I've just measured that the voltage drop on a BTA12 triac is almost constant 0.8V in a wide range of voltages (direct current, 12 ohm load, 5..30V). Why this 'weird' value, which is neither 0.65 nor 2x0.65V of a normal silicon transistor? 0.65V + 0.15V of VCE_sat?
Best regards, Piotr
Makes sense, no? I'd expect some change over a 6:1 current range, though.
0.84V at 30V
Best regards, Piotr
** Your second guess is correct.
The voltage drop is one B-E junction plus one C-E in full saturation.
See page 4.
At currents up to about 20amps, voltage drop reduces as the chip heats due to the negative tempco of one B-E diode of about -2mV per C.
In your test, chip temp rises with current making the drop look nearly constant.
Try a 6amp diode instead of the triac and what you get.
.... Phil
Thank you.
Best regards, Piotr
look there.
You can see why, its a transistor version of a thysistor.
Jamie
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