Voltage Regulator

I had a question on voltage regulators,
So I have an input of 4.5V and want it regulator to 3 volt with an current of 33mA, when I am looking for Regulators to buy I am confused with the specs of it saying “current” is this the max current the regulator can take or is it a current that the regulator needs to operate?

Hello bennettpankow, welcome to the Tech Forum. If you’re referring to our website’s current listing, what we show is generally the “typical” current ratiing. If you take a look at the datasheet for the parts you look at, it will state a minimum, typical, and maximum current ratings.

To add onto Jenny’s response, it appears you are wondering if there is a minimum load current requirement in order to maintain regulation.

Although some devices have certain load requirements, taking a look at 296-31454-1-ND as an example, would only need to meet the voltage input requirement, which would be output voltage + dropout voltage:

Vout: 3v
Vdropout: 0.6v
Voltage input requirement: 3.6v

For this example, the output will always be regulated to 3v as long as you have a minimum of 3.6v on the input.

Here are a few more articles regarding regulator dropout voltage:

TechForum
LDO Regulator Selection
Cooling Requirements for Linear Voltage Regulator

Analog Devices
Understand Low-Dropout Regulator (LDO) Concepts to Achieve Optimal Designs

Texas Instruments
Understanding the Terms and Definitions of LDO Voltage Regulators

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Hi bennettpankow,

For Linear Voltage Regulators, we provide 3 different current specs, “Current - Output”, “Current - Quiescent (Iq)”, and “Current - Supply(Max)”.

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  • Current - Output = Maximum continuous output current
  • Current - Quiescent (Iq) = Current consumed by the device under minimum load conditions
  • Current - Supply (Max) = Maximum current consumed by device (typically under max load conditions)

The first must be greater than or equal to your requirement of 33mA. The latter two relate to how much current you can expect to have to provide to power the regulator under various load conditions. Your power source must provide both the load current plus one of the other values, depending on conditions.

As Ryan describes, make sure that your minimum input voltage meets or exceeds the desired output voltage plus the drop-out voltage (“Voltage Dropout (Max)”) so that it is able to properly regulate your output voltage at 3V with a 33mA or greater load.

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