LTC1873

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 C_IN
` 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: < 100A
` Small 28-Pin SSOP Package


Application

· Microprocessor Core and I/O Supplies
· Multiple Logic Supply Generator
· High Efficiency Power Conversion
· Chipset Power Supply


Pinout




Specifications

Supply Voltage
    V_CC....................................................................... 7V
    BOOST .................................................................15V
    BOOST n SW n................................................... 7V
Input Voltage
    SW n......................................................... 1V to 8V
    VID n...................................................... 0.3V to 7V
    All Other Inputs ........................ 0.3V to V_CC + 0.3V
Peak Output Current < 10s
TGn, BG n..................................................................... 5A
Operating Temperature Range
    (Note 2) ................................................ 40 to 85
Storage Temperature Range ................... 65 to 150
Lead Temperature (Soldering, 10 sec)..................... 300


Description

The LTC^®1873 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^TM 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 100A.