Dual 550kHz Synchronous 2-Phase Switching Regulator Controller with 5-Bit VID

The LTC1703 is a dual switching regulator controller optimized for high efficiency with low input voltages. It includes two complete, on-chip, independent switching regulator controllers. Each is designed to drive a pair of external N-channel MOSFET devices in a voltage mode feedback, synchronous buck configuration. The LTC1703 includes digital output voltage adjustment on side 1 that conforms to the Intel Mobile VID specification. It uses a constant-frequency, true PWM design switching at 550kHz, minimizing external component size and cost and optimizing load transient performance. The synchronous buck architecture automatically shifts to discontinuous and then to Burst Mode® operation as the output load decreases, ensuring maximum efficiency over a wide range of load currents.

The LTC1703 features an onboard reference trimmed to 1% and delivers better than 1.5% regulation at the converter outputs. An optional latching FAULT mode protects the load if the output rises 15% above the intended voltage. Each channel can be enabled independently; with both channels disabled, the LTC1703 shuts down and supply current drops below 100µA.

Applications

* Mobile Pentium® III Processor Systems

* Microprocessor Core and I/O Supplies

* Multiple Logic Supply Generator

* High Efficiency Power Conversion

* Side 1 Output Is Compliant with Intel Mobile VID Specifications (Includes 5-Bit DAC)

* 0.9V to 2.0V Output Voltage with 25mV/50mV Steps

* Two Sides Run Out-of-Phase to Minimize CIN

* Precision Internal 0.8V ±1% Reference

* Two Independent PWM Controllers in One Package

* All N-Channel External MOSFET Architecture

* No External Current Sense Resistor

* 550kHz Switching Frequency Minimizes External Component Size

* Very Fast Transient Response

* Up to 25A Output Current per Channel

* Low Shutdown Current: < 100µA

* Small 28-Pin SSOP Package