Re: Is anybody using NE521 comparators?

On 26/09/2024 9:04 pm, Jean-Pierre Coulon wrote:

"offset" has a particular meaning for its designers. Tha datasheet says: output undefined if abs(Va_Vb) < offset. Forget what you know about the offset of an opamp! One could expect better from a bipolar differential pair :-)

What's wrong with that?
The offset for any particular pair of nominally identical transistors can be more tightly defined than that, though it can be expected to drift with temperature, but this is a data sheet talking about all the possible parts that the manufacturer might sell under that part number.
If the two inputs are closer in voltage than the data sheet value for the maximum offset, they can't say anything reliable about the state of the output.
It can be seen as a cop-out, but it's hard to see how they could be more specific.
--
Bill Sloman, Sydney