MJW16212 Datasheet, PDF (7/8 Pages) Motorola, Inc – POWER TRANSISTOR 10 AMPERES 1500 VOLTS - VCES 50 AND 150 WATTS

EMITTER–BASE TURN–OFF ENERGY, EB(off)
Emitter–base turn–off energy is a new specification
included on the SCANSWITCH data sheets. Typical
techniques for driving horizontal outputs rely on a pulse
transformer to supply forward base current, and a turnoff net-
work that includes a series base inductor to limit the rate of
transition from forward to reverse. An alternate drive scheme
has been used to characterize the SCANSWITCH series of
devices (see Figure 2). This circuit ramps the base drive to
eliminate the heavy overdrive at the beginning of the collec-
tor current ramp and underdrive just prior to turn–off ob-
served in typical drive topologies. This high performance
MJW16212
drive has two additional important advantages. First, the con-
figuration of T1 allows Lb to be placed outside the path of for-
ward base current making it unnecessary to expend energy
to reverse the current flow as in a series based inductor. Se-
cond, there is no base resistor to limit forward base current
and hence no power loss associated with setting the value of
the forward base current. The ramp generating process
stores rather than dissipates energy. Tailoring the amount of
energy stored in T1 to the amount of energy, EB(off), that is
required to turn the output transistor off results in essentially
lossless operation. [Note: B+ and the primary inductance of
T1 (LP) are chosen such that 1/2LPlb2 = EB(off).]
TEST CONDITIONS FOR ISOLATION TESTS* (MJF16212 ONLY)
MOUNTED
FULLY ISOLATED
PACKAGE
LEADS
MOUNTED
FULLY ISOLATED
PACKAGE
0.099” MIN
LEADS
HEATSINK
0.110” MIN
HEATSINK
Figure 14. Screw or Clip Mounting Position
for Isolation Test Number 1
Figure 15. Screw or Clip Mounting Position
for Isolation Test Number 2
* Measurement made between leads and heatsink with all leads shorted together
MOUNTING INFORMATION** (MJF16212 ONLY)
4–40 SCREW
CLIP
PLAIN WASHER
HEATSINK
COMPRESSION WASHER
NUT
Figure 16a. Screw–Mounted
HEATSINK
Figure 16b. Clip–Mounted
Figure 16. 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 con-
stant pressure on the package over time and during large temperature excursions.
Destructive laboratory tests show that using a hex head 4-40 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 4-40 screws indicate that the screw slot fails between 15 to 20 in ^. lbs without adversely affecting the pack-
age. 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.
Motorola Bipolar Power Transistor Device Data
3–7