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Triode voltage regulator circuit simulation problem.

Hardware design
February 3, 2021 by Mohammed 75

1. When I was simulating the voltage regulator circuit of a triode, I found that if the load resistance RL is not connected, the output is not 5V, but 11V. This situation is very different from using an LDO. The LDO should output 5V without load. It is a bit unclear. .

2. In addition, for example, 5V is connected with a single-chip microcomputer, can I simulate it with a resistive load? What is the power consumption of a general MCU? For example, the figure above


3. Later, I can also test to remove the resistor R2. This R2 should be a current limiting resistor. It reduces the voltage of VCE and increases the output current. P=Ic*Vce is the power of the transistor. Is it out of power consumption?

If R2 is removed: P=1.2W, VCE=24-5=19V, Imax=P/VCE=63mA, if the MCU requires 100mA, which exceeds the total power consumption of the transistor, will the transistor be damaged?

All Comments

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Skylar Posted on February 3, 2021

Generally, the power consumption of a single-chip microcomputer is about a few mA to tens of hundreds of mA. You can read the manual for the power consumption. If the LDO no-load output is definitely the nominal value. It should be possible to simulate with resistance.

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Kennedy Posted on February 3, 2021

R2 can indeed reduce the voltage of VCE and reduce the power consumption of the transistor. But this resistance also needs to consider power issues. The transistor cannot exceed its maximum Imax, and at the same time, heat dissipation must be considered. P=1.2W should be done for heat dissipation, please refer to the manual for details.

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Alice Posted on February 3, 2021

It is absolutely possible to use resistance simulation.

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