ADCMP573 latch desable

Hi, Ariel.

In figure 27 of the datasheet, the LE-bar or LE-negate as you call it, is not shown because it is unconnected. The pin with bubble beside the LE pin (highlighted in yellow in the figure below) is the VTT pin (pin8) of ADCMP573.

I think the reason why you're part is not working is because you neglect the connection of the VTT pin. Please try applying Vcco-2V to the VTT pin as stated in page 9 of the datasheet and left the LE-bar unconnected.

Let me know if this works. If not, please share your schematic so we can help you fix your board.

Regards,

Anna

Dear Anna,

Thank you for your prompt answer. Indeed, there was jumper grounding the VTT input instead of receiving the Vcco-2V required. I fixed it but it still does not work. Find attached the used schematic. The extra connections are highlighted in red.

The comparator function does not work. I have tried different input data rates from 622Mbps to 3Gbps. I have also changed the reference voltage with no success.

Is there any tricks I may be missing here? What would be a standard easy test to do?

Thank you!

Best regards,

Ariel

Hi, Ariel.

Apology for replying back very late. Anyhow, can you please provide at least 3.1V to VCCI and VCCO? The 2V you have been applying is below the guaranteed minimum input supply voltage range. I think this is the reason why the part is not working.

Let me know if this works.

Regards,

Anna

Dear Anna,

I am attaching the Power Supply convention and levels I have used (case 3 of the table). VCCI = VVCO = 5.2V. This voltage is is referenced to CGND. In the previous file I sent you, VCCI=VCC0=2V with respect to AGND. These  are all requirement given in the datasheet when desabling the latch.

The chip does not seem to work. We are running out of time to integrate it in our system Is there a way we can get a replacement? I believe we have followed all the procedures and schematics with care and invested a good deal of time to make it work.

Regards,

Ariel

Hi, Ariel.

I just wanted to check on your issue. Have you already resolved it? In case you're still working on this, you may follow the suggestion below.

We have noticed that your Hysteresis Control Pin (Pin14) of ADCMP573 is set to 0V. As specified on the datasheet, this pin should either be left open or pulled down to AGND via Rhys (values are on Figure 7 of the datasheet). In your case, using Case 3 of Table 5 of the datasheet, HYS pin should have -3.2V because you have level shifted your CGND to -3.2V.

I hope that this still helps you. Apology for replying to you very late.

Regards,

Anna

Hi,

Have you resolved the issue? We are facing the same problem with ADCMP573. Any check points would be really helpful.