analog mux. & selectable current

[ffsher100]

hi all,

i got a part of job to design analog mux & variable current source with digital select.

the analog mux is about 32:1


can anyone have experience with both to share?
or, what paper can suggest me?

thank all.

 

[digi001]

Is the analog mux at all related to the variable current source w/ digital select?

What does the digital select need to accomplish? On/Off? or Current? or something else?

 

[ffsher100]

hi templemark,
sorry for your confusing,
my analog mux and variable current source are digital-selected by seperating group.

for current source, current type like: 4mA, 8mA, 16mA, 32mA(2-digital select, maybe 4mA as default)
for analog mux 32 to 1(5-digital select)

 

[digi001]

Ok for the Analog Mux:

You could use a Analog Mux Chip something similar to this:
ADG732
Digi-Key - ADG732BSUZ-ND (Manufacturer - ADG732BSUZ)

For the Digitally Controlled Current Source:
You could use a Digital-to-Analog Converter with Op-Amp feedback control providing the base voltage to a BJT as a current source.
See this: **broken link removed**
but replace zener diode reference with DAC.

 

[ffsher100]

Hi templemark,

thank for your replying.

because of starting to analog world, i need some information or technique document to let me reference and note.