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How Do You Choose the Right Low Dropout Linear Regulator?

With such a large variety of Low Dropouts (LDOs) available in today’s market, it could become difficult to identify the optimal LDO for customer applications. Here are four important characteristics to consider before selecting an LDO.

Low Dropout

This is the main purpose of the linear low dropout regulator. Though there are many ways to utilize an LDO, maintaining a low dropout between the input and output voltage is the LDO’s primary purpose. This is an important aspect to consider before choosing an LDO as a power regulation solution.


As the performance and capability of technology continue to grow at a rapid rate, it is crucial that the core components of these devices meet stringent requirements and operate on a consistent and leading-edge basis. The LDO’s responsibility is not only to have a low input to output dropout but also to ensure that the voltage is outputted with the smallest margin of error.

Power Supply Rejection Ratio (PSRR)

In the process of dropping input voltage to output voltage, various unwanted frequencies could find their way into the integrated circuit. The power supply rejection ratio of a linear regulator is the measurement of how well the integrated circuit filters/rejects out extraneous noise in the input voltage signal before the voltage is outputted. High PSRR typically correlates to a more consistent output accuracy.

Low Quiescent Current

Also known as IQ, the quiescent current is the current that is drawn from an integrated circuited while it is in a quiescent (no-load, non-switching) state. IQ can be understood as the minimal amount of current needed to power the basic functionalities of a device. The lower the rated quiescent current of a linear regulator, the more power efficient the linear regulator is in a no-load state.

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