LM341/LM78MXX

SNVS090E – MAY 2004 – REVISED AUGUST 2005

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APPLICATION INFORMATION

Note that the case temperature is measured at the point where the leads contact with the mounting pad surface

Figure 14. Cross-sectional view of Integrated Circuit Mounted on a printed circuit board.

The LM78MXX/LM341XX regulators have internal thermal shutdown to protect the device from over-heating.

Under all possible operating conditions, the junction temperature of the LM78MXX/LM341XX must be within the

range of 0°C to 125°C. A heatsink may be required depending on the maximum power dissipation and maximum

ambient temperature of the application. To determine if a heatsink is needed, the power dissipated by the

(1)

(2)

Figure 15 shows the voltages and currents which are present in the circuit.

Figure 15. Power Dissipation Diagram

(3)

If the maximum allowable value for

package, no heatsink is needed since the package alone will dissipate enough heat to satisfy these

requirements. If the calculated value for

As a design aid, Table 1 shows the value of the

we used to measure these

test results as what are in the Table 1

Figure 17 shows the maximum allowable power dissipation vs. ambient temperature for the TO-252 device.

see AN-1028 (SNVA036) for power enhancement techniques to be used with TO-252 package.

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