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I'm looking for an analog to digital converter IC with an analog input and 8 bit parallel output. Through hole, not surface mount. Have any suggestions?
Analog to digital converter IC?
- Thread starter Green Bean
- Start date
Thank you.
Based on the depth of the question, "any".
It's not at all unusual or surprising for someone unfamiliar with something not to know what information is important and what is not. That's why they are asking and that's we ask clarifying questions in return.
I don't think speed is an issue for what I'm using it for. And as for voltage, I want 8 bit digital output, so that's 256 different voltages. I'm not sure if it would safe, practical, or even possible to have a range of 0-255 volts going into an integrated circuit, but I'm assuming there are circuits that have say a range of 0-15 volts with increments of 16 in between. For example, 0 volts produces 00000000, 0.9375 (15/16) volts produces 00000001, 0.875 (14/16) volts produces 00000010, and so on. I'm not sure if that exact configuration exists, but you get the idea.
What is it that you are trying to accomplish? Why do you want 8-bit digital output? How do you know that you don't need 12 bits? What are the range of voltages that you are trying to measure? How accurately do you need to know that voltage? If the actual voltage is 3.271874 V and your system says that it is 3.3 V, is that good enough?
Wait! Assuming your chip runs on 5v, an 8 bit digital output only give 8 pins with either zero (0) volts out or near 5v out on each. For example, a 2.5v input would give the following readings on 8 output pins. (with the following output voltages)
5 0 0 0 0 0 0 0 which, in digital speak would be
1 0 0 0 0 0 0 0.
You would need a " resistor ladder" to convert the output of the 8-pins back to a 0 to 5v* output.
Why do you want o convert an analog input to one of 256 discrete output values? What us wrong with the original analog value? Maybe there is another solution to your problem.
* note that the output pins are not always 5v on a 5v logic chip.
I'm trying to use a potentiometer to send a digital signal to an 8 bit register in an 8 bit computer.
Can the computer accept an 8-bit parallel (8-input pins) or do you need 8-bit serial (one data pin and one clock pin).
Details, details, details. Or are we playing a game of 101 questions?
What 8-bit computer?
There are simpler ways to measure the position of a pot. You don't need an ADC.
I'm sure I could write some software to interact with a serial IC, but it would be less complicated if it were parallel.
I'm using a Commodore 64. The Commodore 64 has an external cartridge port in the back that has address and data lines that connect directly to the microprocessor. The idea is this: I will have a pot mapped to a specific register in the Commodore 64 (which will require some glue logic, but I think I can figure that out). The pot will connect to an ADC, which will be connected to the data lines in the cartridge port, so that I can use the pot to change the register without any code. I can turn the pot one way to increment the register, and I can turn it the opposite direction to decrement the register.
If you are familiar with the Commodore 64, you may be thinking "why not just use a paddle controller?". Because then it will be a serial signal, and it won't be fed into the register I need it to be fed into. Code will be required to handle that. And also, I plan on having more than one pot, mapped to more than just one register.
But for now, all I want is an ADC that can handle 256 different analog signals and convert them to a parallel 8 bit digital signal.
If you send 120 VAC into adc0808, you will fry it.
A few options were given earlier. Another option is the ADC080x line.
http://www.ti.com/lit/ds/snosbi1c/snosbi1c.pdf
You might also go to the DigiKey or Mouser website and explore their tables of available devices. You can narrow your selections based on what you want or don't want, such as only considering devices that are in DIP packages, to get a list of parts that are available to choose from plus see what kind of prices you are looking for. By looking at how many are in stock you can get a rough feel for how popular the part is -- the most popular parts are more likely to be found in electronics surplus stores if you happen to have any around.
For instance, if I go to DigiKey and just look for ADC devices, there are over 15,000 options:
https://www.digikey.com/products/en...uisition-analog-to-digital-converters-adc/700
But if I narrow that to 8-bit, 5 V for both the analog and digital supply voltages, parallel interface, single-ended input that is reduced to 299 parts.
If I further refine that to parts I can buy in low quantity (bulk and cut-tape) I'm down to 13 parts.
If I then check which are active and stocked, I get only two, both variants of the ADC1175 from Texas Instruments. The low speed one is $2.73 and they have nearly 10,000 in stock. So you can probably find this elsewhere pretty easily and very possibly at a better price. You may even be able to get TI to sample you a few.
One thing I didn't spec was package type. These are only available in TSSOP, which you may not be able to work with. If you want DIP parts, you may have a harder time finding those (new, anyway, the surplus market may be a better place to look for those parts).
Thank you. I'd prefer DIPs, but I'll do what I must.
Multiplexers. Actually though, I may just use 1 pot and several buttons to select the addresses.
You might play around with that table starting with the limitation that the part has to be in some kind of DIP package. You might find that if you relax one of the other requirements that you can find a suitable part -- keeping in mind that DigiKey and Mouser really don't stock every part ever made, it just seems like it.
