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What is the meaning of output current of the regulator.

For example, IC datasheet's written as "300-mA Output Current Capability", the maximum output current must be 300mA, isn't it.

What'll happen if I connect this regulator output to 4 ICs, which will consume about 100mA per each IC.

Or what'll happen if I connect this regulator output to 2 ICs, which will consume about 100mA per each IC.

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What'll happen if I connect this regulator output to 4 ICs, which will consume about 100mA per each IC.

You'll be asking 400mA from a regulator rated for 300mA. Depending on the regulator it'll either shut down, or deliver 300mA at whatever voltage it can manage, or try to deliver 400mA and burn up, etc.

Or what'll happen if I connect this regulator output to 2 ICs, which will consume about 100mA per each IC.

If you haven't run into some thermal pitfall (and power devices can have very deceptive thermal ratings) then the regulator will deliver its rated voltage at 200mA.

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Output current capability is the maximum usable output current the device can source while still maintaining the specified output voltage. As long as your load requires less than 300mA, the device will operate.

So in your example with 4 IC's drawing 100mA each, that is 400mA total, which is above the 300mA specified output current, so this will not work.

Connecting to two IC's would be a total of 200mA, which is below the specified capability of 300mA, so everything should be fine.

Normally the specifications have a little leeway so that if you had 3 IC's drawing a total of 300mA, the regulator should still work, but I would not suggest running this close to the limit....maybe on a bread board test circuit, but never in something going to production builds...history says something that close to the limit will come back and bite you at some point.

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  • \$\begingroup\$ "So in your example with 4 IC's drawing 100mA each, that is 400mA total, which is above the 300mA specified output current, so this will not work." For this case, which exactly will not work, the regulator or the sink IC or both. \$\endgroup\$ – Electronics newbie Nov 14 '18 at 2:12
  • \$\begingroup\$ @Electronicsnewbie: the regulator will likely not work, causing the sink IC to not work. As long as you deliver the correct supply voltage to the sink IC it should work. \$\endgroup\$ – TimWescott Nov 14 '18 at 4:13

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