5-Bit Adjustable High Efficiency Synchronous Step-Down Switching Regulator

The LTC1736 is a synchronous step-down switching regulator controller optimized for CPU power. The output voltage is programmed by a 5-bit digital-to-analog converter (DAC) that adjusts the output voltage from 0.925V to 2.00V according to Intel mobile VID specifications. The 0.8V reference is compatible with future microprocessor generations.

The operating frequency (synchronizable up to 500kHz) is set by an external capacitor allowing maximum flexibility in optimizing efficiency. The output voltage is monitored by a power good window comparator that indicates when the output is within 7.5% of its programmed value.

Protection features include: internal foldback current limiting, output overvoltage crowbar and optional short-circuit shutdown. Soft-start is provided by an external capacitor that can be used to properly sequence supplies. The operating current level is user-programmable via an external current sense resistor. Wide input supply range allows operation from 3.5V to 30V (36V maximum).

Pin defeatable Burst Mode™ operation provides high efficiency at low load currents. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values.

Applications

* Notebook and Palmtop Computers, PDAs

* Power Supply for Mobile Pentium® II and Pentium III Processors

* Low Voltage Power Supplies

* Dual N-Channel MOSFET Synchronous Drive

* Synchronizable/Programmable Fixed Frequency

* Wide VIN Range: 3.5V to 36V Operation

* 5-Bit Digital-to-Analog VOUT Selection:

* 0.925V to 2.00V Range with 50mV/25mV Steps

* OPTI-LOOP™ Compensation Minimizes COUT

* ±1% Output Voltage Accuracy

* Power Good Output Voltage Monitor

* Output Overvoltage Crowbar Protection

* Internal Current Foldback

* Latched Short-Circuit Shutdown Timer with Defeat Option

* Forced Continuous Control Pin

* Optional Programmable Soft-Start

* Remote Output Voltage Sense

* Available in 24-Lead SSOP Package