Hi Bill,
I got to the conclusion that I can not just do that, because I can not
guaranty proper operation. The problem is that I need 20mA continuous
from the gate to have a bit of margin to allow for fibre TX/RX and fibre
aging. Even 20mA is a bit on the low side looking at the manufactures
datasheet.
I probably need to do a few tests to see how hot it will get in reality.

The best option here is probably stacking, but I am not sure in terms of
the servicing. The other big problem is, if one of the chips in the
stack dies what are the implications.

Best Regards
            Luis  




-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of William "Chops" Westfield
Sent: 19 May 2010 06:01
To: Microcontroller discussion list - Public.
Subject: Re: [EE] CMOS Families


On May 18, 2010, at 9:00 PM, Russell McMahon wrote:

>> I always thought that xxx40xx CMOS chips were pretty much compatible.
>
> No.  Simplistically -
>
> B series are buffered.   A series are not.

That part I knew about, but I didn't think that anyone sold A series  
parts any more (eg I thought all currently sold 4000 series CMOS were  
B series, and I thought it was all alike.)  But the HEF4049B  
definitely has a much different output current spec than the CD4049B.

(Hmm.  Does the original circuit have B-series parts?  If not,  
replacing the A series parts with B series might be sufficient to get  
your extra current...)

BillW

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist