LTC3119 18V, 5A Synchronous Buck-Boost DC/DC Converter Features Description Input Voltage Range: 2.5V to 18V nn Runs Down to V = 250mV After Start-Up IN nn Output Voltage Range: 0.8V to 18V nn 5A Output Current in Buck Mode, V > 6V IN nn 3A Output Current for V = 3.6V, V IN OUT = 5V nn Programmable Switching Frequency: 400kHz to 2MHz nn Synchronizable with an External Clock Up to 2MHz nn Accurate Run Comparator Threshold nn Burst Mode(R) Operation, No-Load I = 35A Q nn Ultralow Noise Buck-Boost PWM nn Current Mode Control nn Maximum Power Point Control nn Power Good Indicator nn Internal Soft-Start nn 28-Lead 4mm x 5mm QFN and TSSOP Packages The LTC(R)3119 is a high efficiency 18V monolithic buckboost converter that can deliver up to 5A of continuous output current. Extensive feature integration and very low resistance internal power switches minimize the total solution footprint for even the most demanding applications. A proprietary 4-switch PWM architecture provides seamless low noise operation from input voltages above, equal to, or below the output voltage. Applications Other features include: output short-circuit protection, thermal overload protection, less than 3A shutdown current, power good indicator, Burst Mode operation, and maximum power point control. nn Wide Input Range Power Supplies 1- to 4-Cell Lithium Battery Powered Products nn RF Power Supplies nn Solar Battery Chargers nn System Backup Power Supplies nn Lead Acid to 12V Regulator nn nn External frequency programming as well as synchronization using an internal PLL enable operation over a wide switching frequency range of 400kHz to 2MHz. The wide 2.5V to 18V input range is well suited for operation from unregulated power sources including battery stacks and backup capacitors. After start-up, operation is possible with input voltages as low as 250mV. The LTC3119 is offered in thermally enhanced 28-lead 4mm x 5mm QFN and TSSOP packages. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and PowerPath and No RSENSE are trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. Typical Application Wide Input Range 5V Regulator Efficiency Efficiency 100 3.3H 0.1F VIN 2.5V TO 18V 10F 100k SW1 BST1 PVIN VIN RUN BURST PWM 4.7F SW2 BST2 PVOUT 150F LTC3119 536k PWM/SYNC FB MPPC VCC PGOOD SVCC VC RT PGND GND 105k VOUT 5V AT 5A, VIN > 6V 5V AT 3A, VIN = 3.6V 3119 TA01a 80 EFFICIENCY (%) 0.1F Burst Mode OPERATION 90 70 60 PWM 50 40 30 102k 78.7k 680pF VIN = 3V VIN = 5V VIN = 9V 20 10 100 1m 10m 100m LOAD CURRENT (A) 1 10 3119 TA01b 3119fb For more information www.linear.com/LTC3119 1 LTC3119 Absolute Maximum Ratings (Note 1) VIN, PVIN, PVOUT, RUN, PGOOD.................. -0.3V to 19V FB, VC, RT, SYNC, MPPC, VCC, SVCC............ -0.3V to 6V BST1 Voltage...................... (SW1 - 0.3V) to (SW1 + 6V) BST2 Voltage......................(SW2 - 0.3V) to (SW2 + 6V) Operating Junction Temperature (Notes 2, 3) LTC3119E/LTC3119I............................ -40C to 125C LTC3119H........................................... -40C to 150C LTC3119MP........................................ -55C to 150C Storage Temperature Range................... -65C to 150C Lead Temperature (Soldering, 10 sec) FE...................................................................... 300C Pin Configuration TOP VIEW N/C 1 28 PWM/SYNC 26 BST1 28 27 26 25 24 23 PGND 4 25 PGND SW2 5 24 SW1 N/C 27 N/C 3 N/C 2 N/C N/C BST2 BST2 BST1 PWM/SYNC TOP VIEW PGND 1 22 PGND SW2 2 21 SW1 PVOUT 3 20 PVIN PVOUT 4 19 PVIN 29 PGND SW2 5 18 SW1 17 PGND PGND 6 PGOOD 7 16 VIN SVCC 8 RT VCC MPPC SGND FB 7 SW2 8 PGND 9 23 PVIN 29 PGND SVCC 11 9 10 11 12 13 14 VC 6 PGOOD 10 15 RUN 22 PVIN 21 SW1 20 PGND 19 VIN 18 RUN FB 12 17 RT VC 13 16 VCC SGND 14 UFD PACKAGE 28-LEAD (4mm x 5mm) PLASTIC QFN TJMAX = 125C, JA = 22C/W EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB Order Information PVOUT PVOUT 15 MPPC FE PACKAGE 28-LEAD PLASTIC TSSOP TJMAX = 150C, JA = 21C/W EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB http://www.linear.com/product/LTC3119#orderinfo LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3119EUFD#PBF LTC3119EUFD#TRPBF 3119 28-Lead (4mm x 5mm) Plastic QFN -40C to 125C LTC3119IUFD#PBF LTC3119IUFD#TRPBF 3119 28-Lead (4mm x 5mm) Plastic QFN -40C to 125C LTC3119EFE#PBF LTC3119EFE#TRPBF 3119 28-Lead Plastic Enhanced TSSOP -40C to 125C LTC3119IFE#PBF LTC3119IFE#TRPBF 3119 28-Lead Plastic Enhanced TSSOP -40C to 125C LTC3119HFE#PBF LTC3119HFE#TRPBF 3119 28-Lead Plastic Enhanced TSSOP -40C to 150C LTC3119MPFE#PBF LTC3119MPFE#TRPBF 3119 28-Lead Plastic Enhanced TSSOP -55C to 150C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. 3119fb 2 For more information www.linear.com/LTC3119 LTC3119 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25C. VIN = PVIN = 12V, PVOUT = 5V, RT = 76.8k unless otherwise stated. PARAMETER Input Operating Voltage CONDITIONS MIN After Start-Up (Note 4) Output Operating Voltage VCC Undervoltage Lockout Threshold VCC Rising VCC Falling TYP MAX 2.5 0.25 18 18 V V l 0.8 18 V l l 2.18 2.4 V V VCC Undervoltage Lockout Hysteresis 2.35 2.25 60 Input Current in Shutdown RUN = 0V Input Current in Sleep FB = 0.9V UNITS l l mV 3 31 A Oscillator Frequency l 900 1100 kHz Oscillator Operating Frequency l 400 2000 kHz PWM/SYNC Frequency Range l 400 2000 kHz PWM/SYNC Logic Threshold PWM/SYNC Pulse Width l Minimum Low or High Duration 0.3 1000 A 0.7 1 Soft-Start Duration 6 Feedback Voltage l 787 779 Feedback Pin Current Error Amplifier Transconductance VRUN Rising 795 795 803 811 1 50 0.3 0.8 1 l 1.17 1.205 1.24 RUN Pin Hysteresis Voltage PGOOD Hysteresis Percentage of FB Voltage l -9.5 -8 700 VPGOOD = 18V MPPC Pin Threshold l 774 l 7 MPPC Pin Current Inductor Current Limit (Note 3) Burst Mode Operation Inductor Current Limit VIN > VOUT (Note 3) Maximum Duty Cycle Percentage of Period SW2 is Low in Boost Mode l 90 Minimum Duty Cycle Percentage of Period SW1 is High in Buck Mode l 0 SW1, SW2 Minimum Low Time V V mV -6.5 1.2 PGOOD Pull Down Resistance nA A 90 Percentage of FB Voltage Falling mV mV S 0.25 PGOOD Threshold nA ms l RUN Pin Hysteresis Current PGOOD Leakage 50 120 RUN Pin Logic Threshold V ns PWM/SYNC Pin Current RUN Pin Comparator Threshold 1.1 100 % % 2000 1 40 nA 798 822 mV 1 50 nA 8 A 0.6 A 92 % 90 ns % 3119fb For more information www.linear.com/LTC3119 3 LTC3119 Electrical Characteristics The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25C. VIN = PVIN = 12V, PVOUT = 5V, RT = 76.8k unless otherwise stated. PARAMETER CONDITIONS N-Channel Switch Resistance Switch A (PVIN to SW1) Switch B (SW1 to PGND) Switch C (SW2 to PGND) Switch D (SW2 to PVOUT) MIN 30 30 30 30 N-Channel Switch Leakage PVIN = PVOUT = 18V, SW1 = SW2 = 0V, 18V 1 10 3.70 3.85 VCC Regulation Voltage VCC Dropout Voltage l 90 VCC Current Limit VCC Reverse Current 3.55 VCC Current = 50mA, VIN = 3V TYP 180 VCC = 5V, VIN = 3V Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3119 is tested under pulsed load conditions such that TJ TA. The LTC3119E is guaranteed to meet specifications from 0C to 85C junction temperature. Specification over the -40C to 125C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3119I specifications are guaranteed over the -40C to 125C operating junction temperature range. The LTC3119H specifications are guaranteed over the -40C to 150C operating junction temperature range. The LTC3119MP specifications are guaranteed and tested over the -55C to 150C operating junction temperature range. High temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than 125C. MAX UNITS m m m m A V mV mA 5 A Note 3: Current measurements are performed when the LTC3119 is not switching. The current limit values measured in operation will be somewhat higher due to the propagation delay of the comparators. Note 4: Minimum input voltage is governed by the VCC UVLO threshold. If VCC is maintained though external bootstrapping, the part will continue to operate until power transfer to the output is no longer possible. Note 5: Switch timing measurements are made in an open-loop test configuration. Timing in the application may vary somewhat from these values due to differences in the switch pin voltage during the non-overlap durations when switch pin voltage is influenced by the magnitude and direction of the inductor current. Note 6: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. The maximum rated junction temperature will be exceeded when this protection is active. Continuous operation above the specified absolute maximum operating junction temperature may impair device reliability or permanently damage the device. 3119fb 4 For more information www.linear.com/LTC3119 LTC3119 Typical Performance Characteristics Output Voltage Line Regulation Line Regulation 0.4 CHANGE IN VOUT (%) 0.6 0.2 0 -0.2 -0.4 0.0 -0.2 -0.4 -0.6 -0.8 -0.8 6 8 10 12 14 INPUT VOLTAGE (V) 16 -1.0 0.001 18 0.01 0.1 LOAD CURRENT (A) 1 35 38 32 26 20 -60 6 -30 0 30 60 90 TEMPERATURE ( C) 120 150 3119 G03 Run Pin Hysteresis Current vs Temperature Power Switch Resistance vs VCC 260 34 HYSTERESIS CURRENT (nA) 255 33 32 31 30 29 28 27 44 3119 G02 3119 G01 SWITCH RESISTANCE (m) 250 245 240 235 230 225 2 2.5 3 3.5 VCC VOLTAGE (V) 220 -60 4 3119 G04 Run Pin Comparator Threshold vs Temperature vs Temperature 1.35 1.25 1.20 1.15 1.10 1.05 -60 -30 0 30 60 90 TEMPERATURE ( C) 120 150 0 30 60 90 120 150 3119 G05 Run Pin Logic Threshold vs Temperature vs Temperature 850 RISING FALLING 1.30 -30 TEMPERATURE ( C) RISING FALLING THRESHOLD VOLTAGE (mV) 4 50 0.2 -0.6 2 Temperature vs Temperature PWM/SYNC = HIGH 0.8 0.4 THRESHOLD VOLTAGE (V) CHANGE IN VOUT (%) 1.0 LOAD = 1A PWM/SYNC = HIGH 0.6 -1 Power Switch Resistance vs Output Voltage Load Regulation SWITCH RESISTANCE (m) 1 0.8 TA = 25C, unless otherwise noted. 770 690 610 530 450 -60 3119 G06 -30 0 30 60 90 TEMPERATURE ( C) 120 150 3119 G07 3119fb For more information www.linear.com/LTC3119 5 LTC3119 Typical Performance Characteristics Run Pin Current vs Run Pin Oscillator Frequency vs RT 2.0 25 1.8 20 15 10 5 0 -5 0 2 4 6 8 10 12 VOLTAGE (V) 14 16 1.6 1.4 1.2 1.0 0.8 0.6 0.4 18 1.0 CHANGE FROM VIN = 12V (%) 30 OSCILLATOR FREQUENCY (MHz) RUN PIN CURRENT (A) Voltage TA = 25C, unless otherwise noted. 20 50 80 110 140 170 RT PIN RESISTOR (k) Oscillator Frequency vs Temperature -0.5 -1.0 -1.5 2 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 3119 G10 FB FB Voltage Voltage vs vs Temperature Temperature 1.0 0.1 CHANGE FROM 25 C (%) 0.7 CHANGE FROM 25 C (%) 0 3119 G09 3119 G08 0.4 0.1 -0.2 -0.5 -0.8 -60 -30 0 30 60 90 TEMPERATURE ( C) 120 0.0 -0.1 -0.2 -0.3 -0.4 -60 150 3119 G11 0 30 60 90 120 150 3119 G12 SW1, SW2 Minimum Low Time vs Temperature 5 0.2 4 0.1 CHANGE FROM 25 C (%) 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -60 -30 TEMPERATURE ( C) MPPC Pin Voltage vs Temperature MPPC Voltage vs Temperature CHANGE FROM 25 C (%) 0.5 -2.0 200 Oscillator Frequency vs VIN IN 3 2 1 0 -1 -2 -3 -4 -30 0 30 60 90 TEMPERATURE ( C) 120 150 -5 -60 3119 G13 -30 0 30 60 90 TEMPERATURE ( C) 120 150 3119 G14 3119fb 6 For more information www.linear.com/LTC3119 LTC3119 Typical Performance Characteristics SW2 Maximum Duty Cycle vs Temperature 94.0 70 93.5 60 93.0 40 30 20 10 2 92.0 91.5 2.5 3 3.5 4 VCC VOLTAGE (V) 4.5 0 30 60 90 TEMPERATURE ( C) 35 fSW = 1MHz 120 16.0 -60 150 17 16 15 14 13 12 3119 G16 VCC Current vs Switching Frequency VCC Current vs Switching Frequency 3 3.5 4 VCC VOLTAGE (V) 4.5 25 20 15 80 -1.0 0 30 60 90 120 150 3119 G20 Inductor Current Limit vs Temperature 9.0 0.4 8.5 0.2 0.1 0.0 -0.1 -0.2 -0.3 -1.2 -30 TEMPERATURE ( C) CURRENT LIMIT (A) -0.8 3119 G17 90 60 -60 2.0 0.5 VCC CHANGE (%) VCC CHANGE (%) -0.6 -1.4 0.6 0.8 1 1.2 1.4 1.6 1.8 SWITCHING FREQUENCY (MHz) 0.3 -0.4 150 100 VCC Line Regulation -0.2 120 110 3119 G19 fSW = 1MHz 90 70 3119 G18 VCC CC Load Regulation 60 120 5 0.4 5 30 130 10 2.5 0 VCC Dropout Voltage vs Temperature 11 2 -30 TEMPERATURE ( C) 30 VCC CURRENT (mA) VCC CURRENT (mA) -30 3119 G15 18 0.0 17.0 16.5 90.0 -60 5 VCC CC Current vs VCC CC 19 10 fSW = 1MHz 90.5 -10 20 92.5 91.0 0 VVCC Current vs vs Temperature Temperature CC Current 17.5 VCC CURRENT (mA) DUTY CYCLE (%) CHANGE (%) 50 -20 18.0 DROPOUT VOLTAGE (mV) 80 SW1, SW2 Minimum Low Time vs VCC TA = 25C, unless otherwise noted. 8.0 7.5 7.0 6.5 -0.4 0 10 20 30 40 50 60 70 80 90 100 VCC LOAD CURRENT (mA) 3119 G21 -0.5 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 3119 G22 6.0 -60 -30 0 30 60 90 TEMPERATURE ( C) 120 150 3119 G23 3119fb For more information www.linear.com/LTC3119 7 LTC3119 Typical Performance Characteristics TA = 25C, unless otherwise noted. VCC UVLO Threshold vs Temperature Efficiency vs Switching Frequency 2.40 95 RISING FALLING 2.38 94 2.34 93 EFFICIENCY (%) THRESHOLD VOLTAGE (V) 2.36 2.32 2.30 2.28 2.26 92 91 2.24 90 2.22 2.20 -60 -30 0 30 60 90 120 TEMPERATURE ( C) 89 0.4 150 200 175 0.8 150 0.7 0.6 0.5 0.4 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 100 75 50 25 0 18 2 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 3119 G27 Maximum Reverse Current During 0.83) MPPC Control (V MPPC < 0.86) VOUT = 12V fSW = 1MHz 180 REVERSE CURRENT (mA) 2.0 VOUT = 5V fSW = 1MHz L = 2.2H 3119 G26 200 1.8 125 VOUT = 3.3V VOUT = 5V VOUT = 12V 2 1 1.2 1.4 1.6 FREQUENCY (MHz) Minimum Current to Avoid Pulse Skipping Avoid Pulse Skipping 0.9 0.2 0.8 3119 G25 Burst Mode Operation Threshold IN 0.3 0.6 3119 G24 LOAD CURRENT (mA) OUTPUT CURRENT (A) 1.0 VOUT = 5V VOUT = 12V 160 L = 2.2H L = 6.8H 140 120 100 80 60 40 20 0 2 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 3119 G28 3119fb 8 For more information www.linear.com/LTC3119 LTC3119 Typical Performance Characteristics 100 100 Burst Mode OPERATION 90 Efficiency, VOUT = 3.3V ffSW 1MHz SW == 1MHz 100 Burst Mode OPERATION 90 80 70 70 70 60 50 PWM 40 30 20 10 100 1m 10m 100m LOAD CURRENT (A) 1 60 PWM 50 40 30 VIN = 2.5V VIN = 5V VIN = 12V 10 100 1m 10m 100m LOAD CURRENT (A) 1 90 90 80 80 70 70 60 50 PWM 40 30 10 100 1m 10m 100m LOAD CURRENT (A) 1 60 PWM 50 40 100 30 VIN = 3V VIN = 5V VIN = 12V 1m 10m 100m LOAD CURRENT (A) 1 10 100 10 Efficiency, VOUT = 12V fSW = 1MHz 100 Burst Mode OPERATION 90 70 1m 10m 100m LOAD CURRENT (A) 1 60 PWM 50 40 30 3119 G35 10m 100m LOAD CURRENT (A) 1 10 100 1m 10m 100m LOAD CURRENT (A) 1 Burst Mode OPERATION 60 PWM 50 40 VIN = 5V VIN = 12V VIN = 15V 20 10 3119 G36 10 Efficiency, VOUT = 12V 2MHz ffSW SW == 2MHz 30 VIN = 5V VIN = 12V VIN = 15V 20 10 EFFICIENCY (%) 80 10 100 1m 3119 G34 70 20 VIN = 3V VIN = 5V VIN = 12V 20 80 VIN = 5V VIN = 12V VIN = 15V PWM 40 70 30 Burst Mode OPERATION 50 80 40 10 Efficiency, VOUT = 5V fSW SW = 2MHz 60 90 50 1 70 90 PWM 10m 100m LOAD CURRENT (A) 3119 G33 Efficiency, VOUT = 12V f SW = 500kHz 60 1m 80 Burst Mode OPERATION 10 100 10 Burst Mode OPERATION VIN = 2.5V VIN = 5V VIN = 12V 3119 G31 100 20 EFFICIENCY (%) EFFICIENCY (%) 40 90 3119 G32 100 PWM 50 10 100 10 Efficiency, VOUT = 5V fSW SW = 1MHz 30 VIN = 3V VIN = 5V VIN = 12V 20 60 20 EFFICIENCY (%) 100 EFFICIENCY (%) EFFICIENCY (%) Efficiency, VOUT = 5V fSW SW = 500kHz Burst Mode OPERATION Burst Mode OPERATION 3119 G30 3119 G29 100 Efficiency, VOUT = 3.3V fSW SW = 2MHz 30 VIN = 2.5V VIN = 5V VIN = 12V 20 10 EFFICIENCY (%) 80 80 EFFICIENCY (%) EFFICIENCY (%) 90 Efficiency, VOUT = 3.3V fSW = 500kHz TA = 25C, unless otherwise noted. 10 100 1m 10m 100m LOAD CURRENT (A) 1 10 3119 G37 3119fb For more information www.linear.com/LTC3119 9 LTC3119 Typical Performance Characteristics PWM Mode No-Load Input Current Input Current 65 38 34 30 26 22 55 50 45 40 3.5 3.0 2.5 2.0 1.5 18 1.0 14 30 0.5 10 25 8 10 12 14 INPUT VOLTAGE (V) 16 18 2 4 6 8 10 12 14 INPUT VOLTAGE (V) Temperature Rise vs Load Current TEMPERATURE RISE ( C) 70 60 50 40 30 20 VIN = 9V VIN = 12V VIN = 15V 10 1.5 2 2.5 3 3.5 4 LOAD CURRENT (A) 4.5 82 70 58 46 34 VIN = 9V VIN = 12V VIN = 15V 22 10 5 1 1.5 2 2.5 3 3.5 4 LOAD CURRENT (A) TEMPERATURE RISE ( C) 50 40 30 20 VIN = 3V VIN = 5V VIN = 12V 10 0 1 1.5 2 2.5 3 3.5 4 LOAD CURRENT (A) 4.5 3119 G44 4.5 80 70 60 60 50 40 30 20 VIN = 3V VIN = 5V VIN = 12V 1 1.5 2 2.5 3 3.5 4 LOAD CURRENT (A) 30 20 0 PULSED LOAD CONTINUOUS LOAD 6.0 5.0 4.0 3.0 DC2129A DEMO BOARD fSW = 750kHz 100Hz PULSE LOAD 20% DUTY CYCLE STANDBY LOAD = 0.25A 2.0 1.0 0 10 20 30 40 50 60 70 80 90 100 LOAD DUTY CYCLE (%) 3119 G45 5 Maximum Output Current VOUT = 5V 7.0 40 4.5 3119 G43 8.0 50 5 70 0 5 10 5 4 10 DC2129A DEMO BOARD VIN = 13V VOUT = 12V fSW = 1MHz 500Hz PULSE LOAD = 5A STANDBY LOAD = 0.25A 90 60 4.5 80 Temperature Rise vs Pulsed Load Duty Cycle 100 70 2.5 3 3.5 BOOST RATIO 3119 G42 DC2129A DEMO BOARD VOUT = 5V fSW = 2MHz 80 2 DC2129A DEMO BOARD VOUT = 5V fSW = 1MHz 90 94 Temperature Load Current Rise vs Load Current 90 1.5 Temperature Load Current Rise vs Load Current 100 DC2129A DEMO BOARD 118 VOUT = 12V f = 2MHz 106 SW 3119 G41 100 1 3119 G40 130 DC2129A DEMO BOARD 90 VOUT = 12V f = 1MHz 80 SW 1 0 18 3119 G39 Temperature Load Current Rise vs Load Current 0 16 TEMPERATURE RISE ( C) 6 OUTPUT CURRENT (A) 4 100 TEMPERATURE RISE ( C) 4.0 35 2 VOUT = 12V fSW = 1MHz 4.5 60 3119 G38 TEMPERATURE RISE ( C) 5.0 VOUT = 3.3V VOUT = 5V VOUT = 12V 70 INPUT CURRENT (A) 42 INPUT CURRENT (mA) 75 VOUT = 3.3V VOUT = 5V VOUT = 12V 46 Maximum Output Current vs Boost Ratio vs Boost Ratio Burst Mode Operation No-Load Input Current OUTPUT CURRENT (A) 50 TA = 25C, unless otherwise noted. 0 2 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 3119 G51 3119fb 10 For more information www.linear.com/LTC3119 LTC3119 Typical Performance Characteristics Maximum Output Current VOUT = 12V 8.0 OUTPUT CURRENT (A) Burst Mode Operation Load Step 400mA to 4A, VIN = 9V PULSED LOAD CONTINUOUS LOAD 7.0 6.0 5.0 3.0 DC2129A DEMO BOARD fSW = 750kHz 100Hz PULSE LOAD 20% DUTY CYCLE STANDBY LOAD = 0.25A 2.0 1.0 2 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 Burst Mode Operation VOUT Ripple OUT FRONT PAGE APPLICATION ILOAD = 50mA, VIN = 9V FRONT PAGE APPLICATION VOUT 200mV/DIV OUTPUT VOLTAGE 20mV/DIV INDUCTOR CURRENT 5A/DIV 4.0 0 TA = 25C, unless otherwise noted. INDUCTOR CURRENT 250mA/DIV LOAD CURRENT 5A/DIV 200s/DIV 3119 G46 3119 G47 20s/DIV 18 3119 G52 PWM Mode Load Step 400mA to 4A, VIN = 9V IN Switching Waveforms, Buck Mode Operation Switching Waveforms, Boost Mode Operation FRONT PAGE APPLICATION ILOAD = 2A, VIN = 3V FRONT PAGE APPLICATION ILOAD = 2A, VIN = 9V FRONT PAGE APPLICATION VOUT 200mV/DIV SW1 10V/DIV SW1 5V/DIV INDUCTOR CURRENT 5A/DIV SW2 5V/DIV SW2 5V/DIV INDUCTOR CURRENT 1A/DIV INDUCTOR CURRENT 400mA/DIV LOAD CURRENT 5A/DIV 200s/DIV Pin Functions 3119 G48 500ns/DIV 3119 G49 500ns/DIV 3119 G50 (QFN/TSSOP) PGND (Pins 1, 6, 17, 22, Exposed Pad Pin 29/Pins 4, 9, 20, 25, Exposed Pad Pin 29): Power Ground Connection. These pins should be connected to the power ground using the shortest and widest connections possible. The exposed pad must be soldered to the PCB and electrically connected to ground through the shortest and lowest impedance path possible and to the PCB ground plane for rated thermal performance. SW2 (Pins 2, 5/Pins 5, 8): Buck-Boost Converter Power Switch Pin. These pins should be connected to one side of the Buck-Boost inductor. PVOUT (Pins 3, 4/Pins 6, 7): Output Voltage Power Connection. These pins is connected to switch D of the buck-boost converter. Connect a low ESR 10F or larger capacitor between this pin and ground using the lowest impedance path possible. PGOOD (Pin 7/Pin 10): Open drain output that pulls to ground when FB drops too far below its regulated voltage. Connect a pull-up resistor from this pin to a positive supply. Refer to the Operation section of the data sheet for more detail. SVCC (Pin 8/Pin 11): Supplies voltage to internal circuits used for production test. This pin must be tied to VCC. 3119fb For more information www.linear.com/LTC3119 11 LTC3119 Pin Functions (QFN/TSSOP) FB (Pin 9/Pin 12): Feedback Voltage Input. A resistor divider connected to this pin sets the output voltage for the buck-boost converter. VC (Pin 10/Pin 13): Error Amplifier Output. A frequency compensation network must be connected between this pin and SGND to stabilize the voltage control loop. SGND (Pin 11/Pin 14): Signal Ground. This pin is the ground connection for the control circuitry of the IC and must be tied to ground in the application. MPPC (Pin 12/Pin 15): Maximum Power Point Control Setpoint. Connect this pin to a resistive divider from VIN to GND to set the input regulation voltage. The MPPC pin should be tied to VCC to disable MPPC operation. VCC (Pin 13/Pin 16): Internal Regulator Output Voltage and Supply Rail for Control Circuits. This pin is the output of the internal low voltage linear regulator used to supply the control circuitry. The VCC output may also be used to power external loads of up to 10mA. A 4.7F capacitor should be connected between this pin and GND using the shortest trace possible. RT (Pin 14/ Pin 17): Oscillator Frequency Programming Input. Connect a resistor between this pin and GND to set the buck-boost converter switching frequency. RUN (Pin 15/Pin 18): Input to Enable and Disable the IC and Set Custom Input UVLO Threshold. The RUN pin can be driven by external logic signals to enable and disable the IC. In addition, the voltage on this pin can be set by a resistor divider connected to the input voltage to provide an accurate undervoltage lockout threshold. The IC is enabled if the RUN pin voltage exceeds 1.205V nominally. Once enabled, a 250nA current is sourced from this pin to provide additional hysteresis. VIN (Pin 16/Pin 19): Input Voltage Pin for Internal VCC Regulator. PVIN (Pins 19, 20/Pins 22, 23): Input Voltage Power Connection. These pins is connected to switch A of the buck-boost converter. Connect a 10F or larger capacitor between this pin and GND using the lowest impedance path possible. SW1 (Pins 18, 21/Pins 21, 24): Buck-Boost Converter Power Switch Pin. These pins should be connected to one side of the Buck-Boost inductor. BST1 (Pin 23/Pin 26): Power Rail for SWA Driver. This pin must be connected to SW1 through a 0.1F capacitor. This pin is used to generate the gate drive rail for power switch A. N/C (Pins 24, 26, 27/Pins 1, 2, 27): No Connection. Can be connected to ground or left open. This pin does not connect to any internal circuitry. PWM/SYNC (Pin 25/Pin 28): Automatic Burst Mode Operation/PWM Mode Control Pin and Synchronization Input. Forcing this pin high causes the IC to operate in fixed frequency PWM mode at all loads using the internal oscillator at the frequency set by the RT Pin. Forcing this pin low causes the IC to enable Burst Mode operation at light loads to maximize efficiency. Clocking this pin will cause the part to synchronize to the clock for frequencies higher than the frequency programmed by the RT Pin. When using this pin for synchronization, a minimum input pulse width of 100ns should be used. BST2 (Pin 28/Pin 3): Power Rail for SWD Driver. This pin must be connected to SW2 through a 0.1F capacitor. This pin is used to generate the gate drive rail for power switch D. 3119fb 12 For more information www.linear.com/LTC3119 LTC3119 Block Diagram Pin numbers are shown for UFD package only. 16 3 4 VIN 13 5 21 18 20 19 SW1 D REVERSE BLOCKING LDO VCC 2 SW2 PVOUT PVIN A BST1 BST2 8 SVCC 28 7 12 9 10 14 25 8A B + - 23 C BST1 BST2 PGND PGND CURRENT LIMIT ZERO CURRENT 0A SOFT-START RAMP PGOOD - + MPPC 798mV + - 795mV - gm + FB + - PWM - + + FB 731mV VIN 0.25A + - CHIP ENABLE VC UVLO RT OSCILLATOR 1.205V 0.795V PWM/SYNC MODE SELECTION BANDGAP REFERENCE + - RUN 15 1.205V VCC 2.35V OVERTEMPERATURE PGND SGND EXPOSED PAD 1 6 17 22 11 29 3119 BD 3119fb For more information www.linear.com/LTC3119 13 LTC3119 Operation Introduction PWM Mode Operation The LTC3119 is a 5A monolithic Buck-Boost DC/DC converter that can operate over a wide range of 2.5V to 18V on VIN and 0.8V to 18V on VOUT. Integrated low RDS(ON) N-Channel DMOS power switches reduce solution complexity and maximize conversion efficiency. Internal high side power switch drivers require only two small external capacitors and further simplify application circuit design. The LTC3119 incorporates many additional features to allow for maximum flexibility when designing application solutions, including an accurate RUN pin comparator, wide operating frequency range of 400kHz to 2MHz, external clock synchronization, power good indicator, and Maximum Power Point Control (MPPC) of the input voltage for operation from current limited sources such as photovoltaic arrays. If the PWM/SYNC pin is held high, or the load current on the converter is high enough to command PWM mode operation with the PWM/SYNC pin held low, the LTC3119 operates in a fixed frequency PWM mode. The operating frequency is defined by the resistance on the RT pin as described in the Applications section of this data sheet. PWM mode minimizes output voltage ripple and yields a low noise switching frequency spectrum. A proprietary switching algorithm provides seamless transitions between operating modes and eliminates discontinuities in the average inductor current, inductor ripple current and loop transfer function throughout all modes of operation. These advantages result in increased efficiency, improved loop stability and lower output voltage ripple in comparison to a traditional buck-boost converter. Figure 1 shows the topology of the LTC3119 power stage which is comprised of four N-channel DMOS switches and their associated gate drivers. High side drive and sense circuitry allow for operation to 0V on the output while maintaining current control and synchronous switch operation. Operation to voltages below 2.5V on the input is also possible when bootstrapping the VCC pin from VOUT, or other alternate sources, allowing for maximum extraction of power from energy storage devices such as supercapacitors. A proprietary ultralow noise PWM switching algorithm maintains output regulation with input voltages that are below, equal to, or above the output voltage. Transitions between buck and boost operating modes occur seamlessly without transients or subharmonic switching. The LTC3119 has an internal oscillator that can be configured to operate over a wide range of frequencies. Using a single programming resistor, the operating frequency can be configure between 400kHz and 2MHz allowing for flexibility when optimizing for board area and efficiency. The internal oscillator can also be synchronized to an external clock applied to the PWM/SYNC pin in noise sensitive applications. Burst Mode operation allows for high efficiency operation at light loads while automatically transitioning to PWM mode at heavier loads. At low output currents, Burst Mode operation is enabled, with a current of only 31A (typical). In shutdown the total supply current is further reduced to 3A (maximum). CBST1 BST1 CBST2 L PVIN SW1 SW2 PVOUT BST2 VCC VCC A D LTC3119 VCC B VCC C PGND PGND 3119 F01 Figure 1. Power Stage Schematic In PWM mode operation both switch pins transition on every cycle independent of the input and output voltages. The internal average current control loop commands the pulse width modulator to generate the appropriate switch duty cycle to maintain regulation of the output voltage. Oscillator and Phase-Locked Loop The LTC3119 operates from an internal oscillator with a switching frequency that is configured by a single external resistor between the RT pin and GND. For noise sensitive applications, an internal phase-locked loop allows the 3119fb 14 For more information www.linear.com/LTC3119 LTC3119 Operation LTC3119 to be synchronized to an external clock signal applied to the PWM/SYNC pin. The phase-locked loop is only able to increase the frequency of the internal oscillator to obtain synchronization. Therefore, the resistor RT must be chosen to program the internal oscillator to a lower frequency than the frequency of the clock applied to the PWM/SYNC pin. Sufficient margin must be included to account for the frequency variation of the external synchronization clock as well as the worst-case variation in frequency of the internal oscillator. Whether operating from its internal oscillator or synchronized to an external clock signal, the LTC3119 is able to operate with a switching frequency from 400kHz to 2MHz, providing the ability to trade-off small solution size and optimum power conversion efficiency. In addition to serving as a logic-level input to enable the IC, the RUN pin features an accurate internal comparator allowing it to be used to set custom rising and falling input undervoltage lockout thresholds with the addition of an external resistor divider. When the RUN pin is driven above its logic threshold (typically 0.8V) the VCC regulator is enabled which provides power to the internal control circuitry of the IC and the accurate RUN pin comparator is enabled. If the RUN pin voltage is increased further so that it exceeds the RUN comparator threshold (1.205V nominal), the buck-boost converter will be enabled. If the RUN pin is brought below the RUN comparator threshold, the buck-boost converter will inhibit switching, but the VCC regulator and control circuitry will remain powered unless the RUN pin is brought below its logic threshold. Therefore, in order to place the part in shutdown and reduce the input current to its minimum level (3A) it is necessary to ensure that the RUN pin is brought below the worst-case logic threshold (0.3V).The RUN pin is a high voltage input and can be connected directly to VIN to continuously enable the part when the input supply is present. If the RUN pin is forced above approximately 5V it will sink a small current as given by the following equation: ( VRUN - 5V ) 5M VIN LTC3119 0.25A VIN RUN Pin Comparator IRUN = With the addition of an external resistor divider as shown in Figure 2, the RUN pin can be used to establish a custom input under voltage lockout threshold. The buck-boost converter is enabled when the RUN pin reaches 1.205V which allows the rising UVLO threshold to be set via the resistor divider ratio. Once the RUN pin reaches the threshold voltage, the comparator switches and the buckboost converter is enabled. When the part is enabled an internal 0.25A (typical) current source is enabled which sources current out of the RUN pin raising the RUN pin voltage away from the threshold. R1 RUN 1.205V - + + - R2 0.8V ENA ENABLE SWITCHING ENABLE VCC REGULATOR AND CONTROL CIRCUITS INPUT LOGIC THRESHOLDS 3119 F02 Figure 2. Accurate Run Pin Comparator In order to disable the part, VIN must be reduced sufficiently to overcome the hysteresis generated by this current as well as the 90mV hysteresis of the RUN comparator. As a result, the amount of hysteresis can be independently programmed without affecting the rising UVLO threshold by scaling the values of both resistors. VCC Regulator An internal low dropout regulator generates the 3.7V (nominal) VCC rail from VIN. The VCC rail powers the internal control circuitry and power device gate drivers of the LTC3119. In addition to powering the internal circuitry of the LTC3119, the VCC regulator can also support an external load of 10mA. The VCC regulator is disabled when the RUN pin is below its logic threshold to reduce quiescent current and is enabled when the RUN pin is above its logic threshold. The VCC regulator includes current limit protection to safeguard against short circuiting and overload conditions. For applications where the output voltage is 3119fb For more information www.linear.com/LTC3119 15 LTC3119 Operation set to 5V, VCC can be driven from the output rail through a Schottky diode. Bootstrapping in this manner can provide a significant efficiency improvement, particularly at large voltage step down ratios, and also allows operation down to lower input voltages. The maximum operating voltage for the VCC pin is 5.5V and care must be taken to ensure that this limit is not exceeded when driving VCC externally. Current Mode Control The LTC3119 utilizes an average current mode control scheme. Current mode control provides simplified loop compensation, rapid response to load transients and inherent line voltage rejection. The voltage on the VC pin defines the commanded average inductor current, and is adjusted by the error amplifiers to maintain regulation of the active control loop (FB or MPPC). The internal current mode control loop error amplifier compares the sensed average inductor current and the commanded average inductor current level to modulate the SW1 and SW2 pins on a cycle-by-cycle basis. The average current mode control technique is similar to peak current mode control except that the average current amplifier, by virtue of its configuration as an integrator, controls average current instead of the peak current. This difference eliminates the peak to average current error of peak current mode control, while maintaining most of the advantages inherent to peak current mode control. Compensation of the inner current loop is accomplished by an internal compensation network that is optimized to PVIN A D B VC - + Integrated into the LTC3119 are two separate error amplifiers to control the input to the inner current mode control loop. These amplifiers monitor voltages at the FB and MPPC pins. The outputs from these amplifiers are summed together and used as the commanded current level for the inner current mode control loop. To ensure stability, a compensation network must be connected between the output of the error amplifiers (VC pin) and GND. A Type II compensation network, as shown in Figure 4, is recommended for most applications since it provides the flexibility to optimize converter response while minimizing DC errors in the output voltage. While the FB error amplifier is the only amplifier with the ability to increase the commanded current level, both amplifiers can reduce the commanded current to maintain regulation for their associated control loop (see Block Diagram). At any given time, only one control loop is active while the other is inactive. Priority is given to the MPPC control loop, which can override the voltage loop and reduce the commanded current level. When under control of the MPPC error amplifier, the compensation network of the VC pin is ignored. VOUT PVOUT RTOP FB VC LTC3119 COUT RZ RBOT CP1 3119 F04 Figure 4. FB and VC Pin Configuration PGND DRIVERS - + Error Amplifiers C PGND CURRENT ERROR AMPLIFIER PVOUT provide high bandwidth and low regulation error under all operating conditions. Current Limit and Zero Current Detection LOGIC RAMP GENERATOR 3119 F03 Figure 3. Inner Average Current Loop Diagram The LTC3119 incorporates limits for both the maximum peak and maximum average inductor current. Using the current sense information, if the inductor current reaches a peak level of 11A (typical), switch A is immediately turned off to ensure that the inductor current remains controlled. 3119fb 16 For more information www.linear.com/LTC3119 LTC3119 Operation The average current mode control loop also clamps the maximum average current in the inductor to 8A (typical). These two current limits help to ensure a smooth transition into regulation as well as protecting against current conditions beyond the capability of the IC. The LTC3119 incorporates dedicated zero current detection comparators to minimize reverse current during switching and provide discontinuous mode operation. The zero current detection thresholds are adjusted based on operating conditions to avoid subharmonic switching and may result in small amounts of negative current under some conditions. When the part is being controlled by the MPPC control loop, the zero cross comparators are set to approximately 150mA to help prevent any reverse current from discharging the output storage element. Soft-Start The LTC3119 soft-start circuit minimizes input current transients and output voltage overshoot on initial power-up. The required timing components for soft-start are internal to the LTC3119 and produce a typical soft-start duration of 6ms. The internal soft-start circuit slowly ramps the command signal to the current mode control loop (VC pin voltage). In doing so, the inductor current is also slowly increased, starting from zero. Soft-start is reset by the VCC UVLO, the RUN pin accurate enable comparator, and thermal shutdown. Maximum Power Point Control (MPPC) The MPPC input of the LTC3119 can be used with an optional external voltage divider to dynamically adjust the commanded inductor current in order to maintain a minimum input voltage. This is primarily useful when using resistive sources, such as photovoltaic panels, to maximize input power transfer and prevent VIN from dropping too low under load. Referring to Figure 5, the MPPC pin is internally connected to the noninverting input of a transconductance amplifier. If the MPPC pin voltage falls below the reference voltage, the output of the amplifier reduces the commanded average inductor current (VC pin voltage) to reduce the input current and regulate VIN to the programmed minimum voltage. External compensation may also be required and is generally provided by a series resistor and capacitor connected between the MPPC pin and GND. This compensation network is in parallel with the lower resistor of the VIN voltage divider network. LTC3119 VIN PVIN 798mV - R5 CIN R6 RC2 MPPC CC2 + VC 3119 F05 Figure 5. MPPC Pin Configuration Burst Mode Operation When the PWM/SYNC pin is held low, the LTC3119 is configured for Burst Mode operation. As a result, the buck-boost DC/DC converter will operate with continuous PWM switching until the output current drops to low levels at which point the converter will automatically transition to power saving Burst Mode operation at lower output currents. When operating in Burst Mode operation, the LTC3119 will go into a sleep state when the output voltage achieves its nominal regulation level. The sleep state halts PWM switching and powers down all nonessential functions of the IC, reducing the quiescent current of the LTC3119 to just 31A (typical). This greatly improves overall power conversion efficiency for light loads. Since the converter is not switching in sleep, the output voltage will slowly decay at a rate determined by the output load resistance and the output capacitor value. When the output voltage has decayed by a small amount, the LTC3119 will wake and initiate PWM switching operation until the output voltage on VOUT is restored to the previous level. If the load is very light, the LTC3119 may only need to switch for a few cycles to restore VOUT and will sleep for extended periods of time, significantly improving efficiency. If the load is suddenly increased above the burst transition threshold, the part will automatically enter continuous PWM operation until the load is once again reduced. Note that Burst Mode operation is inhibited until soft-start is completed and VOUT has reached regulation. Burst Mode operation is also inhibited when the MPPC loop is in control. 3119fb For more information www.linear.com/LTC3119 17 LTC3119 Operation Power Good Indicator The LTC3119 provides an open-drain PGOOD output that pulls low if VOUT falls more than 8% (typical) below its programmed value. When VOUT rises to within 6.5% (typical) of its programmed value, the internal PGOOD pull-down will turn off and PGOOD will go high if an external pull-up resistor has been provided. An internal filter prevents nuisance trips of PGOOD due to short transients on VOUT. Note that PGOOD can be pulled up to any voltage, as long as the absolute maximum rating of 19V is not exceeded. The PGOOD function is active when the RUN pin voltage is above the logic enable threshold of 0.8V (typical). When the RUN pin voltage is below 0.8V (typical) and the VCC supply is still present, the PGOOD pull-down will be enabled. Thermal Considerations The power switches in the LTC3119 are designed to operate continuously with currents up to the internal current limit thresholds. Operating at high current levels results in significant heat generated within the IC. In addition, in many applications the VCC regulator is operated with large input-to-output voltage differentials resulting in significant additional power dissipation in the pass element. As a result, careful consideration must be given to the thermal environment of the IC in order to optimize efficiency and ensure that the LTC3119 is able to provide its full-rated output current. Specifically, the exposed die attach pad of both the QFN and TSSOP packages must be soldered to the PC board. The PC board should be designed to maximize the conduction of heat out of the IC package, utilizing multiple vias from the die attach pad connection to a large area of exposed copper. If the die temperature exceeds approximately 165C, the IC will enter overtemperature shutdown and all switching will be inhibited. The part will remain disabled until the die cools by approximately 10C. The soft-start circuit is re-initialized in over temperature shutdown to provide a smooth recovery when the fault condition is removed. Applications Information VCC Capacitor Selection PVOUT VOUT The VCC output on the LTC3119 is generated from the input voltage by an internal low dropout regulator. The VCC regulator has been designed for stable operation with a wide range of output capacitors. For most applications, a 4.7F low ESR ceramic capacitor is a good choice. The capacitor should connect to the VCC pin and ground through the shortest traces possible. Bootstrapping the VCC Regulator For output voltages between 4.5V and 6V, the VCC regulator can be held up using a diode from VOUT to VCC as shown in Figure 6. The appropriate diode should be selected to ensure that the output voltage, less the diode forward voltage, is within the acceptable external forcing voltage of 4.2V to 5.5V. This may be accomplished through the use of Schottky diodes or silicon diodes. In either case, LTC3119 VCC 4.7F 3119 F06 Figure 6. Bootstrapping VCC to VOUT the diode should have sufficient current handling capability to drive the VCC pin. For applications that use an output voltage that is beyond the maximum ratings for the VCC pin (i.e. VOUT = 7V), a diode-OR can be used between the input voltage and output voltage to power the internal VCC regulator. This is accomplished by tying the diode-OR node to the VIN pin and connecting the PVIN pins to the input source. In this configuration, an additional bypass capacitor is required 3119fb 18 For more information www.linear.com/LTC3119 LTC3119 Applications Information between the VIN pin and GND in addition to the bypass capacitor located between PVIN and GND. This configuration is shown in Figure 7. VIN R1 LTC3119 RUN R2 GND 4.7F 3119 F08 VIN 0.25V TO 18V PVIN 4.7F VOUT > 6V PVOUT LTC3119 VCC 4.7F 3119 F07 Figure 7. Diode-OR of Input Supply and VOUT Powers VCC Regulator Programming Custom VIN UVLO Thresholds With the addition of an external resistive divider connected to VIN as shown in Figure 8, the RUN pin can be used to program the input voltage at which the LTC3119 is enabled and disabled. For a rising input voltage, the LTC3119 is enabled when VIN reaches a threshold given by the following equation, where R1 and R2 are the values of the resistor divider resistors: Figure 8. Setting the Input UVLO and Hysteresis Therefore, the rising UVLO threshold and the amount of hysteresis can be independently programmed via appropriate selection of resistors R1 and R2. For high levels of hysteresis the value of R1 can become larger than is desirable in a practical implementation. In such cases, the amount of hysteresis can be increased further through the addition of an additional resistor RH, as shown in Figure 9. When using the additional RH resistor, the rising RUN pin threshold remains as given by the original equation and the hysteresis is given by the following expression: R R2+RHR1+R1R2 0.25A + R1+R2 0.09V VHYST = H R2 R2 VIN R1+R2 VTH(RISING) = 1.205V R2 R1 RH LTC3119 RUN R2 To ensure robust operation in the presence of noise, the RUN pin has two forms of hysteresis. A fixed 90mV hysteresis within the RUN pin comparator provides hysteresis equal to 7.5% of the input turn-on voltage independent of the resistor divider values. In addition, an internal hysteresis current that is sourced from the RUN pin during operation generates an additive level of hysteresis which can be programmed by the value of R1 to increase the overall hysteresis to suit the requirements of specific applications. Once the IC is enabled, it will remain enabled until the input voltage drops below the comparator threshold by the hysteresis voltage, VHYST, as given by the following equation where R1 and R2 are the values of the voltage divider: R1+R2 * 0.09V VHYST =R1* 0.25A + R2 GND 3119 F09 Figure 9. Increasing Input UVLO hysteresis To improve the noise robustness and accuracy of the UVLO threshold, the RUN pin input can be filtered by adding a 470pF capacitor from RUN to GND. Larger valued capacitors should not be utilized because they could interfere with operation of the hysteresis. Switching Frequency Selection The switching frequency is set by the value of a resistor connected between the RT pin and ground. The switching frequency is related to the resistor value by the following equation where RT is the resistance: fSW = 100MHz 8 + (1.2* R T / k) 3119fb For more information www.linear.com/LTC3119 19 LTC3119 Applications Information Higher switching frequencies facilitate the use of smaller inductors as well as smaller input and output filter capacitors which results in a smaller solution size and reduced component height. However, higher switching frequencies also generally reduce conversion efficiency due to the increased switching losses. Output Capacitor Selection A low ESR output capacitor should be utilized at the buckboost converter output in order to minimize output voltage ripple. Multilayer ceramic capacitors are an excellent option as they have low ESR and are available in small footprints. The capacitor value should be chosen large enough to reduce the output voltage ripple to acceptable levels. Neglecting the capacitor ESR and ESL, the peak-to-peak output voltage ripple can be calculated by the following formulas, where fSW is the switching frequency, COUT is the output capacitance, tLOW is the switch pin minimum low time, and ILOAD is the output current. Curves for the value of tLOW as a function of VCC voltage and temperature can be found in Typical Performance Characteristics section of this data sheet. VP-P(BUCK ) @ ILOAD tLOW COUT VP-P(BOOST ) @ ILOAD VOUT - VIN + tLOW fSW VIN fSW COUT VOUT The output voltage ripple increases with load current and is generally higher in boost mode than in buck mode. These expressions only take into account the output voltage ripple that results from the output current being discontinuous. They provide a good approximation to the ripple at any significant load current but underestimate the output voltage ripple at very light loads where output voltage ripple is dominated by the inductor current ripple. In addition to output voltage ripple generated across the output capacitance, there is also output voltage ripple produced across the internal resistance of the output capacitor. The ESR-generated output voltage ripple is proportional to the series resistance of the output capacitor and is given by the following expressions where RESR is the series resistance of the output capacitor and all other terms are as previously defined. VP-P(BUCK ) @ ILOADRESR @I R 1- tLOW fSW LOAD ESR VP-P(BOOST ) @ V ILOADRESR VOUT @ILOADRESR OUT VIN (1- tLOW fSW ) VIN Input Capacitor Selection The PVIN pin carries the full inductor current and provides power to internal control circuits in the IC. To minimize input voltage ripple and ensure proper operation of the IC, a low ESR bypass capacitor with a value of at least 10F should be located as close to this pin as possible. The traces connecting this capacitor to PVIN and the ground plane should be made as short as possible. The VIN pin provides power to the VCC regulator and other internal circuitry. If the PCB trace connecting VIN to PVIN is long, it may be necessary to add an additional small value bypass capacitor near the VIN pin. When powered through long leads or from a high ESR power source, a larger value bulk input capacitor may be required. In such applications, a 47F to 100F electrolytic capacitor in parallel with a 1F ceramic capacitor generally yields a high performance, low cost solution. When powered through an inductive connection such as a long cable, the inductance of the power source and the input bypass capacitor form a high-Q resonant LC filter. In such applications, hot-plugging into a powered source can lead to a significant voltage overshoot, even up to twice the nominal input source voltage. Care must be taken in such situations to ensure that the absolute maximum input voltage rating of the LTC3119 is not violated. See Linear Technology Application Note 88 for solutions to increase damping in the input filter and minimize this voltage overshoot. Inductor Selection The choice of inductor used in LTC3119 application circuits influences the maximum deliverable output current, the converter bandwidth, the magnitude of the inductor current ripple and the overall converter efficiency. The inductor must have a low DC series resistance, when compared to the 3119fb 20 For more information www.linear.com/LTC3119 LTC3119 Applications Information internal switch resistance (30m), or output current capability and efficiency will be compromised. Larger inductor values reduce inductor current ripple but may not increase output current capability as is the case with peak current mode control as described in the Maximum Output Current section. Larger value inductors also tend to have a higher DC series resistance for a given case size, which will have a negative impact on efficiency. Larger values of inductance will also lower the right half plane zero (RHPZ) frequency when operating in boost mode, which can compromise loop stability. Nearly all LTC3119 application circuits deliver the best performance with an inductor value between 1.5H and 15H. Buck mode only applications can use the larger inductor values as they are unaffected by the RHPZ, while mostly boost applications generally require inductance on the lower end of this range depending on how large the step-up ratio is. Regardless of inductor value, the saturation current rating should be selected such that it is greater than the worst case average inductor current plus half of the ripple current. The peak-to-peak inductor current ripple for each operational mode can be calculated from the following formula, where fSW is the programmed switching frequency, L is the inductance and tLOW is the switch pin minimum low time, typically 90ns. V -V 1 V IL(P-P )(BUCK ) @ OUT IN OUT - tLOW L VIN fSW IL(P-P )(BOOST ) @ VIN VOUT - VIN 1 - t LOW L VOUT fSW It should be noted that the worst-case peak-to-peak inductor ripple current occurs when the duty cycle in buck mode is minimum (highest VIN) and in boost mode when the duty cycle is 50% (VOUT @ 2 * VIN). As an example, if VIN (minimum) = 2.5V and VIN (maximum) = 15V, VOUT = 5V, fSW = 1MHz and L = 4.7H, the peak-to-peak inductor ripples at the voltage extremes (15V VIN for buck and 2.5V VIN for boost) are: 5 15- 5 IL (P-P )(BUCK ) @ * 910ns = 645mA 4.7H 15 2.5 5- 2.5 IL (P-P )(BOOST ) @ * 910ns = 242mA 4.7H 5 One half of this inductor ripple current must be added to the highest expected average inductor current in order to select the proper saturation current rating for the inductor. Programming the Output Voltage The output voltage is set via the external resistive divider comprised of resistors RTOP and RBOT as shown in Figure 4. The resistor divider values determine the output regulation voltage according to: R VOUT = 0.795V * 1+ TOP RBOT Programming the MPPC Voltage The LTC3119 includes an MPPC function to optimize performance when operating from current limited input sources. Using an external voltage divider from VIN (refer to Figure 5), the MPPC function takes control of the average inductor current when necessary to maintain a minimum input voltage VMPPC, as programmed by the user. R5 VMPPC = 0.798V * 1+ R6 This is useful for such applications as photovoltaic powered converters, since the maximum power transfer point occurs when the photovoltaic panel is operated at approximately 75% of its open-circuit voltage. For example, when operating from a photovoltaic panel with an open-circuit voltage of 10V, the maximum power transfer point will be when the panel is loaded such that its output voltage is about 7.5V. When using the MPPC function, the input capacitor should be sized between 100F and 470F. Resistor R6 should be chosen between 50k and 250k. Lower values will result in smaller undershoot of the MPPC tracking point during line and load transient conditions, but will draw more current from the input supply. For this example, a value of 100k will be used. V 7.5 R5 = MPPC -1 * R6 = -1 * 100k 0.798 0.798V = 838k @ 845k 3119fb For more information www.linear.com/LTC3119 21 LTC3119 Applications Information The MPPC loop requires compensation to maintain stability of the input voltage regulation loop. This can be accomplished by means of a pole-zero pair on the MPPC pin created with a series RC network in parallel with the lower MPPC resistor R6. The pole and zero locations should be selected to create a low frequency pole at or below approximately 360Hz and a zero at a frequency that is scaled based on the size of the input capacitor. The equations for determining the values for the compensation capacitor CC2, and zero resistor RC2 are: CC2 = 1 2 * R6 * 360Hz The LTC3119 incorporates an average current mode control architecture which consists of two control loops. Both the inner average current mode control loop and outer control loop require compensation to maintain stability. The inner current mode control loop is internally compensated to maintain wide bandwidth and good transient response. For many applications, the inner current loop can be treated like a voltage controlled current source (VCCS). This current source is commanded by the voltage error amplifier to regulate the output load formed primarily by the load resistance (RLOAD) and output capacitor (COUT). This simplified version is illustrated in Figure 10, showing the key components that need to be considered when compensating the converter. VOLTAGE CONTROLLED CURRENT SOURCE + - Using the divider values determined previously, and a 220F input capacitor, the following compensation values are obtained: 1 = 4.42nF @ 4.7nF 2*100k*360Hz 220F RC2 = = 7.45k @ 7.50k 2* 4.7nF VOLTAGE LOOP ERROR AMP gm VOUT FB 0.795V COUT RTOP RBOT RCOSER RLOAD VC gm = 10.8A/V 0.96V GND RZ CP2 CP1 3119 F10 Figure 10. Simplified Representation of Control Loop Components The bandwidth of the output voltage control loop should be set low enough to avoid the small signal effects of the inner current loop. The maximum loop bandwidth is determined using the inductor value to be approximately: FVLOOP CIN RC2 = 2 * CC2 CC2 = Compensation of the Buck-Boost Converter + - Using these resistor values, the MPPC function is programmed to control the maximum input current so as to maintain VIN at a minimum of 7.56V. Note that if the photovoltaic panel can provide more power than the LTC3119 can draw or the load requires, the input voltage will rise above the programmed MPPC point. Higher input voltages do not present a problem so long as the input voltage does not exceed the maximum operating input voltage. For photovoltaic panel applications, it may be also desirable to use the programmable RUN feature to disable the part when VIN drops too low due to lack of sufficient light. Using the RUN pin provides a well controlled behavior when the input power source is dropping out. Preventing switching while under these conditions is important to minimize discharging of the output storage element due to switching while the input source is dropping out. This custom input UVLO voltage should be programmed to be below the MPPC tracking voltage with sufficient margin to ensure the part does not disable under transient conditions. (4.7H *100kHz) 10 *L With a full-scale command on VC, the LTC3119 buckboost converter will generate an average inductor current of 8A. With a VC voltage range of 220mV to 960mV, the resulting current gain for the inner average current loop is 10.8A/V. Similar to peak current mode control, the inner average current mode control loop effectively turns the inductor into a current source over the frequency range of interest, resulting in a frequency response from the 3119fb 22 For more information www.linear.com/LTC3119 LTC3119 Applications Information power stage that exhibits a single pole (-20dB/decade) roll off. The output capacitor (COUT) and load resistance (RLOAD) form the normally dominant low frequency pole and the effective series resistance of the output capacitor and its capacitance form a zero, usually at a high enough frequency to be ignored. A potentially troublesome right half plane zero (RHPZ) is also encountered if the LTC3119 is operated in boost mode. The RHPZ causes an increase in gain, like a zero, but a decrease in phase, like a pole. This will ultimately limit the maximum converter bandwidth that can be achieved with the LTC3119. The RHPZ is not present when operating in buck mode. The overall open loop gain at DC is the product of the following terms: Voltage Error Amplifier Gain: GEA = gm * REA = 120S * 5M = 600 Voltage Divider Gain: VFB 0.795V = VOUT VOUT Current Loop Transconductance: GCS = 8A = 10.8A / V 0.74V It is important to note that GCS is the transconductance gain from the control voltage VC to the inductor current level, which equals the output current level in buck mode. In boost mode, the output current level will be reduced by the efficiency divided by the boost ratio. Refer to the typical curves for efficiency information. GCS(OUT) = 10.8A / V GCS(OUT) = 10.8A / V * (Buck Mode) VIN *Eff VOUT (Boost Mode) Frequency dependent terms that affect the loop gain include: Output Load Pole (P1) fP1 = 1 2*RLOAD *COUT Error Amplifier Compensation (P2, Z1) fP2 = 1 Hz (close to DC) 2 * REA C P1 fZ1 = 1 Hz 2*R ZCP1 Right Half Plane Zero (RHPZ) fRHPZ = VIN 2 *RLOAD VOUT 2 *2*L Hz In some cases it may not be possible to achieve sufficient loop bandwidth and phase margin using a simple RC network connected to the VC pin. In these cases, additional compensation may be required. This is accomplished by the addition of a feed forward RC network in parallel with the top resistor of the feedback divider. A small feed forward capacitor alone may be sufficient in some applications. A common situation that may require a feed forward network is when the converter is operating in boost mode and the closed loop crossover frequency (fCC) is close the Right Half Plane Zero (RHPZ). This may be done in order to reduce output capacitance requirements by increasing the loop bandwidth. Due to the phase additions of the RHPZ, a simple compensator on the VC pin may not be able to provide sufficient phase boost to stabilize the loop. Compensation Example This section will demonstrate how to derive and select the compensation components for a 5V output supplying 2A from an input voltage as low as 3V. Designing compensation for most other applications is simply a matter of substituting in different values to the equations given in the example and reviewing the resulting Bode Plot, adjusting as needed. Since the compensation design procedure uses a simplified model of the LTC3119, results should be checked using time domain step response tests to validate the effectiveness of the compensation chosen. It is assumed that values and types for capacitors and the inductor will be selected based on the guidance given elsewhere in this data sheet. Particular attention should 3119fb For more information www.linear.com/LTC3119 23 LTC3119 Applications Information be paid to voltage biasing effects on capacitors used for input and output bypassing. Similarly, it is assumed that inductor values and current ratings are selected based on application requirements. Example Operating Conditions: VIN = 3V to 15V ILOAD(MAX) = 2A COUT = 150F Using this information, the gain and phase contributions from the output filter are calculated. L = 3.3H fSW = 1MHz First it is necessary to determine the lowest frequency for fRHPZ. This will determine the maximum bandwidth that can safely be configured for the converter while operating in boost mode. fRHPZ = VOUT 2 * 2 * L = 43.4kHz In order to ensure sufficient safety margin, a closed loop crossover frequency (fCC) should be sufficiently below the RHPZ frequency to account for variability of the internal components of the IC as well as variability of external influences on the converter response at the cost of possibly higher loop bandwidth. If sufficient phase margin exists at the crossover frequency, a higher loop bandwidth may be realizable while still maintaining stability and good transient response. In this example, we will use cross over frequency equal to one sixth of the RHPZ frequency. fCC = Looking in the Typical Curves section, we find the efficiency to be roughly 77%. Using this information, the effective output current gain can be calculated. V GCS(OUT) = GCS * IN * Eff = 4.99 A V VOUT VOUT = 5V VIN 2 * RLOAD Since the converter will be operating in boost mode, the GCS term must be scaled to represent the commanded output current. fRHPZ @7.24kHz 6 The RHPZ will have a negligible effect on the gain at the loop crossover, however it will have a phase contribution that must be considered. fcc = tan-1 1 = 9.5o RHPZ = tan-1 6 fRHPZ GOUT = GCS(OUT) * RLOAD 2 = 0.729 fCC 2 fP1 +1 fcc = tan-1 7240 = 86.5 P1 = tan-1 424 fP1 Choosing a phase margin of 50 degrees, the required phase boost from the compensation network is determined by summing together the phase contributions that were calculated above. A phase contribution of 90 is assumed for P2. Z1 = 50 +P2 +P1 +RHPZ -180 = 56 The compensation network gain is used to adjust the loop gain to crossover at the desired frequency. Using the feedback divider gain and output gain, the compensation network gain is calculated. -1 V REF GCOMP = * GOUT = 8.57 VOUT The compensation network resistor is then found using the error amplifier transconductance and the required compensation gain found above. RZ = GCOMP 8.57 = = 71.4k gm 120s 3119fb 24 For more information www.linear.com/LTC3119 LTC3119 Applications Information With the value of RZ now known, the compensation capacitor can be chosen to place the zero Z1 in the correct location. CP1 = tan ( Z1) = 455pF 2 * fCC * R Z Selecting standard value components, values of RZ = 71.5k and CP1 = 470pF are used. PCB Layout Considerations The LTC3119 buck-boost converter switches large currents at high frequencies. Special attention should be paid to the PC board layout to ensure a stable, noise-free and efficient application circuit. Figures 11 and 12 show a representative PCB layout for each package option to outline some of the primary considerations. A few key guidelines are provided below: 1. The parasitic inductance and resistance of all circulating high current paths should be minimized. This can be accomplished by keeping the routes to all bold components in Figures 11 and 12 as short and as wide as possible. Capacitor ground connections should via down to the ground plane by way of the shortest route possible. The bypass capacitors on PVIN, PVOUT and VCC should be placed as close to the IC as possible and should have the shortest possible paths to ground. 2. The exposed pad is the electrical ground connection for the LTC3119. Multiple vias should connect the back pad directly to the ground plane. In addition, maximization of the metallization connected to the back pad will improve the thermal environment and improve the power handling capabilities of the IC in both the FE and UFD packages. 3. There should be an uninterrupted ground plane under the entire converter in order to minimize the crosssectional area of the high frequency current loops. This minimizes EMI and reduces the inductive drops in these loops thereby minimizing SW pin overshoot and ringing. 4. Connections to all of the components shown in bold should be made as wide as possible to reduce the series resistance. This will improve efficiency and maximize the output current capability of the buckboost converter. 5. To prevent large circulating currents in the ground plane from disrupting operation of the LTC3119, all small-signal grounds should return directly to GND by way of a dedicated Kelvin route. This includes the ground connection for the RT pin resistor, and the ground connection for the feedback network as shown in Figures 11 and 12. 6. Keep the routes connecting to the high impedance, noise sensitive inputs FB and RT as short as possible to reduce noise pick-up. 3119fb For more information www.linear.com/LTC3119 25 LTC3119 Applications Information N/C 1 28 PWM/SYNC N/C 2 27 N/C BST2 3 26 BST1 PGND 4 25 PGND SW2 5 24 SW1 PVOUT 6 23 PVIN PVOUT 7 22 PVIN SW2 8 21 SW1 PGND 9 20 PGND PGOOD 10 KELVIN TO VOUT 19 VIN SVCC 11 FB 12 RTOP RBOT 18 RUN RT 17 VC 13 SGND RT 16 VCC 14 15 MPPC UNINTERRUPTED GROUND PLANE SHOULD EXIST UNDER ALL COMPONENTS SHOWN IN BOLD AND UNDER TRACES CONNECTING TO THOSE COMPONENTS VIA TO GROUND PLANE (AND TO INNER LAYER WHERE SHOWN) 3119 F11 23 BST1 24 N/C 25 PWM/SYNC 26 N/C 27 N/C 28 BST2 Figure 11. PCB Layout Recommended for the FE Package PGND 1 22 PGND PVOUT 4 19 PVIN SW2 5 18 SW1 PGND 6 17 PGND PGOOD 7 16 VIN SVCC 8 15 RUN SGND MPPC 12 FB KELVIN TO VOUT VCC 13 RT 14 20 PVIN 11 21 SW1 3 VC 10 2 9 SW2 PVOUT RT RBOT UNINTERRUPTED GROUND PLANE SHOULD EXIST UNDER ALL COMPONENTS SHOWN IN BOLD AND UNDER TRACES CONNECTING TO THOSE COMPONENTS VIA TO GROUND PLANE (AND TO INNER LAYER WHERE SHOWN) 3119 F12 Figure 12. PCB Layout Recommended for the UFD Package 3119fb 26 For more information www.linear.com/LTC3119 LTC3119 Typical Applications 3.3V, 400kHz Wide Input Regulator 3.3H 0.1F 0.1F SW1 BST1 VIN 2.5V TO 18V 10F SW2 BST2 PVIN VIN 100k 220F LTC3119 RUN PWM/SYNC MPPC VCC SVCC RT 22pF 316k FB PGOOD PGND GND 100k VC 39.2k 3119 TA03 4.7F VOUT 3.3V PVOUT 200k 560pF VIN = 2.5; IOUT = 2.4A; EFFICIENCY = 78% VIN = 5.0; IOUT = 5A; EFFICIENCY = 84% 3.3V, 750kHz Wide Input Regulator 3.3H 0.1F 0.1F SW1 BST1 VIN 2.5V TO 18V 10F 100k SW2 BST2 PVIN VIN PVOUT 330F LTC3119 RUN PWM/SYNC MPPC VCC SVCC RT 316k FB PGOOD PGND GND 4.7F 100k VC 3119 TA04 105k VOUT 3.3V 80.4k 560pF VIN = 2.5; IOUT = 2A; EFFICIENCY = 78% VIN = 5.0; IOUT = 5A; EFFICIENCY = 82% 3119fb For more information www.linear.com/LTC3119 27 LTC3119 Typical Applications 3.3V, 1.5MHz Wide Input Regulator 2.2H 0.1F 0.1F SW1 BST1 VIN 2.5V TO 18V 10F 100k SW2 BST2 PVIN VIN PVOUT 150F LTC3119 RUN 316k PWM/SYNC MPPC VCC SVCC RT FB PGOOD PGND GND 100k VC 3119 TA05 4.7F VOUT 3.3V 52.3k 48.7k 470pF VIN = 2.5; IOUT = 1.75A; EFFICIENCY = 73% VIN = 5.0; IOUT = 5A; EFFICIENCY = 80% 3.3V, 500kHz Wide Input Regulator 4.7H 0.1F VIN 1.3V TO 18V STARTS AT 2.5V 0.1F SW1 BST1 10F 100k SW2 BST2 PVIN VIN PVOUT 220F LTC3119 RUN PWM/SYNC MPPC VCC SVCC RT 4.7F FB PGOOD PGND GND VC 3119 TA06 162k 316k VOUT 3.3V AT 5A, VIN > 4V 3.3V AT 1A, VIN = 1.6V 100k 78.7k 820pF 3119fb 28 For more information www.linear.com/LTC3119 LTC3119 Typical Applications 5V, 500kHz Wide Input Regulator 4.7H 0.1F 0.1F SW1 BST1 VIN 2.5V TO 18V 10F SW2 BST2 PVIN VIN 100k 220F LTC3119 RUN 536k PWM/SYNC MPPC VCC SVCC RT FB PGOOD PGND GND 102k VC 3119 TA07 4.7F VOUT 5.0V PVOUT 100k 162k 560pF VIN = 2.5; IOUT = 1.5A; EFFICIENCY = 78% VIN = 6.0; IOUT = 5A; EFFICIENCY = 88% 5V, 1MHz Wide Input Regulator 2.2H 0.1F 0.1F SW1 BST1 VIN 2.5V TO 18V 10F 100k SW2 BST2 PVIN VIN RUN PVOUT 150F LTC3119 VOUT 5.0V 536k PWM/SYNC MPPC VCC SVCC RT FB PGOOD PGND GND 3119 TA08 4.7F 76.8k 102k VC 127k 330pF VIN =2.5; IOUT = 1.2A; EFFICIENCY = 73% VIN =6.0; IOUT = 5A; EFFICIENCY = 83% 3119fb For more information www.linear.com/LTC3119 29 LTC3119 Typical Applications 5V, 2MHz Wide Input Regulator 12V to 12V, 1MHz Line Conditioner with 8.5V Undervoltage Lockout Threshold 1.5H 2.2H 0.1F VIN 2.5V TO 18V 10F 100k SW1 BST1 SW2 BST2 PVIN VIN PVOUT 100F LTC3119 RUN PWM/SYNC MPPC VCC SVCC RT 0.1F VOUT 5.0V VIN 9V TO 15V RUN 10F MPPC VCC SVCC RT PGOOD PGND GND 102k 34.8k 124k 4.7F 270pF SW1 BST1 8.0 SW2 BST2 PVIN VIN 47F VOUT 12V 1370k FB PGOOD GND VC 3119 TA11 34.8k FB PGOOD PGND GND 97.6k VC 100k 180pF 97.6k 155k 350pF PULSED LOAD CONTINUOUS LOAD 7.0 0.1F PVOUT LTC3119 RUN PWM/SYNC MPPC VCC SVCC RT PGND 4.7F 1370k Maximum Output Current VOUT = 12V OUTPUT CURRENT (A) 100k VOUT 12.0V VIN = 9; IOUT =3A; EFFICIENCY = 92.5% VIN = 13; IOUT =5A; EFFICIENCY = 93.5% ENABLE AT VIN > 8.5V 1.5H 10F 47F LTC3119 76.8k 12V, 2MHz Wide Input Regulator VIN 2.5V TO 18V PVOUT 3119 TA10 VIN = 2.5; IOUT = 1A; EFFICIENCY = 70% VIN = 6.0; IOUT = 4.5A; EFFICIENCY = 80% 0.1F 0.1F SW2 BST2 PWM/SYNC 200k FB VC SW1 BST1 PVIN VIN 1210k 536k 3119 TA09 4.7F 0.1F 6.0 5.0 4.0 3.0 2.0 DC2129A DEMO BOARD fSW = 2MHz 100Hz PULSE LOAD 20% DUTY CYCLE 1.0 0 2 4 6 8 10 12 14 INPUT VOLTAGE (V) 16 18 3119 TA11b 3119fb 30 For more information www.linear.com/LTC3119 LTC3119 Typical Applications 12V, 750kHz Regulator with Input Supply Rundown 3.3H 4.7F 0.1F 0.1F SW1 BST1 PVIN VIN SW2 BST2 VIN 4.22M 1.87M 4700F FB MPPC VCC PGOOD SVCC VC RT PGND GND VIN (ENABLE) = 5V VIN (DISABLE) = 0V 80k 3119 TA12a 4.7F 105k 1370k 97.6k 2200pF Rundown Behavior After Input Disconnect Output Holdup Time vs Input Bulk Capacitor Size 150 ILOAD = 300mA ILOAD = 600mA 125 HOLDUP TIME (ms) INDUCTOR CURRENT 1.0A/DIV 47F LTC3119 VOUT 12V PWM/SYNC 604k 4.7F RUN PVOUT VOUT 10V/DIV VIN 10V/DIV INPUT SUPPLY REMOVED 20ms/DIV 3119 TA12b 100 75 50 25 2 4 6 8 10 INPUT BULK CAPACITANCE (mF) 12 3119 TA12c 3119fb For more information www.linear.com/LTC3119 31 LTC3119 Typical Applications Selectable 12V or 3.3V Output, 1MHz Regulator 3.3H 0.1F VIN 5V TO 18V 10F 100k SW1 BST1 PVIN VIN RUN BURST PWM 0.1F VOUT SELECTABLE VOUT = 3.3V/12V, IOUT = 2A PVOUT VIN 100F LTC3119 1400k PWM/SYNC MPPC VCC SVCC RT 4.7F SW2 BST2 FB PGOOD PGND GND 442k 130k VC 60k GPIO 76.8k 1200pF VOUT SELECT 12V 3.3V 741G05 500k GPIO 3119 TA13a Output Voltage Transition 3.3V to 12V VOUT = 3.3V/12V fSW = 1MHz VOUT SELECT 5V/DIV VOUT 10V/DIV PGOOD 10V/DIV 200s/DIV 3119 TA13b 3119fb 32 For more information www.linear.com/LTC3119 LTC3119 Package Description Please refer to http://www.linear.com/product/LTC3119#packaging for the most recent package drawings. UFD Package 28-Lead Plastic QFN (4mm x 5mm) (Reference LTC DWG # 05-08-1712 Rev C) 0.70 0.05 4.50 0.05 3.10 0.05 2.50 REF 2.65 0.05 3.65 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 3.50 REF 4.10 0.05 5.50 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 0.10 (2 SIDES) 0.75 0.05 R = 0.05 TYP PIN 1 NOTCH R = 0.20 OR 0.35 x 45 CHAMFER 2.50 REF R = 0.115 TYP 27 28 0.40 0.10 PIN 1 TOP MARK (NOTE 6) 1 2 5.00 0.10 (2 SIDES) 3.50 REF 3.65 0.10 2.65 0.10 (UFD28) QFN 0816 REV C 0.200 REF 0.00 - 0.05 0.25 0.05 0.50 BSC BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGHD-3). 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 3119fb For more information www.linear.com/LTC3119 33 LTC3119 Package Description Please refer to http://www.linear.com/product/LTC3119#packaging for the most recent package drawings. FE Package 28-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1663 Rev K) Exposed Pad Variation EA 9.60 - 9.80* (.378 - .386) 7.56 (.298) 7.56 (.298) 28 2726 25 24 23 22 21 20 19 18 1716 15 6.60 0.10 4.50 0.10 3.05 (.120) SEE NOTE 4 0.45 0.05 EXPOSED PAD HEAT SINK ON BOTTOM OF PACKAGE 6.40 3.05 (.252) (.120) BSC 1.05 0.10 0.65 BSC RECOMMENDED SOLDER PAD LAYOUT 4.30 - 4.50* (.169 - .177) 0.09 - 0.20 (.0035 - .0079) 0.25 REF 1.20 (.047) MAX 0 - 8 0.65 (.0256) BSC 0.50 - 0.75 (.020 - .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE IN MILLIMETERS (INCHES) 3. DRAWING NOT TO SCALE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.195 - 0.30 (.0077 - .0118) TYP 0.05 - 0.15 (.002 - .006) FE28 (EA) TSSOP REV K 0913 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE 3119fb 34 For more information www.linear.com/LTC3119 LTC3119 Revision History REV DATE DESCRIPTION A 02/17 Added Maximum Output Current Curves PAGE NUMBER B 03/17 Modified Schematic 10, 11, 30 32, 36 Modified BST2 pin description 12 Output Capacitor Selection, changed switching frequency to VCC voltage 20 Modified Voltage Error Amplifier Gain equation 23 3119fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. For more information www.linear.com/LTC3119 35 LTC3119 Typical Application Photovoltaic Panel Input Lead-Acid Charger with Temperature Correction (1MHz) 4.7H 0.1F SW1 BST1 VIN 220F 1020k SW2 BST2 PVIN VIN 100k RUN PHOTOVOLTAIC PANEL V(MPP) = 9V PVOUT 10F LTC3119 PWM/SYNC 4.7nF MPPC VCC SVCC RT 100k 7.5k PGOOD PGND GND 6-CELL LEAD-CELL BATTERY 2000k NTC 68k FB 220k TEMPERATURE COMPENSATION VC 3119 TA02 4.7F 0.1F 52.3k 76.8k 127k 5.6nF Related Parts PART NUMBER DESCRIPTION COMMENTS LTC3113 5V, 3A Synchronous Buck-Boost VIN = 1.8V to 5.5V, VOUT = 1.8V to 5.25V, IQ = 30A, ISD < 1A, DFN and TSSOP Packages LTC3129/ LTC3129-1 15V, 200mA Synchronous Buck-Boost with 1.3A IQ VIN = 2.42V to 15V, VOUT = 2.5V to 14V, IQ = 1.3A, ISD = 10nA, QFN and MSOP Packages LTC3112 15V, 2.5A Synchronous Buck-Boost VIN = 2.7V to 15V, VOUT = 2.5V to 14V, IQ = 40A, ISD < 1A, DFN and TSSOP Packages LTC3118 18V, 2A Dual Input PowerPathTM Buck-Boost Converter VIN = 2.2V to 18V, VOUT = 2V to 14V, IQ = 50A, ISD < 2A, QFN and TSSOP Packages LTC3130/ LTC3130-1 25V, 600mA Synchronous Buck-Boost Converter VIN = 2.4V to 25V, VOUT = 1V to 25V, IQ = 1.2A, ISD = 500nA LTC3114-1 40V, 1A Synchronous Buck-Boost VIN = 2.2V to 40V, VOUT = 2.7V to 15V, IQ = 30A, ISD < 3A, DFN and TSSOP Packages LTC3115-1/ LTC3115-2 40V, 2A Synchronous Buck-Boost VIN = 2.7V to 40V, VOUT = 2.7V to 40V, IQ = 30A, ISD < 3A, DFN and TSSOP Packages LTC3785 10V, High Efficiency, Synchronous, No RSENSETM Buck-Boost Controller VIN = 2.7V to 10V, VOUT = 2.7V to 10V, IQ = 86A, ISD < 15A, QFN Package LTC3789 38V, High Efficiency, Synchronous, 4-Switch Buck-Boost Controller VIN = 4V to 38V, VOUT = 0.8V to 38V, IQ = 3mA, ISD < 60A, SSOP-28, QFN-28 Packages LT3790 60V, Synchronous, 4-Switch Buck-Boost Controller VIN = 4.7V to 60V, VOUT = 1.2V to 60V, IQ = 3mA, ISD < 1A, TSSOP Package QFN and MSOP Packages 3119fb 36 LT 0317 REV B * PRINTED IN USA For more information www.linear.com/LTC3119 www.linear.com/LTC3119 LINEAR TECHNOLOGY CORPORATION 2016