Dual synchronous buck controller provides complete DDR power solution

December 16, 2011 // Paul Buckley

Linear Technology Corporation has introduced the LTC3876, a high-efficiency dual output synchronous step-down DC/DC controller that generates the VDDQ supply voltage, the VTT bus termination voltage and the VTTR reference voltage for DDR1/DDR2/DDR3 and future standard memory applications.

The output of the LTC3876's first channel produces VDDQ and can be programmed from 2.5 V down to 1 V at up to 25 A. The output of the second channel produces VTT and offers superior load regulation accuracy and efficiency.

An internal LDO provides the precision ±1.2% VTTR reference. Both VTT and VTTR are programmed by an internal resistor divider equal to one-half the VDDQ supply and operate from 1.25 V to 0.5 V to support all DDR standards. The VTT supply offers symmetrical output current capability, with ±25 A (sourcing/sinking) at VTT and ±50 mA at VTTR.     

The LTC3876 operates from an input voltage range of 4.5 V to 38 V. The switching frequency is programmable up to 2 MHz allowing the use of very small external components. For noise-sensitive applications, the LTC3876 switching frequency can be synchronized to an external clock. The two channels can be phase shifted at 0°, 90°, 180° or 270° to reduce input filter components and accommodate multi-phase applications with multiple ICs.

The LTC3876 utilizes a controlled on-time valley current mode architecture. Additional features include output voltage tracking, programmable soft start, R SENSE or DCR current sense, remote VDDQ sensing and a power good output signal.

For optimal thermal performance, the LTC3876 is available in 38-pin thermally enhanced 5 mm x 7 mm QFN and TSSOP packages.

For further information: www.linear.com/product/LTC3876.

Technical papers     

• High Voltage Surge Stoppers Ensure Reliable Operation During Power Surges
• AR RF/Microwave Instrumentation Field Analyzers
• 16-Bit, 100 kSPS Low Power Successive Approximation ADC System
• Replacing the Candle in the Candelabra

December 15, 2011 | Texas instruments | 222901974

Unique Ser/Des technology supports encrypted video and audio content with full duplex bi-directional control channel over a single wire interface.