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Custom board with 21489, Comparison with EZBoard

Question asked by MarcZ on Jan 17, 2016
Latest reply on Jan 31, 2016 by Harshit.Gaharwar

Hi,

 

We have designed a board with the 21489 and we have some question regarding it :

 

1. The Boot Config lines and Clock Config lines are currently pulled high and low using 4.7K resistors. Is that sufficient, or should they be a lower value? So far everything works, but I'm just wondering...

 

2. We use SPI to boot the 21499. In our case, the SCL (serial clock) line is connected from the 21489 directly to the Flash chip. There are no pullups or pulldowns. On the evaluation board, SCL is pulled down. Should it be pulled down, or is it okay to leave it floating like that?

 

3. On the datasheet page 25, it shows a 47-ohm resistor in series with the crystal oscillator. Is this really necessary? It is not present on the EZ board...

 

Thank you,

Marc

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