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HSE Clock Crystal Circuit

jwormsley
Associate III
Posted on June 11, 2012 at 20:03

Looking at the STM3210B evaluation board schematic, the 8Mhz crystal has a 1M resistor in parallel across the crystal. 

Looking at the STM3210E evaluation board schematic, the 8Mhz crystal has a 390 resistor between the OSC_OUT pin and the crystal.

Our older boards using STM32F103C8 parts used the former, and a new design with an STM32F103ZE is using the latter, but both seem to work for either CPU.

Can someone tell me what the difference is, and which is recommended for new designs? 

Thanks,

  Jeff.

1 REPLY 1
John F.
Senior
Posted on June 12, 2012 at 10:00

Please see, AN2867 Oscillator design guide for ST microcontrollers

which is (today anyway) at ...

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00221665.pdf