30 ns/DIV

100°C - 70°C

6W

= 5°C/W

OBSOLETE

LM2476

SNOSAH7B – JANUARY 2004 – REVISED APRIL 2013

www.ti.com

The LM2476 case temperature must be maintained below 100°C. If the maximum expected ambient temperature

is 70°C and the maximum power dissipation is about 6W (from Figure 10, 95 MHz bandwidth), then a maximum

heat sink thermal resistance can be calculated:

(1)

PACKAGE MOUNTING CONSIDERATIONS

Mounting of the TO-220 package to a heat sink must be done such that there is sufficient pressure from the

mounting screws to insure good contact with the heat sink for efficient heat flow. The surface of the heat sink

should be free of contaminants before mounting to insure good contact. Incorrect mounting may lead to both

thermal and mechanical problems. Over tightening the mounting screws will cause the package to warp,

reducing contact area with the heat sink. Less contact with the heat sink will increase the thermal resistance from

the package case to the heat sink (

the mounting screws will cause severe physical stress resulting in a cracked or chipped package and possible

catastrophic IC failure.

The recommended mounting screw size is M3 with a maximum torque of 50 N-cm. It is best to use fiber washers

under the screws to distribute the force over a wider area. Additionally, if the mounting screws are used to force

the package into correct alignment with the heat sink, package stress will be increased. This increase in package

stress will result in reduced contact area with the heat sink increasing die operating temperature and possible

catastrophic IC failure.

TYPICAL APPLICATION

A typical application of the LM2476 is shown in Figure 13. Used in conjunction with an LM123X/4X preamplfier, a

complete video channel from monitor input to CRT cathode can be achieved. Performance is ideal for 1024 x

768 resolution displays with pixel clock frequencies up to 95 MHz. Please see the next two sections below for

hints on how to properly evaluate the LM123X/4X and LM2476 combination in a monitor. Figure 12 shows the

typical cathode response for this application. The peaking component values used are shown in Figure 11 and

Figure 13.

Figure 12. Typical Cathode Response

10

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