Author Topic: On Semi D Type Reg Datasheet weirdness  (Read 1169 times)

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Offline BurnedResistor

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On Semi D Type Reg Datasheet weirdness
« on: July 12, 2017, 10:14:58 am »
Hey All,

Was looking into the MC14076B, a 4-Bit D-Type Register with Three-State Outputs.

Under the function table it states in clear text that if either one or both of the  output disable pins is high, this puts the outputs into HighZ.

Yet, the logic diagram provided seems to contradict this:


Both inputs are hooked into a nor gate, which in tern is connected to a buffer with what seems like a inverted input. Two inversion would then put a high on the buffers if there is a high present on the data disable inputs?

Am I misreading something here? Is there an inconsistency in the data sheet?
 

Offline vealmike

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Re: On Semi D Type Reg Datasheet weirdness
« Reply #1 on: July 12, 2017, 11:53:46 am »
Am I misreading something here? Is there an inconsistency in the data sheet?
They haven't told you what the function of that third pin on the output buffer is.
To be clear, there's an output, an inverting input and a third pin.
I agree it looks like an "Output Enable" OE. Given their use of the bobble to indicate an active low input, we can safely assume that it isn't OE_N. Can we rule out "Output Disable"?

Personally I wouldn't sweat it. I'd believe the text / tables over the drawing.
 
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Offline BurnedResistor

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Re: On Semi D Type Reg Datasheet weirdness
« Reply #2 on: July 12, 2017, 12:03:08 pm »
Am I misreading something here? Is there an inconsistency in the data sheet?
They haven't told you what the function of that third pin on the output buffer is.
To be clear, there's an output, an inverting input and a third pin.
I agree it looks like an "Output Enable" OE. Given their use of the bobble to indicate an active low input, we can safely assume that it isn't OE_N. Can we rule out "Output Disable"?

Personally I wouldn't sweat it. I'd believe the text / tables over the drawing.

Hahahahaha. Alright. I just wanted a bit of a sanity check!

 

Online Ian.M

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Re: On Semi D Type Reg Datasheet weirdness
« Reply #3 on: July 12, 2017, 12:42:03 pm »
Look at someone else's 4076 datasheet.  e.g. http://www.ti.com/lit/gpn/cd4076b
As all manufacturers 4000 series are functionally equivalent (ignoring small differences in electrical specs), and the T.I. (ex Harris) datasheet has no such inverter in its diagram, its a good indication that whoever drafted that for OnSemi goofed.
 
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Offline BurnedResistor

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Re: On Semi D Type Reg Datasheet weirdness
« Reply #4 on: July 12, 2017, 07:25:51 pm »
Look at someone else's 4076 datasheet.  e.g. http://www.ti.com/lit/gpn/cd4076b
As all manufacturers 4000 series are functionally equivalent (ignoring small differences in electrical specs), and the T.I. (ex Harris) datasheet has no such inverter in its diagram, its a good indication that whoever drafted that for OnSemi goofed.

Good  Call!

Any point in notifying On-Semi about this?
 

Online Ian.M

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Re: On Semi D Type Reg Datasheet weirdness
« Reply #5 on: July 12, 2017, 07:32:50 pm »
Its the right thing to do, but unless you are an existing high volume customer of theirs with an assigned rep, don't hold your breath waiting for it to be revised.
 

Offline Benta

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Re: On Semi D Type Reg Datasheet weirdness
« Reply #6 on: July 12, 2017, 08:27:15 pm »
Don't see any reason to question the datasheet. You all seem to think that the line going from the inverter to the output buffers is an "output enable" but the datasheet doesn't say so.
If that line is called an "output disable", the datasheet is 100% coherent.

 


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