Please help me identify the microcircuit

marking BAX N45 039 in QFN-13(2.5mmx3mm) case

Hello,

The information provided is too general, thus I could not find a suitable part that fits those markings. Could you provide a photo which clearly shows the top marking? That may be able to give some better information. Is there any additional information you can provide such as what the input voltage and output voltage is? That can also help narrow down the search.

You can also reference our product package information, which can be found here:
Package Information - Support (monolithicpower.com)

Hello, input voltage 24V - output 12V, in LED circuit, but it seems to be just step-down DCDC, LED drivers are separate. Thank you!
https://drive.google.com/drive/folders/12sG3gkJSpFtuFjxOSbevOhvZdFzyrB72?usp=sharing

Hello,

Looks like it is the MP2491C. See product page below.

MP2491C | 32V, 6A, Step-Down Converter with Programmable Current Limit and Output Voltage Scaling Control | MPS