Anybody have any experience with the above combination? The 21362 is a nice
bridge driver and the IRF540 is a fairly common N-Channel MOSFET. I am using
this in a three phase Brushless DC application (20KHz PWM) and the trouble I
am having is that I am getting shoot-through currents. The 21362 is supposed
to introduce a 100ns Dead time between the top and bottom MOSFETS but I am
getting this weird spike on the bottom MOSFET gate just before the top FET
Gate-Source voltage goes to zero.  This spike (amplitude of 7V) is enough to
turn on the bottom FET before the top one fully turns off and consequently
the bridge is heating up even under no-load conditions. I have enough
bootstrap capacitance (10uF tantalum and a 0.01uF X7R ceramic in parallel),
fast bootstrap diodes (IN4148W) and even a free-wheeling diode between drain
and source of all the FETS(50ns trr).

Any ideas on why the bottom FET gate-source voltage is showing a spike of
about 7V way before (30-40ns) the bottom FET is supposed to turn on? Any
insights would be greatly appreciated. IRF applications engineering has not
yet come up with an explanation and I am hoping that someone on the PIC list
might have gone down this road before.
Thanks in advance.
Madhu

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