Q
I am confused by the data sheet. Can the ADV7125 run with a 3V3 power rail?
If so, what parameters are effected?
From the application schematic, the ground pins on the video output connector
appear to be connected to the main board ground plane, i.e. DGRND. Is this
correct, or should the analogue grnd pins on the video connector be connected
to AGRND?
A
Yes it can run off 3.3 volts - hence the specifications on page 3 of the
datasheet representing our own results with a 3V3 supply.
I assume you ask because the pinlist on page 7 designates Vaa as "5V +/- 5%".
There is no VDD pin on this part only 3 VAA pins.
There is not a lot of digital circuitry on this part and hence no requirement
for a separate digital supply pin.
All three VAA pins should be fed from a clean, decoupled analog supply line via
wide low inductance tracks.
The recommended filtering for the supply is a PI filter consisting of a C to
ground, series inductor in the supply line followed by a C to ground.
This will provide isolation between the converter power supply and the rest of
the power line.