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ILC7071AIM530X 数据表(PDF) 8 Page - Fairchild Semiconductor |
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ILC7071AIM530X 数据表(HTML) 8 Page - Fairchild Semiconductor |
8 / 11 page ILC7071 PRODUCT SPECIFICATION 8 REV. 1.0.2 7/16/03 Application Information Capacitor Selection In general, ceramic capacitors are preferred due to their superior ESR performance. Those with X5R dielectric offer the best temperature coefficient. An input capacitor of 1µF or greater, connected between Input and Ground, located in close proximity to the device will improve the transient response and the noise rejection. An output capacitor of at least 1µF is required to maintain regulator loop stability. Stable operation will be achieved with a wide variety of capacitors with ESR ranging from 10m Ω to 10Ω. An optional capacitor connected between the CN pin and ground can significantly reduce noise on the output.Values ranging up to 10nF can be used, depending upon the sensi- tivity to output noise in the application. Care should be taken to prevent noise from external sources to enter into the CN pin, which is a very sensitive, high impedance pin. Leakage currents into this pin will directly affect the regulator accu- racy and should be kept as low as possible. Control Functions Enable Pin Applying a voltage of 0.6V or less at the Enable pin will disable the output, reducing the quiescent output current to less than 1µA, while a voltage of 2V 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. Thermal Protection The ILC7071 is designed to supply high peak output currents 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 tem- perature of 125 °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. Thermal Characteristics The ILC7071 is designed to supply up to 100mA at the specified output voltage with an operating die (junction) temperature of up to 125 °C. While the power dissipation is calculated from known electrical parameters, the thermal resistance is a result of the thermal characteristics of the compact SOT-23-5 surface-mount package and the surround- ing PC Board copper to which it is mounted. The relationship describing the thermal behavior of the pack- age is: where TJ(max) is the maximum allowable junction tempera- ture of the die, which is 125 °C, and TA is the ambient operating temperature. ΘJA is dependent on the surrounding PC board layout and can be empirically obtained. While the ΘJC (junction-to-case) of the SOT-23-5 package is specified at 130 °C/W, the ΘJA of the minimum PWB footprint will be at least 235 °C/W. This can be improved upon by providing a heat sink of surrounding copper ground on the PCB. Depending on the size of the copper area, the resulting ΘJA can range from approximately 180 °C/W for one square inch, to nearly 130 °C/W for 4 square inches. The addition of backside copper with through-holes, stiffen- ers, and other enhancements can also aid in reducing this value. The heat contributed by the dissipation of other devices located nearby must be included in design consider- ations. Once the limiting parameters in the thermal relationship have been determined, the electrical design should be verified to ensure that the device remains within specified operating conditions. If overload conditions are not considered, it is possible for the device to enter a thermal cycling loop, in which the circuit enters a shutdown condition, cools, reenables, and then again overheats and shuts down repeatedly due to an unmanaged fault condition. P D max () T Jmax () TA – Θ JA -------------------------------- = |
类似零件编号 - ILC7071AIM530X |
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类似说明 - ILC7071AIM530X |
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