Electronics > Beginners

use bjt or mosfet in h-bridge with inductive load?

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David Hess:

--- Quote from: alireza7 on July 26, 2018, 08:38:17 am ---
--- Quote from: blueskull on July 26, 2018, 08:26:38 am ---
--- Quote from: alireza7 on July 26, 2018, 08:17:41 am ---but what about negative Vce voltage which a bjt can tolerate?
--- End quote ---

Very little, ~7V, and this can alter hFE and frequency response irreversibly of the BJT even if it doesn't blow up immediately.
That's why you always need a diode in parallel.
--- End quote ---

so why bjt datasheets don't mention anything about this rating?
--- End quote ---

They do; it is Vbe.

For power transistors, base-emitter breakdown is not as important as it mostly affects hfe at low currents.


Using bipolar transistors or more likely Darlingtons even with external diodes may be less expensive than power MOSFETs simply because for a given current and voltage they use less silicon area making them less expensive.  The advantage in speed that MOSFETs have does not matter at low frequencies.

Bipolar h-bridges are also easier to drive because the same signal and driver may be used to turn on pairs of transistors.

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