The LT3150 drives a low cost external N-channel MOSFET as a source follower to produce a fast transient response, very low dropout voltage linear regulator. Selection of the N-channel MOSFET RDS(ON) allows dropout voltages below 300mV for low VIN to low VOUT applications. The LT3150 includes a fixed frequency boost regulator that generates gate drive for the N-channel MOSFET. The internally compensated current mode PWM architecture combined with the 1.4MHz switching frequency permits the use of tiny, low cost capacitors and inductors. The LT3150's transient load performance is optimized with ceramic output capacitors. A precision 1.21V reference accommodates low voltage supplies. Protection includes a high side current limit amplifier that activates a fault timer circuit. A multifunction shutdown pin provides either current limit time-out with latchoff, overvoltage protection or thermal shutdown. Independent shutdown control of the boost converter provides on/off and sequencing control of the LDO output voltage.
