Why are you trying to re-invent the wheel in the first place?Ĭlick to expand.Thanks again, though ours doesnt have these things. There are numerous integrated gate drives that commercial manufacturers seem to find quite acceptable. High speed PWM systems may have separate drive for the upper and lower halves, to allow a dead time and prevent shoot through. Things that use darlington configuration outputs like that in commercial high power gear often have auxiliary power supplies to allow the drive circuit voltages to exceed the high current power rails, so the devices can be driven nearer full saturation. The drive circuit need an appropriate voltage offset between the base connections of the two halves to allow for the chain of B-E drops and control current appropriately to each, depending if it's on or off. When the drive signal switches, the devices that were previously on have the B-E junctions reverse biased equally, with the voltage divided via the diodes. The only things normally used in high speed / high power circuits with darlingtons are relatively low value base-emitter resistors at each stage and reverse diodes across each base-emitter on each device. You can get better power efficiency using Sziklai pairs.
They are very different in operation and overall characteristics and should not be confused.Ī symmetric push pull with normal darlingtons gives a very reduced output swing and is inefficient power wise, due to the voltage drops across the power transistors when they are switched on. You are talking about a symmetric push-pull type circuit, Class B amp style.
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