>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 09 March 2006 12:27
>To: Microcontroller discussion list - Public.
>Subject: Re: [EE] LVTTL Schmitt trigger non-inverting buffer - 
>do theyexistintiny packages?
>
>
>> ... but the customer is very specific about having LVTTL logic
>> thresholds.
>
>I wondered, "Why?"
>
>Which was answered by -
>
>> but customer is insistant on meeting the actual LVTTL levels after
>> problems with another vendors part.
>
>I don't know how savvy the customer is, but it sounds like they are 
>falling into the all too common trap of telling you how they want 
>something done, rather than specifying what they actually require. In 
>this case I suspect that specs of 0.6V or 0.8V are by themselves 
>likely to be reasonably meaningless. One would need to ensure these 
>were worst case, were over temperature and supply voltage and phase of 
>the moon, and more. One man's / supplier's looser apparent spec may be 
>a better one if it is actually adhered to and a notionally better one 
>isn't.
>
>Anyone system which has problems with levels of eg 0.6V versus 0.8V is 
>probably sailing too close to the wind for comfort in any case. When 
>reality strikes the system is in risk of doing so too.
>
>I'd suggest that you ask the customer to let you *engineer* / *design* 
>the system so that it is guaranteed to work, using whatever parts you 
>deem will do the job. What a novel idea :-). The alternative is to 
>risk giving them what they ask for but failing to deliver what they 
>want. Design may be difficult if the existing system is poorly enough 
>specd to not work with all brands of reasonably compatible ICs, but 
>finding out what it's limitations are and designing for them is 
>superior to follow a recipe book.

The story is that the product is built to meet a multi-source agreemant specification, and the logic thresholds are defined within that spec.  Clearly other vendors have had the same problem as us in meeting these levels...

I totaly agree with what you are saying though, I've seen this exact scenario too many times where a customer will concentrate on a trivial specification to the exclusion of all else due to some experience they have had in the past.  Unfortunately when these trivialities are holding back a potnential order, we have little choice.

Regards

Mike

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