Thermal Management

The LM9072 is packaged in both a TO-263 surface mount

power package and a narrow lead-pitch TO-220 package. To

obtain operation over the highest possible load current and

input voltage ranges, care must be taken to control the oper-

ating temperature of the device. Thermal shutdown protec-

tion is built in with a threshold above 150˚C. Conventional

heat sinking techniques can be used with the TO-220 pack-

age. When applying the TO-263 package on-board heat

sinking is important to prevent shut down. More copper foil

area under the tab of the device will directly reduce the oper-

ating junction temperature. Use of a double sided board with

vias between two planes of copper as shown in

Figure 8 will

improve performance and can optimize the PC board sur-

face area required.

Electro-Magnetic Compatibility (EMC)

The LM9072 offers good immunity to high frequency interfer-

ence in a standard Bulk Current Injection (BCI) test

(ISO11452 Part 4 test method). The following test conditions

and configuration (

Figure 9) can be used to observe this per-

formance.

Frequency Range

1 MHz to 400 MHz

Modulation 1

CW (no modulation)

Modulation 2

1 kHz sine wave, 80% AM

Dwell Time

1 second

Frequency Steps

1 MHz (from 1 MHz to 10 MHz)

2 MHz (from 10 MHz to 200 MHz)

20 MHz (from 200 MHz to 400 MHz)

Test Method

Closed loop current probe

In this test configuration the current injected into either the

input pin or the tracking output pin is increased until a reset

output is generated. These two pins are the most critical as

they typically will connect to a module through long lengths

of wire most likely to pick up high frequency energy.

Figure

10 illustrates examples of test results on the LM9072 with

both types of modulation.

These results are just examples as actual results in any

given application will depend on numerous external factors

such as component selection, pc board layout, etc. The cur-

rent power of the injected signal is expressed in dB relative

to 1 mA (i.e., 40 dBmA = 100 mA).

DS012906-24

FIGURE 8. Typical TO-263 PC Board Heatsinking

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