Flash ADC: convert thermometer code to binary

thermometer code

Hi, i need to know how to use a 8:3 line priority encoder to convert the thermometer code of a 3bit flash adc to a digital word. since the adc has only 7 outputs, what should be done to the remaining input of the encoder? thanks.

thermometer to binary

u just ground the LSB

cheers

thermometer code to binary code

i'm not sure if i am understanding your intentions but... if i'm understood it right, you are mistaken in the use of the encoder...

an 8:3 encoder takes 8 inputs, and translates the active input to a digital number. This is, if you activate input number 0, you will get a 000 output. If you activate input number 5, you will get 110 in the output. The fact that it has priority means that when you already activated an input, it remains active even if you activate another one at the same time. This is, the first active input is the one that counts.

So, unless your ADC gives just 7 different values of reading (which i have never seen, and actually would be very unefficient), i don't see the purpose of connecting that encoder to the ADC...

i recommend you check the ADC's datasheet to see how it works

binary to thermometer code

the adc is a flash adc built from resistor string and 2xLM339 quad comparator. each comparator output is one bit of thermometer code. those 7 bits are fed to encoder (HEF4532B) with I0 connected to VDD (encoder is active hi). i got it to work according to IBO's instruction.

thermometer to binary encoder

Hi,
That is fine, but when you have got eight comparators, I wonder why you have only seven outputs?

Regards,
Laktronics

encoder for flash adc

n-bit flash adc has \[2^{n}\]-1 comparators

thermometer code to binary

Hi,
May be you are right, but, what if you make a circuit as per the site :
https://www.allaboutcircuits.com/vol_4/chpt_13/4.html ?

Regards,
Laktronics

binary to thermometer

i dont know who made this site.. i'd follow something more reliable myself..

**broken link removed**
**broken link removed**