LTC3717-1 - Wide Operating Range, No RSENSE Step-Down Controller for DDR/QDR Memory Termination

The LTC3717-1 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 with or without a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VIN and VOUT.

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 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)
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 x 5mm QFN Package