General > General Technical Chat
Do semiconductor datasheets suck?
magic:
--- Quote from: T3sl4co1l on November 28, 2023, 11:05:27 am ---Not hard to find examples; https://www.ti.com/lit/ds/symlink/cd4011b.pdf perhaps surprising that it's not been updated for such a basic datasheet, when others have (4013 for example).
--- End quote ---
You win, I guess.
But it says "acquired from Harris Semiconductor" so maybe TI never had this document in any sensible digital format and can't be bothered to recreate it.
And by the way, I'm no TI fanboy and their datasheets aren't exactly perfect. When they came up with "recommended operating conditions" they retroactively added them to most existing datasheets, usually something generic like "±15V supply" for opamps, regardless of actual abilities of given model. They shuffle sections around and occasionally mess something up, like the OP07 which had its schematic replaced with a 741 during datasheet overhaul. There are datasheets like TL431 consisting of numerous copy-pasted tables differing in a few digits here and there. There is the TL072H shoved into TL072 datasheet even though all its specs are separate from the latter.
David Hess:
--- Quote from: 16bitanalogue on November 28, 2023, 05:23:33 am ---
--- Quote from: David Hess on November 28, 2023, 02:32:16 am ---If block diagrams are given, then input and output circuits should be shown in detail.
The test circuits used to measure parameters should be published.
--- End quote ---
Depending on the product, yes. Older op-amps TI/NatSemi used to show the transistor level design, but even this was sanitized. More complex products that would be a negative, Ghost Rider. That ESD clamp? We show a Zener, but it's not really a Zener. It simply acts as one. We would not show the logic on how PFM mode is activated in a buck converter mode pin; there would simply be a "PFM Logic" block. It's simply too complex.
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When required, simplified schematics are usually good enough, and often better because they are easier to follow. For instance they are indispensable when understanding what clamp, compensation, and offset null pins do in operational amplifiers.
For some newer operational amplifiers from Texas Instruments, it is impossible to know the differential input range because there is no input schematic, and the specifications either do not say or are conflicting. And which way does the input bias current flow? You just have to measure it.
--- Quote from: magic on November 28, 2023, 11:36:37 am ---And by the way, I'm no TI fanboy and their datasheets aren't exactly perfect.
--- End quote ---
It is not a matter of being perfect. In the past Texas Instruments sometimes misled or deliberately lied on their datasheets. When you read the articles from Bob Pease talking about someone publishing misleading datasheets, he is referring to Texas Instruments.
schmitt trigger:
--- Quote from: magic on November 28, 2023, 11:36:37 am ---
--- Quote from: T3sl4co1l on November 28, 2023, 11:05:27 am ---Not hard to find examples; https://www.ti.com/lit/ds/symlink/cd4011b.pdf perhaps surprising that it's not been updated for such a basic datasheet, when others have (4013 for example).
--- End quote ---
But it says "acquired from Harris Semiconductor" so maybe TI never had this document in any sensible digital format and can't be bothered to recreate it.
--- End quote ---
This datasheet has a long lineage.
I still have an original RCA COS/MOS data book, published on 1980, and the TI datasheet posted by T3sl4co1l is identical to the one on my book.
Harris acquired it from RCA Semi, via a brief detour from GE, and I believe Intersil.
magic:
--- Quote from: David Hess on November 29, 2023, 02:51:34 am ---For some newer operational amplifiers from Texas Instruments, it is impossible to know the differential input range because there is no input schematic, and the specifications either do not say or are conflicting. And which way does the input bias current flow? You just have to measure it.
--- End quote ---
TI's new precision bipolar opamps seem to use bias cancellation.
Maybe it's different with the cheaper LMVxxx stuff.
Kleinstein:
--- Quote from: magic on November 28, 2023, 11:36:37 am --- There is the TL072H shoved into TL072 datasheet even though all its specs are separate from the latter.
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The mess with TL072H is not just a data sheet problem. It starts with naming that is causing more confusion than good. It is still another bad step to have a combined datasheet, as the old TL072 and new CMOS TL072H have not much in common. Not hat the TL072H is a bad part, it just got a bad name.
Combined datasheets that handle multiple parts are often a good thing, if the parts are really the same core (e.g. 1/2/4 fold OP-amps or different voltage regulators).
For the OP-amps it would be good if they directly write if the use bias compensation or not. At least the newer DS give the signs and one finds out.
The main 2 points where I have seen repeatedly wrong values is with the current noise of AZ OP-amps and the DC SOA of MOSFETs. The wrong SOA curves are especially nasty, as this can (but one may be "lucky" with a prototype) cause failures that cause additional damage.
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