TMI3252 (TP29RA) 2 A DC-DC Step-Down Converter – Whatsminer CB2-V16 Control Board
The TMI3252 (silk-screen marking TP29RA) is a 2 A synchronous buck converter in a SOT23-6 package, operating at a fixed 600 kHz constant-on-time (COT) frequency. On the Whatsminer CB2-V16 control board it provides one of the low-voltage rails that powers the Allwinner H3 CPU's I/O domain or peripheral circuitry. When this converter fails, the control board may boot partially then hang, or it may not power on at all — depending on which rail it feeds.
Why the TMI3252 Fails on Mining Control Boards
Control boards in mining environments endure constant thermal cycling and occasional voltage transients from hot-plug events. Over time, the internal MOSFETs in the TMI3252 degrade, causing the output voltage to droop below the CPU's minimum operating level. Symptoms include intermittent network drops, kernel panics visible on the serial console, or a board that boots to the kernel but fails to launch the mining daemon. A quick measurement on the converter's output pad with a multimeter (board powered, no load from hash boards) will confirm whether the rail is present and in spec.
Replacement Procedure
Locate the TMI3252 on the CB2-V16 — it is typically near the main power-input connector. Remove the failed IC with a fine-tip iron or hot air at 300 °C, clean the six pads, and install the replacement observing pin-1 orientation (dot or chamfer). The SOT23-6 pitch is 0.95 mm, making hand soldering straightforward. After replacement, power the board via a bench supply and verify the output rail voltage matches the design target before reconnecting hash boards.
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