On Thursday, March 7, 2013 10:48:14 PM UTC-5, Vladimir Vassilevsky wrote:> On 3/7/2013 8:43 PM, bloggs.fredbloggs.fred@gmail.com wrote: > > > On Thursday, March 7, 2013 1:21:33 PM UTC-5, George Herold wrote: > > >> Hi guys, I need a little digital pulse stretcher. I've got > > >> pulses > > >> > > >> that are 5ns to 25ns in width, and I'd like to bump them all up to > > >> all > > >> > > >> be at least 10ns. I've got a few spare 74HC14 inverters. I was > > >> > > >> thinking of just feeding one through a diode followed by an R/C to > > >> > > >> ground. Any other ways? There might be an extra AND gate too. > > >> > > >> (not my circuit so I'm not quite sure.) > > >> > > > > > > The 5ns is way out of line for HC. > > > > The 5...6 ns per gate is what you can practically expect from today's HC. > > > > VLVPlease link to a datasheet- all I'm seeing is 20ns nominal performance on both Tpd's and minimum pulse widths into edge activated inputs like clk's, R's, and S's.
Simple pulse stretcher
Started by ●March 7, 2013
Reply by ●March 7, 20132013-03-07
Reply by ●March 7, 20132013-03-07
On Mar 7, 6:19=A0pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- Web-Site.com> wrote:> On Thu, 07 Mar 2013 17:02:37 -0600, John Fields > > > > > > <jfie...@austininstruments.com> wrote: > >On Thu, 07 Mar 2013 14:48:53 -0800, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > >>On Thu, 07 Mar 2013 16:36:35 -0600, John Fields <jfie...@austininstrume=nts.com>> >>wrote: > > >>>On Thu, 07 Mar 2013 13:32:22 -0800, John Larkin > >>><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > >>>>Post something better. > > >>>--- > >>>OK, > > >>>From "Einstein's Theory of Relativity" by Max Born, we have: > >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0v=B2 > >>>sqrt (1-beta=B2) =3D sqrt 1- --- > >>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ac=B2 > > >>What a sad old dork. > > >--- > >Commentary, but nothing relevant... > > Another one of JL's non-working "designs". =A0A quick check of 74HC > proves my supposition that a 5ns wide pulse goes nowhere... at least > reliably... something JL never worries about... but that's what you > get when you're pompously ignorant. > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0 ...Jim Thompson> -- > | James E.Thompson =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0 =A0 | =A0 =A0mens =A0 =A0 |> | Analog Innovations =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0 | =A0 =A0 et =A0 =A0 =A0|> | Analog/Mixed-Signal ASIC's and Discrete Systems =A0| =A0 =A0manus =A0 ==A0|> | Phoenix, Arizona =A085048 =A0 =A0Skype: Contacts Only =A0| =A0 =A0 =A0 ==A0 =A0 =A0 |> | Voice:(480)460-2350 =A0Fax: Available upon request | =A0Brass Rat =A0| > | E-mail Icon athttp://www.analog-innovations.com| =A0 =A01962 =A0 =A0 | > > I love to cook with wine. =A0 =A0 Sometimes I even put it in the food.- H=ide quoted text -> > - Show quoted text -Yeah Jim the 5ns pulses weren't getting counted.... Sorry I missed a reply to you. There's a comparator on the input and I put the diode R/C thing between it and the first 74HC14 gate... George H.
Reply by ●March 8, 20132013-03-08
On Mar 7, 9:43=A0pm, bloggs.fredbloggs.f...@gmail.com wrote:> On Thursday, March 7, 2013 1:21:33 PM UTC-5, George Herold wrote: > > Hi guys, =A0I need a little digital pulse stretcher. =A0I've got pulses > > > that are 5ns to 25ns in width, and I'd like to bump them all up to all > > > be at least 10ns. =A0 I've got a few spare 74HC14 inverters. =A0I was > > > thinking of just feeding one through a diode followed by an R/C to > > > ground. =A0Any other ways? =A0There might be an extra AND gate too. > > > (not my circuit so I'm not quite sure.) > > The 5ns is way out of line for HC. You can apply the pulse directly to an=emitter follower loaded with parallel RC and then to HC to stretch it to a= ny width you want. The BE junction is your diode. HC will not work reliably= across VCC and temperature with anything less than about 25ns. Cool 25 ns is just what I'd expect if I cut my C to 4.7pF Thanks Fred. George H.
Reply by ●March 8, 20132013-03-08
On 3/7/2013 9:54 PM, bloggs.fredbloggs.fred@gmail.com wrote:> On Thursday, March 7, 2013 10:48:14 PM UTC-5, Vladimir Vassilevsky > wrote: >> On 3/7/2013 8:43 PM, bloggs.fredbloggs.fred@gmail.com wrote: >> >>> On Thursday, March 7, 2013 1:21:33 PM UTC-5, George Herold >>> wrote: >> >>>> Hi guys, I need a little digital pulse stretcher. I've got >> >>>> pulses >> >>>> >> >>>> that are 5ns to 25ns in width, and I'd like to bump them all up >>>> to >> >>>> all >> >>>> >> >>>> be at least 10ns. I've got a few spare 74HC14 inverters. I >>>> was >> >>>> >> >>>> thinking of just feeding one through a diode followed by an R/C >>>> to >> >>>> >> >>>> ground. Any other ways? There might be an extra AND gate >>>> too. >> >>>> >> >>>> (not my circuit so I'm not quite sure.) >> >>>> >> >>> >> >>> The 5ns is way out of line for HC. >> >> >> >> The 5...6 ns per gate is what you can practically expect from >> today's HC. >> > Please link to a datasheet- all I'm seeing is 20ns nominal > performance on both Tpd's and minimum pulse widths into edge > activated inputs like clk's, R's, and S's.Didn't Karl Marx teach you communists that practice is criterion of truth? Take a good scope, pulse generator and see for yourself. VLV
Reply by ●March 8, 20132013-03-08
On Thursday, March 7, 2013 11:14:01 PM UTC-5, Vladimir Vassilevsky wrote:> truth? Take a good scope, pulse generator and see for yourself.Okay, you know what you measured, but you need to be real careful with layo= ut using that parts family. It used to be a point of advantage for a logic = family that it was unresponsive to full logic level transitions of duration= less than the fastest edge rates in the system. Interwiring capacitive cou= pling into a nice high impedance input converts the transition into a nice = square pulse there. I think Lenin covered that one.
Reply by ●March 8, 20132013-03-08
On Thu, 07 Mar 2013 16:02:49 -0800, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:>http://www.highlandtechnology.com/DSS/T240DS.shtml--- That's not a pulse stretcher, cheater, that's a pulse _generator_. -- JF
Reply by ●March 8, 20132013-03-08
On Mar 8, 2:18=A0am, John Fields <jfie...@austininstruments.com> wrote:> On Thu, 07 Mar 2013 16:02:49 -0800, John Larkin > > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >http://www.highlandtechnology.com/DSS/T240DS.shtml > > --- > That's not a pulse stretcher, cheater, that's a pulse _generator_. > -- > JFA *triggered* pulse generator. -- Cheers, James Arthur
Reply by ●March 8, 20132013-03-08
On Mar 8, 12:44=A0am, bloggs.fredbloggs.f...@gmail.com wrote:> On Thursday, March 7, 2013 11:14:01 PM UTC-5, Vladimir Vassilevsky wrote: > > truth? Take a good scope, pulse generator and see for yourself. > > Okay, you know what you measured, but you need to be real careful with la=yout using that parts family. It used to be a point of advantage for a logi= c family that it was unresponsive to full logic level transitions of durati= on less than the fastest edge rates in the system. Interwiring capacitive c= oupling into a nice high impedance input converts the transition into a nic= e square pulse there. I think Lenin covered that one. Hi Fred, As Vlad said the HC series was really doing just fine with 10ns pulses and perhaps only 'missing' 1% of the 5 or 6 ns ones. I don't have a commercial pulser that will do anything less than ~20ns, so it's hard to test. I had a pulse swallower circuit on a piece of copper clad, but I might have ripped it up to make something else... Anyway I don=92t see any reason not to play it safe and make the minimum pulse 25ns. My =91scope is only 200MHz, so I=92m not really sure I even believe the 5ns... what=92s that rule of thumb for =91scope bandwidth/ rise time? tau= =3D 1/(3*BW) ? George H.
Reply by ●March 8, 20132013-03-08
On Fri, 8 Mar 2013 05:45:37 -0800 (PST), George Herold <gherold@teachspin.com> wrote:>On Mar 8, 12:44�am, bloggs.fredbloggs.f...@gmail.com wrote: >> On Thursday, March 7, 2013 11:14:01 PM UTC-5, Vladimir Vassilevsky wrote: >> > truth? Take a good scope, pulse generator and see for yourself. >> >> Okay, you know what you measured, but you need to be real careful with layout using that parts family. It used to be a point of advantage for a logic family that it was unresponsive to full logic level transitions of duration less than the fastest edge rates in the system. Interwiring capacitive coupling into a nice high impedance input converts the transition into a nice square pulse there. I think Lenin covered that one. > >Hi Fred, As Vlad said the HC series was really doing just fine with >10ns pulses and perhaps only 'missing' 1% of the 5 or 6 ns ones. IThe tinylogic one-shot that John mentioned is guaranteed to trigger off 2.5ns pulses (with a 5V 'Vcc'). Available in a nice friendly 0.65mm pitch 8-pin package (also a 0.5mm pitch or 1 x 2mm BGA if you are in need of pain).
Reply by ●March 8, 20132013-03-08
On Fri, 08 Mar 2013 01:18:53 -0600, John Fields <jfields@austininstruments.com> wrote:>On Thu, 07 Mar 2013 16:02:49 -0800, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >>http://www.highlandtechnology.com/DSS/T240DS.shtml > >--- >That's not a pulse stretcher, cheater, that's a pulse _generator_.It's a one-shot. It has no internal trigger. It generates no pulses. And neither you nor Jim have a clue as to how this might be done. We have a customer who wants us to take this down to 10 ps pulses. At that point, I'm not sure that I know how that might be done. We're thinking about it. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
