Vbe stuff

Robert Baer · 2006-10-15T08:55:59+00:00

Following what Mr Pease had to say about Vbe, ie read, at 27C that it measures 799mV at 100uA, 640mV at 10uA, and 580mV at 1uA for 60mV per decade. But. Measuring a 1N4006 at 21C i get 474mV at 100uA and 387mV at 10uA for 87mV per decade. Measuring a MPSA42 in DCT mode at 21C i get 564mV at 100uA and 505mV at 10uA for 59mV per decade. Seems to make sense; the larger die area will have a lower current density than a small die area, given the same current. Comments?

J

John Larkin 19 years ago

Pease knows that he has to come up with a page of blather once a month, and he does. Check the latest Electronics Design to see his vacation pictures.

But Electronics Design is mainly blather, so he fits right in.

John

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Robert Baer 19 years ago

I am only passing on what i read over 10 years ago..

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Robert Baer 19 years ago

When i have some spare time, i will try just the E-B junction and use a transistor socket wired up for the purpose. Other than measuring the environment (21C) and letting the transistor "soak" in it for over 1/2 hour, how do you suggest i "measure" the transistor temperature? A Tektronix 7D13 that measures temperature with an external transistor agrees with other measurements of the environment temperature; and i used the same MPSA42.

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Robert Baer 19 years ago

The measurement i made of the MPSA452 in DCT mode at 21C was significantly lower than what Mr Pease stated (implied as fact for virtually all transistors).

Why do i have to repeat this so many times?

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