Post by thread:[EE]: Matched Inverter and Buffer

Hello, I have a PWM signal and I need to use both the original singal and the inverse of the signal. Now, putting the signal through an inverter causes a small time delay leaving the two signals to not be exactly 180 degree out of phase. I imagine this is a common problem and suspect an inverter with matched buffer IC exists that allows you to reduce this error. Does such an IC exist? Can anyone give me a part number? (I was suprised to find my search of Digikey turn up nothing, but I'm not sure exactly what to search for) Thanks, Donovan -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Have a look at the TC4428A MOSFET driver which has one inverting and one non-inverting driver. Even Microchip make them! www.microchip.com/1010/pline/analog/anicateg/power/pwrmang/mosf et/tc4_46/tc4428a/ -- Brent Brown, Electronic Design Solutions 16 English Street, Hamilton, New Zealand Ph/fax: +64 7 849 0069 Mobile/txt: 025 334 069 eMail: .....brent.brownKILLspam@spam@clear.net.nz -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

The normal wat to do it is to use an inverting and a non-inverting buffer and to use an adjustable delay at the input of one of them. The edges will never be perfectly synchronous no matter what you do. You need to determine a level of precision you need and implement something that achieves it. Peter -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

You didn't state how much delay you are getting and how much you can tolerate. If you use a fast logic device, you can probably achieve your goal. I believe 74Sxx or 74Hxx device should suffice. If you need closer to zero delay, feed your source through an inverting gate and a non-inverting gate which should give you satisfactory results. Rick Donovan Parks wrote: {Quote hidden}> Hello, > > I have a PWM signal and I need to use both the original singal and the inverse of the signal. Now, putting the signal through an inverter causes a small time delay leaving the two signals to not be exactly 180 degree out of phase. I imagine this is a common problem and suspect an inverter with matched buffer IC exists that allows you to reduce this error. Does such an IC exist? Can anyone give me a part number? (I was suprised to find my search of Digikey turn up nothing, but I'm not sure exactly what to search for) > > Thanks, > Donovan > > -- > http://www.piclist.com hint: To leave the PICList > EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

Hello, Does one typically just use an RC circuit to implement an "adjustable delay"? Thanks, Donovan {Quote hidden}> The normal wat to do it is to use an inverting and a non-inverting buffer > and to use an adjustable delay at the input of one of them. The edges will > never be perfectly synchronous no matter what you do. You need to > determine a level of precision you need and implement something that > achieves it. > > Peter > > -- > http://www.piclist.com hint: To leave the PICList > @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu > > > > -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

Hello, Feeding my source through an inverting gate and a non-inverting gate is exactly what I hope to do. What I am wondering is if you can buy an IC that contains both an inverting gate and a non-inverting gate or if I need to use to different IC's and try and match their delays (or build an adjustable delay circuit). Brent Brown (thanks!) pointed me to the TC4428A - do you know another IC? Donovan > You didn't state how much delay you are getting and how much you can tolerate. If you use a fast logic device, you can probably achieve your goal. I believe 74Sxx or 74Hxx device should suffice. If you need closer to zero delay, feed your source through an inverting gate and a non-inverting gate which should give you satisfactory results. > Rick > > Donovan Parks wrote: > > > Hello, > > > > I have a PWM signal and I need to use both the original singal and the inverse of the signal. Now, putting the signal through an inverter causes a small time delay leaving the two signals to not be exactly 180 degree out of phase. I imagine this is a common problem and suspect an inverter with matched buffer IC exists that allows you to reduce this error. Does such an IC exist? Can anyone give me a part number? (I was suprised to find my search of Digikey turn up nothing, but I'm not sure exactly what to search for) {Quote hidden}> > > > Thanks, > > Donovan > > > > -- > > http://www.piclist.com hint: To leave the PICList > > RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu > > -- > http://www.piclist.com hint: To leave the PICList > spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu > > > > -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu

Donovan Parks <RemoveMEdparksTakeThisOuTUVIC.CA> wrote: > Feeding my source through an inverting gate and a non-inverting gate is > exactly what I hope to do. What I am wondering is if you can buy an IC that > contains both an inverting gate and a non-inverting gate or if I need to use > to different IC's and try and match their delays (or build an adjustable > delay circuit). Brent Brown (thanks!) pointed me to the TC4428A - do you > know another IC? Pretty much any RS-422/RS-485 driver should do exactly what you want. There are older products like the National DS8921/8922 or newer stuff like the Maxim MAX3485 (this particular part has no slew-rate limiting, which may be important for you). -- Dave Tweed -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestEraseME.....mitvma.mit.edu

On Sat, 24 Aug 2002 12:44:03 -0700, Donovan Parks wrote: >Hello, > >Feeding my source through an inverting gate and a non-inverting gate >is exactly what I hope to do. What I am wondering is if you can buy >an IC that contains both an inverting gate and a non-inverting gate or > if I need to use to different IC's and try and match their delays (or > build an adjustable delay circuit). Brent Brown (thanks!) pointed me > to the TC4428A - do you know another IC? Use a quad two input XOR (74HC86 or similar) gate package -- use two gates, connect your input signal to one input of each gate. Connect a logic '1' (+V) to the other pin of one gate and logic '0' (ground) to the other pin of the second gate. You now have an inverted signal on the output of gate with a logic '1' on the input and a non-inverted signal on the output of the gate with a logic '0' on the input. The delay will be the same (or very very close) for both signals. XOR gates make great switchable inverters, dirt cheap too! ;-) Matt Pobursky Maximum Performance Systems -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestmitvma.mit.edu

On Sat, 24 Aug 2002, Dave Tweed wrote: >Donovan Parks <RemoveMEdparksEraseMEEraseMEUVIC.CA> wrote: >> Feeding my source through an inverting gate and a non-inverting gate is >> exactly what I hope to do. What I am wondering is if you can buy an IC that >> contains both an inverting gate and a non-inverting gate or if I need to use >> to different IC's and try and match their delays (or build an adjustable >> delay circuit). Brent Brown (thanks!) pointed me to the TC4428A - do you >> know another IC? > >Pretty much any RS-422/RS-485 driver should do exactly what you want. >There are older products like the National DS8921/8922 or newer stuff >like the Maxim MAX3485 (this particular part has no slew-rate limiting, >which may be important for you). Good idea. I like this. Although he did not say how fast his pwm is. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Sat, 24 Aug 2002, Donovan Parks wrote: >Hello, > >Does one typically just use an RC circuit to implement an "adjustable >delay"? Yes, or a ready made delay line. These were common in DRAM days (discrete dram, not simms). It's a 16 pin dil package with a delay inside, tapped every 20nsec or so. You pick the output you need. The TAxxxx driver may make your day because all other solutions (involving gates) have different Tp for inverting and noninverting gates. So you'll need a delay as above. You really have to set a goal and try to reach it. How 'exactly' must the edges match ? Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Thanks to everyone for helping me out. I like Matt's solution given below and will give it a try. Frankly, I'm not sure "how close" I need the signals to match so I'll see if this works. Regards, Donovan {Quote hidden}> Use a quad two input XOR (74HC86 or similar) gate package -- use two > gates, connect your input signal to one input of each gate. Connect a > logic '1' (+V) to the other pin of one gate and logic '0' (ground) to > the other pin of the second gate. > > You now have an inverted signal on the output of gate with a logic '1' > on the input and a non-inverted signal on the output of the gate with a > logic '0' on the input. > > The delay will be the same (or very very close) for both signals. XOR > gates make great switchable inverters, dirt cheap too! ;-) > > Matt Pobursky > Maximum Performance Systems > > -- > http://www.piclist.com hint: To leave the PICList > RemoveMEpiclist-unsubscribe-requestspam_OUTKILLspammitvma.mit.edu > > > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads