1. Home
  2. Embedded Programming
  3. Using a TVS as a zener, bad idea?

Using a TVS as a zener, bad idea?

Been doing some experimentation with TVS's and have found that they seem to be usable as a zener diode when their clamp voltage has been achieved but with a very low current.

Eg. If I have a TVS with a clamp voltage of 14V with a current flow of less than 1 mA, say from some circuitry that is acting as a constant current source, then it seems to be quite happy to be left on / clamping / (zenering?). Power dissipation is less than 5mW. The clamp / zener voltage doesn't have to be that accurate, just approximately 14V.

Can anyone see a problem with this?

Reply to
Rob
Loading thread data ...

A very active and good group, where you should ask is: nntp://sci.electronics.design

/Glenn

Reply to
Glenn

A TVS diode is basically just a zener optimized for for surge power handling rather than continuous low-current use. So you're not using a TVS as a zener diode, you're using a zener diode as a zener diode.

My only question would be "Why?". In my experience, TVSs are physically larger and more expensive. On a lark I pulled up any old datasheet I had on file, the MAZ3140. It's a SOT-23 14V Zener with a breakover voltage that doesn't barely twitches between 1 and 10 mA, and in fact remains at 13.1V at only 60uA. Less than 30 cents a piece at 25 piece quantities, 8 cents a pop by the reel.

--
Rob Gaddi, Highland Technology -- www.highlandtechnology.com 
Email address domain is currently out of order.  See above to fix.
Reply to
Rob Gaddi

Using ANY device for a purpose other than what it was designed (AND SPECIFIED) for is a problem.

Sometimes, it's genius. But most of the time, it's a problem waiting to happen. Most of us are NOT geniuses.

Reply to
mike

Yes, there's a guy called Larkin who may be able to help :)

--

John Devereux
Reply to
John Devereux

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.