LTC7800 Low IQ, 60V, High Frequency Synchronous Step-Down Controller FEATURESDESCRIPTION n Wide VIN Range: 4V to 60V (65V Abs Max) The LTC®7800 is a high performance step-down switching n Low Operating IQ: 50μA regulator DC/DC controller that drives an all N-channel n Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V synchronous power MOSFET stage. A constant fre- n RSENSE or DCR Current Sensing quency current mode architecture allows a phase-lockable n Phase-Lockable Frequency (320kHz to 2.25MHz) frequency of up to 2.25MHz. n Programmable Fixed Frequency (320kHz to The 50μA no-load quiescent current extends operating run 2.25MHz) time in battery-powered systems. OPTI-LOOP® compensa- n Selectable Continuous, Pulse-Skipping or Low Ripple tion allows the transient response to be optimized over Burst Mode® Operation at Light Load a wide range of output capacitance and ESR values. The n Selectable Current Limit LTC7800 features a precision 0.8V reference and power n Very Low Dropout Operation: 98% Duty Cycle good output indicator. A wide 4V to 60V input supply n Adjustable Output Voltage Soft-Start or Tracking range encompasses a wide range of intermediate bus n Power Good Output Voltage Monitor voltages and battery chemistries. The output voltage of n Output Overvoltage Protection the LTC7800 can be programmed between 0.8V to 24V. n Low Shutdown IQ: < 14μA n Internal LDO Powers Gate Drive from V The TRACK/SS pin ramps the output voltages during IN or EXTVCC n No Current Foldback During Start-Up start-up. Current foldback limits MOSFET heat dissipation n Small 20-Pin 3mm × 4mm QFN Package during short-circuit conditions. The PLLIN/MODE pin se- lects among Burst Mode operation, pulse-skipping mode, APPLICATIONS or continuous conduction mode at light loads. L, LT, LTC, LTM, OPTI-LOOP, Burst Mode, Linear Technology and the Linear logo are registered n Automotive Always-On Systems trademarks of Analog Devices, Inc. All other trademarks are the property of their respective n Battery Powered Digital Devices owners. Patents, including 5481178, 5705919, 6611131, 6498466, 6580258, 7230497. n Distributed DC Power Systems TYPICAL APPLICATIONHigh Efficiency 3.3V 2.1MHz Step-Down RegulatorEfficiency and Power Loss vs VIN Output Current 4V TO 28V CI1 100 10 2.2µF CI2 V V IN INTVCC IN = 12V 56µF ×3 2.2µF 90 VOUT = 3.3V PGND 80 1 LTC7800 100k 70 POWER LOSS (W) INTVCC PGOOD TG 60 0.1 EXTV 0.1µF 100k CC 50 FREQ BOOST 0.33µH 4mΩ 820pF VOUT 40 0.01 2.49k SW 3.3V C EFFICIENCY (%) ITH OUT 10A BG 33µF 30 80pF ×2 20 0.001 0.1µF SENSE+ 10 357k TRACK/SS SENSE– 0 0.0001 SGND V 0.0001 0.001 0.01 0.1 1 10 FB 115k OUTPUT CURRENT (A) 3874 TA01b 7800f For more information www.linear.com/LTC7800 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions FUNCTIONAL Diagram Operation Applications Information Typical Application Related Parts
