LM4782TABD/NOPB National Semiconductor, LM4782TABD/NOPB Datasheet - Page 21

• Manufacturer Part Number: LM4782TABD/NOPB
• Manufacturer: National Semiconductor

Specifications of LM4782TABD/NOPB

• Lead Free Status / Rohs Status: Compliant

Application Information
reduced by increasing the size of the bypass capacitor near
the IC. With at least a 20µF local bypass, these voltage
surges are important only if the lead length exceeds a couple
feet (
and ground leads minimizes the effect.
PHYSICAL IC MOUNTING CONSIDERATIONS
Mounting of the 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.
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 resis-
tance from the package case to the heat sink (θ
in higher operating die temperatures and possible unwanted
thermal shut down activation. Extreme over tightening of the
mounting screws will cause severe physical stress resulting
>
1µH lead inductance). Twisting together the supply
(Continued)
CS
) resulting
21
in cracked die and catastrophic IC failure. The recom-
mended mounting screw size is M3 with a maximum torque
of 50 N-cm. Additionally, it is best to use washers under the
screws to distribute the force over a wider area or a screw
with a wide flat head. To further distribute the mounting force
a solid mounting bar in front of the package and secured in
place with the two mounting screws may be used. Other
mounting options include a spring clip. If the package is
secured with pressure on the front of the package the maxi-
mum pressure on the molded plastic should not exceed
150N/mm
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 fail-
ure.
2
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