Another mystery IC

Tony Duell ard at
Mon Jun 29 13:00:35 CDT 2009

> Tony,
> I believe it is an AD891D Rigid Disk Data Channel Qualifier !! The datasheet
> ( PDF ) is 491K if you want me to send it to you.

I am absolutely sure you're correct -- many thanks... 

If I'd thoguht of searching for 'rigid disk', I might well have found it 
myself. Oh why can't there be standard names for these things :-). 

And of course being an ECL chip means that the power lines appear to be 
the wrong way round at first. But upon reading the datasheet (no need to 
send it,, I've read it on datasheet archinve), I saw the bit about 
running it from +5 and +12V. The input circuit shown seems to match up 
with what I have too...


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