LT1618 Constant-Current/ Constant-Voltage 1.4MHz Step-Up DC/DC Converter U FEATURES DESCRIPTIO ■ The LT®1618 step-up DC/DC converter combines a traditional voltage feedback loop and a unique current feedback loop to operate as a constant-current, constant-voltage source. This fixed frequency, current mode switcher operates from a wide input voltage range of 1.6V to 18V, and the high switching frequency of 1.4MHz permits the use of tiny, low profile inductors and capacitors. The current sense voltage is set at 50mV and can be adjusted using the IADJ pin. ■ ■ ■ ■ ■ ■ Accurate Input/Output Current Control: ±5% Over Temperature Accurate Output Voltage Control: ±1% Wide VIN Range: 1.6V to 18V 1.4MHz Switching Frequency High Output Voltage: Up to 35V Low VCESAT Switch: 200mV at 1A Available in (3mm × 3mm × 0.8mm) 10-Pin DFN and 10-Pin MSOP Packages U APPLICATIO S ■ ■ ■ LED Backlight Drivers USB Powered Boost/SEPIC Converters Input Current Limited Boost/SEPIC Converters Battery Chargers , LTC and LT are registered trademarks of Linear Technology Corporation. U ■ Available in the 10-Pin (3mm × 3mm) Exposed Pad DFN and 10-pin MSOP packages, the LT1618 provides a complete solution for constant-current applications. TYPICAL APPLICATIO USB to 12V Boost Converter (with Selectable 100mA/500mA Input Current Limit) L1 10µH C1 4.7µF 3 D1 2 7 ISN SW ISP 3.3V OFF ON 0V 9 20k IADJ GND 5 C2 4.7µF R2 107k SHDN 4 3.3V 100mA 500mA 0V 1 FB VIN 90 85 R1 909k LT1618 8 Efficiency Curve VOUT 12V VC EFFICIENCY (%) 0.1Ω VIN 5V 80 75 70 10 65 2k 13k C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN EMK316BJ475 D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-100 10nF 60 0 20 60 80 100 120 140 160 40 LOAD CURRENT (mA) 1618 TA01a 1618 TA01b sn1618 1618fas 1 LT1618 U W W W ABSOLUTE AXI U RATI GS (Note 1) VIN, SHDN Voltage ................................................... 18V SW Voltage .............................................................. 36V ISP, ISN Voltage ...................................................... 36V IADJ Voltage ............................................................... 6V FB Voltage .............................................................. 1.5V VC Voltage .............................................................. 1.5V Junction Temperature ........................................... 125°C Operating Temperature Range (Note 2) .. – 40°C to 85°C Storage Temperature Range MSOP ............................................... – 65°C to 150°C DFN ................................................. – 65°C to 125°C Lead Temperature (Soldering, 10 sec) (MSOP) .... 300°C U W U PACKAGE/ORDER I FOR ATIO TOP VIEW FB 1 10 VC ISN 2 9 SHDN ISP 3 IADJ 4 7 SW GND 5 6 SW 11 8 VIN DD PACKAGE 10-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 43°C/W, θJC = 3°C/W EXPOSED PAD (PIN 11) IS GND AND MUST BE SOLDERED TO PCB ORDER PART NUMBER LT1618EDD ORDER PART NUMBER TOP VIEW FB ISN ISP IADJ GND DD PART MARKING 1 2 3 4 5 10 9 8 7 6 VC SHDN VIN SW NC LT1618EMS MS PART MARKING MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 160°C/W LTNH LAFQ Consult LTC marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 1.6V, VSHDN = 1.6V, unless otherwise noted. PARAMETER CONDITIONS MIN Input Voltage TYP 1.6 Quiescent Current VSHDN = 1.6V, Not Switching VSHDN = 0V Reference Voltage Measured at FB Pin ● Reference Voltage Line Regulation 1.6V < VIN < 18V FB Pin Bias Current VFB = 1.263V, VIN = 1.8V 1.250 1.243 ● Error Amplifier Voltage Gain MAX UNITS 18 V 1.8 0.1 2.7 1 mA µA 1.263 1.263 1.276 1.283 V V 0.01 0.03 %/V ±2 ±12 nA 180 V/V Error Amplifier Transconductance ∆IC = ± 5µA 160 µmho Error Amplifier Sink Current VFB = 1.35V, VC = 1V 15 µA Error Amplifier Source Current VFB = 1.10V, VC = 1V 30 µA Current Sense Voltage (ISP, ISN) VFB = 0V, VIADJ = 0V ISP, ISN Pin Bias Currents (Note 3) VISP = 1.85V, VISN = 1.80V, VIADJ = 0V ● 47.5 50 52.5 mV 50 80 µA 1.8 V 1.6 MHz kHz (ISP, ISN) Common Mode Minimum Voltage Switching Frequency VFB = 1V VFB = 0V ● Maximum Switch Duty Cycle Switch Current Limit (Note 4) 1.25 1.4 550 88 92 1.5 2.1 % 2.8 A sn1618 1618fas 2 LT1618 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 1.6V, VSHDN = 1.6V, unless otherwise noted. PARAMETER CONDITIONS Switch VCESAT Switch Leakage Current SHDN Pin Current VSHDN = 1.6V MIN TYP MAX UNITS ISW = 1A (Note 4) 200 260 mV Switch Off, VSW = 5V 0.01 5 µA 5 20 µA 0.3 V Shutdown Threshold (SHDN Pin) Start-Up Threshold (SHDN Pin) 1 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1618 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the – 40°C to 85°C operating V temperature range are assured by design, characterization, and correlation with statistical process controls. Note 3: Bias currents flow into the ISP and ISN pins. Note 4: Switch current limit and switch VCESAT for the DD package is guaranteed by design and/or correlation to static test. U W TYPICAL PERFOR A CE CHARACTERISTICS Switch Saturation Voltage (VCE, SAT) FB Pin Voltage and Bias Current TJ = 125°C 300 TJ = 25°C 200 TJ = –50°C 100 0 0 1.0 0.5 1.5 SWITCH CURRENT (A) 2.0 1.265 2 VOLTAGE 1.260 0 CURRENT 1.255 –2 1.250 – 50 – 25 75 25 50 0 TEMPERATURE (°C) 100 Current Sense Voltage (IADJ Pin = 0V) 1.0 0.5 0 – 50 – 25 –4 125 51 50 49 100 125 1618 G04 75 25 50 0 TEMPERATURE (°C) 100 Quiescent Current 60 2.5 50 2.0 40 30 20 10 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 IADJ PIN VOLTAGE (V) 125 1618 G03 QUIESCENT CURRENT (mA) CURRENT SENSE VOLTAGE (mV) CURRENT SENSE VOLTAGE (mV) 1.5 Current Sense Voltage (VISP, ISN) 52 25 50 75 0 TEMPERATURE (°C) 2.0 1618 G02 1618 G01 48 – 50 – 25 2.5 PEAK CURRENT (A) FEEDBACK VOLTAGE (V) 400 4 FB PIN BIAS CURRENT (nA) SATURATION VOLTAGE (mV) 500 Switch Current Limit 1.270 1.4 1.6 1618 G05 VIN = 18V VIN = 1.6V 1.5 1.0 0.5 0 – 50 – 25 25 50 75 0 TEMPERATURE (°C) 100 125 1618 G06 sn1618 1618fas 3 LT1618 U W TYPICAL PERFOR A CE CHARACTERISTICS Switching Frequency Frequency Foldback 1.8 1.6 1.7 1.4 SHDN Pin Current 50 1.6 1.5 VIN = 18V 1.4 VIN = 1.6V 1.3 1.2 45 1.2 SHDN PIN CURRENT (µA) SWITCHING FREQUENCY (MHz) SWITCHING FREQUENCY (MHz) TJ = 25°C 1.0 0.8 0.6 0.4 0.2 1.1 1.0 – 50 – 25 100 125 35 30 TJ = 25°C 25 20 TJ = 125°C 15 10 5 0 75 25 50 0 TEMPERATURE (°C) TJ = – 50°C 40 0 0 0.2 0.8 0.4 0.6 1.0 FEEDBACK PIN VOLTAGE (V) 1618 G07 1.2 1618 G08 0 5 15 10 SHUTDOWN PIN VOLTAGE (V) 20 1618 G09 U U U PIN FUNCTIONS (MS/DD) FB (Pin 1/Pin 1): Feedback Pin. Set the output voltage by selecting values for R1 and R2 (see Figure 1): ⎛ V ⎞ R1 = R2 ⎜ OUT – 1⎟ ⎝ 1.263V ⎠ SW (NA/Pin 6): Switch Pin for DD Package. Connect this pin to Pin 7. SW (Pin 7/Pin 7): Switch Pin. This is the collector of the internal NPN power switch. Minimize the metal trace area connected to this pin to minimize EMI. ISN (Pin 2/Pin 2): Current Sense (–) Pin. The inverting input to the current sense amplifier. VIN (Pin 8/Pin 8): Input Supply Pin. Bypass this pin with a capacitor to ground as close to the device as possible. ISP (Pin 3/Pin 3): Current Sense (+) Pin. The noninverting input to the current sense amplifier. SHDN (Pin 9/Pin 9): Shutdown Pin. Tie this pin higher than 1V to turn on the LT1618; tie below 0.3V to turn it off. IADJ (Pin 4/Pin 4): Current Sense Adjust Pin. A DC voltage applied to this pin will reduce the current sense voltage. If this adjustment is not needed, tie this pin to ground. VC (Pin 10/Pin 10): Compensation Pin for Error Amplifier. Connect a series RC from this pin to ground. Typical values are 2kΩ and 10nF. GND (Pin 5/Pin 5): Ground Pin. Tie this pin directly to local ground plane. Exposed Pad (NA/Pin 11): The Exposed Pad on the DD package is GND and must be soldered to the PCB GND for optimum thermal performance. NC (Pin 6/NA): No Connection for MS Package. sn1618 1618fas 4 LT1618 W BLOCK DIAGRA D1 L1 RSENSE VIN VOUT C1 SHDN VIN 9 C2 SW 7 8 Q1 DRIVER + 0.02Ω A1 ×25 ×5 – + 1.4MHz OSCILLATOR + S 3 – 2 ISN 4 IADJ Σ + Q R ISP + A3 – 5 A2 – – + R1 1 FB 1.263V R2 10 VC GND RC CC Figure 1. LT1618 Block Diagram U OPERATIO The LT1618 uses a constant frequency, current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Block Diagram in Figure 1. At the start of each oscillator cycle, the SR latch is set, turning on power switch Q1. The signal at the noninverting input of PWM comparator A3 is a scaled-down version of the switch current (summed together with a portion of the oscillator ramp). When this signal reaches the level set by the output of error amplifier A2, comparator A3 resets the latch and turns off the power switch. In this manner, A2 sets the correct peak current level to keep the output in regulation. If the error amplifier’s output increases, more current is delivered to the output; if it decreases, less current is delivered. A2 has two inverting inputs, one from the voltage feedback loop, and one from the current feedback loop. Whichever inverting input is higher takes precedence, forcing the converter into either a constant-current or a constant-voltage mode. The LT1618 is designed to transition cleanly between the two modes of operation. Current sense amplifier A1 senses the voltage between the ISP and ISN pins and provides a 25× level-shifted version to error amplifier A2. When the voltage between ISP and ISN reaches 50mV, the output of A1 provides 1.263V to one of the noninverting inputs of A2 and the converter is in constant-current mode. If the current sense voltage exceeds 50mV, the output of A1 will increase causing the output of A2 to decrease, thus reducing the amount of current delivered to the output. In this manner the current sense voltage is regulated to 50mV. Similarly, if the FB pin increases above 1.263V, the output of A2 will decrease to reduce the peak current level and regulate the output (constant-voltage mode). sn1618 1618fas 5 LT1618 U W U U APPLICATIONS INFORMATION Inductor Selection Several inductors that work well with the LT1618 are listed in Table 1, although there are many other manufacturers and devices that can be used. Consult each manufacturer for more detailed information and for their entire selection of related parts. Many different sizes and shapes are available. Ferrite core inductors should be used to obtain the best efficiency, as core losses at 1.4MHz are much lower for ferrite cores than for the cheaper powdered-iron ones. Choose an inductor that can handle the necessary peak current without saturating, and ensure that the inductor has a low DCR (copper-wire resistance) to minimize I2R power losses. A 4.7µH or 10µH inductor will be a good choice for many LT1618 designs. Table 1. Recommended Inductors L MAX PART (µH) (mΩ) HEIGHT (mm) VENDOR CDRH5D18-4R1 CDRH5D18-100 CR43-2R2 CR43-4R7 CR43-100 CR54-100 4.1 10 2.2 4.7 10 10 57 124 71 109 182 100 2.0 2.0 3.5 3.5 3.5 4.8 Sumida (847) 956-0666 www.sumida.com LQH3C1R0M24 LQH3C2R2M24 LQH3C4R7M24 1.0 2.2 4.7 78 126 260 2.0 2.0 2.0 Murata (814) 237-1431 www.murata.com Capacitor Selection Low ESR (equivalent series resistance) capacitors should be used at the output to minimize the output ripple voltage. Multilayer ceramic capacitors are an excellent choice. They have an extremely low ESR and are available in very small packages. X5R and X7R dielectrics are preferred, as these materials retain their capacitance over wider voltage and temperature ranges than other dielectrics. A 4.7µF to 10µF output capacitor is sufficient for high output current designs. Converters with lower output currents may need only a 1µF or 2.2µF output capacitor. Solid tantalum or OSCON capacitors can be used, but they will occupy more board area than a ceramic and will have a higher ESR for the same footprint device. Always use a capacitor with a sufficient voltage rating. Ceramic capacitors also make a good choice for the input decoupling capacitor, which should be placed as close as possible to the VIN pin of the LT1618. A 1µF to 4.7µF input capacitor is sufficient for most applications. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic parts. Table 2. Recommended Ceramic Capacitor Manufacturers VENDOR PHONE URL Taiyo Yuden (408) 573-4150 www.t-yuden.com Murata (814) 237-1431 www.murata.com Kemet (408) 986-0424 www.kemet.com Diode Selection Schottky diodes, with their low forward voltage drop and fast switching speed, are the ideal choice for LT1618 applications. Table 3 shows several Schottky diodes that work well with the LT1618. Many different manufacturers make equivalent parts, but make sure that the component chosen has a sufficient current rating and a voltage rating greater than the output voltage. The diode conducts current only when the power switch is turned off (typically less than half the time), so a 0.5A or 1A diode will be sufficient for most designs. The companies below also offer Schottky diodes with higher voltage and current ratings. Table 3. Recommended Schottky Diodes 1A PART 0.5A PART VENDOR PHONE/URL UPS120 UPS130 UPS140 Microsemi (510) 353-0822 www.microsemi.com MBRM120 MBR0520 MBRM130 MBR0530 MBRM140 MBR0540 ON Semiconductor (800) 282-9855 www.onsemi.com B120 B130 B140 Diodes, Inc B0520 B0530 B0540 (805) 446-4800 www.diodes.com sn1618 1618fas 6 LT1618 U W U U APPLICATIONS INFORMATION Setting Output Voltage To set the output voltage, select the values of R1 and R2 (see Figure 1) according to the following equation. ⎛V ⎞ R1 = R2 ⎜ OUT – 1⎟ ⎝ 1.263 ⎠ For current source applications, use the FB pin for overvoltage protection. Pick R1 and R2 so that the output voltage will not go too high if the load is disconnected or if the load current drops below the preset value. Typically choose R1 and R2 so that the overvoltage value will be about 20% to 30% higher than the normal output voltage (when in constant-current mode). This prevents the voltage loop from interfering with the current loop in current source applications. For battery charger applications, pick the values of R1 and R2 to give the desired end of charge voltage. the output of the error amplifier (the VC pin) will be pulled down and the LT1618 will stop switching. A pulse width modulated (PWM) signal can also be used to adjust the current sense voltage; simply add an RC filterto convert the PWM signal into a DC voltage for the IADJ pin. If the IADJ pin is not used, it should be tied to ground. Do not leave the pin floating. For applications needing only a simple one-step current sense adjustment, the circuit in Figure 2 works well. If a large value resistor (≥2MΩ) is placed between the IADJ pin and ground, the current sense voltage will reduce to about 25mV, providing a 50% reduction in current. Do not leave the IADJ pin open. This method gives a well-regulated current value in both states, and is controlled by a logic signal without the need for a variable PWM or DC control signal. When the NMOS transistor is on, the current sense voltage will be 50mV, when it is off, the current sense voltage will be reduced to 25mV. Selecting RSENSE/Current Sense Adjustment LT1618 Use the following formula to choose the correct current sense resistor value (for constant current operation). RSENSE = 50mV/IMAX For designs needing an adjustable current level, the IADJ pin is provided. With the IADJ pin tied to ground, the nominal current sense voltage is 50mV (appearing between the ISP and ISN pins). Applying a positive DC voltage to the IADJ pin will decrease the current sense voltage according to the following formula: VISENSE = 1.263V – (0.8)VIADJ 25 For example, if 1V is applied to the IADJ pin, the current sense voltage will be reduced to about 18mV. This adjustability allows the regulated current to be reduced without changing the current sense resistor (e.g. to adjust brightness in an LED driver or to reduce the charge current in a battery charger). If the IADJ pin is taken above 1.6V, IADJ FULL CURRENT 2M 1618 F02 Figure 2 Considerations When Sensing Input Current In addition to regulating the DC output current for currentsource applications, the constant-current loop of the LT1618 can also be used to provide an accurate input current limit. Boost converters cannot provide output short-circuit protection, but the surge turn-on current can be drastically reduced using the LT1618’s current sense at the input. SEPICs, however, have an output that is DCisolated from the input, so an input current limit not only helps soft-start the output but also provides excellent short-circuit protection. sn1618 1618fas 7 LT1618 U U W U APPLICATIONS INFORMATION When sensing input current, the sense resistor should be placed in front of the inductor (between the decoupling capacitor and the inductor) as shown in the circuits in the Typical Applications section. This will regulate the average inductor current and maintain a consistent inductor ripple current, which will, in turn, maintain a well regulated input current. Do not place the sense resistor between the input source and the input decoupling capacitor, as this may allow the inductor ripple current to vary widely (even though the average input current and the average inductor current will still be regulated). Since the inductor current is a triangular waveform (not a DC waveform like the output current) some tweaking of the compensation values (RC and CC on the VC pin) may be required to ensure a clean inductor ripple current while the constant-current loop is in effect. For these applications, the constantcurrent loop response can usually be improved by reducing the RC value, or by adding a capacitor (with a value of approximately CC /10) in parallel with the RC and CC compensation network. Frequency Compensation The LT1618 has an external compensation pin (VC), which allows the loop response to be optimized for each application. An external resistor and capacitor (or sometimes just a capacitor) are placed at the VC pin to provide a pole and a zero (or just a pole) to ensure proper loop compensation. Numerous other poles and zeroes are present in the closed L1 loop transfer function of a switching regulator, so the VC pin pole and zero are positioned to provide the best loop response. A thorough analysis of the switching regulator control loop is not within the scope of this data sheet, and will not be presented here, but values of 2kΩ and 10nF will be a good choice for many designs. For those wishing to optimize the compensation, use the 2kΩ and 10nF as a starting point. For LED backlight applications where a pulse-width modulation (PWM) signal is used to drive the IADJ pin, the resistor is usually not included in the compensation network. This helps to provide additional filtering of the PWM signal at the output of the error amplifier (the VC pin). Switch Node Considerations To maximize efficiency, switch rise and fall times are made as short as possible. To prevent radiation and high frequency resonance problems, proper layout of the high frequency switching path is essential. Keep the output switch (SW pin), diode and output capacitor as close together as possible. Minimize the length and area of all traces connected to the switch pin, and always use a ground plane under the switching regulator to minimize interplane coupling. The high speed switching current path is shown in Figure 3. The signal path including the switch, output diode and output capacitor contains nanosecond rise and fall times and should be kept as short as possible. SWITCH NODE VOUT VIN HIGH FREQUENCY CIRCULATING PATH LOAD 1618 • F03 Figure 3 sn1618 1618fas 8 LT1618 U TYPICAL APPLICATIO S 4.5W Direct Broadcast Satellite (DBS) Power Supply with Short-Circuit Protection 0.068Ω 3 2 7 ISN SW 9 FB VIN 4 5 R3 10k Q1 FMMT717 ZETEX R1 100k 1 C3 3.3µF SHDN IADJ GND C1 4.7µF L2 33µH ISP LT1618 8 L3 2.2µH D1 ADD 5V 3.3V VC 10 RC 2k R5 24.9k R2 10k D2 MURS110 13.5V/18.5V C4 3.3µF 22kHz NETWORK TUNING Q1 MMBT3904 RHCP LHCP 0V R4 1k CC 33nF C1: TAIYO YUDEN EMK316BJ475 C2: TAIYO YUDEN TMK316BJ105 C3, C4: TAIYO YUDEN TMK325BJ335 D1: ON SEMICONDUCTOR MBRM140 L1, L2: SUMIDA CR54-330 L3: SUMIDA CR43-2R2 (408) 573-4150 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 (847) 956-0666 1618 TA02a Efficiency 80 75 EFFICIENCY (%) VIN 12V C2 1µF L1 33µH 70 65 60 0 50 100 150 200 LOAD CURRENT (mA) 250 300 1618 TA02b sn1618 1618fas 9 LT1618 U TYPICAL APPLICATIONS 2-Cell White LED Driver L1 4.7µH VIN 1.6V TO 3V C1 4.7µF 9 10kHz TO 50kHz PWM BRIGHTNESS ADJUST D1 8 7 VIN SW SHDN ISP 4 2 R1 2M LT1618 IADJ 1 FB VC GND 5 20mA 3 ISN R3 5.1k 2.49Ω 10 C2 1µF C3 0.1µF R2 160k CC 0.1µF C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN EMK316BJ105 D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CLQ4D10-4R7 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 1618 • TA03 2-Cell Luxeon LED Driver L1 10µH VIN 1.8V TO 3V 9 D1 8 7 VIN SW SHDN ISP ISN C1 1µF 4 0.15Ω 3 2 LT1618 IADJ FB VC GND 5 350mA 332k 1 D2 10 100nF C1, C2: TAIYO YUDEN JMK107BJ105KA D1: ON SEMICONDUCTOR MBR0520 D2: LUMILEDS LXHL-BW02 L1: SUMIDA CR43-100 C2 1µF 124k 1618 • TA12 sn1618 1618fas 10 LT1618 U TYPICAL APPLICATIONS Li Ion White LED Driver L1 10µH VIN 2.7V TO 5V C1 4.7µF 9 10kHz TO 50kHz PWM BRIGHTNESS ADJUST D1 8 7 VIN SW SHDN ISP ISN R3 5.1k LT1618 4 IADJ GND 2.49Ω 20mA 3 2 R1 2M 1 FB VC 5 10 C2 1µF C3 0.1µF R2 100k CC 0.1µF C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN TMK316BJ105 D1: ON SEMICONDUCTOR MBR0530 L1: SUMIDA CLQ4D10-100 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 1618 • TA04 White LED Driver for 20 LEDs L1 10µH VIN 2.7V TO 5V C1 4.7µF 9 10kHz TO 50kHz PWM BRIGHTNESS ADJUST D1 8 7 VIN SW SHDN ISP ISN R3 5.1k 4 0.619Ω 3 2 R1 2M LT1618 IADJ FB VC GND 5 1 10 C2 1µF C3 0.1µF CC 0.1µF C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN TMK316BJ105 D1: ON SEMICONDUCTOR MBR0530 L1: SUMIDA CR43-100 80mA (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 R2 121k 51Ω 51Ω 51Ω 51Ω 1618 • TA05 sn1618 1618fas 11 LT1618 U TYPICAL APPLICATIONS USB to 5V SEPIC Converter VIN 5V C1 4.7µF 3 C3 0.47µF L1 10µH 0.1Ω VOUT 5V 2 7 ISN SW 3.3V OFF ON 0V 9 L2 10µH ISP 20k 4 3.3V 100mA 500mA 0V 5 75 C2 10µF R2 107k SHDN IADJ GND R1 316k 1 FB VIN Efficiency 80 LT1618 8 D1 VC 10 EFFICIENCY (%) IIN 65 2k 13k 70 10nF 60 C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN JMK316BJ106 C3: TAIYO YUDEN EMK212BJ474 D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-100 (408) 573-4150 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 0 50 100 150 200 250 LOAD CURRENT (mA) 300 350 1618 F09b 1618 • TA09a USB SEPIC During Start-Up USB SEPIC Start-Up with Output Shorted VOUT 2V/DIV VOUT 2V/DIV IIN 50mA/DIV 50mA/DIV 1ms/DIV 1618 TA10 1ms/DIV 1618 TA11 sn1618 1618fas 12 LT1618 U TYPICAL APPLICATIO S 12V Boost Converter with 500mA Input Current Limit IL1 L1 10µH 0.1Ω 3 8 9 VOUT 12V 2 7 ISN SW VIN = 5V 1 FB 5 C2 4.7µF R2 107k SHDN 4 85 R1 909k LT1618 VIN Efficiency 90 ISP IADJ GND C1 4.7µF D1 VC 10 2k EFFICIENCY (%) VIN 1.8V TO 5V 80 VIN = 3.3V 75 70 65 10nF 60 C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN EMK316BJ475 D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-100 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 12V Boost Converter Start-Up with Input Current Limit (VIN = 1.8V, ILOAD = 40mA) 0 20 60 80 100 120 140 160 L0AD CURRENT (mA) 40 1618 TA06b 1618 • TA06a 12V Boost Converter Start-Up without Input Current Limit (VIN = 1.8V, ILOAD = 40mA) VOUT 5V/DIV VOUT 5V/DIV ILI 200mA/DIV ILI 200mA/DIV 50µs/DIV 1618 TA07 50µs/DIV 1618 TA08 sn1618 1618fas 13 LT1618 U PACKAGE DESCRIPTIO DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ±0.05 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) R = 0.115 TYP 0.38 ± 0.10 6 10 5 1 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF (DD10) DFN 1103 0.25 ± 0.05 0.50 BSC 0.75 ±0.05 0.00 – 0.05 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 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 sn1618 1618fas 14 LT1618 U PACKAGE DESCRIPTIO MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.50 0.305 ± 0.038 (.0197) (.0120 ± .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.497 ± 0.076 (.0196 ± .003) REF 10 9 8 7 6 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 1 2 3 4 5 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.86 (.034) REF 1.10 (.043) MAX 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 0.50 (.0197) BSC 0.127 ± 0.076 (.005 ± .003) MSOP (MS) 0603 NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX sn1618 1618fas 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. 15 LT1618 U TYPICAL APPLICATIONS Li-Ion Buck-Boost Mode Luxeon LED Driver Buck Mode Luxeon LED Driver D2 350mA 0.15Ω L1 3.3µH VIN 3.2V TO 5V 2 9 C1 4.7µF D2 D1 D1 3 7 ISP SW L1 47µH 2 7 ISN SW 100k ISN LT1618 8 700mA 0.07Ω VIN 16V 1 FB VIN C2 4.7µF SHDN 10k IADJ GND 4 C1 4.7µF 5 3 9 VC 10 ISP LT1618 8 SHDN IADJ GND 4 10nF C1: TAIYO YUDEN JMK212BJ475KG C2: TAIYO YUDEN EMK316BJ475ML D1: ON SEMICONDUCTOR MBRM120 D2: LUMILEDS DS25 L1: NEC PLC-07453R3 1 FB VIN 5 VC 10 10k 1618 TA13 220pF 2.2nF C1: TAIYO YUDEN TMK325BJ475MN D1: PHILIPS PMEG2010 D2: LUMILEDS DS45 L1: TOKO D104C 1618 TA14 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1613 550mA (ISW), 1.4MHz, High Efficiency Step-Up DC/DC Converter VIN: 0.9V to 10V, VOUT(MAX) = 34V, IQ = 3mA, ISD < 1µA, ThinSOTTM Package LT1615/LT1615-1 300mA/80mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC Converter VIN: 1.2V to 15V, VOUT(MAX) = 34V, IQ = 20µA, ISD < 1µA, ThinSOT Package LT1930/LT1930A 1A (ISW), 1.2MHz/2.2MHz, High Efficiency Step-Up DC/DC Converter VIN: 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD < 1µA, ThinSOT Package LT1932 Constant Current, 1.2MHz, High Efficiency White LED Boost Regulator VIN: 1V to 10V, VOUT(MAX) = 34V, IQ = 1.2mA, ISD < 1µA, ThinSOT Package LT1944/LT1944-1 (Dual) Dual Output 350mA/100mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC Converter VIN: 1.2V to 15V, VOUT(MAX) = 34V, IQ = 20µA, ISD < 1µA, MS Package LT1945 (Dual) Dual Output, Pos/Neg, 350mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC Converter VIN: 1.2V to 15V, VOUT(MAX) = ±34V, IQ = 20µA, ISD < 1µA, MS Package LT1961 1.5A (ISW), 1.25MHz, High Efficiency Step-Up DC/DC Converter VIN: 3V to 25V, VOUT(MAX) = 35V, IQ = 0.9mA, ISD < 6µA, MS8E Package LTC3401/LTC3402 1A/2A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter VIN: 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38µA, ISD < 1µA, MS Package LT3461/LT3461A 0.3A (ISW), 1.3MHz/3MHz, High Efficiency Step-Up DC/DC Converter with Integrated Schottky VIN: 2.5V to 16V, VOUT(MAX) = 38V, IQ = 2.8mA, ISD < 1µA, SC70 and ThinSOT Packages LT3463/LT3463A 250mA (ISW), Boost/Inverter Dual, Micropower DC/DC Converter with Integrated Schottky Diodes VIN: 2.4V to 15V, VOUT(MAX) = ±40V, IQ = 40µA, ISD < 1µA, DFN Package LT3464 0.08A (ISW), High Efficiency Step-Up DC/DC Converter with Integrated Schottky, Output Disconnect VIN: 2.3V to 10V, VOUT(MAX) = 34V, IQ = 25µA, ISD < 1µA, ThinSOT Package LT3465/LT3465A Constant Current, 1.2MHz/2.7MHz, High Efficiency White LED Boost Regulator with Integrated Schottky Diode VIN: 2.7V to 16V, VOUT(MAX) = 34V, IQ = 1.9mA, ISD < 1µA, ThinSOT Package LT3467/LT3467A 1.1A (ISW), 1.3MHz/2.1MHz, High Efficiency Step-Up DC/DC Converter with Integrated Soft-Start VIN: 2.4V to 16V, VOUT(MAX) = 40V, IQ = 1.2mA, ISD < 1µA, ThinSOT Package ThinSOT is a trademark of Linear Technology Corporation. sn1618 1618fas 16 Linear Technology Corporation LT/TP 0504 1K REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2001