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Self-Boot Issue with the ADAU1401

Question asked by Sarmadh on Jun 24, 2010

I'm working on an application board with the ADAU1401 in self boot mode.  I can't get the ADAU1401 to self-boot from the E2PROM (I'm using an ST Micro M24C08 8KB E2PROM). I can load the program using Sigma Studio and the USB/I2C trnsport module and run the program just fine.  I can also program the E2prom from within the Sigma Studio software and was able to verify the programming; however I can't seem to observe any communication on the SDA and SCL lines to the E2PROM upon coming out of reset while holding the WP and SELFBOOT lines high.  I'm using the SELF-BOOT schematic shown on page 49 of the ADAU1401 data sheet, also I'm referring to the AN-923 AP Note ( Designing a System Using the ADAU1701/ADAU1702 in Self-Boot Mode).  I've attached the portion of the schematic relevant to SELF-BOOT.  My reset circuit is working, it's giving me about 140ms of delay (with 10uF in C2) between the time the 3.3V line (IOVDD) and the time the RESET line goes up to VIL (0.8V).  But even if the RESET circuit is not working properly, I still can't get the ADAU1401 to go into Self-Boot mode upon power up even if I manually hold the RESET line down for a couple of seconds then release it.


Any ideas?  


Note: DNS in the schematic stands for "Do not stuff"