Definition
A buck converter is a DC-DC switching regulator that steps a higher voltage down to a lower one. On an ASIC mining hashboard, buck converters are what bridge the gap between the PSU's 12V rail and the very low voltage the hashing chips actually run at — typically somewhere in the 0.3–1.2V range at the chip, depending on generation and clock. (Its counterpart, a boost converter, steps voltage up; hashboards almost exclusively use the step-down buck topology.)
One converter per voltage domain
The chips on a hashboard are split into voltage domains, and each domain has its own buck stage delivering a precisely regulated rail to that cluster of chips. These converters move serious current — often 20A or more per domain — in a cramped, hot space, so they are among the most thermally stressed parts on the board.
Why they fail
A buck converter is built from a switching regulator IC, high-current MOSFETs, an inductor, output capacitors, and current-sense resistors. Heat cycling and overcurrent kill the MOSFETs and dry out the capacitors, which collapses or destabilizes a domain's rail and drops the board's hashrate. Reading each domain's voltage with a meter is how technicians localize a failed converter before rework.
The measurement workflow is detailed in our voltage-domain measurement guide and the broader hashboard repair deep dive.
See measurement points in the diode & voltage reference.
In Simple Terms
A buck converter is a DC-DC switching regulator that steps a higher voltage down to a lower one. On an ASIC mining hashboard, buck converters…