Advantages to dual-tap diodes
Advantages to dual-tap diodes
(OP)
Wondering what the advantages to dual-tap diodes are when it comes to placing them on comm lines (i.e., serial ports, etc.)? My first thought is limiting ringing, especially for long transmission distances, but there must be more uses.
Any downsides?
Any downsides?
Dan
Owner
http://www.Hi-TecDesigns.com





RE: Advantages to dual-tap diodes
I have never even heard of a "dual tap diode"!
Part number please...
RE: Advantages to dual-tap diodes
the SB series (or FMP/FML for higher voltages) with
the common pin unconnected. I have seen them used
as a sort of MOV substitute. Highly dependent on
the device and a good understanding of operating and
breakdown characteristics of the diodes, but perfectly
functional for the particular usage.
Spikes, surges, OVP, maybe, but "ringing"? Dunno.
<als>
RE: Advantages to dual-tap diodes
I have used these types of devices for clamping where I wanted to minimize parts count and or PCB footprint. I am presently working on an ADC interface circuit and I used one dual diode SOT-23 package as opposed to using two discete diodes to clamp the ADC inputs. The packages are nice in that you can connect the line to be clamped to the common and then connect the anode and cathode to the clamping supplies.
As far as any special electrical properties, I haven't considered it but there may be, especially at very high frequencies.
RE: Advantages to dual-tap diodes
RE: Advantages to dual-tap diodes
RE: Advantages to dual-tap diodes
I recently came across an application where they were placed on a series of TTL lines, ground at one end, Vdd the other. Reduction of ringing over long run lengths seemed to be the most obvious answer to me (basic clamping), but I was wondering if I was missing something else in the design. It seems not...
Dan
Owner
http://www.Hi-TecDesigns.com
RE: Advantages to dual-tap diodes
When I came across the article I wasn't looking for diodes for this purpose so I ignored it and hence I can't comment further about its claims.
RE: Advantages to dual-tap diodes
Dan
Owner
http://www.Hi-TecDesigns.com
RE: Advantages to dual-tap diodes
RE: Advantages to dual-tap diodes
http://www.sigcon.com/Pubs/news/2_19.htm
Dan, I too agree that the idea of a diode termination doesn't sound quite right, which is part of the reason the article suprised me. I think I am going to stay with the resistive methods.
RE: Advantages to dual-tap diodes
If the equipment has to withstand direct electrostatic discharge onto the ribbon cable, and CMOS or other ESD susceptible logic is used, it will often fail without this direct hard clamping of logic lines to Vdd and Vss.
RE: Advantages to dual-tap diodes
A current project will be using long transmission lines (30'+) for data in the 200kbps+ range, so it was opportune timeing that I came across this when I did. These little buggers are going to find their way onto any line that leaves the main box.
Dan
Owner
http://www.Hi-TecDesigns.com