The datasheet states that the USB XI frequency is 24Mhz, and only 24 MHz. However, USB XI is not mentioned anywhere else in the datasheet or the hardware manual. Can USB CLKIN only take in a 24MHz? Or is there some range of acceptable frequencies?
Only 24 MHz is supported. This was done in order to ensure the best possible electrical peformance.
Thanks for the response. One additional question: Is the IO voltage for USB0_CLKIN governed by VDD_USB or VDD_EXT? In the eval kit, they are both +3.3V. However, I have VDD_USB = +3.3V and VDD_EXT = +1.8V. Thanks,
The USB0_CLKIN works from the VDD_USB supply, so it's 3.3V regardless of VDD_EXT. Power domains for each signal are listed in the "ADSP-BF70x Designer Quick Reference" in the data sheet.
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