SLB128B datasheet(44/48 Pages) NSC

44 / 48 page

Applications Information (Continued)

4. To configure for dual pixel in to dual pixel out application

using the DS90C2501 with DS90CF364 or DS90CF364A or

DS90CF366, the “DUAL” pin must be set to V

CC. In this

mode, outputs A0-to-A7, and CLK1, CLK2 are enabled. Do

note that scaler will be shut down in this configuration.

Board Layout and Thermal Considerations for the

DS90C2501

Note: The thermal information listed in this document is

based on preliminary simulation results and subject to

change.

The thermal enhancement features of the (CSP) chip scale

package require special considerations and guidelines to be

observed to insure optimal thermal performance in applica-

tions were the cooling method is free-air convection.

The CSP128 package has a 5X5 matrix of thermal pads

designed to efficiently conduct heat from the device to the

plane of the printed circuit board. The package requires this

thermal connection to increase the effective surface area of

the package to maintain safe operating die temperatures.

The vias of the thermal pads should be connected to the

board’s ground plane having a minimum effective area of

2000 mm

For more complex system thermal design situations, it is

recommended that system level thermal analysis tools be

utilized to insure the maximum junction temperature is not

exceeded.

The graph in Figure 24 shows the expected junction tem-

perature for a given plane area under varying ambient tem-

perature conditions. Figure 25 shows the recommended

PCB footprint for the DS90C2501. The following assump-

tions were used:

•

Board Thickness = 1.6mm

•

Board Area = 7742 sq. mm

•

Copper Plane=1oz.

•

Number of layers = 4

•

Signal Trace Length = 25.4mm

•

Maximum Junction Temperature = +150˚C

•

Package

JA = 31.7˚C/W (Natural Convection)

•

The example does not take heating effects from adjacent

system components into consideration.

•

Pd (max) = 1.8W*

*(scaler on, SXGA to SXGA+ scaling, single in -dual output

port mode, V

DD2.5

+10%, V

DD3.3

+10%, max. process

variation)

As a final design verification, the temperature at the top-

center of the case (T

CASE) should not exceed 97˚C.

Junction Temperature vs. Plane Area

20004570

FIGURE 24. Junction Temperature vs. Ground Plane Area

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