UP1542S UP1542SSU8 SOP-8 Synchronous Rectified Buck Controller

UP1542S Synchronous Rectified Buck Controller – Hashboard PCB Replacement IC

The UP1542S (UP1542SSU8) is a synchronous rectified buck controller in an SOP-8 package, designed to step down 5 V or 12 V input rails to outputs as low as 0.6 V. On ASIC miner hash boards it drives the local step-down converter that feeds power to groups of hashing chips. When this controller fails, its downstream ASIC string loses its supply rail and drops out of the hash chain — often appearing as a block of consecutive dead chips on a test-fixture scan rather than a single failed ASIC.

Distinguishing a Controller Fault from a Chip Fault

If a test fixture reports a contiguous group of failed chip positions (e.g. positions 12–18 all dead while 11 and 19 are fine), the fault is almost certainly in the power stage rather than in seven individual ASICs. Measure the output voltage at the inductor pad of the suspect buck converter: if the rail is absent or far below spec, the UP1542S controller is the primary suspect. A secondary check is to measure the switching waveform at the SW pin — a flat line confirms the controller is not switching.

Replacement Procedure

Remove the failed UP1542S with a soldering iron or hot-air station at 300–330 °C, taking care not to disturb the surrounding inductor and capacitors. Clean the eight pads, apply flux, and place the new IC observing pin-1 orientation. Solder by dragging a fine iron tip across the leads, then inspect under magnification for bridges — the 1.27 mm SOP-8 pitch is relatively forgiving. After replacement, power the board and verify the output voltage matches the original design value (typically 0.6–1.0 V depending on the ASIC family) before reinstalling in the miner.

UP1542S Buck Controller Specifications

Related Buck Controllers & Power ICs

• UP1529Q / UP9305W Power Chip – Antminer L3+ / S9
• LM27402S Sync Buck Controller – Antminer
• TPS40322 Dual Buck Controller – Innosilicon A10
• KB6880 PWM Buck Controller – Innosilicon A4/A6

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