POWER LOSS (mW) LTC3788-1 2-Phase, Dual Output Synchronous Boost Controller FEATURES DESCRIPTION n Synchronous Operation for Highest Efficiency and The LTC 3788-1 is a high performance 2-phase dual Reduced Heat Dissipation synchronous boost converter controller that drives all n Wide Input Range: 4.5V to 38V (40V Abs Max) and N-channel power MOSFETs. Synchronous rectification Operates Down to 2.5V After Start-Up increases efficiency, reduces power losses and eases n Output Voltages Up to 60V thermal requirements, allowing the LTC3788-1 to be used n 1% 1.2V Reference Voltage in high power boost applications. n R or Inductor DCR Current Sensing SENSE A constant-frequency current mode architecture allows n 100% Duty Cycle Capability for Synchronous MOSFET a phase-lockable frequency of up to 850kHz. OPTI-LOOP n Low Quiescent Current: 125A compensation allows the transient response to be opti- n Phase-Lockable Frequency (75kHz to 850kHz) mized over a wide range of output capacitance and ESR n Programmable Fixed Frequency (50kHz to 900kHz) values. The LTC3788-1 features a precision 1.2V refer- n Adjustable Output Voltage Soft-Start ence and a power good output indicator. A 4.5V to 38V n Power Good Output Voltage Monitor input supply range encompasses a wide range of system n Low Shutdown Current I : <8A Q architectures and battery chemistries. n Internal LDO Powers Gate Drive from VBIAS or EXTV CC n Independent SS pins for each controller ramp the output Available in a Narrow SSOP Package voltages during start-up. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode or APPLICATIONS continuous inductor current mode at light loads. n Industrial For a leadless 32-pin QFN package with additional features n Automotive of adjustable current limit, clock out, phase modulation n Medical and two PGOOD outputs, see the LTC3788 data sheet. n Military All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 5408150, 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. TYPICAL APPLICATION V 4.5V TO 12V START-UP VOLTAGE IN OPERATES THROUGH TRANSIENTS DOWN TO 2.5V V IN Efficiency and Power Loss 4.7F vs Load Current 4.7F 220F 3m 4m 100 10000 TG1 VBIAS INTV TG2 CC 90 3.3H 1.25H BOOST1 BOOST2 V V OUT OUT 80 1000 0.1F 0.1F 12V AT 5A 24V AT 3A SW1 SW2 70 LTC3788-1 BG1 BG2 60 100 + 50 + SENSE1 SENSE2 40 10 SENSE1 SENSE2 30 PGND V = 12V IN 20 1 110k 232k V = 24V OUT VFB2 10 Burst Mode OPERATION VFB1 FIGURE 9 CIRCUIT FREQ 0 0.1 0.00001 0.0001 0.001 0.01 0.1 1 10 PLLIN/MODE OUTPUT CURRENT (A) ITH1 SS1 SGND SS2 ITH2 37881 TA01b 220F 15nF 15nF 220F 100pF 220pF 12.1k 2.7k 8.66k 12.1k 0.1F 0.1F 37881 TA01a Rev D 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC3788-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1, 3) TOP VIEW VBIAS ........................................................ 0.3V to 40V 1 SS1 ITH1 28 BOOST1, BOOST2 ...................................... 0.3V to 76V 2 PGOOD1 VFB1 27 SW1, SW2 .................................................. 0.3V to 70V + 3 SW1 SENSE1 26 RUN1, RUN2 ................................................ 0.3V to 8V 4 TG1 SENSE1 25 Maximum Current Sourced into Pin 5 BOOST1 FREQ 24 from Source > 8V .............................................100A 6 BG1 PLLIN/MODE 23 PGOOD1, PLLIN/MODE ............................... 0.3V to 6V 7 VBIAS SGND 22 INTV , (BOOST1-SW1, BOOST2-SW2) ...... 0.3V to 6V CC 8 PGND RUN1 21 EXTV ........................................................ 0.3V to 6V CC 9 EXTV RUN2 20 CC + SENSE1 , SENSE1 , 10 INTV SENSE2 19 CC + + SENSE2 , SENSE2 .................................... 0.3V to 40V 11 BG2 SENSE2 18 + 12 BOOST2 SENSE1 SENSE1 , VFB2 17 + 13 TG2 ITH2 16 SENSE2 SENSE2 ................................. 0.3V to 0.3V 14 SW2 SS2 15 SS1, SS2, ITH1, ITH2, FREQ, VFB1, VFB2 ...........................................0.3V to INTV CC GN PACKAGE 28-LEAD PLASTIC SSOP Operating Junction Temperature Range ....40C to 125C T = 125C, = 80C/W JMAX JA Storage Temperature Range .................. 65C to 125C Lead Temperature (Soldering, 10 seconds) ...........300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3788EGN-1 PBF LTC3788EGN-1 TRPBF LTC3788GN-1 28-Lead Plastic SSOP 40C to 125C LTC3788IGN-1 PBF LTC3788IGN-1 TRPBF LTC3788GN-1 28-Lead Plastic SSOP 40C to 125C Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with TRMPBF suffix. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at T = 25C, VBIAS = 12V, unless otherwise noted (Note 2). A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Main Control Loop VBIAS Chip Bias Voltage Operating Range 4.5 38 V VFB1,2 Regulated Feedback Voltage I = 1.2V (Note 4) l 1.188 1.200 1.212 V TH IFB1,2 Feedback Current (Note 4) 5 50 nA V Reference Line Voltage Regulation V = 6V to 38V 0.002 0.02 %/V REFLNREG IN Rev D 2 For more information www.analog.com