Features

• Two Independent PWM Controllers in One Package
• Side 1 Output Is Compliant with Intel Desktop VRM 8.4 Specifications (Includes 5-Bit VID DAC)
• 1.3V to 3.5V Output Voltage with 50mV/100mV Steps
• Two Sides Run Out-of-Phase to Minimize CIN
• All N-Channel External MOSFET Architecture
• No External Current Sense Resistors Required
• Precison Internal 0.8V ±1% Reference
• 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

Typical Application

Description

The LTC1873 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 MOSFETs in a voltage mode feedback, synchronous buck configuration. The LTC1873 includes digital output voltage adjustment on side 1 that conforms to the Intel Desktop VID specification. A constant-frequency, true PWM design minimizes external component size and cost and optimizes 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 LTC1873 features an onboard reference trimmed to 1% and delivers better than 1.5% regulation at the converter outputs over all combinations of line, load and temperature. Each channel can be enabled independently; with both channels disabled, the LTC1873 shuts down and supply current drops below 100µA.