newbie in electronics here and taking self study (don't have time to go to school anymore xD). i just want to ask, regarding the image below:

enter image description here

it came from this datasheet:


how could i determine how much current the IC is consuming on power lines like on voltage regulators? I see a lot of ampere value here.

1) is it the Power Supply Current? Input current? input current supplies? output current?

2) how do i make simple math given on these values?

3) upon looking on other datasheet, they don't have same descriptions, i see Ic, Icc, Iaarms, Ii, etc. What could be the common current description i need to check to determine the current consumption of IC (even on max)?

I want to learn this because i want to make a computation of how much current should a 30 pcs of the given IC here will consume overall, at max, for me to determine what output current value should my voltage regulator have. Or do i have the wrong idea on computing the current consumption in relation to voltage regulator current supply??

EDIT: giving also example of how to compute 2 to 3 different ICs current consumption having different datasheets would be also good for me to understand it clearly OR maybe the image below, how can i compute it even a rough estimation. (included the setup to be future reference for others and to be understand clearly the situation)

enter image description here

uC -> arduino uno https://www.farnell.com/datasheets/1682209.pdf

4 to 16 dmx -> http://www.ti.com/lit/ds/symlink/cd74hc154.pdf

EMIC -> https://d3uzseaevmutz1.cloudfront.net/pubs/proDatasheet/CS5480_F3.pdf

TEMP -> https://datasheets.maximintegrated.com/en/ds/MAX31722-MAX31723.pdf

Relay Hub are collection of SSRs connected to a I/O expander controlling the gnd terminals of SSR via npn transistors

I/O expander -> https://datasheets.maximintegrated.com/en/ds/MAX7317.pdf

SSR -> http://www.crydom.com/en/products/catalog/gnr_22mm.pdf

NPN transistors -> https://www.diodes.com/assets/Datasheets/ds30384.pdf

  • \$\begingroup\$ No, the answers do have enough details. They just don't contain the exact analysis of your particular combination of ICs and loads. You need to do your own legwork. \$\endgroup\$ Feb 19, 2018 at 20:44

2 Answers 2


Historically BJT based IC's with collector to supply used Vcc so Icc is from Vcc. Many CMOS IC's carried forward the same reference designation even though the Drains are used instead of Collectors so they were called Vdd and Idd.

Here with Analog/digital we have Vdda included with PSCA for active Power Supply Currents and I see it is very low current with 12.9mA typ but is capable of driving Iout = 100mA.

If another vendor uses Icc and Iaa(rms) then show us.

Your 3.3V regulator must exceed Iout (your load is undefined) by some margin which includes active current ~13mA

Thats all.

in future include all datasheet links for all IC's and your load.


Each IC may have a typ. and max at rated Vcc and temp. and perhaps rated clock frequency. Dynamic current increases proportionally with transition frequency and static currents like sensors are usually fixed. There will be some variations with supply tolerance and usually are specified at different Vcc levels which can be scaled with some understanding.

There is often a temperature range for the Max current and room temp for the 25'C spec, so your environment may choose choose a value between the typ and max for a large number of IC's

Worst case of course is the sum of max current would be a low probability occurence.

  • \$\begingroup\$ +1 Thanks for the historical perspective on Vcc versus Vdd naming. \$\endgroup\$ Feb 13, 2018 at 22:27
  • \$\begingroup\$ Hi :D thanks for the shared knowledge, also as for your emphasis, i had edit my question to elaborate clearly the purpose of the question with respect to my setup i wanted to solve. i guess this is also a good idea for others future reference also. Thanks :) \$\endgroup\$
    – Mheruian
    Feb 15, 2018 at 1:22

This is a fairly standard (and important) part of design procedure for an electronic board. As a first round of estimations, you look first at power supply rail(s) for the ICs. Usually it is designated as "Vcc". If one certain power rail is common for a number of ICs, you take a sum of "Icc" for this rail, preferably "maximum" under "recommended operating conditions". In your case the manufacturer lists "typical", so you have no other choice as to use that number. But then you better apply a fudge factor of maybe 10%-20% to it. Same estimation applies to other power rails, if any different. These are budget numbers for ICs consumption alone.

But your device might have some loads connected to outputs of ICs, like LEDs, solenoids, etc. That's where "output current" might enter the equation. Your loads shouldn't draw more than "max output current". You need to calculate consumption of these loads, and add these currents to the Icc_total estimation (since the loads will be drawing current from the same Vcc rail). More, the total current from all loads to a certain IC shouldn't result in more that "max power dissipation" of that IC.

Absolute max of "Input current" parameter is likely inconsequential for the purpose of voltage regulator selection.

ADDITION: In this particular CS5480 case, the main power supply is named VDDA, "analog power supply". The digital section, however, doesn't have a separate power rail. It gets its power internally, with internal 1.8V rail exposed on VDDD pin. This pin is not for external power, it needs only a stabilizing capacitor to operate. Power consumption is therefore listed only for VDDA pin, which includes everything internal.

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    \$\begingroup\$ Input current can matter too. It it's TTL that can end up being a substantial current draw from Vcc for a number of low level inputs. \$\endgroup\$
    – Trevor_G
    Feb 13, 2018 at 21:24
  • \$\begingroup\$ Switching currents also play a role if it is a high frequency device. \$\endgroup\$
    – Trevor_G
    Feb 13, 2018 at 21:24
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    \$\begingroup\$ Hi @Trevor_G, I wonder, how lately did you see any TTL-based IC? In the past 20 years I didn't recall a single one... \$\endgroup\$ Feb 13, 2018 at 21:27
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    \$\begingroup\$ Yup, but for completeness it's worth a mention, umpteen inputs at a fraction of a mA each adds up quick. \$\endgroup\$
    – Trevor_G
    Feb 13, 2018 at 21:29
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    \$\begingroup\$ @Trevor_G, yes, that's why it is advisable to build a prototype with substantially beefed-up regulators, with an option to scale them down later for production. And with lots of means for testing/debug/software development. Then just re-spin the board, because likely there will be some other glitches, and debug interfaces will be no longer needed. \$\endgroup\$ Feb 13, 2018 at 22:02

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