I have a simple HF detector, it gets more then 100 V input, so I was wondering if the 2 diodes in a BAT62 can be used in series, to get the voltage. Spice likes it, but then, how will the voltage divide if it heats up? ftp://panteltje.com/pub/rf_detector.jpg
BAT62 is rated at 40 volts.
Is your input 100 peak? p-p? RMS?
Does the output have a filter cap?
Schottkies in series are usually OK, as their reverse conduction curves have nice shapes.
John
On a sunny day (Mon, 27 Oct 2008 14:04:00 GMT) it happened Jan Panteltje wrote in :
Never mind, problem solved, I have changed the capacitive divider, so the voltage is within range for one BAT62.
"Jan Panteltje" schreef in bericht news:ge4hoj$opk$ snipped-for-privacy@news.datemas.de...
The voltage will probably divide pretty badly - in the short term it will depend on the ratio of the capaciatnces of the diodes, and in the longer term the leakage currents will determine how the reverse voltage divides over the diodes. Neither parameter is tightly specified. The capacitance should be similar from diode to diode, since it basically depends on area, with some influence from doping, but leakage currents tend to be erratic.
The saving grace with leakage currents is that leakage current tends to be highly non-linear function of reverse voltage, increasing rapidly as you get close to the breakdown voltage, but it is all very sloppy and uncertain.
-- Bill Sloman, Nijmegen
On a sunny day (Mon, 27 Oct 2008 07:19:57 -0700) it happened John Larkin wrote in :
Thank you John, that is good to know. I have changed the voltage divider a bit however, so it is within the 40V.
You kind of lose the "Schottkey magic" when you pair them up. A plain ol' silicon fast recovery diode should have about the same forward drop as a pair of Schottkeys.
Or a SiC Schottkey from Cree would work and be good to 600V.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
I gather you are using the diode(s) as a rectifier to monitor an RF voltage. If you are clever, you may also find a way to use the diodes where the voltage drop across them is never very great, and still monitor fairly high voltage. That's commonly done in quadrupole mass spectrometry, where there's a need to very accurately monitor RF voltages to over a kilovolt, but the saving grace there is that it's at a constant frequency.
Cheers, Tom
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