ESR for ADV7180WBST48Z

Hi,

   As per expert comment, It is recommended to use crystals with <= 30 series resistance and we need to ensure whether we are calculating the load capacitance accordingly.

   Please note "Adding a 30 Ω to 50 Ω series resistor can suppress reflections, reduce EMI, and reduce the current spikes inside the ADV7180.

   Also if series resistors are used, place them as close as possible to the ADV7180 pins. However, try not to add vias or extra length to the output trace to place the resistors closer.

   Please refer this FAQ (+) Notes about the crystal neeeded for the ADV7180 or ADV7182 - Documents - Video - EngineerZone (analog.com)

Thanks,

Poornima

Hi,

   As per expert comment, It is recommended to use crystals with <= 30 series resistance and we need to ensure whether we are calculating the load capacitance accordingly.

   Please note "Adding a 30 Ω to 50 Ω series resistor can suppress reflections, reduce EMI, and reduce the current spikes inside the ADV7180.

   Also if series resistors are used, place them as close as possible to the ADV7180 pins. However, try not to add vias or extra length to the output trace to place the resistors closer.

   Please refer this FAQ (+) Notes about the crystal neeeded for the ADV7180 or ADV7182 - Documents - Video - EngineerZone (analog.com)

Thanks,

Poornima

First of all, thank you for your help. I am not going to be using series resistor and I couldn't be able to find the transconductance value (gm) of this IC so I can calculate gain margin can you help me with that? Secondly finding a crystal ranges between -40 and +85 with 50 ppm also having 30 ohms ESR is really hard to find so do you have a suggestion for crystal (any brand/variant) or using this crystal which has 60 ohm ESR would work?

Hi,

   I believe, Abracom crystal can meet your requirements at Abracon | Crystals

  Also the equivalent series resistance (ESR) of your crystal is a bit higher than the Golledge crystal we use in analog devices for our evaluation. I would advise contacting your crystal manufacturer for your correct circuit setup.

Attached 4503.ma01377.PDF is a recommended crystal that we are using for our ADV7181 eval board testing and this going to work over extended temperature ranges.

Thanks,

Poornima

Hello, thank you for your reply. I think I am going to use this one for my crystal. Can you help me with the trans-conductance(gm) value of the ADV7180WBST48Z. Because it is not written on the datasheet. I need it to calculate gain margin. Thank you in advance.

Hi,

  We don't find the trans-conductance(gm) value or formula from the ADV7180WBST48Z manuals.

   We have taken the below formula from general link and It is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Please calculate accordingly

     gm = iout/vin

Thanks,

Poornima