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How do we calculate the current consumption of devices like Hall sensors and CMOS gates (for example: sensors like ACS725 and AND gate like MC74VHC1G08)?

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    \$\begingroup\$ Quick answer: Datasheets! \$\endgroup\$ – MCG Jul 2 '19 at 12:39
  • \$\begingroup\$ I am sorry for that. I edited my question. \$\endgroup\$ – PED Jul 2 '19 at 12:42
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If you search in the datasheet of ACS725, you find on page 5:

Supply Current ICC VCC = 3.3 V, output open – nominal: 10 mA, maximum: 14 mA

Datasheet of MC74VHC1G08, page 3: (see important note of Bimpelrekkie below, these are absolute max. ratings, so typical values are /can be (much) lower):

K DC Input Diode Current VIN < GND −20 mA
IOK DC Output Diode Current VOUT < GND ±20 mA
IOUT DC Output Source/Sink Current ±12.5 mA
ICC or IGND DC Supply Current per Supply Pin or Ground Pin ±25 mA

When I started electronics (and I'm still a bit a newbee), I tried to avoid datasheets. My tip ... don't avoid ... as you read, you do not have to understand everything, but there are parts which are important and the only place to find information. And if you cannot find exactly or you are not sure about something, ask more detailed questions.

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    \$\begingroup\$ Regarding the MC74VHC1G08, the numbers you list are the maximum ratings. Meaning, these values should not be exceeded. Although it gives us a hint about the maximum current consumption, it does not tell us much about the typical current consumption. The MC74VHC1G08 is a CMOS logic gate and these consume almost zero current when they are in a static condition. The current increases with operating frequency. Also what load you drive with the output is of importance. Without a circuit and knowing many details, it is not possible to determine the current consumption. \$\endgroup\$ – Bimpelrekkie Jul 2 '19 at 13:03
  • \$\begingroup\$ @Bimpelrekkie Thanks for that remark ... I guess I'm also not that good at reading data sheets. \$\endgroup\$ – Michel Keijzers Jul 2 '19 at 13:14
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    \$\begingroup\$ We all had to learn :-) \$\endgroup\$ – Bimpelrekkie Jul 2 '19 at 13:16
  • \$\begingroup\$ @Bimpelrekkie I'm still learning :-) \$\endgroup\$ – Michel Keijzers Jul 2 '19 at 13:44
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    \$\begingroup\$ Why do people avoid datasheets? That's something I have NEVER understood. Even an overwhelming datasheet gives you something when you don't understand most of it. \$\endgroup\$ – DKNguyen Jul 2 '19 at 17:43
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You use the worst case values for current consumption, unless you characterize the devices for your environmental specs if in reduced range for ambient Temp. & sense current and determine the relationship is the CMOS draws more current due to these parameters towards the maximum.

CMOS runs slower when hot and that draws more dynamic current in the chopper amp. from switched capacitance at a lower gm.

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