I am confused reading the Texas Instruments Data Sheet of Absolute Maximum Ratings for their 74HC595 series in parallel out shift register. On the first page of the data sheet it says: "+/-6mA output drive at 5 volts. Reading the Absolute Maximum Ratings it says: Output clamp current Vo< O or Vo >Vcc max +/-20mA. I don't know what this means?
Next: Continuous output current Vo=0 to Vcc max +/-35mA This is confusing, is that for all the combined outputs?
Next: Continuous current through Vcc or Ground +/-70mA
I am assuming that each output needs to be limited to +/- 6mA
Also assuming that the total current output of the 8 outputs must not exceed +/-35mA
I don't know where the +/-70mA comes into play?
Output can sink or source current.
Operate for extended times at these levels can damage the component.
The sum of internal and external currents not to exceed this value.
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The reason you are confused is that you have no background in TTL or digital circuitry, The load current is whatever the chip is driving, which is supposed to be another digital chip with standard load ratings. You can't just connect anything to it. If you connect it to another (or several ) digital chips, it will draw what is designed to draw. In short, if follow standard practice, you never need to even read the datasheet because you are not going to exceed any ratings. If , on the other hand, you try to drive 10 inputs from 1 output, you might be pushing it and you would need to do the math to find out how much current an input requires and multiply that by 10 to see it it is less
than the maximum rating. You could benefit by studying basic digital electronics and what is standard practice. I have been using TTL and HC series and others for 40 years and have never looked up the maximum current rating for a chip because I follow standard practice. If you want to run multiple leds from an output just do the math
and find out how much each draws and go from there. That chip is popular for driving leds but usually it's only one per output but at 70 mA , you could drive five 10mA leds. If you're serious about learning digital circuitry, you might find this a good read. It's the
book that most people started with, (back in the day)
(yes, I know TTL is practically obsolete but there's still a lot of good info in the book)
Google "FAN OUT"
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You will also need to read it if you are driving things other than MCU's digital pins. For example, LEDs. At 6mA I don't know if it is sufficient.
I think usually it will be good enough to drive 2 or 3 chips at the same time, but you would also need to look at how much current they draw.
There should also be "high-powered" ones with buffers so you can drive more load (e.g. 20mA) per pin. If you do have unusual plans.
This is primarily for inductive loads or long wires that may feed current back into an output by voltage levels outside the chip supply voltage. If such conditions exist you can add a series resistor to the output that limits the current to 20mA. Or use a driver (transistor...) between the logic output and the load.
Each output has an absolute and continuous maximum current rating. All output currents together are restricted to a common (sum) value. Another limit applies to the supply currents caused by internal current plus all output currents. If exceeded the excess currents will damage specific parts of the chip.
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Wow, didn't know about this clever TPIC5A, only used the much cheaper TPIC6B.
In all honesty, all I did was Google "high current version of 74HC595".
Back in the day, would have thumbed through data books thick enough to bulletproof a car.
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Back in the days of data books everybody had a selection of frequently used parts in his grab bag. Need a small transistor -> BC107, big one -> 2N3055. New parts were added from hearsay of friends or magazines or by chance from local dealers or surplus bargains. Not really different from nowadays...
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Hi,
Basic parts list;
LM741
LM555
BC548
BC558
2N3055
LM393
LM324
TIP31
TIP32
Digital ICs added as needed.
Note; no MOSFETs, this was before they became the norm, my tool box had a baggage label for the ARK or was it the TITANIC!!!!!!
Tom.... 
I wouldn't be caught dead uding an LM741 these days. I might as well wear a tiger skin and carry a huge wooden club.
The LM555's on the other hand will never get old.
This lighting special effects controller is mostly
LM555 circuits (about 30 of them)
For an explanation of the controller read post#21
of this thread
(Using AMS1117 3.3v Buck Module on a Serial port - #21 by raschemmel)
The Lm393 and LM324 are still used but personally I prefer the LT1215 for all op amp or comparator
functions UNLESS I NEED an open collector comparator like the LM393.
The whole point of making progress is to improve the quality of life. What's the point if you use an LM741 (circa 1968) in January of 2022 ? You should throw them away and pretend you never saw them.
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Hi,
Yes, I know where I have some LM741 in DIP and round can versions, kept safe for some legacy equipment.
LM324 or TL084, I still have a divided box of LM78xx and LM79xx regulators.
Also a box of tubes of 74LS and HC digital chips.
The way shortage of components are at the moment, might be worth something, but will keep them for my own repairs.
Tom...
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Yes, you can use LM741s during a pandemic supply chain shortage, then use LT1215s untkl the next pandemic.
Aren't we technically still in an Influenza pandemic, it mutates itself each year around the world?
Tom...
I've had my annual flu shot, thank you very much.
Ditto...
Next one in April/May.
Tom...
Wow they literally strapped FETs to every output. That was a beefy boy.
It can drain at 50V and 1A. It cannot supply, though. But I don't think that is relevant.
It is also significantly larger, and come only with the SOIC variant (SOP, shrink outline package, 1.27mm between leads).
Why would anyone actually use these? On breadboard, ok I kind of see what you are talking about. But PCB with integrated microcontroller, chip, screen and USB port? I don't think I have a use of 555 at all.
Tip31/32 are quite some nice Power transistor, though. Although I prefer MOSFETs like FCP165N.
Who knew we would need our old 741s because
a pandemic was coming that would break the
Supply Chain ?
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