11

GM1117S

1A LOW DROPOUT

PRECISION VOLTAGE REGULATOR

Heatsink Requirements

When an integrated circuit operates with an appreciable current, its junction temperature is elevated.

It is important to consider its thermal limits in order to achieve acceptable performance and reliability.

This limit is determined by summing the individual parts consisting of a series of temperature rises

from the semiconductor junction to the operating environment.

The heat generated at the device junction flows through the die to the die attach pad, through the

lead frame to the surrounding case material, to the printed circuit board, and eventually to the

ambient environment. Below is a list of variables that may affect the thermal resistance and in turn

the need to a heatsink.

1.

Lead Frame Size & Material

2.

Number of conducting Pins

3.

Die Size

4.

Die Attach Material

5.

Molding Compound Size & Material

1.

Mounting Pad Size, Material & Location

2.

Placement of Mounting Pad

3.

PCB Size & Material

4.

Traces Length & Width

5.

Adjacent Heat Source

6.

Volume of Air

7.

Ambient Temperature

8.

Shape of Mounting Pad

The GM1117S regulators have internal thermal shutdown to protect the device from over heating.

Under all possible operating conditions, the junction temperature of the GM1117S must be within in

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

ambient temperature which will be encountered in the application.

for TO220 package or > 92°C/W for TO252 package, no heat sink is needed since the package

below these limits, a heat sink is required.

GM1117S

Gnd