POWER LOSS (W) LTC3839 Fast, Accurate, 2-Phase, Single-Output Step-Down DC/DC Controller with Differential Output Sensing FEATURES DESCRIPTION n Wide V Range: 4.5V to 38V, V : 0.6V to 5.5V The LTC 3839 is a 2-phase, single-output PolyPhase IN OUT n 0.67% Output Voltage Accuracy Over Temperature, synchronous step-down switching regulator controller Differential Output Voltage Sensing, Allowing Up to that drives all N-channel power MOSFETs. The controlled 500mV Line Loss at Remote Ground on-time, valley current mode control architecture allows for n Controlled On-Time, Valley Current Mode Control fast transient response and constant frequency switching n Fast Load Transient Response in steady-state operation, independent of V , V and IN OUT n Detect Transient (DTR) Reduces V Overshoot load current. Its load-release transient detection feature OUT n Frequency Programmable from 200kHz to 2MHz, significantly reduces overshoot at low output voltages. Synchronizable to External Clock Differential output voltage sensing, along with a preci- n t = 30ns, t = 90ns ON(MIN) OFF(MIN) sion internal reference, offers an accurate 0.67% output n Up to 12-Phase Operation regulation, even if the remote output ground deviates from n R or Inductor DCR Current Sensing SENSE local ground by 500mV. n Overvoltage Protection and Current Limit Foldback n The switching frequency can be programmed from 200kHz Power Good Output Voltage Monitor n to 2MHz with an external resistor and can be synchronized Output Voltage Tracking and Adjustable Soft Start-Up n to an external clock. Very low t and t times allow for Thermally Enhanced 32-Pin (5mm 5mm) QFN ON OFF near 0% and near 100% duty cycles, respectively. Volt- Package age tracking soft start-up and multiple safety features are provided. APPLICATIONS L, LT, LTC, LTM, PolyPhase, OPTI-LOOP, Linear Technology and the Linear logo are registered trademarks and Hot Swap and Stage Shedding are trademarks of Linear Technology n Distributed Power Systems Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5847554, 6580258, 6304066, 6476589, 6774611. n Point-of-Load Converters n Computing Systems n Data Communication Systems TYPICAL APPLICATION 3.3V/25A Output, 2MHz Step-Down Converter (Refer to Figure 20 for Full Design) V IN 4.5V TO 14V Efficiency/Power Loss 100 10 SENSE1 SENSE2 V = 5V IN + + DISCONTINUOUS SENSE1 SENSE2 MODE V INTV IN CC 8 90 TG1 TG2 LTC3839 SW1 SW2 FORCED 0.3H 0.3H V 80 6 OUT CONTINUOUS 3.3V BOOST1 BOOST2 MODE 25A 0.1F 0.1F 45.3k + 70 4 DRV DRV 100F CC1 CC2 6 BG1 BG2 4.7F 10k 2 60 PGND LOSS MODE/PLLIN FORCED CM LOSS + V OUTSENSE DCM CLKOUT 0 50 V OUTSENSE 0.1 1 10 100 PHASMD TRACK/SS LOAD CURRENT (A) RUN ITH 3839 TA01b 18.7k DTR RT SGND 3839 TA01a 3839fa 1 EFFICIENCY (%)LTC3839 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V Voltage ................................................. 0.3V to 40V IN BOOST1, BOOST2 Voltages ....................... 0.3V to 46V SW1, SW2 Voltages ...................................... 5V to 40V 32 31 30 29 28 27 26 25 INTV , DRV , DRV , EXTV , PGOOD, RUN, CC CC1 CC2 CC PHASMD 1 24 BG2 (BOOST1-SW1), (BOOST2-SW2), MODE/PLLIN MODE/PLLIN DRV 2 23 CC2 Voltages ....................................................... 0.3V to 6V CLKOUT 3 22 EXTV CC + + + V , V , SENSE1 , SENSE2 , SGND 4 21 INTV OUTSENSE OUTSENSE CC 33 PGND SENSE1 , SENSE2 Voltages ....................... 0.6V to 6V RT 5 20 PGND ITH 6 19 V TRACK/SS Voltage ....................................... 0.3V to 5V IN TRACK/SS DRV 7 18 CC1 DTR, PHASMD, RT, V , RNG + V 8 17 BG1 OUTSENSE ITH Voltages ........................... 0.3V to (INTV + 0.3V) CC 9 10 11 12 13 14 15 16 Operating Junction Temperature Range (Notes 2, 3, 4) ........................................ 40C to 125C Storage Temperature Range .................. 65C to 150C UH PACKAGE 32-LEAD (5mm 5mm) PLASTIC QFN T = 125C, = 44C/W JMAX JA EXPOSED PAD (PIN 33) IS PGND, MUST BE SOLDERED TO PCB ORDER INFORMATION (