# Why are both a voltage regulator and 2 MOSFETs used for a 3-5V to 3.3V circuit?

I'm adapting a breakout board for the LMS9DS1 IMU to suit my own needs. This breakout board has an input range of 3-5V and works on 3.3V. However, the circuit, as shown below, seems to have two ways of dropping the voltage. The MIC5225 (bottom left) is a voltage regulator, but don't MOSFETs (BS138, top left) also serve this purpose? What is the purpose of the extra MOSFETs? And can I drop both the regulator and the MOSFETs if I already have 3.3V?

Sorry if this is a silly question.

• @O.H.Bother I'm not sure what's on either side of SDA_3V and SDA_5V, but if you replace them with chips whose logic levels are compatible then you don't need to include Q1 and Q2. If you select some chips and you're not sure if their levels are compatible, you can ask a new question. – Kevin Kruse Dec 19 '18 at 16:31