There are industry standard voltage levels for integrated circuits i.e. 12, 5, 3.3, 1.0, 1.05 , 1.08 and 0.6 volts and etc. My question is around why make it so complex to have this many voltage levels, why not just have one voltage level i.e 12 volts to be universally used across all IC's? Potential answers that am expecting is around power drawn that involves current holding capacity, copper losses and etc but it would be nice to have a good explanation from industry technologist who have spent many years in electronics.

Best Regards Yasir

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    \$\begingroup\$ Why not have just one USB connector standard? Why not have just one wall outlet standard? Why not have just one spoken language? \$\endgroup\$
    – Eugene Sh.
    Nov 7 '17 at 20:23
  • \$\begingroup\$ is there room for simplification? \$\endgroup\$
    – JYasir
    Nov 7 '17 at 20:26
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    \$\begingroup\$ rsg1710 nails it on the head. Historically, IC's needed higher voltages to even activate the transistors. Now the transistors are so small, if you applied that same voltage, you'd let the magic smoke out. Then there's low power and heat concerns to be worried about as well. \$\endgroup\$
    – horta
    Nov 7 '17 at 21:08
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    \$\begingroup\$ I have always wondered how they came up with the odd numbers though. You would think they would be multiples of a cell voltage, like, 1.5. 3.0, 4.5, 9 and 12V. \$\endgroup\$
    – Trevor_G
    Nov 7 '17 at 21:33
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    \$\begingroup\$ @HarrySvensson lol maybe. Back when I, and TTL, started though such things did not exist, and SMPS were rare and expensive. Even LDO regulators were not available, you were basically stuck with a hot 7805 and CMOS was deemed too unreliable before they improved and we learned how to handle ESD. I have always wondered how many battery operated TTL gizmos just never got developed because the cost to power them made them a non-starter. \$\endgroup\$
    – Trevor_G
    Nov 8 '17 at 14:59

The technology trend on ICs are to have them become smaller, faster, cost effective and low power consuming. Shrinking of transistor size is the major drive in this industry but shrinking the size leads to smaller voltage tolerance of breakdown that's is one of the reason why the supply voltage reduces the other being low power consumption of course.

Having said that certain application needs certain ICs with certain requirements for example power ICs are needed to handle high voltage, no escaping that. Or Analog circuits such as amplifier if one requires a high gain then one has to go for an amp with probably higher gain (with higher supply voltage) and so on...

  • \$\begingroup\$ Appreciate the response :) \$\endgroup\$
    – JYasir
    Nov 7 '17 at 21:21
  • \$\begingroup\$ Great answer. You've explained why voltages are dropping. Could be improved by explaining why we still have higher voltage applications such as analog, RS232, 4to20 mA and PLCs. \$\endgroup\$
    – lm317
    Nov 8 '17 at 17:40
  • \$\begingroup\$ @lm317 thank you :) the second part of my answer does address to that as well :) thank you for bringing up specific examples :) \$\endgroup\$
    – rsg1710
    Nov 8 '17 at 17:44

The elephant in the room is often getting the heat out as much as breakdown voltage at this point (Time was that was not so much the case).

For a CMOS device power is usually dominated by switching losses which go linearly in frequency and as the square of the voltage (1/2 CV^2 and all that), so going from 5V to 1V for core power is a huge (~25 times) saving in dynamic heat generation and that matters as clocks speed up.

At the same time, generating low voltages at large currents has become cheap and easy, tens of amps at 1V is trivial with a modern polyphase buck converter. While the 1V for the core, 1.2V for the DDR, 1.8V for the LVDI IO, 2.5V for the Aux IO thing is a little annoying, the inductors required to generate these do not integrate into a silicon process well (On chip magnetics tend to be poor for doing power things), so the supplies need to be separate (Besides the chip vendor cannot know what else I might be running off any given rail, so how do you size it?).

What we are seeing in modern designs is a rail of typically about 12V being regulated on card to whatever that particular circuit needs, (another symptom of cheap switchmode converters), you seldom see a supply having 12/5/3.3 outputs all taken to various circuit boards any more (at tens of amps), it is all either 12V or 48V (sometimes, -48V in the telecomms world for corrosion reasons) regulated down at point of load. This has many advantages starting with simplified wiring, and the fact that the higher bus voltage suffers less for voltage drops, and extending to the fact that an on card POL regulator can trivially easily sense the actual voltage at the load device.


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