Re: [time-nuts] 50 ohm driver
The MOSFET drivers are limited in the max frequency they can operate at without burning. At 1 Hz it is of course not a problem but at 10MHz it most definitely would be. Since Martin did not originally say at what frequency he wanted to operate, it was most relevant. MOSFET drivers can deliver a few nS edges while driving significant capacitance at several hundred kHz. They can be very useful for "low" frequency clock drivers. Didier KO4BB On March 7, 2015 10:10:45 AM CST, Graham / KE9H wrote: >The question is not the frequency, but the edge rate. For a 1 PPS >signal, >how fast a rise time do you need? Do you want to know the time of the >edge to 1/100 second? one microsecond? one nano-second? A few >pico-seconds? > >If you want to know the time of the edge to one nano-second, then you >need a driver that can push sine-waves at over a few GHz. Not 10 MHz. > >--- Graham / KE9H > >== > >On Sat, Mar 7, 2015 at 7:58 AM, Didier Juges >wrote: > >> Martyn, if you only need 1Hz, I recommend you use a MOSFET driver >like the >> MIC4420 series or the UCC27531, powered from 10V with a 50 ohm output >> resistance. These parts have several A current capability, 18V or >more max >> VCC and are designed to drive capacitive loads (large MOSFET gate >> capacitance). It would not work at 10MHz (because of propagation >delay and >> self heating), but at lower frequencies, they work very well. >> The UCC27531 has lower propagation time and comes in an SOT-23 >package, the >> others are available in DIP-8 and SO-8. >> >> Didier KO4BB >> >> On Thu, Mar 5, 2015 at 3:59 PM, Martyn Smith >wrote: >> >> > Hello, >> > Thanks for all the feedback. >> > I should explain. I have an existing product that uses the 74AC14. >> > I have a customer who needs 5V into 50 ohm and can’t wait for the >> > competitive product that does this, or for me to re-design my unit. >> > So I have been looking for a quick fix. >> > I got excited when I found the SN74AS1004AD which has the exact >same >> > function and pin out but delivers 48 mA per channel. >> > While one output did give me 0-3.0 V into 50 ohm, combining them, >as we >> do >> > for the 74AC, actually produced worse results. >> > Maybe the output driver is different. >> > Anyway I’ve managed to get 0-4.8V by jacking up the supply voltage >to 5.7 >> > V for the 74AC14 and making the three 47 ohm resistors 0 ohm. >> > Risetime < 4 ns. >> > Basically to ideas that TimeNuts gave me. >> > I’m just worried the IC may die after a few months. But since the >> > customer will only use it at 1 Hz and hopefully 50:50 duty, or >less, I >> hope >> > to get away with it. >> > Of course if he removes the input and the outputs are on high, then >that >> > may be a problem. >> > BTW, the reason he wants this high voltage is because he is driving >a >> very >> > long cable from the distribution amp to the actual receiver. >> > Anyway I have an IC on test for a week to make sure it lasts. >> > Regards >> > Martyn >> > >> > >> > Today's Topics: >> > >> >1. Re: 50 ohm Driver (Bob Albert) >> >2. Re: 50 ohm Driver (Graham / KE9H) >> >3. Re: 50 ohm Driver (Tom Van Baak) >> >4. Re: 50 ohm Driver (Hal Murray) >> >5. Re: 50 ohm Driver (Dan Kemppainen) >> >6. Re: Trimble Thunderbolt NMEA ? (Didier Juges) >> >7. Re: 50 ohm Driver (Bob Camp) >> >8. Re: 50 ohm Driver (Charles Steinmetz) >> >9. Re: new tdc from Texas (Angus) >> > 10. Re: new tdc from Texas (Attila Kinali) >> > >> > >> > >-- >> > >> > Message: 1 >> > Date: Wed, 4 Mar 2015 16:49:11 + (UTC) >> > From: Bob Albert >> > To: Discussion of precise time and frequency measurement >> > >> > Subject: Re: [time-nuts] 50 ohm Driver >> > Message-ID: >> > <1276775018.2671439.1425487751520.javamail.ya...@mail.yahoo.com> >> > Content-Type: text/plain; charset=UTF-8 >> > >> > 5V into 50 Ohms means 100 mA. Perhaps you need a medium power >transistor >> > amplifier or opamp. >> > Bob >> > >> > >> > On Wednesday, March 4, 2015 6:09 AM, Martyn Smith < >> mar...@ptsyst.com> >> > wrote: >> > >> > >> > Hello, >> > >> > A quick question. >> > >> > My output driver for a simple amplifier. >> > >> > I use three gates (in parallel with resistors) from a 74AC14 to >give me >> > about 0-3.2V into 50 ohm. >> > >> > I want to have a driver that gives me a full 0-5V (at least 0-4.5V) >swing >> > into 50 ohms. >> > >> > Can anyone recommend an IC that can delivery this. >> > >> > But it needs to have similar jitter performance to the 74AC14. >> > >> > I use it up to 10 MHz. >> > >> > Best Regards >> > >> > Martyn >> > >> > ___ >> > time-nuts mailing list -- time-nuts@febo.com >> > To unsubscribe, go to >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> > >> > >> > >> > >> > -- >> > >> > Message: 2 >> > Date: Wed, 4 Mar 2015 12:16:02 -06
Re: [time-nuts] 50 ohm driver
Martyn wrote: Charles asked for a link to the IC I mentioned. Thanks, but I have databooks for the various logic types, including AS. What I asked for is a link to the datasheet for your product -- the product the customer is using -- so we have some context for what you (and they) are trying to accomplish, which will give us a better idea of what sort of solutions might help you. Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Pinout of FEI 5680B
Hi Thanks! The listing is still up at auction if anybody wants to double check it against the usual “Bob types poorly” errors … :) Bob > On Mar 7, 2015, at 9:37 AM, Didier Juges wrote: > > I have added this info to the wiki: > > http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_pin-out > > Thanks > > Didier KO4BB > > > On Sat, Feb 21, 2015 at 2:25 PM, Bob Camp wrote: > >> Hi >> >> Just so it goes into the archives. Here’s the pinout for the FE-5680B with >> a 15 pin connector on it. >> >> Marking shows as part number 2616000-51604 >> >> Pin Function >> 1 >= +15V power in (likely the same spec as 5680A) >> 2 ground >> 3 +5 power in (for some, but not this one) >> 4 ground >> 5 RF out (for some, but not this one) >> 6 spare >> 7 ground >> 8 0 to 5V(?) analog tune in (for some but not all, I’d >> *guess* not for this one) >> 9 factory use only >> 10 ground >> 11 1 pps out (for this one, but not all) lvttl >> 12 lock indicator (open collector) >> 13 reset (lvttl input, active high) >> 14 serial in (lvttl) >> 15 serial out (lvttl) >> >> Yes, this is in answer to a question Skip asked back in 2009. Replying to >> that thread might >> cause something to explode somewhere :) >> >> They seem to be up on eBay for $45 at the moment, along with the info >> above. No idea if this batch >> is any good. I haven’t bought any. I’m sure the question of pinout will >> come up again in about >> 2 years time. By then the listing and the info will be long gone. >> >> Bob >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 50 ohm driver
The question is not the frequency, but the edge rate. For a 1 PPS signal, how fast a rise time do you need? Do you want to know the time of the edge to 1/100 second? one microsecond? one nano-second? A few pico-seconds? If you want to know the time of the edge to one nano-second, then you need a driver that can push sine-waves at over a few GHz. Not 10 MHz. --- Graham / KE9H == On Sat, Mar 7, 2015 at 7:58 AM, Didier Juges wrote: > Martyn, if you only need 1Hz, I recommend you use a MOSFET driver like the > MIC4420 series or the UCC27531, powered from 10V with a 50 ohm output > resistance. These parts have several A current capability, 18V or more max > VCC and are designed to drive capacitive loads (large MOSFET gate > capacitance). It would not work at 10MHz (because of propagation delay and > self heating), but at lower frequencies, they work very well. > The UCC27531 has lower propagation time and comes in an SOT-23 package, the > others are available in DIP-8 and SO-8. > > Didier KO4BB > > On Thu, Mar 5, 2015 at 3:59 PM, Martyn Smith wrote: > > > Hello, > > Thanks for all the feedback. > > I should explain. I have an existing product that uses the 74AC14. > > I have a customer who needs 5V into 50 ohm and can’t wait for the > > competitive product that does this, or for me to re-design my unit. > > So I have been looking for a quick fix. > > I got excited when I found the SN74AS1004AD which has the exact same > > function and pin out but delivers 48 mA per channel. > > While one output did give me 0-3.0 V into 50 ohm, combining them, as we > do > > for the 74AC, actually produced worse results. > > Maybe the output driver is different. > > Anyway I’ve managed to get 0-4.8V by jacking up the supply voltage to 5.7 > > V for the 74AC14 and making the three 47 ohm resistors 0 ohm. > > Risetime < 4 ns. > > Basically to ideas that TimeNuts gave me. > > I’m just worried the IC may die after a few months. But since the > > customer will only use it at 1 Hz and hopefully 50:50 duty, or less, I > hope > > to get away with it. > > Of course if he removes the input and the outputs are on high, then that > > may be a problem. > > BTW, the reason he wants this high voltage is because he is driving a > very > > long cable from the distribution amp to the actual receiver. > > Anyway I have an IC on test for a week to make sure it lasts. > > Regards > > Martyn > > > > > > Today's Topics: > > > >1. Re: 50 ohm Driver (Bob Albert) > >2. Re: 50 ohm Driver (Graham / KE9H) > >3. Re: 50 ohm Driver (Tom Van Baak) > >4. Re: 50 ohm Driver (Hal Murray) > >5. Re: 50 ohm Driver (Dan Kemppainen) > >6. Re: Trimble Thunderbolt NMEA ? (Didier Juges) > >7. Re: 50 ohm Driver (Bob Camp) > >8. Re: 50 ohm Driver (Charles Steinmetz) > >9. Re: new tdc from Texas (Angus) > > 10. Re: new tdc from Texas (Attila Kinali) > > > > > > -- > > > > Message: 1 > > Date: Wed, 4 Mar 2015 16:49:11 + (UTC) > > From: Bob Albert > > To: Discussion of precise time and frequency measurement > > > > Subject: Re: [time-nuts] 50 ohm Driver > > Message-ID: > > <1276775018.2671439.1425487751520.javamail.ya...@mail.yahoo.com> > > Content-Type: text/plain; charset=UTF-8 > > > > 5V into 50 Ohms means 100 mA. Perhaps you need a medium power transistor > > amplifier or opamp. > > Bob > > > > > > On Wednesday, March 4, 2015 6:09 AM, Martyn Smith < > mar...@ptsyst.com> > > wrote: > > > > > > Hello, > > > > A quick question. > > > > My output driver for a simple amplifier. > > > > I use three gates (in parallel with resistors) from a 74AC14 to give me > > about 0-3.2V into 50 ohm. > > > > I want to have a driver that gives me a full 0-5V (at least 0-4.5V) swing > > into 50 ohms. > > > > Can anyone recommend an IC that can delivery this. > > > > But it needs to have similar jitter performance to the 74AC14. > > > > I use it up to 10 MHz. > > > > Best Regards > > > > Martyn > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > > > > > -- > > > > Message: 2 > > Date: Wed, 4 Mar 2015 12:16:02 -0600 > > From: "Graham / KE9H" > > To: Discussion of precise time and frequency measurement > > > > Subject: Re: [time-nuts] 50 ohm Driver > > Message-ID: > > > > Content-Type: text/plain; charset=UTF-8 > > > > Building on top of John's comments, if you are using a logic gate, look > at > > the > > maximum output (pull up) current per pin, set the series resistor so that > > this > > current is not exceeded into a short, then also see if there is a maximum > > total > > current draw for all gates combined, or some power input pin, and do not > > exceed > > that. > > > > You can also look at switching the termination resistor from a simple 50 > >
Re: [time-nuts] Pinout of FEI 5680B
I have added this info to the wiki: http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_pin-out Thanks Didier KO4BB On Sat, Feb 21, 2015 at 2:25 PM, Bob Camp wrote: > Hi > > Just so it goes into the archives. Here’s the pinout for the FE-5680B with > a 15 pin connector on it. > > Marking shows as part number 2616000-51604 > > Pin Function > 1 >= +15V power in (likely the same spec as 5680A) > 2 ground > 3 +5 power in (for some, but not this one) > 4 ground > 5 RF out (for some, but not this one) > 6 spare > 7 ground > 8 0 to 5V(?) analog tune in (for some but not all, I’d > *guess* not for this one) > 9 factory use only > 10 ground > 11 1 pps out (for this one, but not all) lvttl > 12 lock indicator (open collector) > 13 reset (lvttl input, active high) > 14 serial in (lvttl) > 15 serial out (lvttl) > > Yes, this is in answer to a question Skip asked back in 2009. Replying to > that thread might > cause something to explode somewhere :) > > They seem to be up on eBay for $45 at the moment, along with the info > above. No idea if this batch > is any good. I haven’t bought any. I’m sure the question of pinout will > come up again in about > 2 years time. By then the listing and the info will be long gone. > > Bob > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 50 ohm driver
Martyn, if you only need 1Hz, I recommend you use a MOSFET driver like the MIC4420 series or the UCC27531, powered from 10V with a 50 ohm output resistance. These parts have several A current capability, 18V or more max VCC and are designed to drive capacitive loads (large MOSFET gate capacitance). It would not work at 10MHz (because of propagation delay and self heating), but at lower frequencies, they work very well. The UCC27531 has lower propagation time and comes in an SOT-23 package, the others are available in DIP-8 and SO-8. Didier KO4BB On Thu, Mar 5, 2015 at 3:59 PM, Martyn Smith wrote: > Hello, > Thanks for all the feedback. > I should explain. I have an existing product that uses the 74AC14. > I have a customer who needs 5V into 50 ohm and can’t wait for the > competitive product that does this, or for me to re-design my unit. > So I have been looking for a quick fix. > I got excited when I found the SN74AS1004AD which has the exact same > function and pin out but delivers 48 mA per channel. > While one output did give me 0-3.0 V into 50 ohm, combining them, as we do > for the 74AC, actually produced worse results. > Maybe the output driver is different. > Anyway I’ve managed to get 0-4.8V by jacking up the supply voltage to 5.7 > V for the 74AC14 and making the three 47 ohm resistors 0 ohm. > Risetime < 4 ns. > Basically to ideas that TimeNuts gave me. > I’m just worried the IC may die after a few months. But since the > customer will only use it at 1 Hz and hopefully 50:50 duty, or less, I hope > to get away with it. > Of course if he removes the input and the outputs are on high, then that > may be a problem. > BTW, the reason he wants this high voltage is because he is driving a very > long cable from the distribution amp to the actual receiver. > Anyway I have an IC on test for a week to make sure it lasts. > Regards > Martyn > > > Today's Topics: > >1. Re: 50 ohm Driver (Bob Albert) >2. Re: 50 ohm Driver (Graham / KE9H) >3. Re: 50 ohm Driver (Tom Van Baak) >4. Re: 50 ohm Driver (Hal Murray) >5. Re: 50 ohm Driver (Dan Kemppainen) >6. Re: Trimble Thunderbolt NMEA ? (Didier Juges) >7. Re: 50 ohm Driver (Bob Camp) >8. Re: 50 ohm Driver (Charles Steinmetz) >9. Re: new tdc from Texas (Angus) > 10. Re: new tdc from Texas (Attila Kinali) > > > -- > > Message: 1 > Date: Wed, 4 Mar 2015 16:49:11 + (UTC) > From: Bob Albert > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] 50 ohm Driver > Message-ID: > <1276775018.2671439.1425487751520.javamail.ya...@mail.yahoo.com> > Content-Type: text/plain; charset=UTF-8 > > 5V into 50 Ohms means 100 mA. Perhaps you need a medium power transistor > amplifier or opamp. > Bob > > > On Wednesday, March 4, 2015 6:09 AM, Martyn Smith > wrote: > > > Hello, > > A quick question. > > My output driver for a simple amplifier. > > I use three gates (in parallel with resistors) from a 74AC14 to give me > about 0-3.2V into 50 ohm. > > I want to have a driver that gives me a full 0-5V (at least 0-4.5V) swing > into 50 ohms. > > Can anyone recommend an IC that can delivery this. > > But it needs to have similar jitter performance to the 74AC14. > > I use it up to 10 MHz. > > Best Regards > > Martyn > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > > -- > > Message: 2 > Date: Wed, 4 Mar 2015 12:16:02 -0600 > From: "Graham / KE9H" > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] 50 ohm Driver > Message-ID: > > Content-Type: text/plain; charset=UTF-8 > > Building on top of John's comments, if you are using a logic gate, look at > the > maximum output (pull up) current per pin, set the series resistor so that > this > current is not exceeded into a short, then also see if there is a maximum > total > current draw for all gates combined, or some power input pin, and do not > exceed > that. > > You can also look at switching the termination resistor from a simple 50 > Ohm > resistor to ground, to a "Thevenin" load, which is 100 Ohms from +V to the > load point, > and another 100 Ohm resistor from the load point to ground. This way you > still have a 50 Ohm termination, but only draw one half the DC current. > In the event of no input, the receiver voltage will go to half scale. Make > sure your system will not misbehave when this happens. > > Alternate driver is to use a video line driver with sufficient bandwidth. > > --- Graham / KE9H > > == > > On Wed, Mar 4, 2015 at 7:54 AM, John Ackermann N8UR wrote: > > > One comment on the parallel AC gate approach. It may not be directly > > applicable to Martyn's issue, but there is a common confusion about the > > value of the summing re
[time-nuts] 50 ohm driver
Hello, Charles asked for a link to the IC I mentioned. http://www.mouser.com/ds/2/405/sdas074b-192680.pdf It has a 48 mA output drive capability but doesn’t like the outputs in parallel even with resistors. The reason my customer wants 0-5V is that he is feeding the distribution amp output over 100 m of cable to the end receiver (don’t know his actual set-up so can’t comment why the devices are so far away). So Charles's comment on overshoots blowing my device is probably what’s going to happen. Best Regards Martyn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
