How to achieve a 24bit D/A conversion with 3 independent 8 bit D/A converters?

[mithra]

hey im using three TLC5620 D/A converters in my project. My problem is how to achieve a 24bit D/A conversion with 3 independent 8 bit D/A converters connected in cascade.

 

[Davood Amerion]

doubt on D/A

hey!! :arrow: it is not possible

 

[mithra]

Re: doubt on D/A

hi davood ! I think it is possible. One way I got is to connect the o/p of first dac to the reference of second D/A and o/p of second D/A to reference of third and take final o/p from the third one.
howz this?
But is there any other effective cost utilisation method ?

 

[Davood Amerion]

doubt on D/A

sorry, i mistake on reading D/A and think it is A/D!
you can use resistor divider by 256 for second and (65536) for 3rd DAC and summing 3 DAC result.
but i think it has severe accuracy and linearity problem.

 

[mithra]

Re: doubt on D/A

Ya Davood, accuracy and linearity are affected but it is all in between 1/2 to 1LSB or 3 to 4 mvolts. Then how to overcome this?

 

[Davood Amerion]

doubt on D/A

yes it is between 1/2 to 1 LSB , but LSB bit of 8 not LSB bit of 24!

 

[mithra]

Re: doubt on D/A

Well, How to increase the accuracy and linearity?

 

[Davood Amerion]

doubt on D/A

It depend on accuracy of each DAC. specially MSB section (1st DAC), and 2nd. DAC.

 

[mithra]

Re: doubt on D/A

ya, i got it davood. Though the linearity is getting out of track in microvolts it is in the specified range only.