TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 FEATURES APPLICATIONS • • • • • • • • • • Simple Boost Converter Flyback Converters, Single/Multiple Outputs SEPIC Converter With VIN Higher or Lower Than Output Voltage Transformer-Coupled Forward Converters KTT (TO-263) PACKAGE (TOP VIEW) GND • Few External Components Required (As Few As Six) Current Limit, Undervoltage Lockout, and Thermal Shutdown Wide Input Voltage Range: 3 V to 40 V 100-kHz Internal Oscillator Allows for Use of Small Magnetics Current-Mode Operation for Faster Transient Response, Line Regulation, and Cycle-by-Cycle Current Limiting Soft-Start Capability Provides Controlled Startup Current Improved Replacement for LM2577 Series 5 4 3 2 1 VIN SWITCH GND FEEDBACK COMP DESCRIPTION/ORDERING INFORMATION The TL3577 series are easy-to-use devices that incorporate all the active circuitry required to implement either step-up (boost), flyback, forward converter, or SEPIC converter switching regulators. The internal 3-A 65-V switch allows the TL3577 to provide an output voltage of up to 60 V as a simple boost regulator; higher output voltages can be achieved with the TL3577 configured as a flyback or forward converter. Requiring few external components, The TL3577 features a wide input voltage range of 3 V to 40 V and offers an adjustable output voltage. Basic protection features include undervoltage lockout, thermal protection, and soft start, which is provided to reduce input current during startup. Current-mode control provides cycle-by-cycle current limiting, as well as faster line and load regulation. The internal 100-kHz oscillator allows for use of smaller magnetics and filter components, when compared with similar regulators running at 52 kHz. A standard series of inductors and capacitors optimized for use with these regulators is available from several manufacturers and are listed in this data sheet. The TL3577 is characterized for operation over the virtual junction temperature range of –40°C to 125°C. ORDERING INFORMATION TJ –40°C to 125°C (1) VO (NOM) ADJ PACKAGE (1) TO-263 – KTT Reel of 500 ORDERABLE PART NUMBER TL3577-ADJIKTTR TOP-SIDE MARKING TL3577ADJI Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at www.ti.com/sc/package. Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2006, Texas Instruments Incorporated TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 FUNCTIONAL BLOCK DIAGRAM VIN SWITCH Current Limit, Thermal Limit, and Undervoltage Shutdown 2.5-V Regulator 3-A 65-V NPN Switch Driver Stage Logic 100-kHz Oscillator Corrective Ramp Voltage + Comparator S + CurrentSense Voltage Amp FEEDBACK Soft Start Error Amplifier 1.23-V Reference COMP 2 CurrentSense Resistor Submit Documentation Feedback GND www.ti.com TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 Absolute Maximum Ratings (1) over operating free-air temperature range (unless otherwise noted) MIN MAX UNIT VIN Supply voltage 45 V VSW Output SWITCH voltage 65 V ISW Output SWITCH current TJ Maximum junction temperature Tstg Storage temperature range TJ Junction temperature (1) –65 6 A 150 °C 150 °C 150 °C Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Package Thermal Data (1) (1) PACKAGE BOARD θJA θJC θJCB TO-263 (KTT) High K, JESD 51-5 31.8 35.0 1.13 Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can affect reliability. Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN MAX VIN Supply voltage 3 40 V VSW Output SWITCH voltage 0 60 V ISW Output SWITCH current 3 A TJ Operating virtual junction temperature –40 125 °C Submit Documentation Feedback UNIT 3 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 Electrical Characteristics VIN = 5 V, VFEEDBACK = VREF, ISWITCH = 0 (unless otherwise noted) PARAMETER TEST CONDITIONS TL3577-ADJ MIN TYP MAX 12 12.4 VOUT Output voltage VIN = 5 V to 10 V, ILOAD = 100 mA to 800 mA, See Figure 1 25°C 11.6 Full range 11.4 DVOUT DVIN Line regulation VIN = 3.5 V to 10 V, ILOAD = 200 mA, See Figure 1 Full range DVOUT DILOAD Load regulation ILOAD = 100 mA to 800 mA, See Figure 1 η Efficiency ILOAD = 800 mA, See Figure 1 VFEEDBACK = 1.5 V (SWITCH Off) ICC Input supply current ISWITCH = 2 A, VCOMP = 2 V (maximum duty cycle) VUV Input supply undervoltage lockout ISWITCH = 100 mA fO Oscillator frequency Measured at SWITCH, ISWITCH = 100 mA VREF Reference voltage Measured at FEEDBACK, VIN = 3 V to 40 V, VCOMP = 1 V DVREF DVIN Reference voltage line regulation VIN = 3 V to 40 V IB Error amplifier input bias current VCOMP = 1 V GM Error amplifier transconductance ICOMP = –30 µA to 30 µA, VCOMP = 1 V AVOL Error amplifier voltage gain VCOMP = 1.1 V to 1.9 V, RCOMP = 1 MΩ (1) Upper limit, VFEEDBACK = 1 V Error amplifier output swing Lower limit, VFEEDBACK = 1.5 V 25°C 12.6 20 25°C 20 80 25°C 7.5 Full range 45 Full range 25°C 2.7 85 Full range 80 25°C 1.214 Full range 1.206 100 1.23 25°C 100 Full range 25°C 2400 1600 25°C 500 Full range 250 25°C 2.2 3700 ±130 ±90 Switch leakage current VSWITCH = 65 V, VFEEDBACK = 1.5 V (SWITCH off) Full range VSAT Switch saturation voltage ISWITCH = 2 A, VCOMP = 2 V (maximum duty cycle) Full range NPN switch current limit VCOMP = 2 V 25°C 2.5 Full range 1.5 25°C 88 Full range 84 ±200 4800 kHz V nA µmho V/V 0.4 ±300 ±400 5 7.5 9.5 90 12.5 25°C 10 V 0.5 3 4.3 µA A/V 300 0.7 0.9 3.7 µA % 600 25°C 25°C V 2.4 25°C Full range mA 0.55 25°C IL 300 800 0.3 Full range Switch transconductance mV mV 5800 Full range DISWITCH DVCOMP 1.246 2 25°C VCOMP = 1.5 V, ISWITCH = 100 mA 115 800 Full range Maximum duty cyle 2.85 1.254 0.5 D 70 120 25°C VFEEDBACK = 1 V, VCOMP = 0 mV 10 2.95 25°C Soft-start current V 85 Full range ISS UNIT % 14 25°C VFEEDBACK = 1 V to 1.5 V, VCOMP = 1 V 50 100 25°C Full range 50 100 Full range Error amplifier output current (1) 4 TJ 5.3 6 µA V A A 1-MΩ resistor is connected to the compensation pin (which is the error amplifier output) to ensure accuracy in measuring AVOL. In actual applications, this load resistance should be ≥10 MΩ, resulting in AVOL that is typically twice the specified minimum limit. Submit Documentation Feedback www.ti.com TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 Electrical Characteristics (continued) VIN = 5 V, VFEEDBACK = VREF, ISWITCH = 0 (unless otherwise noted) PARAMETER COMP current TEST CONDITIONS VCOMP = 0 V Submit Documentation Feedback TJ 25°C Full range TL3577-ADJ MIN TYP MAX 25 40 50 UNIT µA 5 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 TYPICAL CHARACTERISTICS ∆ REFERENCE VOLTAGE vs SUPPLY VOLTAGE REFERENCE VOLTAGE vs TEMPERATURE 1.25 0.5 1.248 ∆ Reference Voltage – mV VREF – Reference Voltage – V 0.4 1.246 1.244 1.242 1.24 1.238 1.236 1.234 0.3 0.2 0.1 0 -0.1 1.232 -0.2 1.23 -40 -25 -10 0 5 5 10 20 35 50 65 80 95 110 125 15 20 25 30 35 40 VIN – Supply Voltage – V TA – Temperature – °C ERROR AMPLIFIER VOLTAGE GAIN vs TEMPERATURE 5000 1600 4750 1500 AV – Error Amplifier Voltage Gain – V/V G M – Error Amplifier Transconductance – µmho ERROR AMPLIFIER TRANSCONDUCTANCE vs TEMPERATURE 4500 4250 4000 3750 3500 3250 3000 2750 2500 -40 -25 -10 5 20 35 50 65 80 95 110 125 1400 1300 1200 1100 1000 900 800 700 600 -40 -25 -10 20 35 50 65 80 95 110 125 TA – Temperature – °C TA – Temperature – °C 6 5 Submit Documentation Feedback TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 TYPICAL CHARACTERISTICS (continued) QUIESCENT CURRENT vs TEMPERATURE SWITCH CURRENT LIMIT vs TEMPERATURE 6 10.5 5.8 10 5.6 Switch Current Limit – A IQ – Quiescent Current – mA 11 9.5 9 8.5 8 7.5 5.4 5.2 5 4.8 4.6 4.4 7 4.2 6.5 6 -40 -25 -10 4 -40 -25 -10 5 20 35 50 65 80 95 110 125 5 20 35 50 65 80 95 110 125 TA – Temperature – °C TA – Temperature – °C OSCILLATOR FREQUENCY vs TEMPERATURE 130 110 120 108 110 106 f O – Oscillator Frequency – kHz IB – FEEDBACK Bias Current – nA FEEDBACK BIAS CURRENT vs TEMPERATURE 100 90 80 70 60 50 104 102 100 98 96 94 40 92 30 -40 -25 -10 90 -40 -25 -10 5 20 35 50 65 80 95 110 125 5 20 35 50 65 80 95 110 125 TA – Temperature – °C TA – Temperature – °C Submit Documentation Feedback 7 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 TYPICAL CHARACTERISTICS (continued) SWITCH SATURATION VOLTAGE vs TEMPERATURE 0.9 VSAT – Switch Saturation Voltage – V 0.85 0.8 ISW = 2 A VCOMP = 2 V 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 -40 -25 -10 5 20 35 50 65 80 95 110 125 TA – Temperature – °C 8 Submit Documentation Feedback www.ti.com TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 PARAMETER MEASUREMENT INFORMATION 220 µF VIN 10 kW 100 µH VIN 120 W SWITCH TL3577-ADJ 0.1 µF COMP 2 kW R1 24 W COUT 680 µF 0.1 µF LOAD SW1 FEEDBACK GND 60 W SW2 R2 0.33 µF A. R1 = 48.7 kΩ in series with 511 Ω B. R2 = 5.62 kΩ (1%) Figure 1. Test Circuit Submit Documentation Feedback 9 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 APPLICATION INFORMATION Figure 2 shows a typical application of the TL3577 in a boost regulator. 5-V Input 12 V at £800 mA Regulated Output 100 µH 680 µF 0.1 µF VIN SWITCH TL3577-ADJ COMP 2.2 kW 17.4 kW FEEDBACK GND 2 kW 0.33 µF Figure 2. Typical Application – Boost Regulator Figure 3 shows a typical application of the TL3577 in a flyback regulator. 5V (4 V to 6 V) 100 µF 12 V at 150 mA 1:2.5 330 µF 47 µH 1 µF 12 V at 150 mA 330 µF VIN SWITCH TL3577-ADJ 17.4 kΩ COMP 2.4 kΩ FEEDBACK GND 2 kΩ 0.47 µF Figure 3. Typical Application – Flyback Regulator 10 Submit Documentation Feedback www.ti.com www.ti.com TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 APPLICATION INFORMATION (continued) Figure 4 shows a typical application of the TL3577 in a SEPIC regulator. Input 3 V to 12 V 1 µF (See Note A) 100 µH VIN SWITCH 100 µH TL3577-ADJ 22 µF 20 kΩ COMP 10 kΩ Output 3.3 V FEEDBACK GND 12.1 kΩ 10 µF 680 pF A. Low ESR. Voltage rating must be at least VIN + VOUT. Figure 4. Typical Application – SEPIC Regulator Submit Documentation Feedback 11 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 APPLICATION INFORMATION (continued) Step-Up (Boost) Regulator Figure 2 shows a step-up switching regulator utilizing the TL3577. The regulator produces an output voltage higher than the input voltage. The TL3577 turns its switch on and off at a fixed frequency of 100 kHz, thus storing energy in the inductor (L). When the NPN switch is on, the inductor current is charged at a rate of VIN/L. When the switch is off, the voltage at the SWITCH terminal of the inductor rises above VIN, discharging the stored current through the output diode (D) into the output capacitor (COUT) at a rate of (VOUT – VIN)/L. The energy stored in the inductor is thus transferred to the output. The output voltage is controlled by the amount of energy transferred, which is controlled by modulating the peak inductor current. This modulation is accomplished by feeding a portion of the output voltage to an error amplifier that amplifies the difference between the feedback voltage and an internal 1.23-V precision reference voltage. The output of the error amplifier is compared to a voltage that is proportional to the switch current or the inductor current during the switch-on time. A comparator terminates the switch-on time when the two voltages are equal and, thus, controls the peak switch current to maintain a constant output voltage. Figure 5 shows voltage and current waveforms for the circuit. Formulas for calculation are shown in Table 1. Step-Up Regulator Design Procedure Given: VIN(min) = Minimum input supply voltage VOUT = Regulated output voltage VSW(OFF) Switch Voltage Diode Voltage VSAT 0V VF 0V VR Inductor Current Switch Current IIND(AVG) ∆IIND 0 ISW(PK) 0 Diode Current ID(PK) ID(AVG) 0 Figure 5. Step-Up Regulator Waveforms 12 Submit Documentation Feedback TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 Table 1. Step-up Regulator Formulas Duty cycle Average inductor current VOUT + VF – VIN ∆IIND Peak inductor current IIND(PK) VOUT – VIN ≈ VOUT + VF – VSAT VOUT ILOAD IIND(AVG) Inductor current ripple Peak switch current 1–D VIN – VSAT L • ILOAD 1–D ILOAD ISW(PK) 1–D D 100,000 + + ∆IIND 2 ∆IIND 2 Switch voltage when off VSW(OFF) VOUT + VF Diode reverse voltage VR VOUT – VSAT Average diode current ID(AVG) ILOAD Peak diode current ID(PK) Power dissipation (1) D (1) PD ILOAD 1–D 0.25 Ω ( ILOAD 1–D ( + ∆IIND 2 D+ 2 ILOAD • D • VIN 50 (1 – D) VF = forward-biased diode voltage, ILOAD = output load First, determine if the TL3577 can provide these values of VOUT and ILOAD(max) when operating with the minimum value of VIN. The upper limits for VOUT and ILOAD(max) are given by the following equations. VOUT ≤ 60 V and VOUT ≤ 10 × VIN ILOAD(max) ≤ (2.1 A × VIN(min))/VOUT These limits must be greater than or equal to the values specified in this application. 1. Output Voltage Section Resistors R1 and R2 are used to select the desired output voltage. These resistors form a voltage divider and present a portion of the output voltage to the error amplifier, which compares it to an internal 1.23-V reference. Select R1 and R2 such that: R1/R2 = (VOUT/1.23 V) – 1 2. Inductor Selection (L) A. Preliminary Calculations To select the inductor, the calculation of the following three parameters is necessary: Dmax, the maximum switch duty cycle (0 ≤ D ≤ 0.9): Dmax = VOUT + VF – VIN(min)/VOUT + VF – 0.6 V where, typically, VF = 0.5 V for Schottky diodes and VF = 0.8 V for fast-recovery diodes. E • T, the product of volts • time that charges the inductor: E • T = Dmax × (VIN(min) – 0.6V)106/100,000 Hz (Vµs) IIND,DC, the average inductor current under full load: IIND,DC = (1.05 × ILOAD(max))/(1 – Dmax) Submit Documentation Feedback 13 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 B. Identify Inductor Value 1. From Figure 6, identify the inductor code for the region indicated by the intersection of E • T and IIND,DC. This code gives the inductor value in microhenries. The L or H prefix signifies whether the inductor is rated for a maximum E • T of 90 Vµs (L) or 250 Vµs (H). 2. If D < 0.85, go to step C. If D ≥ 0.85, calculate the minimum inductance needed to ensure the switching regulator’s stability: If Lmin is smaller than the inductor values found in step B1, go on to step C. Otherwise, the inductor value found in step 1, above, is too low; an appropriate inductor code should be obtained from Figure 6 as follows: a. Find the lowest-value inductor that is greater than Lmin. b. Find where E • T intersects this inductor value to determine if it has an L or H prefix. If E • T intersects both the L and H regions, select the inductor with an H prefix. C. Inductor Selection Select an inductor from Table 2 which cross references the inductor codes to the part numbers of the three different manufacturers. The inductors listed in Table 2 have the following characteristics: AIE (ferrite, pot-core inductors): Benefits of this type are low electromagnetic interference (EMI), small physical size, and very low power dissipation (core loss). Pulse (powdered iron, toroid core inductors): Benefits are low EMI and ability to withstand E • T and peak current above rated value better than ferrite cores. Renco (ferrite, bobbin-core inductors): Benefits are low cost and best ability to withstand E • T and peak current above rated value. Be aware that these inductors generate more EMI than the other types, and this may interfere with signals sensitive to noise. 200 H2200 150 H1500 H1000 H680 H470 H330 H220 E • T (V • µs) 100 90 H150 80 70 L680 60 50 45 40 L470 L330 L220 L150 L100 L68 35 30 L47 25 20 0.3 0.35 0.4 0.45 0.5 0.6 0.7 0.8 0.9 1.0 1.5 2.0 2.5 3.0 I IND,DC (A) A. This chart assumes that the inductor ripple current inductor is approximately 20% to 30% of the average inductor current (when the regulator is under full load). Greater ripple current causes higher peak switch currents and greater output ripple voltage. Lower ripple current is achieved with larger value inductors. The factor of 20% to 30% is chosen as a convenient balance between the two extremes. Figure 6. Inductor Selection Graph 14 Submit Documentation Feedback www.ti.com TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 Table 2. Standardized Inductors and Manufacturer’s Part Numbers Manufacturer’s Part Number Inductor Code (1) (2) (3) AIE (1) Pulse (2) Renco (3) L47 415 - 0932 PE - 53112 RL2442 L68 415 - 0931 PE - 92114 RL2443 L100 415 - 0930 PE - 92108 RL2444 L150 415 - 0953 PE - 53113 RL1954 L220 415 - 0922 PE - 52626 RL1953 L330 415 - 0926 PE - 52627 RL1952 L470 415 - 0927 PE - 53114 RL1951 L680 415 - 0928 PE - 52629 RL1950 H150 415 - 0936 PE - 53115 RL2445 H220 430 - 0636 PE - 53116 RL2446 H330 430 - 0635 PE - 53117 RL2447 H470 430 - 0634 PE - 53118 RL1961 H680 415 - 0935 PE - 53119 RL1960 H1000 415 - 0934 PE - 53120 RL1959 H1500 415 - 0933 PE - 53121 RL1958 H2200 415 - 0945 PE - 53122 RL2448 AIE Magnetics, Div. Vernitron Corp., (813) 347-2181 2801 72nd Street North, St. Petersburg, FL 33710 Pulse Engineering, (619) 674-8100 12220 World Trade Drive, San Diego, CA 92128 Renco Electronics, Inc., (516) 586-5566 60 Jeffryn Blvd. East, Deer Park, NY 11729 3. Compensation Network (RC, CC) and Output Capacitor (COUT) Selection The compensation network consists of resistor RC and capacitor CC, which form a simple pole-zero network and stabilize the regulator. The values of RC and CC depend upon the voltage gain of the regulator, ILOAD(max), the inductor L, and output capacitance COUT. A procedure to calculate and select the values for RC, CC, and COUT that ensures stability is described below. It should be noted, however, that this may not result in optimum compensation. To guarantee optimum compensation, a standard procedure for testing loop stability is recommended, such as measuring VOUT transient responses to pulsing ILOAD. A. Calculate the maximum value for RC. RC ≤ (750 × ILOAD(max) × VOUT2)/VIN(min)2 Select a resistor less than or equal to this value, not to exceed 3 kΩ. B. Calculate the minimum value for COUT using the following two equations. COUT ≥ (0.19 × L × RC × ILOAD(max))/(VIN(min) × VOUT) and COUT ≥ (VIN(min) × RC × (VIN(min) + (3.74 × 105 × L))/(487,800 × VOUT3) The larger of these two values is the minimum value that ensures stability. Submit Documentation Feedback 15 TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR www.ti.com SLVS633 – OCTOBER 2006 C. Calculate the minimum value of CC. CC ≥ 58.5 × VOUT2 × COUT × RC2 × VIN(min) The compensation capacitor also is used in the soft-start function of the regulator. When the input voltage is applied to the part, the switch duty cycle is increased slowly at a rate defined by the compensation capacitor and the soft-start current, thus eliminating high input currents. Without the soft-start circuitry, the switch duty cycle would instantly rise to about 90% and draw large currents from the input supply. For proper soft starting, the value for CC should be equal to or greater than 0.22 µF. Table 3 lists several types of aluminum electrolytic capacitors that could be used for the output filter. Use the following parameters to select the capacitor: Working Voltage (WVDC): Choose a capacitor with a working voltage at least 20% higher than the regulator output voltage. Ripple Current: This is the maximum RMS value of current that charges the capacitor during each switching cycle. For step-up and flyback regulators, the formula for ripple current is: IRIPPLE(rms) = (ILOAD(max) × Dmax)/(1 – Dmax) Choose a capacitor that is rated at least 50% higher than this value at 100 kHz. Equivalent Series Resistance (ESR): This is the primary cause of output ripple voltage, and it also affects the values of RC and CC needed to stabilize the regulator. As a result, the preceding calculations for CC and RC are only valid if the ESR does not exceed the maximum value specified by the following equations. ESR ≤ (0.01 × 15 V)/IRIPPLE(P-P) and ≤ (8.7 × 10-3 × VIN)/ILOAD(max) where IRIPPLE(P-P) = (1.15 × ILOAD(max))/(1 – Dmax) Select a capacitor with an ESR, at 100 kHz, that is less than or equal to the lower value calculated. Most electrolytic capacitors specify ESR at 120 kHz, which is 15% to 30% higher than at 100 kHz. Also, note that ESR increases by a factor of 2 when operating at –20°C. In general, low values of ESR are achieved by using large-value capacitors (C ≥ 470 µF) and capacitors with high WVDC, or by paralleling smaller-value capacitors. 4. Input Capacitor Selection (CIN) To reduce noise on the supply voltage caused by the switching action of a step-up regulator (ripple current noise), VIN should be bypassed to ground. A good quality 0.1-µF capacitor with low ESR should provide sufficient decoupling. If the TL3577 is located far from the supply-source filter capacitors, an additional electrolytic (47 µF, for example) is required. Table 3. Aluminum Electrolytic Capacitors Recommended for Switching Regulators Nichicon – Types PF, PX, or PZ 927 East State Parkway, Schaumburg, IL 60173 (708) 843-7500 16 United Chemi-CON – Types LX, SXF, or SXJ 9801West Higgens, Rosemont, IL 60018 (708) 696-2000 Submit Documentation Feedback www.ti.com TL3577 100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR SLVS633 – OCTOBER 2006 5. Output Diode Selection (D) In the step-up regulator, the switching diode must withstand a reverse voltage and be able to conduct the peak output current of the TL3577. Therefore, a suitable diode must have a minimum reverse breakdown voltage greater than the circuit output voltage and should also be rated for average and peak current greater than ILOAD(max) and ID(pk). Because of their low forward-voltage drop (and higher regulator efficiencies), Schottky barrier diodes often are used in switching regulators. Refer to Table 4 for recommended part numbers and voltage ratings of 1-A and 3-A diodes. Table 4. Diode Selection Chart (1) VOUT(max) (V) Schottky Fast Recovery 1A 3A 20 1N5817 MBR120P 1N5820 MBR320P 30 1N5818 MBR130P 11DQ03 1N5821 MBR330P 31DQ03 40 1N5819 MBR140P 11DQ04 1N5822 MBR340P 31DQ04 50 MBR150 11DQ05 MBR350 31DQ05 3A 1N4933 MUR105 1N4934 MUR110 10DL1 100 (1) 1A MR851 30DL1 MR831 MBRxxx and MURxxx are manufactured by Motorola. 1DDxxx, 11Cxx and 31Dxx are manufactured by International Rectifier Submit Documentation Feedback 17 PACKAGE OPTION ADDENDUM www.ti.com 21-Nov-2006 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing TL3577-ADJIKTTR ACTIVE DDPAK/ TO-263 KTT Pins Package Eco Plan (2) Qty 5 500 Green (RoHS & no Sb/Br) Lead/Ball Finish CU SN MSL Peak Temp (3) Level-3-245C-168 HR (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. 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Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Amplifiers amplifier.ti.com Audio www.ti.com/audio Data Converters dataconverter.ti.com Automotive www.ti.com/automotive DSP dsp.ti.com Broadband www.ti.com/broadband Interface interface.ti.com Digital Control www.ti.com/digitalcontrol Logic logic.ti.com Military www.ti.com/military Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security Low Power Wireless www.ti.com/lpw Telephony www.ti.com/telephony Mailing Address: Video & Imaging www.ti.com/video Wireless www.ti.com/wireless Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright © 2007, Texas Instruments Incorporated PACKAGE OPTION ADDENDUM www.ti.com 21-Nov-2006 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing TL3577-ADJIKTTR ACTIVE DDPAK/ TO-263 KTT Pins Package Eco Plan (2) Qty 5 500 Green (RoHS & no Sb/Br) Lead/Ball Finish CU SN MSL Peak Temp (3) Level-3-245C-168 HR (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. 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Reproduction of information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Amplifiers amplifier.ti.com Audio www.ti.com/audio Data Converters dataconverter.ti.com Automotive www.ti.com/automotive DSP dsp.ti.com Broadband www.ti.com/broadband Interface interface.ti.com Digital Control www.ti.com/digitalcontrol Logic logic.ti.com Military www.ti.com/military Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security Low Power Wireless www.ti.com/lpw Telephony www.ti.com/telephony Mailing Address: Video & Imaging www.ti.com/video Wireless www.ti.com/wireless Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright © 2007, Texas Instruments Incorporated