Questions about NAND gate at WR in this ADC

[ahcheong]

some question to ask

from the file i attached, anyone know about how does this ADC work??

and what is the use of the NAND gate at WR???

then what is the voltage that used at pin 9 (is it 6V) if VSS is 12V???

thank you~~

 

[IanP]

Re: some question to ask

There are a couple of things that can be more the less identified:
- the nand gate with resistor and capacitor form an oscillator .. see picture below ..
- voltage at pin 9 will be 1/2 of pin 20, but how high is the supply voltage one can only guess - maybe 5V ..
- 12kΩ and 150pF could be RC components used by the internal oscillator ..
- there are 8 outputs - most likely this is 8-bit converter ..

It is possible that each time the WR input is pulled-down by the output of the 4093 Schmitt triger gate the input analog signal is converted and the outputs are then written with the result of the A/D conversion ..

And that's about it .. the rest is just guessing work ..

Regards,
IanP

 

[ahcheong]

some question to ask

"the nand gate with resistor and capacitor form an oscillator" means the 4093 NAND gate is used as oscillator????

 

[IanP]

Re: some question to ask

Correct, an oscillator can be build from one 4093 gate .. see details below ..

Regards,
IanP

 

[ahcheong]

Re: some question to ask

so in the design i attached, what is the function of the NAND gate to control the ADc??


Another design is attached, what is the function and operation of the CA3130 and 40106???

 

[tania_04]

Re: some question to ask

Hey,
Can't say I'm 100% sure about this but I think the NAND gate acts as an embedded oscillator,
the voltage at pin9 is ½pin20 and input voltage should be a standard value which would be 5 or 12V though sometimes 15V is also a standard input for an IC, try simulating and see what happens.