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Q&A Select resistor for a diode

A diode obeys the Shockley diode equation and for this circuit we have: The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current be...

posted 3y ago by MissMulan‭  ·  edited 3y ago by MissMulan‭

Answer
#4: Post edited by user avatar MissMulan‭ · 2021-09-01T21:16:49Z (about 3 years ago)
  • A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)
  • ![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)
  • The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:
  • For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V
  • ![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)
  • ![hi](https://electrical.codidact.com/uploads/FAw9mG4JGdu6fFFvjVmebNjf)
  • (120mA).
  • Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode
  • ![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)
  • If we solve this equation we get:
  • ![hi](https://electrical.codidact.com/uploads/DGaDxEbb1q4PCLGddQbL8BR2)
  • So in order for LTL-307EE to not be damaged the resistance of R1 > 73.46Ω
  • Hope this helps
  • A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)
  • ![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)
  • The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:
  • For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V
  • ![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)
  • ![hi](https://electrical.codidact.com/uploads/JqTiD2tr5Ln8MkjtRDpCM4e5)
  • (30mA).
  • Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode
  • ![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)
  • If we solve this equation we get:
  • ![hi](https://electrical.codidact.com/uploads/G67NFKRqV8soLtuSA78h8rgc)
  • So in order for LTL-307EE to not be damaged the resistance of R1 > 295.05Ω
  • Hope this helps
#3: Post edited by user avatar MissMulan‭ · 2021-09-01T21:07:56Z (about 3 years ago)
  • A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)
  • ![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)
  • The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:
  • For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V
  • ![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)
  • ![hi](https://electrical.codidact.com/uploads/FAw9mG4JGdu6fFFvjVmebNjf)
  • (120mA).
  • Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode
  • ![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)
  • If we solve this equation we get:
  • ![hi](https://electrical.codidact.com/uploads/aZUkz1RsEHNbxKhpTxf8TWKr)
  • So in order for LTL-307EE to not be damaged the resistance of R1 > 73.46Ω
  • Hope this helps
  • A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)
  • ![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)
  • The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:
  • For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V
  • ![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)
  • ![hi](https://electrical.codidact.com/uploads/FAw9mG4JGdu6fFFvjVmebNjf)
  • (120mA).
  • Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode
  • ![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)
  • If we solve this equation we get:
  • ![hi](https://electrical.codidact.com/uploads/DGaDxEbb1q4PCLGddQbL8BR2)
  • So in order for LTL-307EE to not be damaged the resistance of R1 > 73.46Ω
  • Hope this helps
#2: Post edited by user avatar MissMulan‭ · 2021-09-01T20:27:59Z (about 3 years ago)
  • A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)
  • ![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)
  • The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:
  • For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V
  • ![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)
  • ![hi](https://electrical.codidact.com/uploads/FAw9mG4JGdu6fFFvjVmebNjf)
  • (120mA).
  • Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode
  • ![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)
  • If we solve this equation we get:
  • ![hi](https://electrical.codidact.com/uploads/5H5JgiXSXYLVQyEzoUM1oKzw)
  • So in order for LTL-307EE to not be damaged the resistance of R1 > 73.46Ω
  • Hope this helps
  • A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)
  • ![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)
  • The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:
  • For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V
  • ![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)
  • ![hi](https://electrical.codidact.com/uploads/FAw9mG4JGdu6fFFvjVmebNjf)
  • (120mA).
  • Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode
  • ![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)
  • If we solve this equation we get:
  • ![hi](https://electrical.codidact.com/uploads/aZUkz1RsEHNbxKhpTxf8TWKr)
  • So in order for LTL-307EE to not be damaged the resistance of R1 > 73.46Ω
  • Hope this helps
#1: Initial revision by user avatar MissMulan‭ · 2021-09-01T20:25:13Z (about 3 years ago)
A diode obeys the Shockley diode equation and for this circuit we have:![hi ](https://electrical.codidact.com/uploads/CvokYKHDRToYpsF7M2xp9yZN)



![hi](https://electrical.codidact.com/uploads/y152DrxkBAWbxciJDE6agTEP)

The current through the diode must not pass a limit so for LTL-307EE we go to the datasheet to find the maximum current before the diode is destroyed:

For the LTL-307EE at 20C we have 10^4 A Isat and Vth=0.026V

![hi](https://electrical.codidact.com/uploads/3p9GBDtrkrZcYoUkHHwXKgaw)

![hi](https://electrical.codidact.com/uploads/FAw9mG4JGdu6fFFvjVmebNjf)

(120mA).

Now in order to find the resistance we find the resistance of the resistor if max current was flowing through the diode

![hi](https://electrical.codidact.com/uploads/HvZTbQ5NUVUCTF2vcbVoZoC4)

If we solve this equation we get:

![hi](https://electrical.codidact.com/uploads/5H5JgiXSXYLVQyEzoUM1oKzw)

So in order for LTL-307EE to not be damaged the resistance of R1 > 73.46Ω

Hope this helps