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Ultra low Drop Linear Voltage Regulator

Ultra low Drop Linear Voltage RegulatorUltra low Drop Linear Voltage Regulator Circuit

The ambit is a MOSFET based beeline voltage regulator with a voltage bead of as low as 60 mV at 1 ampere. Bead of a beneath millivolts is accessible with bigger MOSFETs accepting lower RDS(on) resistance. The ambit in Fig. 1 uses 15V-0-15V accessory from a step-down agent and employs an n-channel MOSFET IRF 540 to get the adapted 12V achievement from DC input, which could be as low as 12.06V.

The aboideau drive voltage appropriate for the MOSFET is generated application a voltage doubler ambit consisting of diodes D1 and D2 and capacitors C1 and C4. To about-face the MOSFET absolutely on, the aboideau terminal should be about 10V aloft the antecedent terminal which is affiliated to the achievement here. The voltage doubler feeds this voltage to the aboideau through resistor R1. Adjustable blow regulator TL431 (IC2) is acclimated actuality as an absurdity amplifier, and it dynamically adjusts the aboideau voltage to advance the acclimation at the output. With able heatsink for the MOSFET, the ambit can accommodate up to 3A achievement at hardly animated minimum voltage drop. Trimpot VR1 in the ambit is acclimated for accomplished acclimation of the achievement voltage.

Combination of capacitor C5 and resistor R2 provides error-amplifier compensation. The ambit is provided with a circumlocute crow-bar aegis to bouncer the apparatus adjoin over-stress during adventitious abbreviate at the output. This crow-bar aegis will assignment as follows: Under accustomed alive conditions, the voltage beyond capacitor C3 will be 6.3V and diode D5 will be in the off accompaniment back it will be reverse-biased with the achievement voltage of 12V. However, during achievement circumlocute condition, the achievement will briefly drop, causing D5 to conduct and the opto-triac MOC3011 (IC1) will get triggered, affairs bottomward the aboideau voltage to ground, and appropriately attached the achievement current.

The ambit will abide latched in this state, and ascribe voltage has to be switched off to displace the circuit. The ambit apparent in Fig. 2 follows a agnate scheme. It can be utilised back the regulator has to assignment from a DC abuse in abode of 15V-0-15V AC supply. The aboideau voltage actuality is generated application an LM555 allegation pump ambit as follows: Back 555 achievement is low, capacitor C2 will get answerable through diode D1 to the ascribe voltage.