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LTC3876 - Dual DC/DC Controller for DDR Power with Differential VDDQ Sensing and ±50mA VTT Reference

The LTC®3876 is a complete DDR power solution, compatible with DDR1, DDR2, DDR3 and future DDRX lower voltage standards. The LTC3876 includes VDDQ and VTT DC/DC controllers and a precision linear VTT reference. A differential output sense amplifier and precision internal reference combine to offer an accurate VDDQ supply. The VTT controller tracks the precision VTTR linear reference with less than 20mV total DC error. The precision VTTR reference maintains 1.2% regulation accuracy tracking onehalf VDDQ over temperature for a ±50mA reference load.

The LTC3876 allows operation from 4.5V to 38V maximum at the input. The VDDQ output can range from 1.0V to 2.5V, with a corresponding VTT and VTTR output range of 0.5V to 1.25V. Voltage tracking soft-start, PGOOD and fault protection features are provided.

Features Complete DDR Power Solution with VTT Reference Wide VIN Range: 4.5V to 38V, VDDQ: 1V to 2.5V ±0.67% VDDQ Output Voltage Accuracy VDDQ and VTT Termination Controllers ±1.2% ±50mA Linear VTTR Reference Output Controlled On-Time, Valley Current Mode Control Frequency Programmable from 200kHz to 2MHz Synchronizable to External Clock tON(MIN) = 30ns, tOFF(MIN) = 90ns RSENSE or Inductor DCR Current Sensing Power Good Output Voltage Monitor Overvoltage Protection and Current Limit Foldback Thermally Enhanced 38-Pin (5mm × 7mm) QFN and TSSOP Packages Typical Application

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