42V, 2µA IQ Low Dropout Switcher 750mA Output Current Start-Up and Dropout Performance 9 8 VOUT LT3973 7 Voltage (V) VIN VIN 6 5 VOUT 4 530mV 3 2 1 0 Time (s) 530mV Maximum Dropout ® The LT 3973 is the newest member of our growing family of ultralow quiescent current high voltage monolithic buck regulators. It consumes only 1.8µA of quiescent current while regulating an output of 3.3V from a 12V input source. A high efficiency switch is included on-chip along with the catch diode, boost diode and all necessary control and logic circuitry. A minimum dropout voltage of 530mV is maintained when the input voltage drops below the programmed output voltage, ® providing a regulated output to the downstream load. Its low ripple Burst Mode operation maintains high efficiencies at low output currents while keeping output ripple below 10mVP-P. Features Efficiency Curve, VOUT = 5V •Ultralow Quiescent Current: 1.8µA IQ at 12VIN to 3.3VOUT 90 •Integrated Boost and Catch Diodes •Excellent Start-Up & Dropout Performance Efficiency (%) •Input Voltage Range: 4.2V to 42V Info & Free Samples www.linear.com/product/LT3973 VIN = 12V 1-800-4-LINEAR 80 •Low Ripple Burst Mode Operation VIN = 24V 70 VIN = 36V 60 50 •750mA Output Current 40 •Adjustable Switching Frequency: 200kHz to 2.2MHz 30 0 0.1 0.2 0.3 0.4 0.5 Load Current (A) 0.6 0.7 , LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.