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USB superspeed peripherals Forum Discussions

kebu_4418491
Level 1
Level 1

I am using a CYUSB3025 with an Epson FA-20H 19.2000MF12Y-AG3 crystal. A 100K - 1M ohm resistor across the crystal is needed to get the crystal to startup and oscillate while the SD3 is in reset. Without the resistor, it won't oscillate. When using a startup resistor, bringing the CYUSB3025 out of reset causes the oscillator to stop oscillating. 12pF caps are used for Cext on both sides of the crystal.

The Epson crystal has a load capacitance value of 6pF to infinity. I am not sure what Cext should be. Does anyone have experience using an Epson FA-20H crystal with a CYUSB3025?

According to Cypress lierature, the NDK NX3225SA-19.2M-EXS00A-CS03082 was used to test the FX3. I can't find this oscillator for purchase.

Does anyone have a suggestion for a crystal and Cext values? I have seen examples as low as 2pF and as high as 39pF for Cext.

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YatheeshD_36
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hello,

Please refer to the Crystal section in the FX3 Hardware design guidelines: https://www.cypress.com/file/139936/download

The Epson FA-20H crystal is characterized for FX3/FX3S.

You can also calculate the power dissipation of the crystal using the equations 1 and 2 from the FX3 hardware design guidelines.

Make sure that the calculated power dissipation does not cross the max drive level value mentioned in the crystal datasheet.

Thanks,

Yatheesh

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YatheeshD_36
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hello,

Please refer to the Crystal section in the FX3 Hardware design guidelines: https://www.cypress.com/file/139936/download

The Epson FA-20H crystal is characterized for FX3/FX3S.

You can also calculate the power dissipation of the crystal using the equations 1 and 2 from the FX3 hardware design guidelines.

Make sure that the calculated power dissipation does not cross the max drive level value mentioned in the crystal datasheet.

Thanks,

Yatheesh

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