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I'm trying to make a clock, and as part of that I need to power some IC's. To give a specific example I'm looking at the TI SN74HC163 4 bit counter. After some searching around, I found myself directed to this (basically Ohm's law) equation from the sacred texts: enter image description here

The problems I'm facing are:

  1. I'm not sure what to use for current in the equation (I'm that not good at reading datasheets and I'm not sure whether to use ±50 mA or one of the other numbers given to me in the MicroAmp range.)
  2. Conceptually the equation doesn't make sense to me. If the Voltage drop across a resistor depends on it's proportion of the total resistance of the (series) circuit, then shouldn't I need to have the resistance of the IC? Apparently I don't, but in that case I don't understand how this works.
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If the voltage drop across a resistor depends on it's proportion of the total resistance of the (series) circuit, then shouldn't I need to have the resistance of the IC?

Exactly right and since the "resistance" of the IC varies with whatever it is doing the resultant voltage to the IC would vary too. That's why we don't regulate voltage in this manner.

Instead, you require a regulated power supply which will hold the output voltage steady across a wide range of currents. The chip you have chosen has a 2 to 6 V operating range but 5 V would be standard and a suitable ready-made PSU such as USB chargers are readily available and provide the voltage regulation you require.

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  • \$\begingroup\$ I think using zener diode is simpler, right? or does it have any downsides ? \$\endgroup\$ – Mohamed Abduljawad Jul 2 '19 at 8:07
  • \$\begingroup\$ Simpler than what? A Zener regulator will require as many components as a linear regulator, probably waste more power and not provide the same regulation. Sketch your idea as an answer. \$\endgroup\$ – Transistor Jul 2 '19 at 11:29
  • \$\begingroup\$ What if I have other components that can't all work off of the same Voltage? (Ex: I have an Oscillator that can only take a maximum of 3.63V and decoders that need at least 4.75V to function.) I guess could just use a different PSU for each Voltage, but it seems like there is a smarter way to do this that I don't know about. \$\endgroup\$ – jcu Jul 3 '19 at 0:53
  • \$\begingroup\$ That's a different question, but you either design using components that will work on the same voltage or you supply all the voltages required. \$\endgroup\$ – Transistor Jul 3 '19 at 6:12

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