STM32F401RBT6 HSE Clock Issue with TCXO

[Alaeddine_Chamsi]

I’m designing a board with the STM32F401RBT6 and have decided to use a 48 MHz TCXO for the HSE clock.
I’ve written a simple "Hello World" program that communicates through USART.
the TCXO i used : TG2016SMN 48.0000M-MCGNNM3 
Observations: When using the HSI (internal oscillator), the program works fine. When switching to the HSE (with the TCXO), the program does not work. I measured the TCXO OUTPUT SIGNAL using an oscilloscope. The waveform is shown in the attached image.

 value of R8 and R9 = 0 , C13 = 10 pF , C16 = 1000pF 
What could be causing the program to fail with the HSE clock? Are there any specific considerations or configurations required to use a TCXO with the HSE input on this MCU?

[STOne-32]

Dear @Alaeddine_Chamsi ,

Welcome in STCommunity and thank you for sharing your use case .  

1) Can You try to remove R9 so to leave PH1 Open .

2) by software, did you switched the HSE ON and in bypass mode ? Out of reset as you have seen HSI is always ON . 

3) How do you know the program is not working ?  Can you share where the code is stuck ? Using the debugger . You can put a LED blinking infinite loop and let us know .

Hope it helps you . 
STOne-32