CM3109 Datasheet | California Micro Devices

Features Ideal for both PC Front Side Bus and DDR memory VTT applications - Sinks and sources 2A - Over current protection - Over temperature protection - Shutdown function .. - Integrated power MOSFETs - Excellent accuracy (0.5% of load regulation) - Minimum external ponents - 8 pin PSOP package - Lead-free version available - Product Description The CM3109 is a sinking and sourcing regulator specifically designed for series-parallel bus termination for high speed chip set buses as well as DDR memory systems. It can source and sink current up to 2A with high accuracy of 0.5 %. The VTT output voltage is selectable by VDDQSEL and FSBSEL pins. The VDDQSEL pin controls whether the CM3109 is in DDR memory mode with VTT = VDDQ/2, or in FSB mode. In FSB mode, FSBSEL controls whether VTT is 1.225V or 1.45V. This allows the same chip to be used in two different circuits on PC motherboards that support both Northwood and Prescott processors. The CM3109 requires no external ponents to use the GMCH Enable signal in Intel chipset or corresponding signals for other chip sets when powering up the PC. For the boards which support Suspend to RAM (STR) functionality, CM3109 provides a shutdown (SD) pin. When SD is set low, VTT will be in tri-state mode, causing the output to go high impedance. In this mode, CM3109 power is saved by significantly reducing the quiescent current. The CM3109 provides over current and over temperature protection. These features protect the chip from excessive heating due to high current and high temperature. The CM3109 is housed in an 8-pin PSOP package and is available with optional lead-free finishing. Applications - - - - PC Front Side Bus termination regulator DDR Memory termination regulator Active termination buses Graphics card DDR memory termination Simplified Electrical Schematic VDDQSEL FSBSEL VDDQ 50K Output Select Over Temp Over Current Reference Driver 50K VSENSE © 2004 California Micro Devices Corp. All rights...