FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Features Description ■ 95% Efficiency, Synchronous Operation 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. ■ 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 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. ■ Excellent Load Transient Response ■ 3x3mm 6-lead MLP Package 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. Applications ■ Hard Disk Drive ■ Set Top Box ■ Point of Load Power ■ Notebook Computers Protection features include input under-voltage lockout, short circuit protection and thermal shutdown. Soft-start limits in-rush current during start-up conditions. ■ Communications Equipment 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. Ordering Information Product Number Output Voltage Package Type Ambient Operating Temperature Order Code FAN2011 Adjustable 3x3mm 6-Lead MLP 0°C to 85°C FAN2011MPX FAN2012 Adjustable 3x3mm 6-Lead MLP 0°C to 85°C FAN2012MPX FAN2011I Adjustable 3x3mm 6-Lead MLP -40°C to 85°C FAN2011EMPX FAN2012I Adjustable 3x3mm 6-Lead MLP -40°C to 85°C 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 April 2006 FB 1 R2 6 10KΩ PGND R1 VOUT P1 (AGND) 2 5 SW L1 3 4 3.3µH EN FB 1 NC +5V VIN R2 PGND R1 L1 VOUT PVIN 6 10KΩ SW 2 P1 (AGND) 3 4 3.3µH 10µF 5 VIN +5V PVIN 10µF 4 x 10µF 4 x 10µF FAN2011 FAN2012 Figure 1. Typical Application Pin Assignment Top View FB 1 PGND 2 SW 3 P1 (AGND) 6 NC FB 1 5 VIN PGND 2 4 PVIN SW 3 FAN2011 3x3mm 6-Lead MLP P1 (AGND) 6 EN 5 VIN 4 PVIN FAN2012 3x3mm 6-Lead MLP Figure 2. Pin Assignment Pin Description FAN2011 (3x3mm 6-Lead MLP) Pin No. Pin Name P1 AGND Pin Description 1 FB 2 PGND 3 SW Switching Node. This pin is connected to the internal MOSFET switches. 4 PVIN Supply Voltage Input. This pin is connected to the internal MOSFET switches. 5 VIN Supply Voltage Input. 6 NC Not Connected. This pin is not internally connected. 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. FAN2012 (3x3mm 6-Lead MLP) Pin No. Pin Name P1 AGND 1 FB 2 PGND 3 SW 4 PVIN 5 VIN Supply Voltage Input. 6 EN 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 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. 2 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Typical Application Parameter VIN PVIN and any other pin Thermal Resistance-Junction to Tab (θJC), 3mm x 3mm 6-lead MLP(1) Lead Soldering Temperature (10 seconds) Storage Temperature Junction Temperature Level(2) Min. Max. Unit -0.3 7 V -0.3 VIN V – 8 °C/W – 260 °C -65 150 °C -40 150 °C kV HBM 4 – CDM 2 – Min. Typ. Max. Unit Supply Voltage Range 4.5 – 5.5 V Output Voltage Range, Adjustable Version 0.8 – VIN V Electrostatic Discharge (ESD) Protection Recommended Operating Conditions Parameter Output Current – – 1500 mA Inductor(3) – 3.3 – µH – 10 – µF – 4 x 10 – µF FAN2011 and FAN2012 0 – +85 °C FAN2011I and FAN2012I -40 – +85 Input Capacitor(3) Output Capacitor(3) 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 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 Conditions Input Voltage Min. Typ. Max. Units 4.5 – 5.5 V Quiescent Current IOUT = 0mA – 7 10 mA UVLO Threshold VIN Rising 3.4 3.7 4 V Hysteresis – 150 – mV PMOS On Resistance VIN = VGS = 5V – 150 290 mΩ – 150 290 mΩ 2200 2600 3500 mA Rising Temperature – 150 – °C Hysteresis – 20 – °C NMOS On Resistance VIN = VGS = 5V P-channel Current Limit 4.5V < VIN < 5.5V Over-Temperature Protection Switching Frequency 1000 1300 1600 kHz Line Regulation VIN = 4.5 to 5.5V, IOUT = 100mA – 0.16 – %/V Load Regulation 0mA ≤ IOUT ≤ 1500mA – 0.2 0.5 % Output Voltage During Load Transition(4) IOUT from 700mA to 100mA – – 5 % Output Voltage During Load Transition(4) IOUT from 100mA to 700mA -5 – – % Reverse Leakage Current Into Pin SW VIN = Open, EN = GND, Vsw = 5.5V – 0.1 1 µA – 0.8 FAN2011 FAN2012 -2 – 2 % FAN2011I FAN2012I -40°C to +85°C -3 – 3 % Reference Voltage, VREF Output Voltage Accuracy VIN = 4.5 to 5.5V 0mA ≤ IOUT ≤ 1500mA V 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 Conditions Min. Typ. Max. Units – 0.1 1 µA EN Bias Current – – 0.1 µA EN High Voltage 1.3 – – V EN Low Voltage – – 0.4 V ILOAD (mA) Shutdown Mode Supply Current VEN = 0V 700 t r = 67nS 100 t f = 67nS ss 0 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 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. TA = 25°C, CIN = 10µF, COUT = 40µF, L = 3.3µH, VIN = 5V, unless otherwise noted. Switching Frequency vs. Ambient Temperature Output Voltage vs. Ambient Temperature 1260 Temp Temp Temp Temp Temp Output Voltage (V) 1.212 1.210 1.208 (∞C) (∞C) (∞C) (∞C) (∞C) vs vs vs vs vs Switching Frequency (KHz) 1.214 Vout@ 0 mA Vout@ 100mA Vout@ 500 mA Vout@ 1000 mA Vout@ 1500 mA 1.206 1.204 1.202 1.200 1.198 1.196 1.194 -40 -20 0 20 40 60 80 100 120 1255 1250 1245 1240 1235 1230 0 Ambient Temperature (°C) 20 40 60 80 100 120 Ambient Temperature (°C) Efficiency vs. Load Current Power Efficiency (%) 100 VOUT = 3.3V 90 80 VOUT = 1.2V 70 VIN = 4.5V 60 VIN = 5V 50 40 VIN = 5.5V 30 10 100 1000 10000 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 TA = 25°C, CIN = 10µF, COUT = 40µF, L = 3.3µH, VIN = 5V, unless otherwise noted. Start-up Response Start-up Response Input Voltage (5V/div) Input Voltage (5V/div) SW Node Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (200mA/div) Inductor Current (200mA/div) Output Voltage (500mV/div) Output Voltage (1V/div) VOUT = 1.2V IOUT = 100mA VOUT = 3.3V IOUT = 100mA Time (100µs/div) Time (50µs/div) Start-up Response Start-up Response Input Voltage (5V/div) Input Voltage (5V/div) SW Node Voltage (5V/div) SW Node Voltage (5V/div) Inductor Current (500mA/div) Inductor Current (500mA/div) Output Voltage (500mV/div) Output Voltage (1V/div) VOUT = 1.2V IOUT = 1500mA VOUT = 3.3V IOUT = 1500mA Time (100µs/div) Time (100µs/div) Transient Response Transient Response 700mA Load Current Load Current 100mA 100mA SW Node Voltage (5V/div) SW Node Voltage (5V/div) Output Voltage (20mV/div) Output Voltage (20mV/div) Inductor Current (200mA/div) 700mA VOUT = 1.2V Inductor Current (200mA/div) 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 Typical Performance Characteristics (Continued) VIN EN DIGITAL SOFT START UNDER VOLTAGE LOCKOUT IS CURRENT SENSE FB ERROR AMP LOGIC CONTROL COMP MOSFET DRIVER SW 0.8V GND IS OVER VOLTAGE COMP OSC SLOPE COMPENSATION REF FB GND Figure 4. Block Diagram Detailed Operation Description UVLO and Soft Start 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. The reference and the circuit remain reset until the VIN crosses its UVLO threshold. 100% Duty Cycle Operation Thermal Shutdown 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: 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. 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. VOUT = VIN – ILOAD × (RDS_ON + RL), where RDS_ON = P-channel switch ON resistance ILOAD = Output current RL = Inductor DC resistance FAN2011/FAN2012 Rev. 1.0.4 7 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Block Diagram PCB Layout Recommendations Setting the Output Voltage 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 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: R V OUT = V REF 1 + ------1- R 2 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 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. 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 Vendor Part Number 3.3µH Panasonic ELL6PM3R3N 3.3µH Murata LQS66C3R3M04 3.3µH Coiltronics 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 Part Number Taiyo Yuden JMK212BJ106MG TDK C2012X5ROJ106K JMK316BJ106KL C3216X5ROJ106M Murata FAN2011/FAN2012 Rev. 1.0.4 GRM32ER61C106K 8 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator Applications Information 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 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. 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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. I18 FAN2011/FAN2012 Rev. 1.0.4 10 www.fairchildsemi.com FAN2011/FAN2012 1.5A Low Voltage Current Mode Synchronous PWM Buck Regulator TRADEMARKS