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CM3107

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

California Micro Devices Corp 

CM3107

Performance Information (cont’d)

Typical Thermal Characteristics (cont’d)

Front Side Bus Application

If the CM3107-00SN is instead used for the Front Side

Bus application, where VDDQ could be connected to

the 3.3V VCC rail for ease of connectivity, the power

dissipated will increase to [3.3V-1.4V] = 1.9V times the

sourcing current, or [1.4V - 0V] = 1.4V times the sink-

ing current.

So the worst case is with all FSB outputs low for a

period of time, such that the maximum average source

current at an ambient of 40°C is [0.73W / 1.9V] =

0.38A. If this average current is exceeded, the device

will go over-temperature and the output will drop to 0V.

If it is likely that this average current will be exceeded

for the FSB application, then the version with the heat

spreader, CM3107-00SB, should be used, or for com-

monality of device type for both applications, the VDDQ

pin should instead be connected to 2.5V. The maxi-

mum average source current at an ambient of 40°C is

[2.75W/1.9V] = 1.45A.

The theoretical calculations of these relationships

show the safe operating area of the CM3107 in the

SOIC and PSOP packages.

Thermal characteristics were measured using a double

sided board with two square inches of copper area

connected to the GND pins for "heat spreading".

Measurements showing performance up to a junction

temperature of 150°C were performed under light load

conditions (5mA). This allows the ambient temperature

to be representative of the internal junction tempera-

ture.

Note: The use of multi-layer board construction with

separate ground and power planes will further enhance

the overall thermal performance.

Figure 15. Output Voltage vs. Ambient

Temperature (ILOAD=5mA)

Figure 14. Reference Voltage vs. Temperature

Figure 16. Quiescent Current vs. Temperature

Figure 17.

© 2004 California Micro Devices Corp. All rights reserved.

02/02/04 430 N. McCarthy Blvd., Milpitas, CA 95035-5112 L Tel: 408.263.3214 L Fax: 408.263.7846 L www.calmicro.com

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