TCXO HSE to NUCLEO f446re

[TimMcGilly]

I need a accurate time source for time synchronisation between boards and timestamping of sensor data so want to add a accurate HSE. I'm currently considering a 7N-26.000MBP-T

26MHz TCXO connected to OSC_IN. I would have a 10nf bypass capacitor and directly connect OUTPUT to OSC_IN. (I've attached schematic) This would be setup on a breadboard by the board.

I would plan to run the system clock at 78 MHz.

Are there any additional components I am missing to get it working correctly? Is 26MHz a suitable clock frequently or is another one better for microsecond timestamping and synchronisation?

Thank you!

TCXO https://www.digikey.co.uk/en/products/detail/txc-corporation/7N-26-000MBP-T/5222407

Capacitor https://www.digikey.co.uk/en/products/detail/txc-corporation/7N-26-000MBP-T/5222407

[Tesla DeLorean · Accepted solution]

You'd need to remove the 8 MHz ST-LINK MCO source. Check the schematic/layout that there aren't stubs

I've used 30.72 MHz ppb sources on some NUCLEO-144 boards. And can benchmark that, and PLL generated frequencies, against a 1PPS source

[TimMcGilly]

Thank you, I've found the solder bridges and resistors I need to remove to use OSC_IN instead of ST-LINK.