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We used the crystal specs mentioned in the datasheet for the 920719.
Parameter | Symbol | Conditions | Minimum | Typical | Maximum | Unit |
Output frequency | Foscout | – | – | 32.768 | – | kHz |
Frequency tolerance | – | Crystal-dependent | – | 100 | – | ppm |
Start-up time | Tstartup | – | – | 500 | – | ms |
XTAL drive level | Pdrv | For crystal selection | – | – | 0.5 | μW |
XTAL series resistance | Rseries | For crystal selection | – | – | 70 | kΩ |
XTAL shunt capacitance | Cshunt | For crystal selection | – | – | 2.2 | pF |
External AC Input Amplitude | VIN (AC) | Ccouple = 100 pF; Rbias= 10 Mohm | 400 | – | – | mVpp |
We actually used a 20 PPM industrial temp grade XTL and the frequency turned out 60ppm to the high side. By increasing the caps which didn't meet the XTL specs, I got it on frequency but now the startup time is about 1.5secs. I even tried removing the 10MΩ feedback resistor which sped it up some since this increased gain but this isn't right. I am sampling lower ESR XTLs now.
Can someone tell me what the part number is for the 32.768KHz XTL used on the EVB? The markings on the part don't help. The EVB came with a schematic but no BOM.
Thanks,
Rex
Solved! Go to Solution.
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I believe the BOMs for the base and carrier boards are included in the Hardware Files .zip here on the corporate website: https://www.cypress.com/documentation/development-kitsboards/cyw920719q40evb-01-evaluation-kit
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I believe the BOMs for the base and carrier boards are included in the Hardware Files .zip here on the corporate website: https://www.cypress.com/documentation/development-kitsboards/cyw920719q40evb-01-evaluation-kit
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It appears I got a "hand me down" zip file that did not include it. The spreadsheet was missing. It appears that the particular part used is not on their website anymore but I figured out the next closest one. Thanks so much for the link.
Rex
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You may check out TXC 9H03270073.
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Yes, thanks... you helped!
Rex