Dear Engineer Zone,
Please, I would need your help in orr to be sure that my circuit wil lbe stable and/or have some conclusions about AD75019 behaviuor (I have used two chips).
I'm using AD75019 with following configuration:
Pin 1: PCLK
Pin 2: SCLK
Pin 3: SIN
Pin 4: VSS (-12 Vdc) - capacitor and diodes used according data sheet
Pin 5: NC (not connected)
Pin 6: NC (not connected)
Pin 39: NC (not connected)
Pin 40: NC (not connected)
Pin 41: VDD (+12 Vdc) - capacitor and diodes used according data sheet
Pin 42: VCC (+5 Vdc) - capacitor and diodes used according data sheet
Pin 43: DGND (connected to both analog and digital ground)
Pin 44: SOUT (not connected)
Finally, some Analog Input/Output are connected to some +5Vdc or Leds in order to test the switches.
Just powering up the chip, following voltages are on not connected pins:
Pin 5: NC (not connected) --> 0-15 mV
Pin 6: NC (not connected) --> 0-15 mV
Pin 39: NC (not connected) --> 0-15 mV
Pin 40: NC (not connected) --> 5 V
Pin 44: SOUT (not connected) --> 5 V
First time that I sent the 256 bits via serial communication it seems to work and AD75019 closes desired switches.
Then , when I try to open them again it doesn't work and nothing happens. They are still closed.
I could note that if Pin 40 is shorted to ground just for a few miliseconds, then the crosspoint is resetted and I am able to close the switches via serial communication.
For this reason, I have connected Pin 40 to a Resistor Pull-Down (1 MOhm) and before start the serial communication the chip is resetted programmatically.
With this workarround, it seems to work. But..., Could I ensure the circuit's stability? Why it is not working?
Please, could you help me with this questions?
If you need more information about my circuit, don't hesistate to contact me.
Thanks in advance,
Thank you for your reply David,
To be honest, my work is finished, but I will really appreciate it for future developments in case I will need switch signals bigger than 10vpp.
Finally it is perfectly working.
I have changed the power supply scheme to:
Pin 4: VSS (-5 Vdc) - capacitor and diodes used according data sheet
Pin 41: VDD (+5 Vdc) - capacitor and diodes used according data sheet
My last questions are:
1- Is it a known issue? Do you have cases like this?
2- Is there available more detailed information about the AD751019 behaviour for diffrenet power sources?
I really would need to understand why it is not working when I use the power supply scheme according data sheet.
It looks like you did not get an answer to this issue. Is this still an issue for you?