On a sunny day (Thu, 09 Jan 2014 08:18:56 -0700) it happened RobertMacy <robert.a.macy@gmail.com> wrote in <op.w9fd5ubs2cx0wh@ajm>:>On Thu, 09 Jan 2014 07:34:09 -0700, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: > >> ..snip... >> I have used zeners in big data networks that way, no problem. >> Zeners have quite a bit of capacitance too. >> >> If u want 100% protection use optocouplers. > >What you can 'get away with' and what happens are two different things. >For example, I don't use an anti-static wrist band, nor am very careful >about handling components, no problem. Sure, no problem ...today! but >probably shortened their little lives so they'll fail in anywhere from 2, >6 months out to one year, instead of lasting 10 years.Tell it to the PLC guys who use optos by the thousands. I have used optos too, where spikes made other solutions impossible.>And, optocouplers? not quite the panacea one would expect. kind of work >for AC mains isolation and some on voltage protection, except capacitive >coupling high voltage can still 'punch' through.Come on, there are all sort of optocouplers, also for HV and low capacitance. But for 500$ I will say u are 100% right>and worst of all magnetic >pulsessigh make that 600 :-)
Series Resistor and TVS diode placement
Started by ●January 9, 2014
Reply by ●January 9, 20142014-01-09
Reply by ●January 9, 20142014-01-09
On Thu, 09 Jan 2014 08:20:51 -0700, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:> On a sunny day (Thu, 09 Jan 2014 08:06:53 -0700) it happened RobertMacy > <robert.a.macy@gmail.com> wrote in <op.w9fdlrvg2cx0wh@ajm>: >> ...snip... >> I usually use series R and RF Bead, to get a 'well-rounded' response. > > [diode]C and L will resonate somewhere... >NO!, not if done CORRECTLY. Also, RF Beads are NOT L, they're very lossy, very low Q inductors. Again, DESIGN the solution. Don't 'throw' parts at the problem and wait until it "worked this time."
Reply by ●January 9, 20142014-01-09
On a sunny day (Thu, 09 Jan 2014 08:51:12 -0700) it happened RobertMacy <robert.a.macy@gmail.com> wrote in <op.w9ffnmyk2cx0wh@ajm>:>On Thu, 09 Jan 2014 08:20:51 -0700, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: > >> On a sunny day (Thu, 09 Jan 2014 08:06:53 -0700) it happened RobertMacy >> <robert.a.macy@gmail.com> wrote in <op.w9fdlrvg2cx0wh@ajm>: >>> ...snip... >>> I usually use series R and RF Bead, to get a 'well-rounded' response. >> >> [diode]C and L will resonate somewhere... >> > >NO!, not if done CORRECTLY. Also, RF Beads are NOT L, they're very lossy, >very low Q inductors. > >Again, DESIGN the solution. Don't 'throw' parts at the problem and wait >until it "worked this time."700$ eeh Euro
Reply by ●January 9, 20142014-01-09
On Thu, 09 Jan 2014 08:59:13 -0700, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:>> ...snip... > 700$ > eeh > EuroThank you. Accolade indeed. Jan, if you ever want some of the LTspice models and designs for 'pure' bypass filtering on uC chips done for n ADC mounted in and about Bluetooth, let me know. When I say pure, I mean the bypass looks resistive in AND out, all that happens is 'rerouting' the energy to GND. That way, you don't get that pesky ringing on the power terminals caused by the impedance of the bypass at some spectrum suddenly going up to 10, and even 100 ohms reactance! Had to abandon many of the manufacturer's recommended bypass components to do it, but gives BETTER performance.
Reply by ●January 9, 20142014-01-09
On a sunny day (Thu, 09 Jan 2014 09:10:08 -0700) it happened RobertMacy <robert.a.macy@gmail.com> wrote in <op.w9fgi60m2cx0wh@ajm>:>On Thu, 09 Jan 2014 08:59:13 -0700, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: > >>> ...snip... >> 700$ >> eeh >> Euro > >Thank you. Accolade indeed. > >Jan, if you ever want some of the LTspice models and designs for 'pure' >bypass filtering on uC chips done for n ADC mounted in and about >Bluetooth, let me know. When I say pure, I mean the bypass looks >resistive in AND out, all that happens is 'rerouting' the energy to GND. >That way, you don't get that pesky ringing on the power terminals caused >by the impedance of the bypass at some spectrum suddenly going up to 10, >and even 100 ohms reactance! Had to abandon many of the manufacturer's >recommended bypass components to do it, but gives BETTER performance.Thank you, cool. Yes it sometimes needs to be looked at a bit closer, but some basic guidelines like optos works in 99,99% of the normal industrial cases, especially as one also has to cope with ground loops, and I can tell you that there can be a lot of volts ground difference in for example a factory, not to mention machines starting up increasing that momentarily etc. Optos are very safe,
Reply by ●January 9, 20142014-01-09
On 1/9/2014 9:16 AM, RobertMacy wrote:> On Thu, 09 Jan 2014 05:28:55 -0700, Jan Panteltje > <pNaonStpealmtje@yahoo.com> wrote: > >>>> ...snip... >> I used zeners as it limits the voltage to both +zener voltage (use for >> example a 5.6V zener for 5V micro), and -0.7V. >> Or transzorbs. >> >> It also depends on speed required, and power environment, 24V, 110V, >> 230V etc.. >> >> > > Jim, be careful of using zeners as circuit protection. They turn on > EXTREMELY slowly and during that time can let a lot through. > > For grins, take two 5.6V zeners and put in series 'facing each other' as > feedback on a high speed OpAmp. Then drive the thing and you won't get a > square wave out, you'll get an extremely 'spikey' square wave out. We're > talking audio frequencies, too. I've seen 20kHz spikes.I suspect that's the turn-on of the forward biased diode. Try the same thing with a couple of 2N4007s in inverse parallel, and you'll see spikes too. Zeners are usually fast.> > Do again with tranzorbs and you can really see the difference. > > Or, you can do what we used to do, slightly turn the zener on ahead of > time, that helps. but takes a fast switching diode into the turned on > zener. Today, too many parts, then, the only way.Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●January 10, 20142014-01-10
On Thu, 09 Jan 2014 12:28:55 GMT, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:>On a sunny day (Thu, 9 Jan 2014 04:20:32 -0800 (PST)) it happened mahen ><mahen.jnk@gmail.com> wrote in ><619de8d9-3b4b-4a9b-b2d5-3dc3aa16dda2@googlegroups.com>: > >>If I have to put ESD diode and current limiting series resistor to protect the IO pin of MCU from ESD and over current, which is >>the suggested way? >> >>MCU Pin -------------- Series R -- TVS to GND -- Connector > >This one, but perhaps add an extra R in case somebody connects it directy to a power source: > MCU Pin --- Series R1 -- zener to gnd -- series R2 ---- ConnectorDisagree. The resistor between the TVS and I/O pin is better for the reason stated (current limiting) and the capacitance of the TVS also helps (assuming the R and C don't cause functional problems).>I used zeners as it limits the voltage to both +zener voltage (use for example a 5.6V zener for 5V micro), and -0.7V. >Or transzorbs.So do unidirectional TVS diodes. They're a faster than zeners and will take a lot more abuse. Low voltage zeners are horrible.>It also depends on speed required, and power environment, 24V, 110V, 230V etc.. >Of course. The R gets problematic at high currents. ;-)
Reply by ●January 10, 20142014-01-10
On Thursday, January 9, 2014 5:58:55 PM UTC+5:30, Jan Panteltje wrote:> On a sunny day (Thu, 9 Jan 2014 04:20:32 -0800 (PST)) it happened mahen > > <mahen.jnk@gmail.com> wrote in > > <619de8d9-3b4b-4a9b-b2d5-3dc3aa16dda2@googlegroups.com>: > > > > >If I have to put ESD diode and current limiting series resistor to protect the IO pin of MCU from ESD and over current, which is > > >the suggested way? > > > > > >MCU Pin -------------- Series R -- TVS to GND -- Connector > > > > This one, but perhaps add an extra R in case somebody connects it directy to a power source: > > MCU Pin --- Series R1 -- zener to gnd -- series R2 ---- Connector > > > > I used zeners as it limits the voltage to both +zener voltage (use for example a 5.6V zener for 5V micro), and -0.7V. > > Or transzorbs. > > > > It also depends on speed required, and power environment, 24V, 110V, 230V etc..Thanks Jan. may be a dump Q. Series R2 b/w zener and connector already limiting the current into the pin, correct? Why series R1 again?
Reply by ●January 10, 20142014-01-10
On Thursday, January 9, 2014 4:27:50 PM UTC+1, Jan Panteltje wrote:> On a sunny day (Thu, 09 Jan 2014 08:18:56 -0700) it happened RobertMacy > > <robert.a.macy@gmail.com> wrote in <op.w9fd5ubs2cx0wh@ajm>: > > > > >On Thu, 09 Jan 2014 07:34:09 -0700, Jan Panteltje > > ><pNaonStpealmtje@yahoo.com> wrote: > > > > > >> ..snip... > > >> I have used zeners in big data networks that way, no problem. > > >> Zeners have quite a bit of capacitance too. > > >> > > >> If u want 100% protection use optocouplers. > > > > > >What you can 'get away with' and what happens are two different things. > > >For example, I don't use an anti-static wrist band, nor am very careful > > >about handling components, no problem. Sure, no problem ...today! but > > >probably shortened their little lives so they'll fail in anywhere from 2, > > >6 months out to one year, instead of lasting 10 years. > > > > > > Tell it to the PLC guys who use optos by the thousands. > > I have used optos too, where spikes made other solutions impossible. > >They use optos for galvanic isolation, to combat common mode noise, since they handle signals in industrial environments with a lot of ground bounce etc. For DM noise, use the tranzorb, resistor, diode, resistor combo Cheers Klaus
Reply by ●January 10, 20142014-01-10
On a sunny day (Thu, 9 Jan 2014 22:29:53 -0800 (PST)) it happened mahen <mahen.jnk@gmail.com> wrote in <d260f5e2-315f-4544-9eba-fffb6d27bc6a@googlegroups.com>:>> MCU Pin --- Series R1 -- zener to gnd -- series R2 ---- Connector >> >> >> >> I used zeners as it limits the voltage to both +zener voltage (use for example a 5.6V zener for 5V micro), and -0.7V. >> >> Or transzorbs. >> >> >> >> It also depends on speed required, and power environment, 24V, 110V, 230V etc.. > >Thanks Jan. may be a dump Q. Series R2 b/w zener and connector already limiting the current into the pin, correct? Why series R1 >again?If the zener limits to a bit[1] above supply, and bit[1] below ground, then R1 limits the current into the on chip[2] diodes in the chip[2]. [1] as in 'a little bit' [2] as in 'silicon chip', better 'integrated circuit'. :-)
