Other Parts Discussed in Thread: LP-AM243
I am planning to use a crystal for the 25MHZ.
Is there any documentation or guidelines regarding the acceptable drive level for a targeted crystal. I want to use one with 100uW specification.
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Hi Iance,
Our AM243x device supports up to 163.84uW drive level so it should be fine to use the one with the specification you are targeting. Currently this information is not in the datasheet but we are planning to include it in future revisions of it.
Hope this helps!
Best,
Daniel
Thank you for the reply.
is it possible to get the circuit model for the oscillator so it could be simulated with the crystal manufacturers data.
thanks
lance
Hi Iance,
Sure, in our device datasheet under section 7.10.4.1.1 MCU_OSC0 Internal Oscillator Clock Source you should be able to find the recommended crystal circuit to implement the oscillator input in your design.
In the following subsections you should also be able to find details in how to calculate the required load capacitances and shunt capacitances for you application by using the provided formulas.
Best,
Daniel
Thank you for the reply. I am still uncertain regarding the crystal selection. Do you have any crystals that have been already qualified for use in the AM2431 or similar family?
Hi Iance,
You are welcome!
In regards the crystal selection, 25MHz is actually what we use in our LP-AM243. You can actually go to our product page and download the design files for the LaunchPad to use as reference for your projects.
To do this:
1) visit our product website: https://www.ti.com/tool/LP-AM243
2) Click on "Design Files"
3) Download "LP-AM243 Design Package - SPRR433.ZIP"
In this package you will be able to find schematics and the BOM for our product. For your convenience, if you check "Item Number" 106 in the BOM you will be able to see what crystal oscillator we use along with the Manufacturer Part number.
Hopefully this helps you select the appropriate crystal for you application.
Best,
Daniel
Thank you for replying.
Unfortunately the example you have pointed me to is not a crystal but instead is an oscillator. The launch Pad design uses an Oscillator from Wurth Electronik 831055678
If you could review if there any designs which use the crystal as the datasheet show a crystal connection as shown in the diagram below
Sorry for the confusion!
You are correct, the Launchpad uses an oscillator. On the other hand, our GPEVM does use a 25MHz crystal that you can potentially use and follows a similar datasheet crystal design example that was shown before. this would be the ABM10W-25.0000MHZ-8-K1Z-T3 that you can find here:
https://www.digikey.com/en/products/detail/abracon-llc/ABM10W-25-0000MHZ-8-K1Z-T3/7172507
As a quick note:
Our devices are designed to support both Oscillators and Crystals as input clock to the SOC depending on resistor configurations. In its current implementation, you will see the following in the GPEVM schematic:
SOC_CLK_IN in the top left is providing the system clock from the same oscillator used in our LaunchPad design. If you would like to use the Crystal as input instead, the GPEVM would have to be modified to in order to populate R158 and R155 with 0ohm resistors and leave R161 as a DNI instead.
If you are not planning to use alternate clock sources then the 0-ohm resistors are not needed and the crystal terminals can be routed directly to the SOC, which would yield a schematic that resembles the one in the datasheet
You can follow the same procedure as before to download the schematic and BOM from our product page if you'd like to go and take a look at the documents yourself
Link to the GPEVM Product Page: https://www.ti.com/tool/TMDS243GPEVM?keyMatch=AM243%20GPEVM
Best,
Daniel