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LM1085-XXXJ3 データシート(PDF) 5 Page - Cystech Electonics Corp. |
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LM1085-XXXJ3 データシート(HTML) 5 Page - Cystech Electonics Corp. |
5 / 9 page CYStech Electronics Corp. Spec. No. : C540J3 Issued Date : 2003.06.25 Revised Date :2013.09.11 Page No. : 5/9 LM1085-XXXJ3 CYStek Product Specification Stability The LM1085 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable. For most applications, the addition of 150μF aluminum electrolytic capacitor or a 22μF solid tantalum on the output will ensure stability for all operating conditions. When the adjustment terminal is bypassed with a capacitor to improve the ripple rejection, the requirement for an output capacitor increases. The value of 22μF tantalum or 150μF aluminum covers all cases of bypassing the adjustment terminal. Without bypassing the adjustment terminal smaller capacitors can be used with equally good results. To ensure good transient response with heavy load current changes capacitor values on the order of 100μF are used in the output of many regulators. To further improve stability and transient response of these devices larger values of output capacitor can be used. Protection Diodes Unlike older regulators, the LM1085 family does not need any protection diodes between the adjustment pin and the output and from the output to the input to prevent over-stressing the die. Internal resistors are limiting the internal current paths on the adjustment pin, therefore even with capacitors on the adjustment pin, no protection diode is needed to ensure device safety under short-circuit conditions. If high value output capacitors are used, such as 1000μF to 5000μF, and the input pin is instantaneously shorted to ground, damage can occur. A diode from output to input is recommended, when a crowbar circuit at the input of the LM1085 is used. Normal power supply cycling or even plugging and unplugging in the system will not generate current large enough to do any damage. Thermal Design The LM1085 incorporates an internal power and thermal limiting circuitry designed to protect the device under overload conditions. However maximum junction temperature ratings should not be exceeded under continuous normal load conditions. Careful consideration must be given to all sources of thermal resistance from junction to ambient, including junction- to-case, case to heat sink interface and heat sink resistance itself. To ensure safe operating temperatures and reflect more accurately the device temperature, new thermal resistance specifications have been developed. Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for the heat flow. In order to ensure the best possible thermal flow from this area of the package to the heat sink, proper mounting is required. Thermal compound at the case-to-heat sink interface is recommended. A thermally conductive spacer can be used, if the case of the device must be electrically isolated, but its added contribution to thermal resistance has to be considered. Layout Consideration The output capacitors must be located as close to the Vout terminal of the device as possible. It is recommended to use a section of a layer of the PC board as a plane to connect the Vout pin to the output capacitors to prevent any high frequency oscillation that may result due to excess trace inductance. |
同様の部品番号 - LM1085-XXXJ3 |
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同様の説明 - LM1085-XXXJ3 |
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