Linear Technology Launches Step-Down DC/DC Controller
Use of non-linear control and differential output sensing for strict output voltage regulation

August 11, 2011 – Linear Technology Korea (CEO Hong Sa-kwak, www.linear.com ) announced the release of the LTC3867, a fixed-frequency synchronous step-down DC/DC controller featuring nonlinear control, differential output voltage sensing, and clock synchronization. Nonlinear control minimizes output voltage excursion by increasing the operating frequency during load transient events, allowing the LTC3867 to recover within a few cycles during heavy load phases. This feature reduces the nominal maximum deviation by up to 50% compared to conventional controllers. The LTC3867's input range of 4V to 38V targets a wide range of applications, including most intermediate bus voltages. A powerful onboard N-channel MOSFET gate driver enables the use of high-power external MOSFETs for high-current loads up to 25A. The LTC3867 provides an output voltage range of 0.6V to 14V, making it ideal for telecom, datacom, automotive, and industrial applications.

The differential amplifier of the LTC3867 provides remote output voltage sensing for the positive and negative terminals, enabling high-accuracy regulation regardless of trace run, bias, and IR loss in the interconnect (up to ±300mV). The low minimum on-time of 65ns accommodates power supplies with high step-down ratios during high-frequency operation. The operating frequency is selectable in the range of 200 kHz to 1.2 MHz or can be synchronized with an external clock. For high efficiency, the output current is monitored via voltage drop (DCR) measurement at the output inductor or the use of a sensing resistor. Additional features include DCR temperature compensation, an onboard bias voltage LDO, soft start or tracking, adjustable current limiting, smooth recovery from output overcurrent conditions, overvoltage protection, external VCC control, and a reference voltage accuracy of ±1% over an operating junction temperature range of -40°C to 125°C.

The LTC3867 is available in a thermally enhanced 4mm x 4mm QFN-24 package. Pricing starts at $2.76 per unit for orders of 1,000. For more information, please visit www.linear.com/product/LTC3867 .

Product Features: LTC3867

• Non-linear control for minimum output voltage excursion during transient events
• Differential amplifier for remote output voltage sensing
• Wide VIN range: 4V ~ 38V
• VOUT Range: 0.6V ~ 14V
• Powerful onboard MOSFET gate driver
• High step-down rate: Minimum on-time of 65ns
• Selectable operating frequency in the range of 200kHz to 1.2MHz
• Synchronizable with an external clock in the range of 250kHz to 1.1MHz
• ±1% reference voltage accuracy over the temperature range
• RSENSE or DCR current sensing
• DCR temperature compensation
• Output voltage tracking or programmable soft start
• Adjustable current limit
• Smooth recovery from overcurrent output
• Overvoltage protection

Linear Technology Company Introduction
Linear Technology Corporation, an S&P 500 company, has been designing, manufacturing, and selling a wide range of high-performance analog integrated circuits for major global companies for over 30 years. Linear Technology's products play a critical role in bridging the digital world with the analog world in communications, networking, industrial, automotive, computer, medical, instrumentation, consumer electronics, military, and aerospace systems. Linear Technology currently produces power management, data conversion, signal conditioning, RF, interface ICs, and µModule® subsystems.

LT, LTC, LTM, µModule, and are registered trademarks of Linear Technology Corp. All other trademarks are the property of their respective owners.