I am trying to choose an regulator to drive an IC with 3.3V TYPICAL current consumption of 132mA at it's full operation(says datasheet)

The regulator we normally use has 150mA capacity.

Will it be safe to use this regulator? or should I look for something with bigger current capacity?

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    \$\begingroup\$ For a start, where are the links to the datasheets which you are referring to? \$\endgroup\$ – Nick Alexeev Sep 23 '15 at 2:35
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    \$\begingroup\$ You should use maximum consumption not typical consumption of the chip plus the maximum of whatever else is being powered by the regulator. Also, the stated regulator capacity may not be achievable because of other limitations (such as thermal limits or other reasons). \$\endgroup\$ – Spehro Pefhany Sep 23 '15 at 3:15
  • \$\begingroup\$ I suggest using something like LF33 (sos.sk/a_info/resource/c/pdf/LF33.pdf) if it's possible. \$\endgroup\$ – HOPE Sep 23 '15 at 5:12

Whether or not the regulator is safe to use depends on the input voltage and the ability of the package to dissipate heat. Suppose that your external voltage source is 12V. Then, the voltage drop across the regulator is (12V - 3.3V) = 8.7V. At 150ma, the regulator would dissipate 8.7V * 0.15A = 1.3W. That is a LOT of power and most regulators would get quite warm (hot actually) at that load current. But, if the input is 5V, then the drop is 1.7V and the power in the regulator is 0.255W and most devices WOULD handle that.

The key specs to look for are the minimum input-output difference (also called drop-out voltage) and the rated package power dissipation.

  • \$\begingroup\$ This poor efficiency (10%-15%) is only about linear regulators like 78xx, Switching regulators have more efficiency about 85%-90% like LM2576 . \$\endgroup\$ – HOPE Sep 23 '15 at 5:08

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