FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Features Description ■ 1.6MHz Switching Frequency The FAN5331 is a general purpose, fixed-frequency boost converter designed to operate at high switching frequencies in order to minimize switching noise measured at the battery terminal of hand-held communications equipment. Quiescent current in normal mode of operation as well as in shutdown mode is designed to be minimal in order to extend battery life. Normal mode of operation or shutdown mode can be selected by a logic level shutdown circuitry. ■ Low Noise ■ Low RDS(ON): 0.5Ω ■ Adjustable Output Voltage ■ 1A Peak Switch Current ■ Low Shutdown Current: <1µA ■ Cycle-by-Cycle Current Limit ■ Over-Voltage Protection The low ON-resistance of the internal N-channel switch ensures high efficiency and low power dissipation. A cycle-by-cycle current limit circuit keeps the peak current of the switch below a maximum value of 1A. The FAN5331 is available in a 5-lead SOT-23 package. ■ Fixed -Frequency PWM Operation ■ Internal Compensation ■ 5-lead SOT-23 Package Applications ■ Cell Phones ■ PDAs ■ Handheld Equipment ■ Display Bias ■ LED Bias Typical Application BAT54 L 2.7V to 5.5V VIN VOUT 10µH CIN COUT 4.7µF 4.7µF 5 SW FAN5331 VIN FB R1 1 CF 120pF 3 R2 4 ON OFF SHDN GND 2 Figure 1. Typical Application Diagram ©2004 Fairchild Semiconductor Corporation FAN5331 Rev. 1.0.1 1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch October 2004 Top View SW VIN GND FB SHDN 5-Lead SOT-23 Figure 2. Pin Assignment Pin Description Pin No. Pin Name 1 SW 2 GND 3 FB 4 SHDN 5 VIN Pin Description Switching node. Analog and power ground. Feedback node that connects to an external voltage divider. Shutdown control pin. Logic HIGH enables, logic LOW disables the device. Input voltage. Absolute Maximum Ratings (Note1) Parameter Min VIN to GND Max Unit 6.0 V FB, SHDN to GND -0.3 VIN + 0.3 V SW to GND -0.3 23 V Lead Soldering Temperature (10 seconds) 300 °C Junction Temperature 150 °C Storage Temperature -55 Thermal Resistance (ΘJA) Electrostatic Discharge Protection (ESD) Level (Note 2) HBM 2.5 CDM 1 Min Typ 150 °C 265 °C/W kV Recommended Operating Conditions Parameter Input Voltage 2.7 Output Voltage VIN Operating Ambient Temperature -40 Output Capacitance (Note 3) 1.6 25 Max Unit 5.5 V 20 V 85 °C µF Notes: 1. Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Absolute maximum ratings apply individually only, not in combination. 2. Using EIA/JESD22A114B (Human Body Model) and EIA/JESD22C101-A (Charge Device Model). 3. This load capacitance value is required for the loop stability. Tolerance, temperature variation, and voltage dependency of the capacitance must be considered. Typically a 4.7µF ceramic capacitor is required to achieve specified value at VOUT = 15V. 2 FAN5331 Rev. 1.0.1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Pin Assignment Unless otherwise noted, VIN = 3.6V, TA = -40°C to +85°C, Typical values are at TA = 25°C, Test Circuit, Figure 3. Parameter Conditions Min. Typ. 1 Max. Units Switch Current Limit VIN = 3.2V 0.7 Load Current VOUT = 15V, V IN ≥ 2.7V 35 mA VOUT = 15V, V IN ≥ 3.2V 50 mA Switch On-resistance Quiescent Current OFF Mode Current Shutdown Threshold A VIN = 5V 0.5 Ω VIN = 3.6V 0.7 Ω VSHDN = 3.6V, No Switching 0.7 VSHDN = 3.6V, Switching 1.6 3.0 mA VSHDN = 0V 0.1 2 µA 0.5 V Device ON mA 1.5 V Device OFF Shutdown Pin Bias Current VSHDN = 0V or VSHDN = 5.5V Feedback Voltage ILoad = 0mA 10 1.205 nA 1.230 Feedback Pin Bias Current 1.255 10 Feedback Voltage Line Regulation 2.7V < VIN < 5.5V, ILOAD = 0mA V nA 0.6 1.2 % Switching Frequency 1.15 1.6 1.85 MHz Maximum Duty Cycle 87 93 % Enable Delay VIN = 2.7V, IOUT = 35mA, VOUT = 15V 0.8 5 mS Power on Delay VIN = 2.7V, IOUT = 35mA, VOUT = 15V 0.8 5 mS Switch Leakage Current No Switching, VIN = 5.5V 1 µA Test Circuit BAT54 L 2.7V to 5.5V VIN VOUT 10µH CIN COUT 4.7µF 4.7µF 5 SW V 1 R1 150KΩ 120pF FAN5331 IN 4 ON FB 3 R2 SHDN CF GND 2 13.4KΩ OFF Figure 3. Test Circuit 3 FAN5331 Rev. 1.0.1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Electrical Characteristics TA = 25°C, Test Circuit Figure 3, unless otherwise noted. Maximum Load Current vs Input Voltage Output Voltage vs Input Voltage Maximum Load Current (mA) Output Voltage (V) 14.98 14.96 14.94 14.92 VIN(V) VIN(V) VIN(V) VIN(V) VIN(V) VIN(V) 14.90 14.88 vs vs vs vs vs vs VOUT(V) at Iload=0mA VOUT(V), at load=10mA VOUT(V), at load=20mA VOUT(V) at Iload=30mA VOUT(V) at Iload=40mA VOUT(V) at Iload=50mA 14.86 2.5 3.0 3.5 4.0 4.5 5.0 5.5 350 300 250 200 UT = V 12 UT VO VO 150 = T V 15 1V =2 VOU 100 50 0 6.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Input Voltage (V) Input Voltage (V) Efficiency vs Input Voltage Feedback Voltage vs Ambient Temperature 0.92 1.25 0.90 Feedback Voltage (V) 0.88 0.86 Efficiency 0.84 0.82 0.80 0.78 VIN(V) VIN(V) VIN(V) VIN(V) VIN(V) 0.76 0.74 vs vs vs vs vs Efficiency Efficiency Efficiency Efficiency Efficiency at at at at at Iload Iload Iload Iload Iload =10mA =20mA =30mA =40mA =50mA 1.24 1.23 1.22 3.0 3.5 4.0 4.5 5.0 5.5 Temperature (°C) vs Vf (Vin=2.7V, Iload=15m A) Temperature (°C) vs Vf (Vin=3.6V, Iload=15m A) Temperature (°C) vs Vf (Vin=5.5V, Iload=15m A) 1.21 0.72 2.5 IOUT = 15mA -50 6.0 0 Input Voltage (V) 50 100 150 Ambient Temperature (ºC) Supply Current vs Input Voltage Switching Frequency vs Ambient Temperature Switching Frequency (MHz) Supply Current (mA) 3.0 IOUT = 0mA 2.5 2.0 Switching 1.5 Non Switching 1.0 0.5 0.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 1.6 1.4 1.2 1.0 -40 6.0 Input Voltage (V) -20 0 20 40 60 80 100 120 140 Ambient Temperature (ºC) 4 FAN5331 Rev. 1.0.1 IOUT = 15mA VOUT = 15V VIN = 3.6V 1.8 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Typical Performance Characteristics TA = 25°C, Test Circuit Figure 3, unless otherwise noted. Startup After Enable Line Transient Response IOUT = 30mA Tr = Tf = 10µS VOUT = 15V Inductor Current= 0mA Time (200µs/div) VIN = 3.2V +0.6V -0.6V Time (100µs/div) Load Transient Response Output Power Spectral Density (100mV/Div) (10mA/Div) VIN = 4.2V Output Voltage (200mA/div) (5V/div) Input Voltage RL = 300Ω VIN = 3V VOUT = 15V VIN = 3.6V IOUT = 35mA Tr = Tr = <1µS VOUT = 15V IOUT = 0 to 35mA Time (20µs/div) 5 FAN5331 Rev. 1.0.1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Typical Performance Characteristics (Contd.) VIN 5 SHDN 4 Shutdown Circuitry FB SW 1 + Comp - 1.15 x VREF Thermal Shutdown R FB 3 - Error Amp + S + Comp - R Current Limit Comparator - Ramp Generator Q R n Driver S + Oscillator + Amp Reference 0.05 Soft-Start 2 GND Figure 4. Block Diagram Circuit Description reset by other events as well. Over-current condition is monitored by the current limit comparator which resets the latch and turns off the switch instantaneously within each clock cycle. Over-voltage condition is detected by a fast comparator limiting the duty cycle in a similar manner to over-current monitoring described above. The FAN5331 is a pulse-width modulated (PWM) current-mode boost converter. The FAN5331 improves the performance of battery powered equipment by significantly minimizing the spectral distribution of noise at the input caused by the switching action of the regulator. In order to facilitate effective noise filtering, the switching frequency was chosen to be high, 1.6MHz. An internal soft start circuitry minimizes in-rush currents. The timing of the soft start circuit was chosen to reach 95% of the nominal output voltage within maximum 5mS following an enable command when VIN = 2.7V, VOUT = 15V, ILOAD = 35mA and COUT (EFFECTIVE) = 3.2µF. Applications Information Setting the Output Voltage The internal reference is 1.23V (Typical). The output voltage is divided by a resistor divider, R1 and R2 to the FB pin. The output voltage is given by The device architecture is that of a current mode controller with an internal sense resistor connected in series with the N-channel switch. The voltage at the feedback pin tracks the output voltage at the cathode of the external Schottky diode (shown in the test circuit). The error amplifier amplifies the difference between the feedback voltage and the internal bandgap reference. The amplified error voltage serves as a reference voltage to the PWM comparator. The inverting input of the PWM comparator consists of the sum of two components: the amplified control signal received from the 50mΩ current sense resistor and the ramp generator voltage derived from the oscillator. The oscillator sets the latch, and the latch turns on the FET switch. Under normal operating conditions, the PWM comparator resets the latch and turns off the FET, thus terminating the pulse. Since the comparator input contains information about the output voltage and the control loop is arranged to form a negative feedback loop, the value of the peak inductor current will be adjusted to maintain regulation. R V OUT = V REF 1 + ------1- R 2 According to this equation, and assuming desired output voltage of 15V, good choices for the feedback resistors are, R1=150kΩ and R2=13.4kΩ. Inductor Selection The inductor parameters directly related to device performances are saturation current and dc resistance. The FAN5331 operates with a typical inductor value of 10µH. The lower the dc resistance, the higher the efficiency. Usually a trade-off between inductor size, cost and overall efficiency is needed to make the optimum choice. The inductor saturation current should be rated around 1A, which is the threshold of the internal current limit circuit. This limit is reached only during the start-up and with heavy load condition; when this event occurs the converter can shift over in Every time the latch is reset, the FET is turned off and the current flow through the switch is terminated. The latch can be 6 FAN5331 Rev. 1.0.1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Block Diagram Some recommended inductors are suggested in the table below: Inductor Value Vendor Part Number Comment 10µH Panasonic ELL6GM100M Lower Profile (1.6mm) 10µH Murata LQS66SN100M03L Highest Efficiency 10µH Coilcraft DO1605T-103Mx Small Size Table 1: Recommended Inductors Figure 5. Recommended Layout Capacitors Selection Application Examples For best performance, low ESR input and output capacitors are required. Ceramic capacitors in the range 4.7µF to 10µF, placed as close to the IC pins, are recommended for the lower input and output ripple. The output capacitor voltage rating should be according to the VOUT setting. 1. LED Driver One or more serial LED strings can be driven with a constant current, set by the series resistor, given by 1.23V I LED = ---------------R1 A feed forward capacitor CF, is required for stability. The recommended value (R1 x CF) is around 18µS. Some capacitors are suggested in the table below. Capacitor Value Vendor Part Number 4.7µF Panasonic ECJ3YB1C475K 4.7µF Murata GRM31CR61C475 BAT54 L 2.7V to 5.5V VIN 10µH CIN VOUT COUT 4.7µF 4.7µF 5 SW V 1 IN FAN5331 Table 2: Recommended Capacitors Diode Selection The external diode used for rectification is usually a Schottky diode. Its average forward current and reverse voltage maximum ratings should exceed the load current and the voltage at the output of the converter respectively. A barrier Schottky diode such as BAT54 is preferred, due to its lower reverse current over the temperature range. 4 ON OFF GND SHDN R1 2 R2 Figure 6. Low Noise Boost LED Driver Care should be taken to avoid any short circuit of VOUT to GND, even with the IC disabled, since the diode can be instantly damaged by the excessive current. LED Current vs Input Voltage (String Connected to FB Pin) Thermal Shutdown When the die temperature exceeds 150°C, a reset occurs and will remain in effect until the die cools to 130°C, at that time the circuit will be allowed to restart. LED Current (mA) 20.2 PCB Layout Recommendations The inherently high peak currents and switching frequency of power supplies require careful PCB layout design. Therefore, use wide traces for high current paths and place the input capacitor, the inductor, and the output capacitor as close as possible to the integrated circuit terminals. The resistor divider that sets the output voltage should be routed away from the inductor to avoid RF coupling. A four layer PCB with at least one 20.1 20.0 19.9 19.8 19.7 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Input Voltage (V) 7 FAN5331 Rev. 1.0.1 3 FB www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch ground plane connected to the pin 2 of the IC is recommended. This ground plane acts as an electromagnetic shield to reduce EMI and parasitic coupling between components. discontinuous conduction mode due to the automatic turn-off of the switching transistor, resulting in higher ripple and reduced efficiency. While the feedback loop tightly regulates VOUT, the negative output voltage (-VOUT) can supply a light load with a negative voltage. Nevertheless, the negative voltage depends on the changes of the load current in both -VOUT and +VOUT, as shown in the graph below. A Zener diode (VZ = 22V) connected between VOUT and GND can prevent the FAN5331 from being damaged by over-voltage, if the load is accidently disconnected during operation. Negative Output Voltage vs Load Current -18 Negative Output Voltage (V) 2. Dual Boost Converter A negative voltage can be provided by adding an external charge pump (C1, C2, D2, and D3). BAT54S D2 C1 0.1µF IOUT = 10mA 4.7µF BAT54 L 2.7V to 5.5V VIN -VOUT C2 D3 VOUT 10µH CIN COUT I OUT = 50mA D1 4.7µF 4.7µF 5 SW V 1 R1 FAN5331 4 ON OFF FB -15V/10mA Load -14 -12 -10 CF 0 120pF IN -15V/Unloaded -16 10 20 30 40 50 Load Current On Positive Output Side (mA) 3 R2 SHDN GND 2 Figure 7. Dual (±) Boost Converter 8 FAN5331 Rev. 1.0.1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch The feedback loop tightly regulates the current in the branch connected to FB pin, while the current in the other branch depends on the sum of the LED’s forward voltages, VOUT and the ballast resistor. The input and the output ripple is less than 3mVRMS, for load currents up to 40mA. FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch Mechanical Dimensions 5-Lead SOT-23Package B L c e E H e1 D A A1 Symbol Inches Min Millimeters Max Min Max A .035 .057 .90 1.45 A1 .000 .006 .00 .15 B .008 .020 .20 .50 c .003 .010 .08 .25 D .106 .122 2.70 3.10 E .059 .071 1.50 1.80 e .037 BSC .95 BSC e1 .075 BSC 1.90 BSC H .087 .126 2.20 3.20 L .004 .024 .10 .60 α 0º 10º 0º 10º Notes Ordering Information Product Number Package Type Order Code FAN5331 5-Lead SOT23 FAN5331SX 9 FAN5331 Rev. 1.0.1 www.fairchildsemi.com The following are registered and unregistered trademarks Fairchild Semiconductor owns or is authorized to use and is not intended to be an exhaustive list of all such trademarks. ACEx™ FACT Quiet Series™ ActiveArray™ FAST Bottomless™ FASTr™ CoolFET™ FPS™ CROSSVOLT™ FRFET™ DOME™ GlobalOptoisolator™ EcoSPARK™ GTO™ E2CMOSTM HiSeC™ EnSignaTM I2C™ FACT™ ImpliedDisconnect™ Across the board. Around the world.™ The Power Franchise™ Programmable Active Droop™ ISOPLANAR™ LittleFET™ MICROCOUPLER™ MicroFET™ MicroPak™ MICROWIRE™ MSX™ MSXPro™ OCX™ OCXPro™ OPTOLOGIC OPTOPLANAR™ PACMAN™ POP™ Power247™ PowerTrench QFET QS™ QT Optoelectronics™ Quiet Series™ RapidConfigure™ RapidConnect™ SILENT SWITCHER SMART START™ SPM™ Stealth™ SuperFET™ SuperSOT™-3 SuperSOT™-6 SuperSOT™-8 SyncFET™ TinyLogic TINYOPTO™ TruTranslation™ UHC™ UltraFET VCX™ DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component is any component of a life 1. Life support devices or systems are devices or support device or system whose failure to perform can systems which, (a) are intended for surgical implant into be reasonably expected to cause the failure of the life the body, or (b) support or sustain life, or (c) whose support device or system, or to affect its safety or failure to perform when properly used in accordance with instructions for use provided in the labeling, can be effectiveness. reasonably expected to result in significant injury to the user. PRODUCT STATUS DEFINITIONS Definition of Terms Datasheet Identification Product Status Definition Advance Information Formative or In Design This datasheet contains the design specifications for product development. Specifications may change in any manner without notice. Preliminary First Production This datasheet contains preliminary data, and supplementary data will be published at a later date. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design. No Identification Needed Full Production This datasheet contains final specifications. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design. Obsolete Not In Production This datasheet contains specifications on a product that has been discontinued by Fairchild semiconductor. The datasheet is printed for reference information only. Rev. I7 10 FAN5331 Rev. 1.0.1 www.fairchildsemi.com FAN5331 1.6MHz Boost Converter with 20V Integrated FET Switch TRADEMARKS