Hi all, I use two LM98640 on the same board to digitize a 4-output CCD. In a first step, I used the test patterns to validate my digital part inside FPGA. All were fine and I checked the LVDS voltage which were good too. In a second step, when I wanted to digitize the CCD video outputs, the behavior of the LM98640 changed: - the LVDS voltages are not the same : 300mV low and 1.5V high (with 100Ohm terminaison resistor) and only the low voltage changes when I change the "LVDS Amplitude and Common Mode Voltage" register - the result of the conversion looks very noisy around a fixed mean value whatever we put on the OS- input video signal (fixed voltage from fonction generator) and whatever the values of the PGA and offset registers: Mean value (decimal) ~10200 and the 10 LSB are flickering thus from ~9700 to 10700 Is this behavior is known ? Is there something to do to check the health of the parts ? Thanks a lot vincent
↧