# A/D Converter

Discussion in 'Homework Help' started by hncelectronics123, Jun 4, 2008.

1. ### hncelectronics123 Thread Starter Member

May 23, 2008
10
0
Hello again Guys

Another question id like to ask is;

I have an output from an analogue device of 0.699mV

Using An 8bit A/D converter work out the output.

Nov 17, 2003
6,960
146

Dave

3. ### hncelectronics123 Thread Starter Member

May 23, 2008
10
0

The only other information i have on it is

Number of bits = 8
Input to achieve ful scale output = 4 volts

Does this help?

Thanks

4. ### hncelectronics123 Thread Starter Member

May 23, 2008
10
0
Ok i have worked out the Resolution of the A/D converter.

8 bits = 256 codes

full scale output = 4v

so....... 4v/256codes = 15.62mV

Can anybody work out the final output of the A/D converter if the input is 0.699mV

Apr 5, 2008
15,806
2,390
Hello,

In you first post you say 0.699V and in the last 0.699mV.
With 0.699V ( that is 699 mV ).
Per step you calculated 4 V / 256 = 15.625 mV
If you divide 699 mV / 15.625 mV you will get 44.736.
Depending on the accuracy you will get 44 or 45 as a digital value.

Greetings,
Bertus

6. ### Dave Retired Moderator

Nov 17, 2003
6,960
146
Yes that is the ADC range.

15.62mV is correct as the resolution.

Are you sure you want to know the output for 0.699mV? 0.699mV is considerably less than the 15.62mV resolution of the ADC; therefore an input of 0.669mV would not register a reading at the output, i.e. the output would be 00000000

If it is 0.699V and not 0.699mV, then the answer is as bertus has explained of 45 (in base 10) or 00101101 as an 8-bit binary output.

Dave

7. ### hncelectronics123 Thread Starter Member

May 23, 2008
10
0
Thanks alot Yeah my mistake with the mv, v thing. been along day.

So, lets say that the output of the analogue/digital converter is 45.
I understand that this is the output but can this be displayed in a binary format, Such as 11010110

Thanks very much

8. ### Dave Retired Moderator

Nov 17, 2003
6,960
146
No problem, thanks for clearing it up.

45 (decimal) is 00101101 (binary) - this is the 8-bit output of the ADC for an input voltage of 0.699V.

Dave

9. ### hncelectronics123 Thread Starter Member

May 23, 2008
10
0
Many thanks for all your help!!!!!!
Sorry for the mistake, you are right with 0.699v.

Once again thank you very much

10. ### Dave Retired Moderator

Nov 17, 2003
6,960
146
No problems. Lets us know if you have any further queries.

Dave