DESCRIPTION
The LTC®3717-1 is a synchronous step-down switching regulator controller for double data rate (DDR) and Quad Data RateTM (QDRTM) memory termination. The controller uses a valley current control architecture to deliver very low duty cycles with or without a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VIN and VOUT.

FEATURES
■ VOUT = 1/2 VREF
■ Adjustable and Symmetrical Sink/Source
   Current Limit up to 20A
■ True Current Mode Control with Optional Use of
   Sense Resistor
■ VON and ION Pins Allow Constant Frequency
   Operation During Input and Output Voltage Changes
■ ±0.65% Output Voltage Accuracy
■ Up to 97% Efficiency
■ Ultrafast Transient Response
■ 2% to 90% Duty Cycle at 200kHz
■ tON(MIN) ≤ 100ns
■ Stable with Ceramic COUT
■ Power Good Output Voltage Monitor
■ Wide VIN Range: 4V to 36V
■ Adjustable Switching Frequency up to 1.5MHz
■ Output Overvoltage Protection
■ Optional Short-Circuit Shutdown Timer
■ Available in a 5mm × 5mm QFN Package

APPLICATIONS
■ Bus Termination: DDR and QDR Memory, SSTL, HSTL, ...
■ Notebook Computers, Desktop Servers
■ Tracking/Margining Power Supply