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I am looking at using this logic switch in my circuit:

https://www.onsemi.com/pub/Collateral/FSTD16211-D.pdf

Looking at the datasheet I am finding it hard to figure out what the maximum current draw would be.

As far as I can see, I need to supply:

5v drawing potentially up to (what)mA?

Am I safe to assume that it will be 5v and definitely under 100mA? I need to know so I choose the correct level shifter supplying the 5v!

Many thanks!

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  • \$\begingroup\$ Bit strange yes. 7 ohms times the current squared will give you the heat dissipation in watt, but without the thermal resistance (K/W), you can only estimate how much headroom there is. \$\endgroup\$ – winny Jan 7 at 16:49
  • \$\begingroup\$ shall I assume that it will be 5v and definitely under 100mA? I need to know so I choose the correct level shifter supplying the 5v! \$\endgroup\$ – RenegadeAndy Jan 7 at 17:00
  • \$\begingroup\$ But what is your output or downstream load current? \$\endgroup\$ – winny Jan 7 at 17:02
  • \$\begingroup\$ On page 3: Incraese in \$I_{CC}\$ per Cotrol Input = 2.5mA max + Quiescent Supply Current = 1.5mA. There are only two control inputs. \$\endgroup\$ – StainlessSteelRat Jan 7 at 17:14
  • \$\begingroup\$ Ok so that means it would likely draw a max current of 8mA? \$\endgroup\$ – RenegadeAndy Jan 7 at 20:02
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I think the maximum current is 61.5mA. 24 inputs at 2.5mA and the quiescent current of 1.5mA. That current will occur with all inputs at 3.4V. If any of the inputs are at Vcc or 0V the current will be less.

If you look at an older version of the datasheet, it seems apparent they are referring to inputs, not control inputs.

enter image description here

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  • \$\begingroup\$ Which suggests @stainlesssteelrat comment above misinterprets the datasheet? \$\endgroup\$ – RenegadeAndy Jan 7 at 20:53
  • \$\begingroup\$ I think the "new" datasheet is misleading. \$\endgroup\$ – Spehro Pefhany Jan 7 at 20:54

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