ADG5462F is not giving output as expected_required immediate support

Awaiting of your response

Hi,

Thank you for contacting Engineerzone.

Initially I do not see anything obviously wrong with your schematic.

Are you using the TSSOP device or the LFCSP? your pin out is consistent with the TSSOP but I notice you have an EP pin in your schematic. The TSSOP does not have an EP pin.

Do you have any scope plots you could share with me? This would help me to debug the issue.

Regards,

David

Hi,

Thank you for contacting Engineerzone.

Initially I do not see anything obviously wrong with your schematic.

Are you using the TSSOP device or the LFCSP? your pin out is consistent with the TSSOP but I notice you have an EP pin in your schematic. The TSSOP does not have an EP pin.

Do you have any scope plots you could share with me? This would help me to debug the issue.

Regards,

David

Dear David, 

Thanks for your reply.

We are using LFCSP package part.  It has exposed pad  connected to GND_A net  in our design which supposed to be connected to -15V as recommended in datasheet.

Is this wrong connection causing this issue? 

We checked resistance between GND_A and -15V,.  It is 84K ohm.

We have measured -15V rail with respect to GND_A net.. It is -15V. No voltage drop.  

Random voltages measured at the other end of resistors  R445, R446, R447 and R448 by applying 5V DC to input ends of the same resistors. 

I can capture waveforms and share you for your analysis if this EP pin wrong connection is not root cause for this issue. Please confirm.

Regards

Nrupathunga

Hi Nrupathunga,

Can you check your pin outs? from your schematic it looks like you are using the pinout for the TSSOP package. The pin numbers are not the same for TSSOP and LFCSP. see image below from datasheet.

In your schematic pin 1 is NEGFV, for LFCSP Pin 1 is S1.

Regards,

David

Thank you David.. I got the root cause. 

No problem,

Can I ask about your application? your inputs are +/-10 V correct? What type of sensor input is this?

Regards,

David

Dear Daivd,

These are sensor inputs used in military applications.  Yes. inputs are +/- 10V only

Regards

Nrupathunga

 Can you please suggest , is there any drop-in replacement solution.

I don't option to change PCB design.

Dear David,

Could you please suggest drop-in replacement?  This is 15Lakhs board.  All other interfaces are up and only this ADC is not ok.

I don't have time and money to redesign the board. Could you please help us to get drop-in replacement part.

Hi Nrupathunga,

Are you looking for a drop in replacement for the ADG5462F LFCSP that fits the TSSOP pinout?

Unfortunately all of our similar devices such as the ADG5412F ADG5412 or ADG1412 follow the same pinout structure.

David

Dear David,

Yes, We are looking for drop in replacement for the ADG5462F LFCSP. 

Can we get custom part which can be configured to resolve this issue.  

Regards

Nrupathunga

Dear Analog,

Awaiting for your reply.

Regards

Nrupathunga