FAN2011I

FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator April 2006 FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Features ■ 95% Efficiency, Synchronous Operation ■ Adjustable Output Voltage from 0.8V to VIN ■ 4.5V to 5.5V Input Voltage Range ■ Up to 1.5A Output Current ■ Fixed Frequency 1.3 MHz PWM Operation ■ 100% Duty Cycle Low Dropout Operation (LDO) ■ Soft Start ■ Excellent Load Transient Response ■ 3x3mm 6-lead MLP Package Description The FAN2011/FAN2012 is a high-efficiency, low-noise synchronous Pulse Width Modulated (PWM) current mode DC-DC converter, designed for low voltage applications. It provides up to 1.5A continuous load current from the 4.5V to 5.5V input. The output voltage is adjustable over a wide range of 0.8V to VIN by means of an external voltage divider. The FAN2011 is always on, while the FAN2012 has an “Enable Input,” and the device can be put in the shutdown mode, in which the ground current falls below 1µA. A current mode control loop with a fast transient response ensures excellent line and load regulation. The fixed 1.3MHz switching frequency enables the user to choose a small, inexpensive external inductor and capacitor. Filtering is also easily accomplished with very small components. Protection features include input under-voltage lockout, short circuit protection and thermal shutdown. Soft-start limits in-rush current during start-up conditions. The device is available in a 3x3mm 6-lead MLP package, making it possible to build a 1.5A complete DC-DC converter in a tiny space on the PCB. Applications ■ Hard Disk Drive ■ Set Top Box ■ Point of Load Power ■ Notebook Computers ■ Communications Equipment Ordering Information Product Number FAN2011 FAN2012 FAN2011I FAN2012I Output Voltage Adjustable Adjustable Adjustable Adjustable Package Type 3x3mm 6-Lead MLP 3x3mm 6-Lead MLP 3x3mm 6-Lead MLP 3x3mm 6-Lead MLP Ambient Operating Temperature 0°C to 85°C 0°C to 85°C -40°C to 85°C -40°C to 85°C Order Code FAN2011MPX FAN2012MPX FAN2011EMPX FAN2012EMPX FAN2011/FAN2012 Rev. 1.0.4 ©2006 Fairchild Semiconductor Corporation 1 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Typical Application R2 R1 VOUT L1 10K Ω FB 1 PGND SW 3 4 2 P1 (A GND) 6 5 NC VIN PVIN 10µF +5V R1 VOUT 4 x 10µF L1 R2 10K Ω FB 1 PGND SW 2 3 P1 (AGND) EN 6 5 4 VIN PVIN 10µF +5V 3.3µH 4 x 10µF 3.3µH FAN2011 FAN2012 Figure 1. Typical Application Pin Assignment Top View FB PGND SW NC VIN PVIN FB PGND SW EN VIN PVIN 1 2 3 6 1 2 3 6 P1 (AGND) 5 4 P1 (AGND) 5 4 FAN2011 3x3mm 6-Lead MLP FAN2012 3x3mm 6-Lead MLP Figure 2. Pin Assignment Pin Description FAN2011 (3x3mm 6-Lead MLP) Pin No. P1 1 2 3 4 5 6 Pin Name AGND FB PGND SW PVIN VIN NC Pin Description Analog Ground. P1 must be soldered to the PCB ground. Feedback Input. Adjustable voltage option; connect this pin to the resistor divider. Power Ground. This pin is connected to the internal MOSFET switches. This pin must be externally connected to AGND. Switching Node. This pin is connected to the internal MOSFET switches. Supply Voltage Input. This pin is connected to the internal MOSFET switches. Supply Voltage Input. Not Connected. This pin is not internally connected. FAN2012 (3x3mm 6-Lead MLP) Pin No. P1 1 2 3 4 5 6 Pin Name AGND FB PGND SW PVIN VIN EN Pin Description Analog Ground. P1 must be soldered to the PCB ground. Feedback Input. Adjustable voltage option; connect this pin to the resistor divider. Power Ground. This pin is connected to the internal MOSFET switches. This pin must be externally connected to AGND. Switching Node. This pin is connected to the internal MOSFET switches. Supply Voltage Input. This pin is connected to the internal MOSFET switches. Supply Voltage Input. Enable Input. Logic high enables the chip and logic low disables the chip, reducing the supply current to less than 1µA. Do not float this pin. FAN2011/FAN2012 Rev. 1.0.4 2 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Absolute Maximum Ratings 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. Unless otherwise specified, all other voltages are referenced to AGND. Parameter VIN PVIN and any other pin Thermal Resistance-Junction to Tab (θJC), 3mm x 3mm 6-lead Lead Soldering Temperature (10 seconds) Storage Temperature Junction Temperature Electrostatic Discharge (ESD) Protection Level(2) HBM CDM MLP(1) Min. -0.3 -0.3 – – -65 -40 4 2 Max. 7 VIN 8 260 150 150 – – Unit V V °C/W °C °C °C kV Recommended Operating Conditions Parameter Supply Voltage Range Output Voltage Range, Adjustable Version Output Current Inductor(3) Input Capacitor(3) Capacitor(3) FAN2011 and FAN2012 FAN2011I and FAN2012I Output Min. 4.5 0.8 – – – – 0 -40 Typ. – – – 3.3 10 4 x 10 – – Max. 5.5 VIN 1500 – – – +85 +85 Unit V V mA µH µF µF °C Operating Ambient Temperature Range Notes: 1. Junction to ambient thermal resistance, θJA, is a strong function of PCB material, board thickness, thickness and number of copper planes, number of via used, diameter of via used, available copper surface, and attached heat sink characteristics. 2. Using Mil Std. 883E, method 3015.7(Human Body Model) and EIA/JESD22C101-A (Charge Device Model). 3. Refer to the applications section for further details. FAN2011/FAN2012 Rev. 1.0.4 3 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Electrical Characteristics VIN = 4.5V to 5.5V, VOUT = 1.2V, IOUT = 200mA, CIN = 10µF, COUT = 4 x 10µF, L = 3.3µH, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C. Parameter Input Voltage Quiescent Current UVLO Threshold PMOS On Resistance NMOS On Resistance P-channel Current Limit Over-Temperature Protection Switching Frequency Line Regulation Load Regulation Output Voltage During Load Transition(4) Output Voltage During Load Transition(4) Reverse Leakage Current Into Pin SW Reference Voltage, VREF Output Voltage Accuracy IOUT = 0mA VIN Rising Hysteresis Conditions Min. 4.5 – 3.4 – – – 2200 – – 1000 – – – -5 – – -2 -3 Typ. – 7 3.7 150 150 150 2600 150 20 1300 0.16 0.2 – – 0.1 0.8 – – Max. 5.5 10 4 – 290 290 3500 – – 1600 – 0.5 5 – 1 2 3 Units V mA V mV mΩ mΩ mA °C °C kHz %/V % % % µA V % % VIN = VGS = 5V VIN = VGS = 5V 4.5V < VIN < 5.5V Rising Temperature Hysteresis VIN = 4.5 to 5.5V, IOUT = 100mA 0mA ≤ IOUT ≤ 1500mA IOUT from 700mA to 100mA IOUT from 100mA to 700mA VIN = Open, EN = GND, Vsw = 5.5V VIN = 4.5 to 5.5V 0mA ≤ IOUT ≤ 1500mA FAN2011 FAN2012 FAN2011I FAN2012I -40°C to +85°C Notes: 4. Load transient response test waveform. Additional Electrical Characteristics for FAN2012 TA = 0°C to +85°C, VIN = 4.5 to 5.5V. Typical values are at TA = 25°C. Parameter Shutdown Mode Supply Current EN Bias Current EN High Voltage EN Low Voltage Conditions VEN = 0V Min. – – 1.3 – Typ. 0.1 – – – Max. 1 0.1 – 0.4 Units µA µA V V ILOAD (mA) 700 t r = 67nS t f = 67nS 100 0 ss 0.6 4.6 Time (mSec) Figure 3. Load Transient Response Test Waveform FAN2011/FAN2012 Rev. 1.0.4 4 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Typical Performance Characteristics TA = 25°C, CIN = 10µF, COUT = 40µF, L = 3.3µH, VIN = 5V, unless otherwise noted. Output Voltage vs. Ambient Temperature 1.214 1.212 Temp T emp T emp T emp T emp vs vs vs vs vs Vout@ 0 mA Vout@ 100mA Vout@ 500 mA Vout@ 1000 mA Vout@ 1500 mA (∞ C) (∞ C) (∞ C) (∞ C) (∞ C) Switching Frequency vs. Ambient Temperature 12 60 Switching Frequency (KHz) 120 Output Voltage (V) 1.210 1.208 1.206 1.204 1.202 1.200 1.198 1.196 1.194 -40 -20 0 20 40 1255 1250 1245 1240 1235 1230 0 20 40 60 80 100 12 0 60 80 100 Ambient Temperature (°C) Ambient Temperature (°C) Efficiency vs. Load Current 100 Power Efficiency (%) 90 80 70 60 50 40 VIN = 5.5V VIN = 5V VOUT = 3.3V VOUT = 1.2V VIN = 4.5V 30 10 100 1000 1000 0 Load Current (mA) FAN2011/FAN2012 Rev. 1.0.4 5 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Typical Performance Characteristics (Continued) TA = 25°C, CIN = 10µF, COUT = 40µF, L = 3.3µH, VIN = 5V, unless otherwise noted. Start-up Response Input Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (200mA/div) Output Voltage (500mV/div) Input Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (200mA/div) Output Voltage (1V/div) Start-up Response VOUT = 1.2V IOUT = 100mA Time (50µs/div) VOUT = 3.3V IOUT = 100mA Time (100µs/div) Start-up Response Input Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (500mA/div) Output Voltage (500mV/div) Input Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (500mA/div) Output Voltage (1V/div) Start-up Response VOUT = 1.2V IOUT = 1500mA Time (100µs/div) VOUT = 3.3V IOUT = 1500mA Time (100µs/div) Transient Response 700mA Transient Response Load Current SW Node Voltage (5V/div) Output Voltage (20mV/div) VOUT = 1.2V Inductor Current (200mA/div) 700mA 100mA Load Current SW Node Voltage (5V/div) Output Voltage (20mV/div) Inductor Current (200mA/div) 100mA VOUT = 1.2V Time (5µs/div) Time (5µs/div) FAN2011/FAN2012 Rev. 1.0.4 6 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Block Diagram EN VIN DIGITAL SOFT START UNDER VOLTAGE LOCKOUT IS CURRENT SENSE FB ERROR AMP COMP LOGIC CONTROL MOSFET DRIVER SW 0.8V GND IS OVER VOLTAGE COMP OSC SLOPE COMPENSATION REF FB GND Figure 4. Block Diagram Detailed Operation Description The FAN2011 is a step-down pulse width modulated (PWM) current mode converter with a typical switching frequency of 1.3MHz. At the beginning of each clock cycle, the P-channel transistor is turned on. The inductor current ramps up and is monitored via an internal circuit. The P-channel switch is turned off when the sensed current causes the PWM comparator to trip when the output voltage is in regulation or when the inductor current reaches the current limit (set internally, typically 2600mA). After a minimum dead time, the N-channel transistor is turned on and the inductor current ramps down. As the clock cycle is completed, the N-channel switch is turned off and the next clock cycle starts. The duty cycle is solely given by the ratio of output voltage and input voltage. Therefore, the converter runs with a minimum duty cycle when output voltage is at minimum and input voltage is at maximum. UVLO and Soft Start The reference and the circuit remain reset until the VIN crosses its UVLO threshold. The FAN2011 has an internal soft-start circuit that limits the in-rush current during start-up. This prevents possible voltage drops of the input voltage and eliminates the output voltage overshoot. The soft-start is implemented as a digital circuit, increasing the switch current in four steps to the P-channel current limit (2600mA). Typical start-up time for a 40µF output capacitor and a load current of 1500mA is 800µs. Short Circuit Protection The switch peak current is limited cycle by cycle to a typical value of 2600mA. In the event of an output voltage short circuit, the device operates with a frequency of 400kHz and minimum-duty cycle, therefore the average input current is typically 350mA. 100% Duty Cycle Operation As the input voltage approaches the output voltage and the duty cycle exceeds the typical 95%, the converter turns the P-channel transistor continuously on. In this mode, the output voltage is equal to the input voltage minus the voltage drop across the P-channel transistor: VOUT = VIN – ILOAD × (RDS_ON + RL), where RDS_ON = P-channel switch ON resistance ILOAD = Output current RL = Inductor DC resistance Thermal Shutdown When the die temperature exceeds 150°C, a reset occurs and remains in effect until the die cools to 130°C, at which point, the circuit restarts. FAN2011/FAN2012 Rev. 1.0.4 7 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Applications Information Setting the Output Voltage The internal reference is 0.8V. The output is divided down by a voltage divider, R1 and R2 to the FB pin. The output voltage is: R1 V OUT = V REF  1 + ------  R 2 PCB Layout Recommendations The inherently high peak currents and switching frequency of power supplies require a 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. To minimize voltage stress to the device resulting from ever-present switching spikes, use an input bypass capacitor with low ESR. Use of an external Schottky diode, with its anode connected to SW node and cathode connected to PVIN, further reduces switching spikes. Note that the peak amplitude of the switching spikes depends upon the load current; the higher the load current, the higher the switching spikes. The resistor divider that sets the output voltage should be routed away from the inductor to avoid RF coupling. The ground plane at the bottom side of the PCB acts as an electromagnetic shield to reduce EMI. The recommended PCB layout is shown below in Figure 5. According to this equation, and assuming desired output voltage of 1.5096V, and given R2 = 10KΩ, the calculated value of R1 is 8.87KΩ. Inductor Selection The inductor parameters directly related to device performances are saturation current and DC resistance. The FAN2011/FAN2012 operates with a typical inductor value of 3.3µH. The lower the dc resistance, the higher the efficiency. For saturation current, the inductor should be rated higher than the maximum load current, plus half of the inductor ripple current calculated as follows: ∆ I L = V OUT 1 – ( V OUT ⁄ V IN ) × -----------------------------------------L×f where: ∆IL = Inductor Ripple Current f = Switching Frequency L = Inductor Value Some recommended inductors are suggested in the table below: Table 1. Recommended Inductors Inductor Value 3.3µH 3.3µH 3.3µH Vendor Panasonic Murata Coiltronics Part Number ELL6PM3R3N LQS66C3R3M04 SD-3R3-R Figure 5. Recommended PCB Layout Capacitors Selection For best performances, a low ESR input capacitor is required. A ceramic capacitor of at least 10µF, placed as close to the VIN and AGND pins of the device is recommended. The output capacitor determines the output ripple and the transient response. Table 2. Recommended Capacitors Capacitor Value 10µF Vendor Taiyo Yuden TDK Murata Part Number JMK212BJ106MG JMK316BJ106KL C2012X5ROJ106K C3216X5ROJ106M GRM32ER61C106K FAN2011/FAN2012 Rev. 1.0.4 8 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Mechanical Dimensions 3x3mm 6-Lead MLP FAN2011/FAN2012 Rev. 1.0.4 9 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator TRADEMARKS 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™ FAST® ActiveArray™ FASTr™ Bottomless™ FPS™ Build it Now™ FRFET™ CoolFET™ GlobalOptoisolator™ CROSSVOLT™ GTO™ DOME™ HiSeC™ EcoSPARK™ I2C™ E2CMOS™ i-Lo™ EnSigna™ ImpliedDisconnect™ FACT™ IntelliMAX™ FACT Quiet Series™ Across the board. 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PRODUCT STATUS DEFINITIONS Definition of Terms Datasheet Identification Advance Information Product Status Formative or In Design Definition This datasheet contains the design specifications for product development. Specifications may change in any manner without notice. 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. This datasheet contains final specifications. Fairchild Semiconductor reserves the right to make changes at any time without notice in order to improve design. Preliminary First Production No Identification Needed Full Production 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. I18 FAN2011/FAN2012 Rev. 1.0.4 10 www.fairchildsemi.com