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DS90UB921-Q1: want to connect the '921 LVCMOS SER to an LVDS DES which will connect to an LVDS frame grabber or to a LVCMOS into an FPGA

bandit gangwere
Intellectual 855 points
Part Number: DS90UB921-Q1

Paranoia check:

I want to connect the '921 LVCMOS SER to an ev2 EV76C560 camera (data<>, PCLK, etc) to a Link-III to a DES with LVDS outputs so I can connect it to an LVDS frame grabber. This will be used for development and for the production/calibration/factory

I also want to use the same SER to an LVCMOS DES for the actual production units. The '921 LVCMOS SER has a number of choices for the DES - seems best for my needs.

so:

camera LVCMOS => '921 SER =>  DES => LVDS => LVDS frame grabber  (for development and factory calibration)

camera LVCMOS => '921 SER =>  DES => LVCMOS => FPGA  (for the product)

According to the the DS90UB921 SER datasheet, these DES's should play well with the '921: (LVDS) '924, '928Q, '940, '948;  (LVCMOS) '926Q .

Question: Is this still reality?

Since the '926 is the only  DES LVCMOS chip, it wins the LPCMOS DES by default. 

(BTW, searching for '922 is forwarded to the '921)

Also see e2e.ti.com/.../672749

Question: Since that post about the '922-Q1 DES says one should use the '926Q as DES, I assume the '922 is obsoleted. Correct?

Since there are 4 viable LVDS chips, what is the selection criteria? well:

'940  is two lanes - don't need both - reject

'948  is two lanes - don't need both - reject

'924   96 MHz

'928Q   85 MHz

BUT - '921 is 85 MHz - so a 96 MHz chip is too fast (actually, the handshake should be limited by the slowest, but the extra speed is wasted).

So - go with the '928Q

Question: Is this analysis correct?

Question: Are you planning on obsoleting the '924 or '928Q?

Question: is there a better choice than the '921?

so:

camera LVCMOS => '921 SER => '928Q DES => LVDS => LVDS frame grabber  (for development and factory calibration)

camera LVCMOS => '921 SER => '926Q DES => LVCMOS => FPGA  (for the product)

Question: Is this a viable path? (I am assuming yes)

I will be using eval boards. I see both mouser and digikey have a few in stock for $415. (I noticed your price is $400.)

Question: if both of them are out of stock, would you still have some?

Question: And what's up with the "Q" at the end of the part number ('926Q)? Why/how is it different from the '926?? It appears to be a note the rev is changed...

Thanks ... bandit