DDR Bus Termination Regulator Handles Upgrades to DDR4
Diodes Incorporated has introduced a low-dropout linear regulator capable of generating the bus termination voltages needed by DDR 2, 3, 3L and 4 SDRAM memory systems. For applications including next generation set-top boxes, mother boards and graphics cards, the AP2303 continuously sources and sinks current up to 1.75A and provides a tightly-regulated VTT output voltage to DDR standards with an accuracy of ±2% up to full load.
The required DDR memory termination supply is set via a simple external resistor network and is output via a standard MLCC ceramic capacitor that helps simplify assembly processes and reduce component cost and PCB size. The regulator is offered in a choice of space-saving 8-pin SO and PSOP packages and operates from a recommended input voltage range of 1.2V to 5.5V. Ambient operating temperature range is -40 to +85 degrees C.
To minimize inrush currents induced by large capacitive loads the AP2303 offers a flexible soft-start facility, activated by a rising voltage on either VCNTL or VREFEN pins. In addition, to help reduce power consumption, a falling voltage applied to VIN, VCNTL or VREFEN pins causes the device to shutdown.
Current limit protection is provided on both source and sink sides, with device output voltage dropping towards 0V once current exceeds 1.75A. Over temperature protection is also included, with the AP2303 output turning off once junction temperature exceeds +160 degrees C. The AP2303 DDR bus termination regulator from Diodes Incorporated is priced at $0.1USD each in 4K quantities.
