Low IQ, 60V Monolithic Boost/Sepic/Inverting Converter in ThinSOT or 3mm x 2mm DFN Owen Jong The LT8330 monolithic DC/DC converter enables boost, SEPIC or inverting topologies in a low profile 6-lead ThinSOT™ or an 8-lead (3mm × 2mm) DFN package. It meets the demand for small, efficient power supply solutions with a 3V-to-40V input range, internal 1A, 60V switch and 6µA quiescent current. It easily satisfies the requirements of numerous industrial and automotive applications. power switches and fast switching times with low AC losses. The low minimum on- and off-times of the power switch allow a wide range of duty cycles at the high 2MHz switching frequency, reducing the cost and size of the required magnetic components and capacitors. VIN 12V Figure 1. 12V to 48V boost converter and efficiency L1 6.8µH C1 4.7µF VIN 100 D1 C3 4.7µF SW VOUT 48V 135mA LT8330 INTVCC FBX GND R2 34.8k C2 1µF Figure 2. 8V–16V to 24V boost converter and efficiency VIN 8V TO 16V L1 6.8µH C1 4.7µF R3 1M R4 287k VIN C2 1µF 10 | February 2016 : LT Journal of Analog Innovation FBX GND 70 50 BOOST: VOUT = 48V VIN = 12V 0 40 80 120 LOAD CURRENT (mA) 160 100 D1 LT8330 EN/UVLO 80 60 D1: NXP PMEG6010CEJ L1: WÜRTH WE-MAPI 3015 74438335068 C3: MURATA GRM32ER71H475k VOUT 24V C3 4.7µF 210mA AT VIN = 8V 320mA AT VIN = 12V 450mA AT VIN = 16V SW INTVCC C4 4.7pF R1 1M EN/UVLO 90 EFFICIENCY (%) The LT®8330 is the first in a new family of monolithic boost/SEPIC/inverting converters that take advantage of new design techniques and a new process technology to achieve low output ripple Burst Mode® operation, rugged Overall converter design is simplified, and parts count is minimized by using internal compensation. Positive or negative output voltages are easily programmed using a resistor divider from the output to a single FBX pin. Integrated frequency foldback and soft-start allow the output capacitor to be charged gradually toward its final value during start-up while limiting inductor peak currents. Undervoltage lockout can be programmed for the input supply using an accurate EN/UVLO pin threshold. R1 1M C4 4.7pF R2 71.5k 90 EFFICIENCY (%) NEW FAMILY OF SPACE-SAVING MONOLITHIC CONVERTERS EASY TO USE 80 70 BOOST : VOUT = 24V D1: DIODES INC. SBR140S3 L1: WÜRTH WE-MAPI 3015 74438335068 C3: MURATA GRM32ER71H475k 60 50 VIN = 8V VIN = 12V VIN = 16V 0 100 200 300 400 LOAD CURRENT (mA) 500 design features Summary of ThinSOT monolothic boost/inverting/SEPIC converters PART V IN IQ f SW POWER SWITCH PACKAGE LT8330 3V–40V 6μA 2.0MHz 1A/60V DMOS ThinSOT–6 3mm × 2mm DFN LT1615/17 1.1V–15V 20μA constant off-time 0.3A/36V NPN ThinSOT–5 LT1613/11 1.1V–10V 3mA 1.4MHz 0.55A/36V NPN ThinSOT–5 LT1930/31 LT1930A/31A 2.6V–16V 5.5mA 1.2MHz 2.2MHz 1A/36V NPN ThinSOT–5 1.1A/40V NPN ThinSOT–6 3mm × 2mm DFN 2A/40V NPN ThinSOT–5 LT3467 LT3467A 2.6V–16V 1.2mA 1.3MHz 2.1MHz LT1935 2.6V–16V 3mA 1.2MHz achieve a very high step-up ratio. When configured in continuous conduction mode (CCM), the LT8330 is capable of delivering higher output power. 12V Input to 48V Output Boost The converter in Figure 1 operates from a 12V input supply to generate 48V at up to 6.5W at 90% peak efficiency. 8V–16V Input to 24V Output Boost Figure 2 shows a 24V boost converter, powered from an 8V-to-16V input. It is capable of delivering up to 10.8W at an efficiency of 94%. PIN COMPATIBILITY BOOST CONVERTERS 3V–6V to 48V Boost The LT8330 is pin compatible with LT3467/67A for those applications requiring higher input voltage or higher switch voltage (LT3467/67A SS pin becomes INTVCC pin). For applications requiring output voltages greater than the input, the 3V-to-40V input capability and internal 60V/1A power switch make LT8330 an attractive choice for many boost converter applications. Figure 3 shows the LT8330 configured to operate in discontinuous conduction mode (DCM) to achieve a 16:1 step up ratio. This 48V boost converter maintains an efficiency of 75% when loaded at 14m A (for a 6V input voltage). In some of the applications shown here, the converter is operated in discontinuous conduction mode (DCM) to C1 4.7µF VIN VOUT 48V C3 4.7µF 12mA AT VIN = 3V 13mA AT VIN = 5V 14mA AT VIN = 6V SW LT8330 R1 1M EN/UVLO FBX GND INTVCC R2 34.8k C2 1µF C5 1µF L1 6.8µH VIN 8V TO 30V Figure 4. 8V–30V to 24V SEPIC converter and efficiency C1 4.7µF VIN R4 287k INTVCC C2 1µF FBX GND 70 60 50 40 30 BOOST : VOUT = 48V 20 D1: NXP PMEG6010CEJ L1: WÜRTH WE-MAPI 3012 744383340068 C3: MURATA GRM32ER71H475k VIN = 3V VIN = 5V VIN = 6V 10 0 0 2 4 6 8 10 12 LOAD CURRENT (mA) 14 16 100 VOUT 24V C3 4.7µF 160mA AT V IN = 8V 200mA AT V IN = 12V ×2 250mA AT V IN = 24V 250mA AT V IN = 30V SW LT8330 EN/UVLO 80 D1 L2 6.8µH R3 1M 90 R1 1M C4 4.7pF 90 EFFICIENCY (%) Figure 3. 3V–6V to 48V boost converter and efficiency 100 D1 EFFICIENCY (%) L1 0.68µH VIN 3V TO 6V 80 70 SEPIC: VOUT = 24V VIN = 8V VIN = 12V VIN = 24V VIN = 30V 60 R2 71.5k D1: NXP PMEG6010CEJ L1: WÜRTH WE-TDC 8038 74489440068 C3: MURATA GRM32ER71H475k 50 0 60 120 180 240 LOAD CURRENT (mA) 300 February 2016 : LT Journal of Analog Innovation | 11 The LT8330 is ideal for applications requiring efficient power supply solutions in a compact space. The LT8330’s 3V-to-40V input voltage range and 60V/1A rugged power switch enable a wide variety of boost/SEPIC/inverting converter solutions. C5 1µF Figure 5. 4V–36V to 12V SEPIC converter and efficiency C1 4.7µF L2 4.7µH VIN R3 1M SW LT8330 EN/UVLO R4 806k R1 1M FBX GND INTVCC C5 1µF L1 6.8µH C1 4.7µF Figure 6. 8V–30V to −24V Cuk converter and efficiency R2 154k VIN INTVCC C2 1µF 12 | February 2016 : LT Journal of Analog Innovation C3 2.2µF R1 1M FBX GND 80 70 SEPIC: V OUT = 12V VIN = 4V VIN = 12V VIN = 24V VIN = 36V 50 0 60 120 180 240 LOAD CURRENT (mA) 300 100 VOUT –24V 160mA AT VIN = 8V 200mA AT VIN = 12V 250mA AT VIN = 24V 250mA AT VIN = 30V 90 LT8330 R4 287k Automotive and industrial applications often operate from input voltages that are above and below the required output voltage. For applications where the DC/DC converter is required to both step-up and step-down its input, the SEPIC topology is commonly chosen. The SEPIC topology is also useful for applications that require output disconnect. This feature ensures no output voltage during shutdown and also tolerates output short-circuit faults since there is no DC path from output to input. The high 60V switch rating of the LT8330 and the low minimum on and off times of the power switch allow wide D1: NXP PMEG6010CEJ L1: WÜRTH WE-TDC 8038 74489440047 C3: MURATA GRM31CR61C475k SW EN/UVLO SEPIC CONVERTERS C4 4.7pF L2 6.8µH D1 R3 1M 90 60 C2 1µF VIN 8V TO 30V VOUT 12V C3 4.7µF 170mA AT VIN = 4V 270mA AT VIN = 12V ×2 280mA AT VIN = 24V 280mA AT VIN = 36V EFFICIENCY (%) VIN 4V TO 36V 100 D1 EFFICIENCY (%) L1 4.7µH C4 4.7pF 80 70 INVERTING: VOUT = –24V VIN = 8V VIN = 12V VIN = 24V VIN = 30V 60 R2 34.8k D1: NXP PMEG6010CEJ L1: WÜRTH WE-TDC 8038 74489440068 C3: MURATA GRM32ER71H475k input voltage ranges even at the high 2MHz switching frequency of the LT8330. 8V–30V Input to 24V Output SEPIC The circuit in Figure 4 shows a 24V SEPIC converter with a wide input range, delivering up to 6W at up to 86.6% efficiency. 4V–36V Input to 12V Output SEPIC Figure 5 shows another solution with a wide input range, with an operating input voltage that can be as low as 4V while delivering 2W of power at up to 85% efficiency. For input voltages above 24V, the circuit in Figure 5 can supply up to 3.4W. 50 0 60 120 180 240 LOAD CURRENT (mA) 300 CUK CONVERTERS Negative supplies are commonly used in today’s electronics. However, many applications only have a positive input voltage from which to operate. The LT8330, when configured in the Cuk inverting topology, can regulate from a positive input voltage that is above or below the magnitude of the negative output voltage. As with the SEPIC topology, the high 60V switch rating of the LT8330 and the low minimum on and off times of the power switch allow wide input voltage ranges even at the high 2MHz switching frequency of the LT8330. design features The LT8330, when configured in the Cuk inverting topology, can regulate from a positive input voltage that is above or below the magnitude of the negative output voltage. The low minimum on- and off-times of the power switch allow wide input voltage ranges even at the high 2MHz switching frequency of the LT8330. C1 4.7µF Figure 7. 4V–36V to −12V Cuk converter and efficiency VOUT –12V C3 4.7µF 170mA AT VIN = 4V 270mA AT VIN = 12V 280mA AT VIN = 24V 280mA AT VIN = 36V D1 R3 1M VIN SW LT8330 EN/UVLO R4 806k INTVCC FBX GND Figure 6 shows the LT8330 regulating a negative output voltage using the Cuk topology. This circuit delivers up to 6W of power and maintains its efficiency up to 87%. R2 71.5k D1: NXP PMEG6010CEJ L1: Coilcraft LPD5030-472MR C3: MURATA GRM21BR71C475k boost/SEPIC/inverting converter solutions. Its low output ripple burst mode capability allows efficiency to be maintained at light loads. The low minimum on- and off-times of the power switch allow operation at 2MHz to reduce component 4V–36V to −12V Cuk Converter A −12V output CUK converter is shown in Figure 7. This circuit has a wide input range and high efficiency operation— at up to 3.4W, it achieves a peak efficiency of 86%. 8V–40V to ±15V Figure 8 shows a dual output, +15V/−15V converter. This circuit has a wide input range and high efficiency operation—at up to 4.8W of power, it reaches a peak efficiency of 87%. CONCLUSION The LT8330 is ideal for applications requiring efficient power supply solutions in a compact space. The LT8330’s 3V-to-40V input voltage range and 60V/1A rugged power switch enable a wide variety of 70 INVERTING : VOUT = –12V VIN=4V VIN=12V VIN=24V VIN=36V R3 1M R4 287k SW 300 FBX GND C2 1µF D1, D2: NXP PMEG6010CEJ L1A, L1B, L1C: COILTRONICS VP4-0075 C3, C4: MURATA GRM32ER71H475k –VOUT –15V C3 4.7µF D1 LT8330 EN/UVLO INTVCC 120 180 240 LOAD CURRENT (mA) 120mA AT VIN = 8V LOAD 160mA AT VIN = 24V 170mA AT VIN = 40V L1B 6µH C5 1µF VIN 60 +VOUT +15V C4 4.7µF L1C 6µH C1 4.7µF 0 D2 Figure 8. 8V–40V to ±15V converter and efficiency L1A 6µH 50 sizing for compact power supply solutions in a tiny, low profile 6-lead ThinSOT, or an 8-lead (3mm × 2mm) DFN. n C6 1µF VIN 8V TO 40V 80 60 C2 1µF 8V–30V Input to −24V Output Cuk Converter C4 4.7pF R1 1M 90 EFFICIENCY (%) VIN 4V TO 36V 100 L2 4.7µH R1 1M 100 R2 56.2k 90 EFFICIENCY (%) C5 1µF L1 4.7µH 80 70 +VOUT = +15V –VOUT = –15V 60 50 VIN = 8V VIN = 24V VIN = 40V 0 40 80 120 160 LOAD CURRENT (mA) 200 February 2016 : LT Journal of Analog Innovation | 13