NJM7818FA

The NJM7818FA is a voltage regulator designed to produce a fixed positive output voltage of 8 V. It is a three-terminal positive-voltage regulator with a datasheet accuracy of ±2%. The device offers excellent thermal stability and output accuracy. It is a voltage regulator designed to provide a maximum output current of 2A with a current limit set by the built-in thermal shutdown circuit. The device features an internal bandgap voltage reference and a current limiting circuit for improved control of output noise.

Application Field

The NJM7818FA is ideally suited for applications where low drop out, good thermal stability and output accuracy are required. It is especially suited for AC/DC adapter, battery operated systems and low noise step-down voltage converters. The device is suitable for a wide range of applications such as chargers for notebook computers, digital still cameras, cellular phones and hand held devices, as well as low dropout supplies for microprocessor-based systems.

Working Principle

The NJM7818FA is designed to maintain a regulated output voltage when its input voltage is greater than its output voltage. The device consists of two main sections: an error amplifier and a comparator. The error amplifier produces an output voltage proportional to the difference between its non-inverting input and its inverting input. This output voltage is then compared to the output voltage of the internal bandgap voltage reference. If the voltage of the error amplifier is higher than the reference voltage, the output is turned off and the output voltage starts to fall. When the voltage of the error amplifier falls below the reference voltage, the output is turned on again and the output voltage rises.

The current limit circuit of the NJM7818FA protects the device from overload conditions by turning off the output until the supply current falls below its predetermined current limit value. In addition, the device also incorporates a thermal shutdown circuit to protect it from excessive operating temperature.