I would like to synchronize 4 DDS (AD9910) , is there a good circuit that work for
synchronizing the I/O update of all of the 4 DDS, i have understood that it should be synccronized
with Sync Clock ?
You should do it for all DDS. The master device only serve as a reference for SYNC_CLK but not I/O_UPDATE. So each I/O_UPDATE should have it's own logic control, not unless you are intending to reconfigure them at the same time. If that is the case, you can have a buffer instead wherein each I/O_UPDATE is tied only to a single logic signal.
I'd like to refer you to this circuit note.
I am familiar with this Article,i have seen there that the I/O UPDATE should be synchronzied
for the 4 DDS from the Master Sync_Clk , I am intrested if you have a circuit that employs the Sync of the I/O UPDATE ,and is it enough to synchronize it to the Sync_Clk of the Master ?
In my understanding, the reason why I/O_UPDATE don't have any additional circuitry that was added to its signal path (as seen in the app note) is of the presumption that the signal need not to be coincident on each device simultaneously. There are cases that you want to commit a configuration on a device but not on the others -maybe because of the reason that they are still in the process of being configured. If you are using an MCU and use a GPIO on each device's I/O_UPDATE, then just ensure that the traces don't introduce a significant propagation delay relative to each other. No need to buffer, not unless your using only one GPIO for more than one device.
Ok, what i am started to do is a circuit that recieves the Sync_clk with a Flip flop and trigeer the IO_UPDATE to
the DDS,do you think i should to this circuit for each DDS or if the Syn_clk is alighned ,for all DDS, so it is enough doing this on the master ?
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