LT3663 1.2A Step-Down Switching Regulator with Output Current Limit Features Description Wide Input Range: Operation from 7.5V to 36V Overvoltage Lockout Protects Circuit through 60V Transients n Programmable Output Current Limit (0.4A to 1.2A) n 3.3V and 5V Fixed Output Voltage Options n Integrated Boost Diode n Fixed Frequency, Peak Current Mode Control LT3663 fSW = 1.5MHz LT3663-X fSW = 1MHZ n Low Switch V CESAT: 275mV at 1A n Internally Compensated n Thermal Protection n Thermally Enhanced 8-Pin 2mm × 3mm DFN and MSOP Packages The LT®3663 is a current mode step-down switching regulator with programmable output current limit. The current limit accurately controls the system power dissipation and reduces the size of the power path components. n Applications n n n n The wide operating input voltage range of 7.5V to 36V (60V transient) suits the LT3663 to a variety of input sources, including unregulated 12V wall adapters, 24V industrial supplies, and automotive power. The LT3663 includes a low current shutdown mode, input overvoltage and undervoltage lockout, and thermal shutdown. Internal compensation and boost diode minimize the number of external exponents. 3.3V and 5V fixed output voltage versions are available. The LT3663 is available in 8-lead DFN and MSOP packages with exposed pads for low thermal resistance. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Distributed Supply Regulation Automotive Battery Regulation Industrial Supplies Wall Transformer Regulation Typical Application 5V Step-Down Converter VIN 100 BOOST VIN 2.2µF Efficiency 90 0.1µF LT3663 ON OFF EFFICIENCY (%) SW 6.8µH RUN ISENSE ILIM VOUT 28.7k VOUT 59k 22µF VIN = 8V VIN = 15V 80 VIN = 30V 70 60 50 FB GND 11k 3663 TA01 40 0.1 0.3 0.5 0.7 0.9 OUTPUT CURRENT (A) 1.1 1.3 3663 TA01b 3663fc For more information For more information www.linear.com/LT3663 1 LT3663 Absolute Maximum Ratings (Note 1) Input Voltage (VIN) (Note 2).......................................60V BOOST Pin Voltage....................................................50V BOOST Pin Above SW Pin..........................................25V VOUTS, VOUT, ISENSE, FB Pins........................................6V RUN Pin (Note 2).......................................................60V Operating Junction Temperature Range (Note 3) LT3663E.............................................. –40°C to 125°C LT3663I............................................... –40°C to 125°C LT3663H............................................. –40°C to 150°C Storage Temperature............................... –65°C to 150°C Pin Configuration LT3663 LT3663-X TOP VIEW TOP VIEW RUN 2 9 GND FB 3 7 BOOST RUN 2 6 ISENSE VOUTS 3 θJA = 64°C/W EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB θJA = 64°C/W EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB LT3663-X TOP VIEW VIN RUN FB ILIM 1 2 3 4 9 GND 8 7 6 5 6 ISENSE 5 VOUT DCB PACKAGE 8-LEAD (2mm × 3mm) PLASTIC DFN DCB PACKAGE 8-LEAD (2mm × 3mm) PLASTIC DFN LT3663 7 BOOST 9 GND ILIM 4 5 VOUT ILIM 4 8 SW VIN 1 8 SW VIN 1 TOP VIEW SW BOOST ISENSE VOUT VIN 1 RUN 2 VOUTS 3 ILIM 4 MSE PACKAGE 8-LEAD PLASTIC MSOP 9 GND 8 7 6 5 SW BOOST ISENSE VOUT MSE PACKAGE 8-LEAD PLASTIC MSOP θJA = 35°C/W EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB θJA = 35°C/W EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB order information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3663EDCB#PBF LT3663EDCB#TRPBF LDVK 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LT3663IDCB#PBF LT3663IDCB#TRPBF LDVK 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LT3663EDCB-3.3#PBF LT3663EDCB-3.3#TRPBF LFMW 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LT3663IDCB-3.3#PBF LT3663IDCB-3.3#TRPBF LFMW 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LT3663EDCB-5#PBF LT3663EDCB-5#TRPBF LFMY 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LT3663IDCB-5#PBF LT3663IDCB-5#TRPBF LFMY 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LT3663EMS8E#PBF LT3663EMS8E#TRPBF LTDWT 8-Lead Plastic MSOP –40°C to 125°C LT3663IMS8E#PBF LT3663IMS8E#TRPBF LTDWT 8-Lead Plastic MSOP –40°C to 125°C LT3663HMS8E#PBF LT3663HMS8E#TRPBF LTDWT 8-Lead Plastic MSOP –40°C to 150°C LT3663EMS8E-3.3#PBF LT3663EMS8E-3.3#TRPBF LTFMX 8-Lead Plastic MSOP –40°C to 125°C LT3663IMS8E-3.3#PBF LT3663IMS8E-3.3#TRPBF LTFMX 8-Lead Plastic MSOP –40°C to 125°C LT3663HMS8E-3.3#PBF LT3663HMS8E-3.3#TRPBF LTFMX 8-Lead Plastic MSOP –40°C to 150°C LT3663EMS8E-5#PBF LT3663EMS8E-5#TRPBF 8-Lead Plastic MSOP –40°C to 125°C 2 LTFMZ 3663fc For more information www.linear.com/LT3663 LT3663 order information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3663IMS8E-5#PBF LT3663IMS8E-5#TRPBF LTFMZ 8-Lead Plastic MSOP –40°C to 125°C LT3663HMS8E-5#PBF LT3663HMS8E-5#TRPBF LTFMZ 8-Lead Plastic MSOP –40°C to 150°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. 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/ Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, RILIM = 36.5k unless otherwise noted. PARAMETER CONDITIONS VIN Undervoltage Lockout Rising MIN l VIN Undervoltage Lockout Hysteresis VIN Overvoltage Lockout TYP MAX 7 7.5 500 Rising l 36 VIN Overvoltage Lockout Hysteresis 39 Not Switching VIN Supply Current in Shutdown VRUN = 0V Run Input Voltage High 41 V 2.4 3.2 mA 0.01 2 µA V 2.5 V Run Input Voltage Low Run Pin Bias Current VRUN = 2.3V (Note4) VRUN = 0V V mV 1 VIN Supply Current UNITS 6 0.01 0.3 V 15 0.1 µA µA VOUT Current Limit Range l 0.4 1.2 A VOUT Current Limit l 0.8 1 1.2 A 1350 900 1500 1000 1650 1100 l 80 92 l 784 800 816 mV 50 150 nA 3.3 5 3.366 5.100 V V 90 120 µA 2 2.5 Operating Frequency LT3663 LT3663-X Maximum Duty Cycle % Feedback Voltage LT3663 FB Bias Current VFB = 0.8V, LT3663 Regulated Output Voltage LT3663-3.3 LT3663-5 VOUTS Bias Current LT3663-X Switch Peak Current Limit (Note 5) Switch VCESAT ISW = 1A 275 Minimum BOOST Voltage ISW = 1A (Note 6) 1.85 2.2 Boost Diode Drop IDIODE = 60mA 0.9 1.2 Boost Pin Current ISW = 1A 28 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: Absolute Maximum Voltage at VIN and RUN pins is 60V for nonrepetitive 1 second transients. Note 3: The LT3663E is guaranteed to meet performance specifications from 0°C to 125°C. Specifications over the –40°C to 125°C operating temperature range are assured by design, characterization, and correlation with statistical process controls. The LT3663I specifications l l l 3.234 4.900 1.6 kHz kHz A mV V V mA are guaranteed over the full –40°C to 125°C temperature range. The LT3663H specifications are guaranteed over the –40°C to 150°C operating temperature range. High junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125°C. Note 4: Current flows into pin. Note 5: Switch Peak Current Limit guaranteed by design and/or correlation to static test. Note 6: This is the minimum voltage across the boost capacitor needed to guarantee full saturation of the switch. 3663fc For more information For more information www.linear.com/LT3663 3 LT3663 Typical Performance Characteristics VIN Overvoltage Lockout VIN Undervoltage Lockout 8.0 42 800 7.5 41 700 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 40 6.5 FALLING 6.0 5.5 5.0 RISING 38 FALLING 37 36 35 0 32 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 0 Output Current Limit 1.20 40 1.15 30 25 20 15 10 50 RILIM = 36.5k 1.05 1.00 0.95 0.90 Switching Frequency 0 LT3663-X 0 25 50 75 100 125 150 TEMPERATURE (°C) 3663 G02 4 0 25 50 75 100 125 150 TEMPERATURE (°C) 0 0.2 0.4 0.6 0.8 1 OUTPUT CURRENT (A) 1.2 1.4 3663 G12 Feedback Voltage 0.84 120 FEEDBACK VOLTAGE (V) MINIMUM SWITCH-ON TIME (ns) 1.1 0.9 –50 –25 2 Minimum Switch On-Time 1.2 1.0 3 1 140 1.3 60 3663 G08 4 3663 G04 1.6 1.4 50 RILIM = 28.7k 1.10 3663 G11 LT3663 20 30 40 VIN VOLTAGE (V) 5 0.80 –50 –25 60 1.5 10 Output Current Limit 0.85 5 20 30 40 RUN PIN VOLTAGE (V) 0 6 OUTPUT VOLTAGE (V) 35 OUTPUT CURRENT LIMIT (A) RUN PIN CURRENT (µA) RUN Pin Current 10 300 3663 G06 45 0 400 0 25 50 75 100 125 150 TEMPERATURE (°C) 3663 G03 0 500 100 33 4.0 –50 –25 VRUN = 0V 200 34 4.5 VIN Shutdown Current 600 39 VIN CURRENT (µA) RISING 7.0 SWITCHING FREQUENCY (MHz) TA = 25°C, unless otherwise noted. 100 80 60 40 0.82 0.80 0.78 20 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3663 G10 0.76 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 3663 G05 3663fc For more information www.linear.com/LT3663 LT3663 Typical Performance Characteristics Switch Voltage Drop 400 1.4 125°C BOOST Pin Current 35 1.2 30 250 –45°C 200 150 100 BOOST PIN CURRENT (mA) 300 1 0.8 0.6 0.4 0.2 50 0 Boost Diode Vf 25°C BOOST DIODE VF (V) SWITCH VOLTAGE DROP (mV) 350 TA = 25°C, unless otherwise noted. 0 0.2 0.4 0.6 0.8 SWITCH CURRENT (A) 1 1.2 0 25 20 15 10 5 0 50 100 150 200 250 DIODE CURRENT (mA) 3663 G01 300 3653 G09 0 0 0.2 0.4 0.5 0.8 SWITCH CURRENT (A) 1.0 1.2 3653 G07 Pin Functions BOOST: The BOOST pin is used to provide a drive voltage, higher than the input voltage, to the internal power switch. The BOOST pin is also internally connected to the cathode of the BOOST diode. RUN: The Run pin is used to put the LT3663 into shutdown mode. Tie to ground to shut down the LT3663. Tie to 2.5V or more for normal operation. If the shutdown feature is not used, connect this pin to VIN. GND (Exposed Pad Pin 9) : Ground. The exposed pad must be soldered to the PCB and electrically connected to ground. Use a large ground plane and thermal vias to optimize thermal performance. SW: The SW pin is the output of the internal power switch. Connect this pin to the inductor, catch diode and boost capacitor. FB (LT3663): The LT3663 regulates the FB pin to 0.8V. Connect the feedback resistor divider tap to this pin. VIN: The VIN pin supplies current to the LT3663’s internal regulator and internal power switch. Capacitively bypass the pin to ground. ILIM: Output Current Limit Program Pin. Connect a resistor to ground to program the regulator output current limit. VOUT: The VOUT pin is connected to the negative terminal of the internal output current limit sense resistor. ISENSE: The ISENSE pin is the positive input to the internal output current limit sense resistor. The ISENSE pin is also the anode to the internal BOOST diode. VOUTS (LT3663-X): Output Voltage Sense Pin. Connect to the positive terminal of the output capacitor. 3663fc For more information For more information www.linear.com/LT3663 5 LT3663 Functional Block Diagram VIN VIN RSENSE1 C1 Q1 – + RUN BOOST D1 C3 + Σ A1 – SLOPE COMPENSATION 2.5V INTERNAL REGULATOR, REFERENCE, UVLO AND OVP SW R Q L S DRIVER D2 ISENSE OSCILLATOR + – G2 – + RSENSE2 VOUT VOUT C2 ILIM RILIM – VC G1 INTERNAL COMPENSATION + FB R1 R2 0.8V NOTE: RESISTOR DIVIDER IS INTERNAL ON LT3663-X VERSIONS. EXPOSED PAD (GND) 3663 BD 6 3663fc For more information www.linear.com/LT3663 LT3663 Operation (Refer to Block Diagram) The LT3663 is a constant frequency, current mode step down regulator. A switch cycle is initiated when the oscillator enables the RS flip flop, turning on the internal power switch, Q1. The sense amplifier (A1) monitors the switch current via the voltage dropped across the current sense resistor RSENSE1. The comparator compares the amplified current signal with the output (VC) of the error amplifier (G1). The switch is turned off when this current exceeds a value determined by the VC voltage. The error amplifier monitors the VOUT voltage through an internal resistor divider and, when not driven externally, servos the VC voltage to regulate VOUT. If the VOUT voltage drops, the VC voltage will be driven higher increasing the output current and VOUT voltage. An active clamp (not shown) on the VC node provides current limit. The LT3663 is internally compensated with a pole-zero combination on the VC node. An external capacitor and internal diode, D2, generate a voltage at the BOOST pin that is higher than the input supply. This allows the driver to fully saturate the internal bipolar NPN power switch for efficient operation. The switch driver operates from either VIN or BOOST to ensure startup. An internal regulator provides power to the control circuitry. This regulator includes input undervoltage and overvoltage protection which disables switching action when VIN is out of range. When switching is disabled, the LT3663 safely sustains input voltages up to 60V. Note that while switching is disabled the output will discharge. Output current limiting is provided via the servo action of amplifier G2. The voltage across sense resistor, RSENSE2, is compared to a voltage programmed by external resistor RILIM on the ILIM pin. A capacitor averages the inductor ripple current. If the average inductor current exceeds the programmed value then the VC voltage is pulled low, reducing the current in the regulator. The output current limit circuit allows for a lower current rated inductor and diode and provides better control of system power dissipation. 3663fc For more information For more information www.linear.com/LT3663 7 LT3663 Applications Information FB Resistor Network The output voltage of the LT3663 is programmed with a resistor divider. Choose the 1% resistors according to: Figure 2. illustrates switching waveforms in pulse skip mode a 3.3V output application with VIN = 30V. R1 = R2 (VOUT/0.8 – 1) Reference designators refer to the Block Diagram. The resistor divider is internal on the fixed output voltage versions, LT3663-X. IL 1A/DIV Minimum Duty Cycle As the input voltage increases the duty cycle decreases. At some point, the minimum duty cycle of the IC is reached and pulse skipping begins. The output voltage continues to regulate but the output voltage ripple increases. The input voltage at which this occurs is calculated as follows: VIN = ( VOUT + VF ) – V DCMIN VSW 20V/DIV VOUT 200mV/DIV AC-COUPLED 2.5µs/DIV 3663 F02 Figure 2. Pulse-Skip Mode Inductor Selection F + VSW A good first choice for the inductor value is: Where VF is the forward voltage drop of the catch diode, D1, and VSW is the voltage drop on the internal switch, Q1. LT3663 DCMIN is typically 0.12. For VF = 0.4V, VSW = 0.3V, and VOUT = 3.3V pulse skipping occurs at about 24.5V. Figure 1 illustrates switching waveforms in normal mode for a 3.3V output application with VIN = 20V. VSW 20V/DIV IL 1A/DIV VOUT 200mV/DIV AC-COUPLED 2.5µs/DIV L = VOUT + VD (µH) where VD is the voltage drop of the catch diode (~0.4V) and L is in µH. With this value there is no sub-harmonic oscillation for applications with 50% or greater duty cycle. The inductor’s RMS current rating must be greater than the maximum load current. Size the inductor so the saturation current rating is about 30% higher than the maximum load current. The output current limit circuit tightly controls the maximum average inductor current, therefore the inductor RMS current rating does not have to be overrated to handle short circuit or overload conditions. For high efficiency, keep the series resistance (DCR) less than 0.1Ω. A higher value inductor is larger in size and slows transient response but reduces output voltage ripple. A lower value inductor has higher ripple currents but is physically smaller or, for the same size, it has lower DCR typically resulting in higher efficiency. 3663 F01 Figure 1. Normal Operation 8 3663fc For more information www.linear.com/LT3663 LT3663 Applications Information Catch Diode The catch diode conducts current only during switch-off time. Average forward current in normal operation is calculated from: ID( AVG) = IOUT VIN – VOUT VIN where IOUT is the maximum output load current programmed by the ILIM resistor. Peak reverse voltage is equal to the regulator input voltage. Use a Schottky diode with a reverse voltage rating greater than the input voltage. The overvoltage protection feature in the LT3663 keeps the switch off when VIN > 39V (typical) allowing the use of a 45V rated Schottky even when VIN ranges up to 60V. Input Capacitor Bypass the input of the LT3663 circuit with a 1µF or higher value ceramic capacitor of X7R or X5R type. Y5V types have poor performance over temperature and applied voltage and are not recommended. If the input power source has high impedance, or there is significant inductance due to long wires or cables, additional bulk capacitance may be necessary. This can be provided with a low performance electrolytic capacitor. Step-down regulators draw current from the input supply in pulses with very fast rise and fall times. The input capacitor is required to reduce the resulting voltage ripple at the LT3663 and to force this very high frequency switching current into a tight local loop, minimizing EMI. Place the capacitor in close proximity to the LT3663 and the catch diode; (see the PCB Layout section). Use X5R or X7R types and keep in mind that a ceramic capacitor biased with VOUT has less than its specified nominal capacitance. High performance electrolytic capacitors can be used for the output capacitor. Low ESR is important, so choose one that is intended for use in switching regulators. Keep the ESR less than 0.1Ω. ILIM Resistor The LT3663 output current limit controls the maximum current delivered from the LT3663 regulator. This allows tighter control of the system power dissipation and also protects the inductor and diode from overheating during an overload or short circuit condition. A resistor connected from ILIM pin to GND programs the output current. Table 1 details the ILIM resistor values for specific output current limits. Table 1. Output Current Limit vs RLIM Value OUTPUT CURRENT LIMIT (A) RILIM VALUE (kΩ) 0.4 140 0.6 75 0.8 48.7 1.0 36.5 1.2 28.7 There may be a reason in some applications to move the output current limit. The following simple circuit demonstrates how the output current limit can be adjusted: ILIM Output Capacitor A 10µF or greater ceramic capacitor is recommended to provide low output ripple and good transient response. Ceramic capacitors have very low equivalent series resistance (ESR) and provide the best ripple performance. LT3663 RA ON, RILIM = RA OFF, RILIM = RA + RB 3663 F03 RB Figure 3. Circuit for Multiple Values of Output Current Limit 3663fc For more information For more information www.linear.com/LT3663 9 LT3663 Applications Information BOOST and BIAS Pin Considerations boost diode. For reliable BOOST pin operation with 2.5V outputs use a good external Schottky diode (such as the ON Semi, MBR0540) and a 1µF boost capacitor (see Figure 4b). For lower output voltages connect an external Schottky diode to the input (Figure 4c), or to another supply greater than 2.8V. Using VIN reduces the maximum input voltage to 25V. The circuit in Figure 4a is more efficient because the BOOST pin current comes from a lower voltage source. Take care to ensure that the maximum voltage ratings of the BOOST pin is not exceeded. Capacitor C3 and the internal boost diode (see the Block Diagram) are used to generate a boost voltage that is higher than the input voltage. In most cases a 0.1µF capacitor works well. Figure 4 shows three ways to arrange the boost circuit. The BOOST pin must be more than 2.3V above the SW pin for best efficiency. For outputs of 3V and above, the standard circuit (Figure 4a) is best. For outputs between 2.8V and 3V, use a 1µF boost capacitor. A 2.5V output presents a special case because it is marginally adequate to support the boosted drive stage while using the internal VIN VIN BOOST VIN VIN BOOST C3 LT3663 C3 SW SW LT3663 ISENSE D3 ISENSE VOUT VOUT VOUT (4a) For VOUT > 2.8V VOUT (4b) For 2.5V < VOUT < 2.8V D3 VIN VIN BOOST C3 LT3663 SW ISENSE VOUT VOUT 3663 F04 (4c) For VOUT < 2.5V; VIN(MAX) = 25V Figure 4. Three Circuits to Generate BOOST Pin Voltage 10 3663fc For more information www.linear.com/LT3663 LT3663 Applications Information PCB Layout Proper operation and minimum EMI, requires careful printed circuit board layout. Figure 5 shows the recommended component placement with trace, ground plane and via locations. Note that large, switched currents flow in the LT3663’s VIN and SW pins, the catch diode (D2) and the input capacitor (C1). Keep the loop formed by these components as small as possible and tied to system ground in only one place. Locate these components, along with the inductor and output capacitor, on the same side of the circuit board, and keep their connections on that layer. Place a local, unbroken ground plane below these components, and tie this ground plane to system ground at one location, ideally at the ground terminal of the output capacitor C1. Make the SW and BOOST PCB trace as short as possible. Include vias near the exposed GND pad of the LT3663 to help remove heat from the LT3663 to the ground plane. High Temperature Considerations The die temperature of the LT3663 must not exceed the maximum rating. This is generally not a concern unless VIN the ambient temperature is above 85°C. For higher temperatures, take care in the layout of the circuit to ensure good heat sinking of the LT3663. De-rate the maximum load current as the ambient temperature approaches the maximum temperature rating. Calculate the die temperature by multiplying the LT3663 power dissipation by the thermal resistance from junction to ambient. Estimate the power dissipation within the LT3663 by calculating the total power loss from an efficiency measurement and subtracting the catch diode loss. Thermal resistance depends on the layout of the circuit board, but 64°C/W is typical for the (2mm × 3mm) DFN (DCB) package. Other Linear Technology Publications Application Notes 19, 35 and 44 contain more detailed descriptions and design information for Buck regulators and other switching regulators. The LT1376 data sheet has a more extensive discussion of output ripple, loop compensation and stability testing. Design Note 100 shows how to generate a bipolar output supply using a Buck regulator. GND C1 D1 RUN 1 8 2 7 3 6 4 5 R1 C3 L LT3663 R2 RILIM C2 VOUT 3663 F05 Figure 5. LT3663 PCB Layout 3663fc For more information For more information www.linear.com/LT3663 11 LT3663 Typical Applications 5V Step-Down Converter VIN 7.5V TO 36V TRANSIENT TO 60V VIN 7.5V TO 36V TRANSIENT TO 60V BOOST VIN C1 4.7µF 2.5V Step-Down Converter C3 0.1µF LT3663 BOOST VIN C1 4.7µF C3 1µF LT3663 SW ON OFF SW D1 RUN L 6.8µH ISENSE RILIM 28.7k ILIM VOUT R1 59k C2 22µF D1 RUN ON OFF ISENSE VOUT 5V 1.2A ILIM RILIM 28.7k VOUT FB GND 3663 TA02 D1: DIODES INC, DFLS260 L: TDK, VLCF5020T-6R8N1R3-1 3663 TA04 LT3663-5 5V Step-Down Regulator with Isolated 3.3V Output C4 47pF 50V 0603 C3 0.22µF LT3663 1 L 3.3µH R1 49.9k FB GND 3663 TA05 R2 100k C2 22µF 3 CMPSH-3E SOT-23 C5 2.2µF 0603 10V 2 3 1761ES5-3.3 IN OUT 5 GND SHDN BYP 4 C6 0.01µF 10V 0403 C7 10µF 6.3V 0603 3.3V 50mA RTN VOUT 1.2V 1.2A 10µH 3 VIN 7.5V TO 36V NOTE: 60V MAX TRANSIENT VOLTAGE R1 10k C1 2.2µF 50V 1206 1 • VOUT 1 SW VIN LT3663-5 C2 0.1µF 16V BOOST RUN R2 100k • ISENSE ILIM D2 2 D1 RUN D1: DIODES INC, DFLS240 D3: ON SEMI, MBR0540 L: TDK, VLCF5020T-3R3N2R0-1 R3 100 0805 BOOST SW RILIM 28.7k VOUT 2.5V 1.2A D1: DIODES INC, DFLS260 D3: ON SEMI, MBR0560 L: TDK, VLCF5020T-3R3N2R0-1 VIN ON OFF C2 22µF R2 100k GND D3 C1 4.7µF R1 210k FB R2 11k 1.2V Step-Down Converter VIN 7.5V TO 23V D3 L 3.3µH ISENSE ILIM VOUT RILIM 75k GND C3 47µF 1206 10V 20% 10µH 4 L16-0017 T1 BH ELECTRONICS 2 D1 DFLS260 60V 2A HVBUCK 5V 600mA VOUTS 3663 TA07 12 3663fc For more information www.linear.com/LT3663 LT3663 Package Description DCB Package 8-Lead Plastic DFN (2mm × 3mm) (Reference LTC DWG # 05-08-1718 Rev A) 0.70 ±0.05 1.35 ±0.05 3.50 ±0.05 1.65 ±0.05 2.10 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.45 BSC 1.35 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 2.00 ±0.10 (2 SIDES) R = 0.05 TYP R = 0.115 TYP 5 0.40 ±0.10 8 1.35 ±0.10 1.65 ±0.10 3.00 ±0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.25 × 45° CHAMFER PIN 1 BAR TOP MARK (SEE NOTE 6) (DCB8) DFN 0106 REV A 4 0.200 REF 1 0.23 ±0.05 0.45 BSC 0.75 ±0.05 1.35 REF 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 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 3663fc For more information For more information www.linear.com/LT3663 13 LT3663 MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev J) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 (.074) 1 1.88 ±0.102 (.074 ±.004) 0.29 REF 1.68 (.066) 0.889 ±0.127 (.035 ±.005) 0.05 REF 5.23 (.206) MIN DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 1.68 ±0.102 3.20 – 3.45 (.066 ±.004) (.126 – .136) 8 3.00 ±0.102 (.118 ±.004) (NOTE 3) 0.65 (.0256) BSC 0.42 ±0.038 (.0165 ±.0015) TYP 8 7 6 5 0.52 (.0205) REF RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 0.53 ±0.152 (.021 ±.006) DETAIL “A” 1 2 3 4 1.10 (.043) MAX 0.86 (.034) REF 0.18 (.007) SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP 0.65 (.0256) BSC 0.1016 ±0.0508 (.004 ±.002) MSOP (MS8E) 0911 REV J 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 6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 14 3663fc For more information www.linear.com/LT3663 LT3663 Revision History (Revision history begins at Rev B) REV DATE DESCRIPTION PAGE NUMBER B 11/09 Additions to Features 1 Text Changes to Description 1 Addition of MSE Package to Pin Configuration Additions Made to Order Information Changes to Electrical Characteristics Expanded Temperature Range of Typical Performance Curves Addition of Note to Functional Block Diagram C 05/13 2 2, 3 3 4, 5 6 Text Changes to Applications Information 8, 11 Addition of Typical Applications Drawing 12 Addition of MS8E Package Drawing 14 Clarified PCB Layout 11 3663fc 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 representaFor more information For more information www.linear.com/LT3663 tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LT3663 Typical Application 3.3V Step-Down Converter BOOST VIN C1 4.7µF 90 C3 0.1µF LT3663 ON OFF D1 RUN ISENSE RILIM 28.7k ILIM VOUT R1 316k L 4.7µH VOUT 3.3V C2 1.2A 22µF FB R2 100k GND D1: DIODES INC, DFLS240 L: TDK, VLCF5020T-4R7N1R7-1 VIN = 8V 80 SW 3663 TA03 EFFICIENCY (%) VIN 7.5V TO 36V Efficiency 100 VIN = 15V 70 VIN = 30V 60 50 40 30 0.1 0.3 0.5 0.7 0.9 OUTPUT CURRENT (A) 1.1 1.3 3663 TA06 Related Parts PART NUMBER DESCRIPTION LT1766 COMMENTS 60V, 1.2A (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter VIN: 5.5V to 60V, VOUTMAX = 1.20V, IQ = 2.5mA, ISD = 25µA, TSSOP16/TSSOP16E Packages VIN: 3.6V to 36V, VOUTMAX = 1.2V, IQ = 1.6mA, ISD <1µA, LT1933 500mA(IOUT), 500kHz Step-Down Switching Regulator in SOT-23 ThinSOT Package VIN: 3.6V to 36V, VOUTMAX = 1.2V, IQ = 1.9mA, ISD <1µA, LT1936 36V, 1.4A(IOUT) , 500kHz High Efficiency Step-Down DC/DC Converter MS8E Package VIN: 3.6V to 25V, VOUTMAX = 1.20V, IQ = 3.8mA, ISD <30µA, LT1940 Dual 25V, 1.4A (IOUT), 1.1MHz, High Efficiency Step-Down DC/DC Converter TSSOP16E Package LT1976/LT1977 60V, 1.2A (IOUT), 200/500kHz, High Efficiency Step-Down DC/DC Converter VIN: 3.3V to 60V, VOUTMAX = 1.20V, IQ = 100µA, ISD <1µA, with BurstMode® Operation TSSOP16E Package LTC3407/ Dual 600mA/800mA, 1.5/2.25 MHz Syncronous Step-Down DC/DC VIN: 2.5V to 5.5V, VOUTMAX = 0.6V, IQ = 40µA, ISD <1µA, 3mm × 3mm DFN, MS10E Packages LTC3407-2 Converter LT3434/LT3435 60V, 2.4A (IOUT), 200/500kHz, High Efficiency Step-Down DC/DC Converter VIN: 3.3V to 60V, VOUTMAX = 1.20V, IQ = 100µA, ISD <1µA, with BurstMode Operation TSSOP16E Package VIN: 3.3V to 60V, VOUTMAX = 1.25V, IQ = 100µA, ISD <1µA, LT3437 60V, 400mA (IOUT),MicroPower Step-Down DC/DC Converter with BurstMode Operation 3mm × 3mm DFN, TSSOP16E Packages VIN: 3.6V to 36V, VOUTMAX = 0.8V, IQ = 1.9mA, ISD <1µA, LT3493 36V, 1.4A(IOUT), 750kHz High Efficiency Step-Down DC/DC Converter 2mm × 3mm DFN Package LT3501 Dual 25V, 3A (IOUT), 1.5MHz, High Efficiency Step-Down DC/DC Converter VIN: 3.3V to 25V, VOUTMAX = 0.8V, IQ = 3.7mA, ISD <10µA, TSSOP-20E Package VIN: 3.6V to 20V, VOUTMAX = 0.78V, IQ = 1.9mA, ISD <1µA, LT3503 20V, 1A (IOUT), 2.2MHz, High Efficiency Step-Down DC/DC Converter 2mm × 3mm DFN, Package VIN: 3.6V to 36V, VOUTMAX = 0.78V, IQ = 2mA, ISD <2µA, LT3505 36V, 1.2A (IOUT), 3MHz, High Efficiency Step-Down DC/DC Converter 3mm × 3mm DFN, MS8E Packages LT3506/ Dual 25V, 1.6A (IOUT), 575kHz/1.1MHz, High Efficiency Step-Down DC/DC VIN: 3.6V to 25V, VOUTMAX = 0.8V, IQ = 3.8mA, ISD <30µA, Converter 4mm × 5mm DFN Package LT3506A VIN: 3.6V to 36V, VOUTMAX = 0.8V, IQ = 4.3mA, ISD <1µA, LT3508 Dual 36V, 1.4A (IOUT), 2.5MHz, High Efficiency Step-Down DC/DC Converter 4mm × 4mm QFN, TSSOP16E Packages LT3510 Dual 25V, 2A (IOUT), 1.5MHz, High Efficiency Step-Down DC/DC Converter VIN: 3.3V to 25V, VOUTMAX = 0.8V, IQ = 3.7mA, ISD <10µA, TSSOP-20E Package LTC3548 Dual 400mA + 800mA, 2.25 MHz Syncronous Step-Down DC/DC Converter VIN: 2.5V to 5.5V, VOUTMAX = 0.6V, IQ = 40µA, ISD <1µA, 3mm × 3mm DFN, MS10E Packages BurstMode is a registered trademark of Linear Technology Corporation. 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LT3663 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LT3663 3663fc LT 0513 REV C • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2009