The TL431 is a three-terminal adjustable voltage regulator that can provide an output voltage of 1.24 V to 36 V. It is used in a wide variety of applications, from simple voltage regulation to complex feedback systems. The TL431 is very accurate and reliable, making it a must-have for any electronics toolkit.

that's all true.. despite of your bad written english. lol

Thank you very much ,,,,,,

30 mA ,,,,,,

An adjustable DC supply is a power supply that can provide a range of voltages. This is handy for powering electronics projects, as you can select the voltage that is most appropriate for your needs. You can buy adjustable DC supplies, or you can make your own using a voltage regulator circuit. There are a few different types of voltage regulator circuits, but the most common is the linear regulator. This type of regulator uses a transistor to control the amount of current flowing through the circuit. By varying the amount of current, the voltage can be controlled. There are two main factors that you need to consider when choosing a voltage regulator: the maximum input voltage and the maximum output current. The maximum input voltage is the highest voltage that the regulator can handle, while the maximum output current is the maximum current that the regulator can provide.

Thanks

According to my simulation in the Falstad circuit applet, If the input voltage is 12.6V and you want to stay within USB limits (4.4V minimum) the limit is 37mA but the voltage starts already dropping below 5V at 34mA.