What is the max. current that can be drawn on VDD2?
Per the datasheet, table 4, the max current on VDD2 is 50mA, but this total
includes the internal current to supply the side 2 channels at the data rate of
the signals, which can be up to 25Mbps. See the spec for available VISO supply
current to see the amount left at 25Mbps data rate, for example the 3470 can
deliver 91mA, which means it consumes 9mA of the max 100mA VISO to drive the
In a practical sense, you need to balance the load on VDD2 with the load on
VISO or else the VISO voltage will fall and regulation of VDD2 will not be
maintained and if VDD2 goes below 3V the side 2 controller will fail to
operate. So, they can use VDD2 with these limitations.