AnsweredAssumed Answered

AD75019

Question asked by diego.alvarezt on May 25, 2018
Latest reply on Jun 5, 2018 by diego.alvarezt

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,

Best Regards

Diego

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