LP3891EMRX-1.8

LP3891EMRX-1.8 is a linear voltage regulator from National Semiconductor, a reputed manufacturer of linear power management integrated circuits (PMICs). It is designed to deliver reliable operation in a wide range of applications. This article provides an overview of its application field, working principle and features.

Application Field

LP3891EMRX-1.8 is a low dropout (LDO) linear voltage regulator, suitable for applications like PDAs, digital audio players, and embedded systems that require reliable, low-power solutions. It is suitable for low-current, low-voltage applications which may need a higher accuracy than that achieved by switching regulators. This regulator operates with input voltages ranging from 2.7V to 6.5V and provides an output voltage of up to 1.8V, with a variance in output current up to 200 mA.

Working Principle

At its core, the LP3891EMRX-1.8 is a linear voltage regulator. It is based on a series pass-transistor design and uses a current-limited driver stage to provide a regulated voltage output. The linear regulator works by comparing the output voltage with a reference voltage and, if the two values differ, adjusting the pass-transistor’s supply current so that the reference and the output are equal. The stability of the voltage output is ensured by the power feedback loop which maintains a constant output voltage by adjusting the drive current of the pass-transistor.

Features

LP3891EMRX-1.8 provides some useful features and protection mechanisms that ensure reliable operation and higher efficiency. It features an on-chip enable and disable pin which makes it easy to enable/disable the circuit with external logic signals. Similarly, it has an output enable pin which can be used to enable/disable the output buffer. It also features built-in thermal shutdown and current limiting protection, making it a robust and safe regulator to use in critical applications. Ultra-low-dropout operation ensures that the regulated output voltage is always maintained, even with a very low input voltage.

In summary, LP3891EMRX-1.8 is a linear voltage regulator designed for applications which require reliable, low-power solutions. It features an on-chip enable and disable pin, along with other features and protection mechanisms that ensure reliability and higher efficiency. It uses a series pass-transistor design, where the stability of the voltage output is ensured by the power feedback loop which maintains a constant output voltage by adjusting the drive current of the pass-transistor.