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I've got this schematic of a device I need some information about. It it was in electronics class I had, but I do not know the name of the schematic.

The problem is, I can pretty much see what it does, it buffers the DataOut signal, when the Enable pin is HIGH, but why do we need the PullUpEnable, and shouldn't it be "PullUpDisable", sice we stop pulling up when it is HIGH.

Can someone tell me if he/she has used this device, or if you know the name of the device and where it is used, so I can make a further google research?

enter image description here

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    \$\begingroup\$ That's not a diagram of a specific device. That's a diagram of a type of circuit. \$\endgroup\$
    – JRE
    Commented Nov 9, 2020 at 12:58
  • \$\begingroup\$ So, what are your initial impressions or deductions about this circuit ? \$\endgroup\$
    – Mitu Raj
    Commented Nov 9, 2020 at 13:02
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    \$\begingroup\$ You're likely to find a whole bunch of those circuit blocks in one single device - probably one for each IO pin. \$\endgroup\$
    – brhans
    Commented Nov 9, 2020 at 13:03
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    \$\begingroup\$ So you're relying on our experience to recognize that circuit? Is that the goal of your class, I mean, just ask the experts? Or are you supposed to make your own reasoning what the circuit could be used for based on the schematic and the names of the signals? If I were your teacher I and you said it is an output buffer, I would ask: "Why do you that is so?" Can you then answer something different than: "The experts at SEEE said so."? \$\endgroup\$
    – Bimpelrekkie
    Commented Nov 9, 2020 at 13:18
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    \$\begingroup\$ If I were your teacher I'd rather have my students come up with weird and wonderful but completely wrong answers as long as they had a good story (a good explanation) with their answer. ...see what it does... If you know how a MOSFET can be switched on/off you're already close to figuring out what this circuit does. \$\endgroup\$
    – Bimpelrekkie
    Commented Nov 9, 2020 at 13:21

1 Answer 1

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That looks like a tristate-capable output buffer, as used on the output pins of various microcontrollers. It can be set to output a value, disabled (floating/tristate), or to have weak active pullup.

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  • \$\begingroup\$ Ah, that is very good. I think the teacher would give full marks. You remind me ages ago I graduated from a technical college with an EE diploma, and earned my living as a technician, troubleshoot semiconductor testing machines. In those days the schematic is a big blue print sheet of paper, with perhaps one hundred logic gates forming a bowl of spagetti, ... and of course there were no hint labels like enable, pull up, data out etc. I usually gave up after a while and went home to sleep. But some of my team mates would not sleep, and once he had an eraka and got so excited, / cont \$\endgroup\$
    – tlfong01
    Commented Nov 9, 2020 at 14:13
  • \$\begingroup\$ jumped out of bed, 3 am in the morning, took a taxi back to the factory to verify if his guess was correct. I guess my team mate saw electronic troubleshooting as playing chess. Ah, bed time, call it a day. \$\endgroup\$
    – tlfong01
    Commented Nov 9, 2020 at 14:15

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