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  • High input Linear Regulator with High PSRR

  • Created: Jun 16, 2016

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Linear regulators use resistive component in dropping excess voltages through heat. It acts like a variable resistor that keeps adjusting the voltage divider network to have a constant output voltage. The advantages of using linear regulator for having simple design, good reliability, and have a low noise levels. The circuit is an evaluation board of the MIC5282. The MIC5282 is a high-performance, low-dropout linear regulator that has an input voltage range of 6V to 120V with output current of up to 50mA. It features an adjustable output from 1.27V to 5.5V that has an output accuracy of +/- 3% and a high Power Supply Rejection Ratio (PSRR) of 80dB at 10kHz.

The circuit is operated with a single power supply Vin with an operating voltage between 6V and 120V. The board does not have a reverse polarity protection, so applying a negative voltage to the Vin terminal may damage the device. The output of the evaluation board can be adjusted to 1.8V, 2.5V, 3.3V, or 5V by connecting one of the feedback resistors (R3, R4, R5, and R6) into the circuit via a jumper short. All the output options offer 50mA of output current. The output voltages can be modified through replacing some of the resistor. The equation for the output voltage is Vout=Vref(1+(R1/Rfb)), where Vref= 1.27V, R1 is the combination of R1 and R2 in the circuit, and Rfb is the feedback resistor amongst R3, R4, R5, and R6. The capacitor (C2) helps maintain high power supply rejection. In the case of excessive heating, it has internal thermal shutdown for protection. The device will turn-on when the temperature cools by 15 degree C.

The MIC5282’s input operating voltage ranges makes it suitable for high input voltage applications, such as industrial, off-line power supply, and telecommunications. It is optimized for high-voltage line transients, making it ideal for harsh and noisy environment applications.



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