Can you tell me what kind of SMD component U32 U31 "MDt" is?
Here’s what Google Gemini said:
These two chips are ElectroStatic Discharge (ESD) protection diode arrays, utilized to protect the KrakenSDR’s USB ports from static shocks when plugging and unplugging cables.
Both components are housed in a SOT-23-6 (also known as SOT-457 or SC-74) 6-pin surface-mount package. Here is the breakdown of each:
U31 (Marked 4DW): This marking code specifically identifies the chip as a PRTR5V0U4D manufactured by NXP/Nexperia. It is an ultra-low capacitance, 4-channel ESD protection array. The 4D indicates the base part number, and the W is a factory/date code.
U32 (Marked ·MDt): While MDt is a less standardized manufacturer marking, you can deduce its identity by looking at the physical PCB traces. Notice the perfect structural symmetry on the board: U31 is surrounded by capacitors C7/C21/C13, and U32 is surrounded by the exact same mirrored layout with C16/C84. Furthermore, the visible copper traces route to the exact same I/O pins (1, 3, 4, and 6) on both chips.
Because the KrakenSDR utilizes two USB ports (one for data, one for power) that require identical electrical protection, U32 is guaranteed to be a pin-compatible ESD protection array serving the exact same function as U31.
Hardware manufacturers frequently substitute generic protection ICs from different vendors to keep production lines moving during supply chain shortages, which results in mismatched SMD top-codes for components that do the exact same job.