% efficiency with a 25A output when operating at 2 MHz. The operating frequency is selectable from 200 kHz to 2 MHz and can be synchronized with an external clock. With a low minimum on-time of 30 ns, it provides a high step-down ratio even at high operating frequencies. Additionally, the Controlled On-Time, Valley Current Mode Architecture, and Detect Transient Release functions increase the operating frequency during transient events to provide a very fast transient response, allowing the output voltage to recover within a few clock cycles. For high-current applications, parallel connection and out-phase clocking of up to 12 phases are possible (up to 250A).
The LT3839 operates over an input voltage range of 4.5V to 38V and can be used in a wide variety of applications, including most intermediate bus voltages. The powerful onboard N-channel MOSFET gate driver allows for the use of high-power external MOSFETs for higher output currents up to 50A over an output voltage range of 0.6V to 5.5V, making this device ideal for PoL requirements. The LTC3839's differential amplifier enables high-precision regulation regardless of PCB IR losses (up to ±500mV) by providing true remote output voltage sensing for the positive and negative terminals. The output current can be monitored by detecting a voltage drop in the output inductor (DCR) for high efficiency or by using a sensing resistor to further increase precision. Other features include an onboard bias voltage LDO, soft start or tracking, adjustable current limit, overvoltage protection, current limit foldback, and external VCC control.
The LTC3839 provides excellent total regulation accuracy and is designed to identify all error sources, including line, load, and differential sensing. The LTC3839's total output voltage accuracy is +/-0.25% at 25°C, +/-0.67% from 0°C to 85°C, and a maximum DC error of ±1% over the entire operating temperature range of -40°C to 125°C. The LTC3839 is available in a thermally enhanced 5mm x 5mm QFN-32 package and is priced at $3.18 per unit in 1,000-piece quantities. For more information, please visit www.linear.com/product/LTC3839 .

Photo caption: High-frequency/high-efficiency step-down DC/DC controller

Product Features: LTC3839

• On-time and valley current mode control for very fast transient response
• Programmable operating frequency from 200kHz to 2MHz, synchronized with an external clock
• Wide input voltage range: 4.5V ~ 38V
• Output voltage range: 0.6V ~ 5.5V
• Maximum output current of 50A
• High step-down ratio: 30ns minimum on-time
• Up to 12-phase motion
• Detect Transient Release function
• Differential amplifier for remote output voltage sensing
• Provides ±0.67% output voltage accuracy over the specified temperature range
• RSENSE or DCR current sensing
• Output voltage tracking or programmable soft start
• Adjustable current limit
• Provides overvoltage protection
• Foldback current limiting function