POWER LOSS (W) LTC3838-1 Dual, Fast, Accurate Step-Down DC/DC Controller with Dual Differential Output Sensing Fea T Descrip T n Wide V Range: 4.5V to 38V, V : 0.6V to 5.5V The LTC 3838-1 is a dual-channel, PolyPhase syn- IN OUT n Two Independent Channels: Dual/Single Output chronous step-down DC/DC switching regulator controller. n Output Voltage Regulation Accuracy: 0.67% Two independent channels drive all N-channel power (V ) and 0.75% (V ) Over Temperature MOSFETs. The controlled on-time, valley current mode OUT1 OUT2 n Differential Remote Output Sensing: Up to 500mV control architecture allows for not only fast response to (V ) and 200mV (V ) Ground Deviations transients without clock delay, but also constant frequency OUT1 OUT2 n Controlled On-Time, Valley Current Mode Control switching at steady load condition. Its proprietary load- n Fast Load Transient Response Without Clock Delay release transient detection feature (DTR) significantly n Detect Transient Release (DTR) Reduces V reduces overshoot at low output voltages. OUT Overshoot A precision internal reference enables accurate differential n Frequency Programmable from 200kHz to 2MHz, output regulation. The dual channels can either provide Synchronizable to External Clock two independent output voltages, or be combined into n t = 30ns, t = 90ns ON(MIN) OFF(MIN) multiphase single-output configuration. n R or Inductor DCR Current Sensing SENSE n The switching frequency can be programmed from 200kHz Overvoltage Protection and Current Limit Foldback n to 2MHz with an external resistor and can be synchronized to Power Good Output Voltage Monitor n an external clock. Very low t and t times allow for near Output Voltage Tracking and Adjustable Soft Start-Up ON OFF n 0% and near 100% duty cycles, respectively. Voltage track- Thermally Enhanced 38-Pin (5mm 7mm) QFN Package ing soft start-up and multiple safety features are provided. a T See Table 1 for a comparison of LTC3838, LTC3838-1 and n Distributed Power Systems Power Supply for ASIC LTC3838-2. n Computing, Data Storage, Communication Systems L, LT, LTC, LTM, PolyPhase, OPTI-LOOP, Module, Linear Technology and the Linear logo are n registered trademarks of Linear Technology Corporation. All other trademarks are the property Low Voltage, High Current, and/or High Step-Down Ratio of their respective owners. Protected by U.S. Patents, including 5481178, 5847554, 6580258, Converters That Demand Tight Load Transient Regulation 6304066, 6476589, 6774611. Typical a T 1.2V/1.5V, 15A, 350kHz Step-Down Converter (Refer to Figure 16 for Complete Design) V IN Efficiency/Power Loss 4.5V TO 38V 100 2.5 SENSE1 SENSE2 FORCED CONTINUOUS MODE + + SENSE1 SENSE2 DISCONTINUOUS MODE 90 V INTV IN CC 2.0 TG1 TG2 LTC3838-1 80 SW1 SW2 0.56H 0.56H 1.5 V V OUT1 OUT2 EFFICIENCY 1.2V BOOST1 BOOST2 1.5V 70 15A 15A POWER 0.1F 0.1F 15k 10k 1.0 + + LOSS DRV DRV CC1 CC2 330F 330F 60 2 2 BG1 BG2 10k/ 10k 4.7F 10k 0.5 15k PGND EXTV 50 CC V = 12V IN + + V = 1.2V V V OUT OUTSENSE1 DFB2 40 0 V V OUTSENSE1 DFB2 0.1 1 10 TRACK/SS1 TRACK/SS2 LOAD CURRENT (A) ITH1 ITH2 38381 TA01b 115k RT MODE PLLIN SGND CLKOUT V PHASMD RNG RUN1 RUN2 38381 TA01a 38381fa 1 For more information www.linear.com3838-1 EFFICIENCY (%) ion pplica ions pplica ion uresLTC3838-1 a T e Maxi Mu M r a T p c F T (Note 1) TOP VIEW V Voltage ................................................. 0.3V to 40V IN BOOST1, BOOST2 Voltages ....................... 0.3V to 46V SW1, SW2 Voltages ...................................... 5V to 40V 38 37 36 35 34 33 32 INTV , DRV , DRV , EXTV , PGOOD1, + CC CC1 CC2 CC V 1 31 TG2 DFB2 PGOOD2, RUN1, RUN2, (BOOST1-SW1), V 2 30 SW2 RNG ITH2 BG2 (BOOST2-SW2), MODE/PLLIN Voltages ...... 0.3V to 6V 3 29 + + TRACK/SS2 4 28 DRV CC2 SENSE1 , SENSE2 ,SENSE1 , SENSE2 MODE/PLLIN 5 27 EXTV CC Voltages ....................................................... 0.6V to 6V CLKOUT 6 26 INTV + CC 39 V Voltage ............... 0.6V to (INTV + 0.3V) OUTSENSE1 CC PGND SGND 7 25 PGND + V Voltage .....................0.6V to V OUTSENSE1 OUTSENSE1 RT V 8 24 IN TRACK/SS1, TRACK/SS2 Voltages .............. 0.3V to 5V PHASMD 9 23 DRV CC1 + DTR1, DTR2, PHASMD, RT, V , V , V , ITH1 10 22 BG1 RNG DFB2 DFB2 TRACK/SS1 11 21 SW1 ITH1, ITH2 Voltages ................ 0.3V to (INTV + 0.3V) CC + V 12 20 TG1 OUTSENSE1 Operating Junction Temperature Range 13 14 15 16 17 18 19 (Notes 2, 3, 4) ........................................ 40C to 125C Storage Temperature Range .................. 65C to 150C UHF PACKAGE 38-LEAD (5mm 7mm) PLASTIC QFN T = 125C, = 34C/W JMAX JA EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB o r D i n F Ma T (