CM3109-00SH Ver la hoja de datos (PDF) - California Micro Devices Corp

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CM3109-00SH

2A Sink/Source Regulator for Front Side Bus and DDR Memory Bus Termination

California Micro Devices Corp 

CM3109

2A Sink/Source Regulator for Front Side Bus and

DDR Memory Bus Termination

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 components

• 8 pin PSOP package

• Lead-free version available

Applications

• PC Front Side Bus termination regulator

• DDR Memory termination regulator

• Active termination buses

• Graphics card DDR memory termination

Product Description

The CM3109 is a sinking and sourcing regulator specif-

ically 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 dif-

ferent circuits on PC motherboards that support both

Northwood and Prescott processors.

The CM3109 requires no external components to use

the GMCH Enable signal in Intel chipset or correspond-

ing 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 tempera-

ture protection. These features protect the chip from

excessive heating due to high current and high temper-

ature. The CM3109 is housed in an 8-pin PSOP pack-

age and is available with optional lead-free finishing.

Simplified Electrical

Schematic

SD

VCC

VDDQSEL FSBSEL

Over Temp

Over Current

Reference

Output

Select

Driver

VDDQ

VTT

VSENSE

GND

© 2004 California Micro Devices Corp. All rights reserved.

01/15/04 430 N. McCarthy Blvd., Milpitas, CA 95035-5112 ▲ Tel: 408.263.3214 ▲ Fax: 408.263.7846 ▲ www.calmicro.com

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