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FAN2502S28X

製品説明
仕様・特性

www.fairchildsemi.com FAN2502, FAN2503 150 mA CMOS LDO Regulators Features • • • • • • • wide variety of external capacitors, and the compact SOT23-5 surface-mount package. The FAN2502/03 family of products offer significant improvements over older BiCMOS designs and are pin-compatible with many popular devices. The output is thermally protected against overload. Ultra Low Power Consumption 150 mV dropout voltage at 150 mA 25 µA ground current at 150 mA Enable/Shutdown Control SOT23-5 package Thermal limiting 300 mA peak current The FAN2502 and FAN2503 devices are distinguished by the assignment of pin 4: FAN2502: pin 4 – ADJ, allowing the user to adjust the output voltage over a wide range using an external voltage divider. Applications • • • • Cellular Phones and accessories PDAs Portable cameras and video recorders Laptop, notebook and palmtop computers FAN2502-XX: pin 4 – BYP, to which a bypass capacitor may be connected for optimal noise performance. Output voltage is fixed, indicated by the suffix XX. Description The FAN2502/03 family of micropower low-dropout voltage regulators utilize CMOS technology to offer a new level of cost-effective performance in GSM and TDMA cellular handsets, Laptop and Notebook portable computers, and other portable devices. Features include extremely low power consumption and low shutdown current, low dropout voltage, exceptional loop stability able to accommodate a FAN2503-XX: pin 4 – ERR, a flag which indicates that the output voltage has dropped below the specified minimum due to a fault condition. The standard fixed output voltages available are 2.5V, 2.6V, 2.7V, 2.8V, 2.85V, 3.0V, and 3.3V. Custom output voltage are also available: please contact your local Fairchild Sales Office for information. Block Diagrams EN EN VIN VIN Bandgap Error Amplifier BYP Bandgap p VOUT Error Amplifier p VOUT ADJ Thermal Sense Thermal Sense GND FAN2502 GND FAN2502-XX EN VIN ERR Bandgap Error Amplifier p VOUT Thermal Sense GND FAN2503-XX REV. 1.1.7 2/14/03 FAN2502/FAN2503 Depending on the model selected, a number of control and status functions are available to enhance the operation of the LDO regulator. An Enable pin, available on all devices, allows the user to shut down the regulator output to conserve power, reducing supply current to less than 1µA. The adjustable-voltage versions of the device utilize pin 4 to connect to an external voltage divider which feeds back to the regulator error amplifier, thereby setting the voltage as desired. Two other functions are available at pin 4 in the fixed-voltage versions: in noise-sensitive applications, an external Bypass capacitor connection is provided that allows the user to achieve optimal noise performance at the output, while the Error output functions as a diagnostic flag to indicate that the output voltage has dropped more than 5% below the nominal fixed voltage. PRODUCT SPECIFICATION Bypass Capacitor (FAN2502 Only) In the fixed-voltage configuration, connecting a capacitor between the bypass pin and ground can significantly reduce noise on the output. Values ranging from 470pF to 10nF can be used, depending on the sensitivity to output noise in the application. At the high-impedance Bypass pin, care must be taken in the circuit layout to minimize noise pickup, and capacitors must be selected to minimize current loading (leakage). Noise pickup from external sources can be considerable. Leakage currents into the Bypass pin will directly affect regulator accuracy and should be kept as low as possible; thus, highquality ceramic and film types are recommended for their low leakage characteristics. Cost-sensitive applications not concerned with noise can omit this capacitor. Applications Information Control Functions External Capacitors – Selection The FAN2502/03 allows the user to utilize a wide variety of capacitors compared to other LDO products. An innovative design approach offers significantly reduced sensitivity to ESR (Effective Series Resistance), which degrades regulator loop stability in older designs. While the improvements featured in the FAN2502/03 family greatly simplify the design task, capacitor quality still must be considered if the designer is to achieve optimal circuit performance. In general, ceramic capacitors offer superior ESR performance, at a lower cost and a smaller case size than tantalums. Those with X7R or Y5Vdielectric offer the best temperature coefficient characteristics. The combination of tolerance and variation over temperature in some capacitor types can result in significant variations, resulting in unstable performance over rated conditions. Input Capacitor An input capacitor of 2.2µF (nominal value) or greater, connected between the Input pin and Ground, located in close proximity to the device, will improve transient response and noise rejection. Higher values will offer superior input ripple rejection and transient response. An input capacitor is recommended when the input source, either a battery or a regulated AC voltage, is located far from the device. Any good quality ceramic, tantalum, or metal film capacitor will give acceptable performance, however tantalum capacitors with a surge current rating appropriate to the application must be selected to avoid catastrophic failure. Output Capacitor An output capacitor is required to maintain regulator loop stability. Unlike many other LDO regulators, the FAN2502/ 03 family of products are nearly insensitve to output capacitor ESR. Stable operation will be achieved with a wide variety of capacitors with ESR values ranging from 10mΩ to 10Ω or more. Tantalum or aluminum electrolytic, or multilayer ceramic types can all be used. A nominal value of at least 1µF is recommended. REV. 1.1.7 2/14/03 Enable Pin Applying a voltage of 0.4V or less at the Enable pin will disable the output, reducing the quiescent output current to less than 1µA, while a voltage of 2.0V or greater will enable the device. If this shutdown function is not needed, the pin can simply be connected to the VIN pin. Allowing this pin to float will cause erratic operation. Error Flag (FAN2503 only) To indicate conditions such as input voltage dropout (low VIN), overheating, or overloading (excessive output current), the ERR pin indicates a fault condition. It is an opendrain output which is HIGH when the voltage at VOUT is greater than 95% of the nominal rated output voltage and LOW when VOUT is less than 95% or the rated output voltage, as specified in the error trip level characteristics. A logic pullup resistor of 100KΩ is recommended at this output. The pin can be left disconnected if unused. Thermal Protection The FAN2502/03 is designed to supply high peak output currents of up to 1A for brief periods, however this output load will cause the device temperature to increase and exceed maximum ratings due to power dissipation. During output overload conditions, when the die temperature exceeds the shutdown limit temperature of 150°C, onboard thermal protection will disable the output until the temperature drops below this limit, at which point the output is then re-enabled. During a thermal shutdown situation the user may assert the power-down function at the Enable pin, reducing power consumption to the minimum level IGND x VIN. 3

ブランド

FAIRCHILD

会社名

Fairchild Semiconductor International, Inc

本社国名

U.S.A

事業概要

アメリカ合衆国の半導体メーカー。世界で初めて半導体集積回路の商業生産を開始した企業である。後に同社からは様々な人材が独立、幾つかはインテルを始めとする世界的な半導体メーカーへと成長していった。

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