AD8194

Question

Hi everyone, 
 I've a PCB with an AD8194 and AD9880. The AD8194 mux is connected to a DVI and HDMI connector. 
 I've a trouble with the AD8194. The AD9880 doesn't detect signal with some DVI sources like personal computers. 
 If I remove the AD8194 and I do a bypass with some wires, the AD9880 detects the video source. Please, could anybody help me? 
 Thank you 
 Best regards 
 Jose

daverowe · Accepted Answer

Hi Jose, 
 We do try very hard to make our solutions robust even when interfacing to non-compliant sources and sinks. There's always a limit to how for out of spec a source can be and still work. I am not a AD9880 expert, but it would certainly seem the AD9880 is more tolerant in this scenario. The AD9880 is deserializing and processing the TMDS data. The AD8194 is essentially an analog differential comparator. So if one side of the differential pair is at the rail, there's very little gain and not surprising that bit errors are occuring. 
 It's common for this type of problem to be a mechanical (broken pin) problem with the connector. If the graphics card is removable, perhaps you can check and if necessary replace the DVI connector. 
 Dave)

Electronic Design Services - PartnerZone

Products Mentioned

AD8194