ICs are semiconductors, they don't obey Ohm's law, ie. their voltage drop is not proportional to the current flowing through them, like it is for a resistor.
While true, ICs do have an equivalent effective resistance , which is their power voltage divided by their current.
This information has limited value but can be useful for testing power circuits with dummy loads.
As I am sure it is obvious, there does not seem to be any basis for asking this question as resistors are not
normally placed in series with the power to an IC.
If you can explain why you even asked this question perhaps we can clarify it for you.
As already pointed out, semiconductors are nonlinear so measuring their resistance with power off would not
yield any useful info (other than for comparison to a similar known good IC when troubleshooting).
Their is , however, (not that it is relevant to this post) a way to calculate the 'effective resistance of an IC or group
of ICs, by measuring the current draw. The arduino, UNO R3 for example , draws about 50mA. It is powered by
5V. Simple math shows that V =IR=>.'. R = V/I = 5V/0.050A = 100 ohms. We would not say "it's resistance is
100 ohms". We would say , the 'effective equivalent resistance" (for the purpose of testing a battery discharge time
with a dummy load) is 100 ohms. Which means we can replace the arduino with a 100 ohm/1/4W (50.05=0.250W)
resistor for the purpose of determining how long the battery would power the arduino.
I am trying to use my Arduino (mega 2560) to interface with an SRAM chip (UPD431000ACZ-70L). The datasheet says input voltage is 4.5-5.5V and the input high is 2.2-(Vcc+0.5)V. This fits into the basic output voltages of the board but I'm concerned about current. If I create a short I'll fry my equipment, but if I put too much resistance in I won't reach my necessary voltage levels.
One might make a case for "that depends on where the short is..." If you are going to have a short , the best place
to have is across the power supply because then it bypasses all your circuits.
You can have shorts from input pins to GND because both digital and analog input pins are typically high impedance in the order of 10Mohms, but not OUTPUT pins, which would probably damage the IC.
Interfacing two circuits both rated for 5V (+/-0.5V) (this spec is a throwback from TTL in the early 1970s)
I might point out that your statement here"
and the input high is 2.2-(Vcc+0.5)V
does not state the Vcc voltage for the SRAM, but since they usually operate at 5V we would assume that.
The problem , if there is one , with your post is you have not asked a specific question :
ie ; "If I had a short from an SRAM INPUT pin to GND, would that damage my SRAM ?"
Instead you say:
If I create a short I'll fry my equipment, but if I put too much resistance in I won't reach my necessary voltage levels.
No mention of where the short is (point A to point B) and the mention of adding resistance sets off alarm bells
because NOBODY puts RESISTORS IN SERIES WITH SRAM INPUTS, resulting in a WTF? response from anyone
reading it...
