POWER LOSS (W) LTC7800 Low I , 60V, High Q Frequency Synchronous Step-Down Controller FEATURES DESCRIPTION n Wide V Range: 4V to 60V (65V Abs Max) The LTC 7800 is a high performance step-down switching IN n Low Operating I : 50A regulator DC/DC controller that drives an all N-channel Q n Wide Output Voltage Range: 0.8V V 24V synchronous power MOSFET stage. A constant fre- OUT n R or DCR Current Sensing quency current mode architecture allows a phase-lockable SENSE n Phase-Lockable Frequency (320kHz to 2.25MHz) frequency of up to 2.25MHz. n Programmable Fixed Frequency (320kHz to The 50A 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 I : < 14A Q n The TRACK/SS pin ramps the output voltages during Internal LDO Powers Gate Drive from V or EXTV IN CC n start-up. Current foldback limits MOSFET heat dissipation No Current Foldback During Start-Up n during short-circuit conditions. The PLLIN/MODE pin se- Small 20-Pin 3mm 4mm QFN Package 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 owners. Patents, including 5481178, 5705919, 6611131, 6498466, 6580258, 7230497. n Battery Powered Digital Devices n Distributed DC Power Systems TYPICAL APPLICATION High Efficiency 3.3V 2.1MHz Step-Down Regulator Efficiency and Power Loss vs V IN Output Current 4V TO 10 100 28V CI1 C V = 12V I2 IN 2.2F V INTV IN CC 56F 90 V = 3.3V 3 OUT 2.2F PGND 80 1 LTC7800 70 100k INTV PGOOD CC TG 60 0.1 EXTV 0.1F CC 100k 50 FREQ BOOST 0.33H 4m V OUT 0.01 820pF 40 SW 3.3V 2.49k C OUT 10A ITH 30 33F BG 80pF 2 20 0.001 + 0.1F SENSE 10 357k TRACK/SS SENSE 0 0.0001 0.0001 0.001 0.01 0.1 1 10 V SGND FB OUTPUT CURRENT (A) 115k 3874 TA01b 7800f 1 For more information www.linear.com/LTC7800 EFFICIENCY (%)LTC7800 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Input Supply Voltage (V ) ......................... 0.3V to 65V IN Topside Driver Voltage (BOOST) .................0.3V to 71V Switch Voltage (SW) ..................................... 5V to 65V 20 19 18 17 (BOOST-SW) ................................................ 0.3V to 6V PLLIN/MODE 1 16 PGND BG, TG ............................................................... (Note 8) SGND 2 15 EXTV CC RUN ............................................................. 0.3V to 8V INTV SGND 3 14 CC 21 Maximum Current Sourced into Pin from SGND RUN 4 13 BG Source > 8V ......................................................100A SENSE 5 12 BOOST + + SENSE , SENSE Voltages ......................... 0.3V to 28V SENSE 6 11 SW PLLIN/MODE, INTV Voltages ................... 0.3V to 6V CC 7 8 9 10 I , FREQ Voltages ..............................0.3V to INTV LIM CC EXTV ...................................................... 0.3V to 14V CC ITH, V Voltages ......................................... 0.3V to 6V FB UDC PACKAGE 20-LEAD (3mm 4mm) PLASTIC QFN PGOOD Voltage ............................................ 0.3V to 6V T = 150C, = 52C/W JMAX JA TRACK/SS Voltage ....................................... 0.3V to 6V EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB Operating Junction Temperature Range (Notes 2, 3) LTC7800E, LTC7800I ......................... 40C to 125C LTC7800H .......................................... 40C to 150C Maximum Junction Temperature (Notes 2, 3) LTC7800E, LTC7800I ........................................ 125C LTC7800H ......................................................... 150C Storage Temperature Range .................. 65C to 150C ORDER INFORMATION