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MBRF745 Datasheet, PDF (3/4 Pages) Motorola, Inc – SWITCHMODE™ Schottky Power Rectifirer | |||
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TEST CONDITIONS FOR ISOLATION TESTS*
MOUNTED
CLIP
FULLY ISOLATED
PACKAGE
LEADS
MOUNTED
FULLY ISOLATED
CLIP
PACKAGE
0.107â³ MIN
LEADS
MBRF745
MOUNTED
FULLY ISOLATED
PACKAGE
0.107â³ MIN
LEADS
HEATSINK
0.110â³ MIN
HEATSINK
Figure 3. Clip Mounting Position
for Isolation Test Number 1
Figure 4. Clip Mounting Position
for Isolation Test Number 2
* Measurement made between leads and heatsink with all leads shorted together.
HEATSINK
Figure 5. Screw Mounting Position
for Isolation Test Number 3
MOUNTING INFORMATION**
4â40 SCREW
CLIP
PLAIN WASHER
HEATSINK
COMPRESSION WASHER
NUT
HEATSINK
6a. ScrewâMounted
6b. ClipâMounted
Figure 6. Typical Mounting Techniques
Laboratory tests on a limited number of samples indicate, when using the screw and compression washer mounting technique, a screw torque of 6 to 8 in . lbs is sufficient to provide
maximum power dissipation capability. The compression washer helps to maintain a constant pressure on the package over time and during large temperature excursions.
Destructive laboratory tests show that using a hex head 4â40 screw, without washers, and applying a torque in excess of 20 in . lbs will cause the plastic to crack around the mounting
hole, resulting in a loss of isolation capability.
Additional tests on slotted 4â40 screws indicate that the screw slot fails between 15 to 20 in . lbs without adversely affecting the package. However, in order to positively ensure
the package integrity of the fully isolated device, Motorola does not recommend exceeding 10 in . lbs of mounting torque under any mounting conditions.
**For more information about mounting power semiconductors see Application Note AN1040.
Rectifier Device Data
3
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