LTC3621/LTC3621-2 17V, 1A Synchronous Step-Down Regulator with 3.5µA Quiescent Current FeaTuresDescripTion n Wide VIN Range: 2.7V to 17V The LTC®3621/LTC3621-2 is a high efficiency 17V, 1A n Wide VOUT Range: 0.6V to VIN synchronous monolithic step-down regulator. The switch- n 95% Max Efficiency ing frequency is fixed to 1MHz or 2.25MHz with a ±40% n Low I synchronizing range. The regulator features ultralow quies- Q < 3.5µA, Zero-Current Shutdown n Constant Frequency (1MHz/2.25MHz) cent current and high efficiencies over a wide VOUT range. n Full Dropout Operation with Low IQ The step-down regulator operates from an input voltage n 1A Rated Output Current range of 2.7V to 17V and provides an adjustable output n ±1% Output Voltage Accuracy range from 0.6V to VIN while delivering up to 1A of output n Current Mode Operation for Excellent Line and Load current. A user-selectable mode input is provided to allow Transient Response the user to trade off ripple noise for light load efficiency; n Synchronizable to External Clock Burst Mode operation provides the highest efficiency at n Pulse-Skipping, Forced Continuous, Burst Mode® light loads, while pulse-skipping mode provides the lowest Operation voltage ripple. The MODE pin can also be used to allow the n Internal Compensation and Soft-Start user to sync the switching frequency to an external clock. n Overtemperature Protection n LTC3621 Options Compact 6-Lead DFN (2mm × 3mm) Package or PART NAMEFREQUENCYVOUT Thermally-Enhanced MS8E Package with Power LTC3621 1.00MHz Adjustable Good Output and Independent SGND Pin LTC3621-3.3 1.00MHz 3.3V LTC3621-5 1.00MHz 5V applicaTions LTC3621-2 2.25MHz Adjustable n Portable-Handheld Scanners LTC3621-23.3 2.25MHz 3.3V n Industrial and Embedded Computing LTC3621-25 2.25MHz 5V n Automotive Applications n Emergency Radio L, LT, LTC, LTM, Burst Mode, Linear Technology, the Linear logo and LTSpice are registered trademarks and Hot Swap and LTpowerCAD are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 6580258, 6498466, 6611131, 6177787, 5705919, 5847554. Typical applicaTionEfficiency and Power Loss vs Load at 1MHz2.5V VOUT with 400mA Burst Clamp, fSW = 1MHz 100 0.6 VIN = 12V 90 4.7µH VOUT EFFICIENCY 0.5 VIN 80 VIN SW 2.5V 2.7V TO 17V POWER LOSS (W) 10µF LTC3621 604k 22pF 1A 70 0.4 RUN FB 22µF 60 MODE/SYNC 191k 3621 TA01a 50 0.3 INTVCC POWER LOSS GND 40 1µF EFFICIENCY (%) 30 0.2 20 VOUT = 5V 0.1 10 VOUT = 3.3V VOUT = 2.5V 0 0 0 0.2 0.4 0.6 0.8 1 LOAD CURRENT (A) 3621 TA01b 3621fc For more information www.linear.com/LTC3621 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts