STI3472 S42BCK 600KHz 18V 2A Step-down Converter Whatsminer Control Board

STI3472 S42BCK 600KHz / 18V / 2A Synchronous Step-Down Converter | High-Efficiency Buck Replacement IC in SOT23-6 for Whatsminer Control Board Repair

The STI3472 (S42BCK silkscreen marking) is a synchronous-rectification step-down (buck) converter in compact SOT23-6 surface-mount package — used on the Whatsminer control board for local rail generation. Drop-in replacement when the original buck fails: restores the rail and clears the control-board boot failures, peripheral reset issues, and unstable behaviour that come from a degraded local DC-DC converter. The fully integrated design eliminates the need for an external power MOSFET.

Operates at 600KHz switching frequency with 18V maximum input and 2A continuous output. 95% maximum efficiency minimises heat dissipation in the SOT23-6 package — critical at this small footprint where thermal headroom is tight. Supports two operating modes: PWM control for tight regulation at heavy load and PFM mode for high efficiency at light load. Operates from -40°C to +85°C, RoHS-compliant package.

When to Replace the STI3472 / S42BCK

• Control board rail dead — buck failed open, downstream peripheral receives no power.
• Excessive heating at the SOT23-6 package — degraded switching or output stage drawing abnormal current.
• Output ripple or oscillation on the regulated rail — degraded internal feedback loop or compensation.
• Visible damage on the SOT23-6 package — burn marks, lifted pins, surge damage.
• Preventive control-board refurbishment — refresh local DC-DC converters alongside other small-signal ICs during a complete overhaul.

STI3472 / S42BCK Specifications

FAQ — STI3472 Step-Down Converter

Q: How do I identify the STI3472 on a Whatsminer control board?
A: Look for the S42BCK silkscreen marking on a 6-pin SOT23 package. Position is typically near the local rail decoupling capacitors and inductor for the rail it serves.

Q: Why synchronous rectification rather than a diode?
A: Synchronous rectification replaces the freewheeling diode with a low-Rds(on) MOSFET, eliminating the diode forward-voltage drop. Result: significantly higher efficiency (95% peak here vs ~85% for asynchronous). At 2A, that's the difference between barely warm and uncomfortably hot in a SOT23-6.

Q: What's the difference between PWM and PFM modes?
A: PWM (Pulse Width Modulation) gives constant switching frequency with variable duty cycle — best regulation at heavy load. PFM (Pulse Frequency Modulation) skips pulses at light load to maintain high efficiency. The STI3472 switches automatically between the two based on load — maximises efficiency across the full load range.

Q: Bulk pricing for repair shops?
A: Yes — email contact@lys-sz.com with your monthly volume. Reel and tape quantities are stocked.

Related products

• STI3474 S43BOEA – Whatsminer M20 / M30 Control Board
• MP1471GJZ AGMH Buck Switching Regulator
• SGM4157YC6 CMOS Switch – Whatsminer CB2 V8 Control Board
• RS3236-1.8YF5 CMOS LDO 1.8V – Whatsminer Control Board

Repair shops stocking STI3472 step-down converters by the reel? Email contact@lys-sz.com for bulk pricing. Worldwide shipping from our Shenzhen warehouse.