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LTC3717 - Wide Operating Range, No RSENSE Step-Down Controller for DDR/QDR Memory Termination

The LTC3717 is a synchronous step-down switching regulator controller for double data rate (DDR) and Quad Data Rate (QDR) memory termination. The controller uses a valley current control architecture to deliver very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VIN.

Forced continuous operation reduces noise and RF interference. Output voltage is internally set to half of VREF, which is user programmable.

Fault protection is provided by an output overvoltage comparator and optional short-circuit shutdown timer. Soft-start capability for supply sequencing is accomplished using an external timing capacitor. The regulator current limit level is symmetrical and user programmable. Wide supply range allows operation from 4V to 36V at the VCC input.

Features VOUT = 1/2 VIN (Supply Splitter) Adjustable and Symmetrical Sink/Source Current Limit up to 20A ±0.65% Output Voltage Accuracy Up to 97% Efficiency No Sense Resistor Required Ultrafast Transient Response True Current Mode Control 2% to 90% Duty Cycle at 200kHz tON(MIN) Stable with Ceramic COUT Dual N-Channel MOSFET Synchronous Drive Power Good Output Voltage Monitor Wide VCC Range: 4V to 36V Adjustable Switching Frequency up to 1.5MHz Output Overvoltage Protection Optional Short-Circuit Shutdown Timer Available in a 16-Pin Narrow SSOP Package Typical Application

Applications Bus Termination: DDR and QDR Memory, SSTL, HSTL,.... Notebook Computers, Desktop Servers Tracking Power Supply Packaging

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