The current source dissipates (10 - 5) * 0.13 = 0.65 watts. Its case rises to 58C which is 33C above ambient air. That means its thermal resistance from case to ambient air (theta_CA) equals (33 / 0.65) = 51C per watt. That's a pretty impressive transistor, since most TO-126 medium power transistors are rated 100C per watt.
{And if there's no load on the regulator output, the shunt device dissipates the same: (5 - 0) * 0.13 = 0.65 watts}
{And if there's no load on the regulator output, the shunt device dissipates the same: (5 - 0) * 0.13 = 0.65 watts}
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@Vunce
I finished the design, I preferred to put two pads in the case I would like to implement the cascode for the dn2540, so as to be able to experiment with new solutions with a small daughter pcb. I tested the operation for an output voltage of 5v and a current of about 80mA, everything works correctly, as soon as I complete the assembly of the pcb I will start preparing everything to be able to power the dac and see if everything is fine. I am attaching the eagle files if someone might need them.
Ad maiora.
I finished the design, I preferred to put two pads in the case I would like to implement the cascode for the dn2540, so as to be able to experiment with new solutions with a small daughter pcb. I tested the operation for an output voltage of 5v and a current of about 80mA, everything works correctly, as soon as I complete the assembly of the pcb I will start preparing everything to be able to power the dac and see if everything is fine. I am attaching the eagle files if someone might need them.
Ad maiora.
i would make place for some 10-100 ohm resistor at opamp output to improve stability while rolling opamps🙂
In all my regulators, I use 10R at the output of the op amp, but when problems start, it doesn't help much 🙂 .
@Tix88
Thanks for the additional clarity Tix88.
Given the various changes since 12/27/14 on this topic, I am reposting the design document of 12/27/14, as it was updated in 2018.
The PDF can be found at: https://refsnregs.waltjung.org/UnivReg_122714_121718c.pdf
Note that the RED level shift LED should run at high current as set by the 220ohm R3 (not 1k!).
Thanks for the additional clarity Tix88.
Given the various changes since 12/27/14 on this topic, I am reposting the design document of 12/27/14, as it was updated in 2018.
The PDF can be found at: https://refsnregs.waltjung.org/UnivReg_122714_121718c.pdf
Note that the RED level shift LED should run at high current as set by the 220ohm R3 (not 1k!).