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