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lm317 [2016/06/02 14:54] admin [Compared to 78xx/79xx] |
lm317 [2016/06/02 21:22] (当前版本) gongyu |
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| ====规格==== | ====规格==== | ||
| - | cvb Part pinout of LM317T showing its constant voltage reference. Package is TO-220. | + | ^符号 |参数 |值 |单位 | |
| - | + | ||
| - | ^Symbol |Parameter |Value |Unit | | + | |
| ^Vout |1.25 |– 37 |V | ^Vout |1.25 |– 37 |V | ||
| - | ^Vin |– Vout |difference |3 – 40 V | + | ^Vin |– Vout |差别 |3 – 40 V |
| - | ^TJ |Operating junction temperature range |0 – 125 |°C | | + | ^TJ |工作结温范围 |0 – 125 |°C | |
| - | ^IO(MAX) |Maximum output current |1.5 |A| | + | ^IO(MAX) |最大输出电流 |1.5 |A| |
| - | ^IL(MIN) |Minimum load current |3.5 mA typical, 12 mA maximum || | + | ^IL(MIN) |最小负载电流 |3.5 mA typical, 12 mA maximum || |
| - | ^PD |Power dissipation |Internally Limited |W [1]| | + | ^PD |功率消耗 |内部限制 |W [1]| |
| - | ^RθJA |Thermal resistance, Junction to ambient |80 |°C/W | | + | ^RθJA |结到环境热阻 |80 |°C/W | |
| - | ^RθJC |Thermal resistance, Junction to case |5 |°C/W | | + | ^RθJC |结壳热阻 |5 |°C/W | |
| Without a heat sink with an ambient temperature at 50 ⁰C such as on a hot summer day inside a box, a maximum power dissipation of (TJ-TA)/RθJA = ((125-50)/80) = 0.98 W can be permitted. (A piece of shiny sheet metal of Aluminum with the dimensions 6 x 6 cm and 1.5 mm thick, results in a thermal resistance that permits 4.7 W of heat dissipation[2][3]). | Without a heat sink with an ambient temperature at 50 ⁰C such as on a hot summer day inside a box, a maximum power dissipation of (TJ-TA)/RθJA = ((125-50)/80) = 0.98 W can be permitted. (A piece of shiny sheet metal of Aluminum with the dimensions 6 x 6 cm and 1.5 mm thick, results in a thermal resistance that permits 4.7 W of heat dissipation[2][3]). | ||
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| <WRAP centeralign> LM317内部功能框图 </WRAP> | <WRAP centeralign> LM317内部功能框图 </WRAP> | ||
| - | ====Operation==== | + | ====工作==== |
| {{ :lm317_front.png |}} | {{ :lm317_front.png |}} | ||
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| In packages with a heat-dissipating mounting tab, such as TO-220, the tab is connected internally to the output pin which may make it necessary to electrically isolate the tab or the heat sink from other parts of the application circuit. Failure to do this may cause the circuit to short. | In packages with a heat-dissipating mounting tab, such as TO-220, the tab is connected internally to the output pin which may make it necessary to electrically isolate the tab or the heat sink from other parts of the application circuit. Failure to do this may cause the circuit to short. | ||
| - | ====Voltage regulator==== | + | ====稳压==== |
| {{ :577px-lm317_typical_schematic.svg.png |}} | {{ :577px-lm317_typical_schematic.svg.png |}} | ||
| <WRAP centeralign> Schematic of LM317 in a typical voltage regulator configuration, including decoupling capacitors to address input noise and output transients.</WRAP> | <WRAP centeralign> Schematic of LM317 in a typical voltage regulator configuration, including decoupling capacitors to address input noise and output transients.</WRAP> | ||
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| To make the output more stable, the device is designed to keep the quiescent current at or below 100µA, making it possible to ignore the error term in nearly all practical cases.[4] | To make the output more stable, the device is designed to keep the quiescent current at or below 100µA, making it possible to ignore the error term in nearly all practical cases.[4] | ||
| - | ====Current regulator==== | + | ====稳流==== |
| {{ :640px-lm317_1a_constcurrent.svg.png |}} | {{ :640px-lm317_1a_constcurrent.svg.png |}} | ||
| <WRAP centeralign> A constant current source circuit constructed with LM317 </WRAP> | <WRAP centeralign> A constant current source circuit constructed with LM317 </WRAP> | ||