LTC7803 40V Low I , 3MHz Synchronous Step-Down Q Controller with Spread Spectrum FEATURES DESCRIPTION n Low Operating I : 12A (14V V to 3.3V V ) The LTC 7803 is a high performance, 100% Duty Cycle Q IN OUT n Wide Input Voltage Range: 4.5V to 40V Capable, synchronous step-down DC/DC switching n Output Voltage Up to 40V regulator controller that drives an all N-channel power n Spread Spectrum Operation MOSFET stage. Synchronous rectification increases effi- n R or DCR Current Sensing ciency, reduces power losses and eases thermal require- SENSE n PassThru/100% Duty Cycle Capable ments. A constant frequency current mode architecture n Programmable Fixed Frequency (100kHz to 3MHz) allows a phase-lockable switching frequency of up to n Phase-Lockable Frequency (100kHz to 3MHz) 3MHz. The LTC7803 operates from a wide 4.5V to 40V n Selectable Continuous, Pulse-Skipping, or Low input supply range. Ripple Burst Mode Operation at Light Loads The very low no-load quiescent current extends operating n Low Shutdown I : 1.2A Q runtime in battery powered systems. OPTI-LOOP com- n Thermally Enhanced 16-Pin 3mm 3mm QFN and pensation allows the transient response to be optimized MSOP Packages over a wide range of output capacitance and ESR values. n AEC-Q100 Qualification in Progress The MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads. APPLICATIONS The LTC7803 additionally features spread spectrum oper- n Automotive and Transportation ation which significantly reduces the peak radiated and n Industrial conducted noise on both the input and output supplies, n Military/Avionics making it easier to comply with electromagnetic interfer- n Telecommunications ence (EMI) standards. All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. TYPICAL APPLICATION High Efficiency Wide Input Range 375kHz 3.3V/20A Step-Down Regulator Efficiency vs Output Current Efciency vs Output Current RUN 100 10k V IN V V = 3.3V IN OUT + 5V TO 38V 10F 56F 2 TG TRACK//SS 90 4 2 1k BOOST ITH 0.1F 0.68H V 1m OUT 80 0.1F LTC7803 SW 3.3V 6.19k 39pF + 20A 100 470F BG 2 70 4.7nF INTV 60 CC 100F 10 4 4.7F V = 12V IN 50 V = 24V IN + V = 36V PLLIN/SPREAD SENSE 1 IN 40 MODE BURST MODE OPERATION SENSE FIGURE 11 CIRCUIT FREQ 30 0.1 215k EXTV CC 0.0001 0.001 0.01 0.1 1 10 GND V OUTPUT CURRENT (A) FB 7803 TA01b 68.1k 7803 TA01a Rev. A 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC7803 ABSOLUTE MAXIMUM RATINGS (Note 1) ITH ............................................................... 0.3V to 2V Input Supply Voltage (V ) ......................... 0.3V to 40V IN PLLIN/SPREAD, MODE, V ......................... 0.3V to 6V BOOST ....................................................... 0.3V to 46V FB BG, TG ............................................................... (Note 9) SW ............................................................... 5V to 40V Operating Junction Temperature Range (Note 2,8) RUN ........................................................... 0.3V to 40V + LTC7803E, LTC7803I ......................... 40C to 125C SENSE , SENSE ....................................... 0.3V to 40V LTC7803H, LTC7803J ........................ 40C to 150C EXTV Voltage ......................................... 0.3V to 30V CC Storage Temperature Range .............. 65C to 150C INTV , (BOOST-SW) .................................. 0.3V to 6V CC TRACK/SS, FREQ ......................................... 0.3V to 6V PIN CONFIGURATION TOP VIEW TOP VIEW 16 15 14 13 TRACK/SS 1 16 SW + TG 1 12 INTV SENSE 2 15 TG CC SENSE 3 14 BOOST SW 2 11 MODE 17 17 V 4 13 BG FB GND ITH 5 GND 12 V TRACK/SS PLLIN/SPREAD IN 3 10 RUN 6 11 EXTV CC + SENSE 4 9 FREQ FREQ 7 10 INTV CC PLLIN/SPREAD 8 9 MODE 5 6 7 8 MSE PACKAGE 16-LEAD PLASTIC MSOP T = 125C, = 40C/W, = 10C/W JMAX JA JC EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB UD PACKAGE 16-LEAD (3mm 3mm) PLASTIC QFN T = 125C, = 68C/W, = 4.2C/W JMAX JA JC EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB Rev. A 2 For more information www.analog.com SENSE BOOST V BG FB ITH V IN RUN EXTV CC