Principle block diagram for the Xiaomi Redmi 3A, titled in Chinese, supplied as a compact 193 KB PDF. It outlines the main circuit blocks and their links, giving an overview of how power management, the processor, memory and peripherals connect. Technicians use such a diagram to narrow down which section to probe before opening the full schematic. Any PDF viewer opens it. It is a summary rather than a component-level drawing, so pair it with the detailed Redmi 3A schematic for actual measurements.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @mobileschematicshub. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.