> Hi Guys,
> I am looking into a board that we are using that as a HEF4049 to drive a
> fibre-optic transmitter. I need to increase the sink capability from
> 13mA to around 20mA but that is the max for the HEF. I looked around and
> the CD4049 can sink up to 40mA which gives me sufficient headroom. I
> looked the datasheets and it seems that the CD type is better than the
> HEF in most cases.
> My question is do you see any reason why I can not just change it?

On the basis of what Russell wrote, and your reply to that, I would be 
tempted to just piggyback another couple of chips of the same type on the 
one already installed. This would give you triple the current capability, 
which in your immediate situation should allow a lower voltage drop, and 
therefore a lower power dissipation, without a messy rework of the PCB. 

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