How fast do you need it to be? Do you absolutely need the -5V? My last post was made before I saw yours. Been a while since I've worked with ECL.

ECL is fundimentally differential amps wired as logic, which is where the speed and heat come from. If you HAVE to have the -5 then I would go with a fast transitor differential amp.

Well I plan to use four of these ICs. 9 of the outputs I need both the inverting and non-inverting outputs. On those outputs I need 0V (high) on the non-inverting and -5V (low). Or the inverting or the other way around. Doesn't matter. What I also need is to be able to reverse the values on those inputs from whatever they are set to. So if it is high on the inverting and low on the non-inverting ... I want to be able to change it to low on the inverting and high on the non-inverting output.

Hope I explained it good enough.

So currently, I have -1.7V and -0.8V. Depends on the strobe value which ones appear on which output (inverting or non-inverting).

I would like to go from this to 0V and -5V and have the ability to reverse them. Probably the easiest way would be to change the value on the strobe.

What would be a good way of going about this? Addition circuitry (architecture) on the outside of the mentioned IC? I haven't thought of anything yet.

Thank you all for your help.

EDIT: I found this PDF. I will start from here and see if I can alter it to get what I want. Seems odd but the reason for all this is because I have a chip that need 0V and -5V diff. input and I have a NI-USB DAC that can output TTL. So I'm going from TTL to MECL to the voltages mentioned above. I was given the former two to begin with. I though i could just invert the TTL but I need diff. not direct input. For the other 5 inputs that use direct then I am thinking I can just invert the TTL signal.

 

Could you clear up a bit of mystery here? Do you need the extreme switching speeds of ECL logic, or simply to invert a signal? If there is no real speed requirement, a fast op amp set up as an inverter will give you what you want. ECL to anything else is a bit more difficult.

 

I keep asking about speed, because there are other ways of accomplishing this. The only reason to use ECL is speed. What kind of data rate or transition do you need to do the positive to negitive logic transition. If it isn't very fast then you could use a fast op amp circuit. I suspect you are needing something in the gighertz range, I just need to peg some numbers to it.

Here is a transistor version I've seen.

 

I keep asking about speed, because there are other ways of accomplishing this. The only reason to use ECL is speed. What kind of data rate or transition do you need to do the positive to negitive logic transition. If it isn't very fast then you could use a fast op amp circuit. I suspect you are needing something in the gighertz range, I just need to peg some numbers to it.

Here is a transistor version I've seen.

Excuse the absence. Been really busy doing other stuff.
I am really learning a lot just talking with you all. That looks like a good circuit. I will make a note of it and study how it works.

At first I wasn't told anything about speed. I don't think I need to worry about speed. I have this NI DAQCard that has 24 channels. I need 23 if I was to tie a single channel to the chip my co-worker has (won't be seeing that chip for a while). So if I don't need the speed I can just scrape the MECL IC and the other idea I had using opamps. The NI card I am using now does TTL (0V and 5V) output on each channel. I finished my labview program where I can control when the TTL goes high or low as well as my differential outputs (and some direct).

Example:

channel 1: 0V (0)
channel 2: 5V (1)

Flip the switch (in labview):

channel 1: 5V (1)
channel 2: 0V (0)

What I want the chip to see is:

channel 1: 0V (1)
channel 2: -5V (0)

Flip the switch (in labview):

channel 1: -5V (0)
channel 2: 0V (1)

What I am using is the CB-50 picture the attachment. The top row (all even) is all GND and is tied to my laptop's GND. The bottom row (all odd) is the I/O from the card (24 channels). The voltages are reference to that top row when I mention 5V and 0V.

Is there a way for me to get those 5V to -5V? Can I just float the top row and use the I/O as my GND reference for the chip to get it to see -5V? I am kind of over thinking this probably. If someone can help me out for a sec.

Thank you for all the help.

 

I had a similar problem several years ago. With a little tweaking this design should work for your needs. It is EXTREMELY slow however.

It has both directions, a -12/0 to TTL convertor and a +5/0 to -12 convertor.

 

I had a similar problem several years ago. With a little tweaking this design should work for your needs. It is EXTREMELY slow however.

It has both directions, a -12/0 to TTL convertor and a +5/0 to -12 convertor.

It funny, that is what I was gonna do if I used opamps. But I was referring to the other option I mentioned. Let me know if that makes any sense. Thank you again.

 

Actually that might work. What do you need the -5V for again though? One thing, if you do this it will be reverse logic, and will probably need inverted if it is digital. With reverse logic -5V is a 0, and 0V is a 1. In the case of TTL your logic levels will be a 1 = -1.6V, and a 0 = -4.3V.

My drawing was preliminary, I cleaned it up for my specific application, looked quite professional when I was done, but completely useless for what you were needing. TTL to -12 V is flawed for your application, the -12 side goes between +5 (0) to -12 (1).

 

What is the part number of your NI DAQ module?

And what is the conversion rate of your A/D? You mentioned having an NI USB DAC that you want to interface with, but a DAC doesn't make sense to me in this context (I may be missing something), so I assume you meant you have an A/D. If not, perhaps you can explain.

 

Actually that might work. What do you need the -5V for again though? One thing, if you do this it will be reverse logic, and will probably need inverted if it is digital. With reverse logic -5V is a 0, and 0V is a 1. In the case of TTL your logic levels will be a 1 = -1.6V, and a 0 = -4.3V.

My drawing was preliminary, I cleaned it up for my specific application, looked quite professional when I was done, but completely useless for what you were needing. TTL to -12 V is flawed for your application, the -12 side goes between +5 (0) to -12 (1).

I understand that it would be reverse logic. That is what I want not TTL's traditional +5V and 0V for 1 and 0 respectively. I want the reverse logic. I have been saying it all along, -5V for 0 and 0V for 1. Thanks for the confirmation about what I asked at the end of my previous post.

At first I was thinking about just using comparators with +5V supply and reference on the non-inverting input which is similar to what you had pictured.

 

What is the part number of your NI DAQ module?

And what is the conversion rate of your A/D? You mentioned having an NI USB DAC that you want to interface with, but a DAC doesn't make sense to me in this context (I may be missing something), so I assume you meant you have an A/D. If not, perhaps you can explain.

It is the NIDAQ-DIO-24 card for a notebook. I finished the labview program that controls the I/O (well configured for output only) the way I want it to be. Now I just have to connect it to get the reverse logic that I want.

I did mention that I had a NI USB but decided I can just use this as well. But this is it: http://sine.ni.com/nips/cds/view/p/lang/en/nid/205181. Sorry I don't mean DAQ in this context ha-ha. Sorry. Mistake on my part.

 

It is the NIDAQ-DIO-24 card for a notebook. I finished the labview program that controls the I/O (well configured for output only) the way I want it to be. Now I just have to connect it to get the reverse logic that I want.

I did mention that I had a NI USB but decided I can just use this as well. But this is it: http://sine.ni.com/nips/cds/view/p/lang/en/nid/205181. Sorry I don't mean DAQ in this context ha-ha. Sorry. Mistake on my part.

Can you point to the manual, and the page number where the I/O levels are specified? The manual for the PC unit appears to accept TTL (zero and +5V) levels. I will be very surprised if the laptop unit is different.

 

Can you point to the manual, and the page number where the I/O levels are specified? The manual for the PC unit appears to accept TTL (zero and +5V) levels. I will be very surprised if the laptop unit is different.

No no no, the laptop is the same. What I did is finish the program that outputs 0V and +5V over 23 of the 24 channels and then changes when I flip its switch in labview to +5V and 0V (inverts kinda). What I asked Bill was could I float the ground reference and use the outputs as the ground reference to get 0V and -5V seen by what I am connecting to the output this card. Do you think I would be able to do that? What I am thinking about what would I connect to the input of the chip? There are 23 inputs of the chip and 23 outputs from the NI card. Can you confirm or let me know how I can get the chip to see -5V and 0V (I know that 0V would be 1 and -5V would be 0)? Because there is only one ground. Do I just make make GND on the chip 5V?

 

No no no, the laptop is the same. What I did is finish the program that outputs 0V and +5V over 23 of the 24 channels and then changes when I flip its switch in labview to +5V and 0V (inverts kinda). What I asked Bill was could I float the ground reference and use the outputs as the ground reference to get 0V and -5V seen by what I am connecting to the output this card. Do you think I would be able to do that? What I am thinking about what would I connect to the input of the chip? There are 23 inputs of the chip and 23 outputs from the NI card. Can you confirm or let me know how I can get the chip to see -5V and 0V (I know that 0V would be 1 and -5V would be 0)? Because there is only one ground. Do I just make make GND on the chip 5V?

I don't fully understand what you are trying to do, much less why you would want to do it. It sounds unfeasible, or maybe even impossible.
Why are you wanting to do this? What is wrong with the straight TTL interface? If you simply want to invert the inputs/outputs, there are easy ways to do this.

 

When I was first starting on TTL, before I even went to college, I bought several types and used a -5VDC on ground and 0V on the +5 (1 was a -5V, 0 was 0V to me). I was more than green at the time, just barely starting out. The inverters worked fine (7404) but someone mislabeled all those NAND gates, they were NOR gates! Felt a bit dumb when I figured it out, there wasn't an internet or personal computers in those days, and I was a teenager (had a lot more hair then too).

I don't understand why Management needs a -5 signal, just going with the flow. I've had circuits that used negitive logic myself.

 

The OP needs to clarify if he really wishes a negative-going logic level, or has a situation where he needs to invert the TTL levels (high for low, low for high).

 

I don't understand why Management needs a -5 signal, just going with the flow. I've had circuits that used negitive logic myself.

This is the situation. There is a chip that has its controls bits as (1: 0 V and 0: -5V). Why I don't know? I just had to figure out a way to test it and there was this labview card that outputs TTL. At first I was told to use some MECL IC but was confused then there was the OpAmp (comparators with reference on the non-inverting input) but then asked if I can just have 5V as reference and I would get up with my negative logic. Bill confirmed that I can just do that a few posts ago. So that seems like the easiest route.

My apologies for all the confusion. I was a little confused at times so is hard to say what I want to say sometimes. Thanks guys for all the help.

I posted another thread about bondpad capacitance. Feel free to drop by if your interested.

Thank you.

 

This is the situation. There is a chip that has its controls bits as (1: 0 V and 0: -5V).

What is the part number of this chip? Where does it reside in your system?

 

What is the part number of this chip? Where does it reside in your system?

It has no part number and is in house. I currently have no system with this chip in it. What I did is just make up a way to test it. Can't really talk about it and plus I'm at the bottom of the food chain.