General Description
The APW7055 provides the power control and protections for two output voltages on M/B DDR applications. It integrates one PWM controller , one source-sink linear controller(LC) for DDR source-sink purpose, as well as the monitor and protection functions into a single package. The PWM controller supplies the VMEM(2.5V) with a standard buck converter. The source-sink linear controller regulates VTT(1.25V) power for DDR Termination.
Additional built-in over-voltage protection (OVP) will be started when the VMEM output is above 115% of the internal DAC setting(VDAC) . OVP function will shut down the upper MOSFET and disable all output voltage . The PWM controller’s over-current function monitors the output current by sensing the voltage drop across the upper MOSFET‘s rDS(ON) , eliminating the need for a current sensing resistor .

Features
• Operates from 5V input supply
• 2 Regulated Voltage are provided
   − Standard Buck Switching Power for VMEM (2.5V)
   − Linear Controller with Source-Sink Regulation for VTT(1.25V)
• Simple Single-Loop Control Design
   − Voltage-Mode PWM Control
• Excellent Output Voltage Regulation
   − VMEM Output : VMEM ±1.5% Over Tem-perature
   − VTT Output : 1/2 VIN ±25mV Over Temperature
• Fast Transient Response
   − Built-in Feedback Compensation
   − Full 0% to 100% Duty Ratio
• Over-Voltage and Over-Current Fault Monitors
• Constant Frequency Operation(200kHz)
• 16 pins, SSOP Package

Applications
• M/B DDR Power Regulation
• AGP/PCI Graphics Power Regulation
• SSTL-2 Termination