MAX77812 Buck1 and Buck2 share a common input (IN12) while Buck3 and Buck4 share a common input (IN34). Hence, IIN12 measures the total input currents of Buck1 and Buck2. To measure the input current for Buck1 only, please disable Buck Masters 2, 3 and 4. Use the same approach to measure the input currents of Buck 2, 3 or 4.