There are several schemes to realize dimming, one is to adjust the voltage and the other is to adjust the current. If the voltage is adjusted (1) the three terminal voltage regulator can realize Lm317 (2) LDO such as mic29302. If you want to adjust the current to adjust the light, (1) the accuracy does not need to be very high. You can use a triode. The constant current source circuit can be adjusted with the potentiometer, but you need to be careful when calculating the power of the triode. (2) Recommend one I often use. The PT4115C (3) LM317 also has a constant current connection, which can be used with a potentiometer to adjust the current. In addition, Baidu is not a reliable way to find the chip I want. Usually, I go to the official website of a large factory to find it.