AMS1117 LDO 3.3V Voltage Regulator for Avalon Hash Board Repair

AMS1117 LDO 3.3V Voltage Regulator | SOT-223 1A Low-Dropout Replacement for Avalon Hashboard Repair

The AMS1117 is a 3.3V low-dropout (LDO) linear voltage regulator in a SOT-223 surface-mount package, widely used on Avalon hashboards to derive stable 3.3V rails from a higher upstream supply. Delivers up to 1A output current with a 1V dropout — typical for the 3.3V housekeeping rails feeding clock buffers, level shifters, and control logic around the ASIC chains.

Common failure mode on Avalon boards: shorted output (downstream cap or load failure) drives the LDO into thermal limit, the die opens, and the entire 3.3V housekeeping rail goes dead. The control logic stops responding, the chain refuses to scan, and the board reads as "dead" even though the ASIC chips themselves are fine. Replacing the AMS1117 — after clearing the downstream short — is the fastest path back to a working board.

When to Replace the AMS1117

• 3.3V housekeeping rail dead on the Avalon hashboard — measure VOUT, confirm short to GND or open.
• Visible discolouration on the SOT-223 — overheated from a downstream short event.
• Board scanned briefly then went dead — LDO opened mid-boot after a transient over-current.
• Control logic intermittent — drifted dropout voltage pulling the rail out of spec under load.

AMS1117 LDO Specifications

FAQ — AMS1117 LDO 3.3V

Q: How do I confirm the AMS1117 is the dead part?
A: Power off, isolated from mains. Measure resistance from VOUT pin to GND — a shorted load will read very low ohms (and was the original cause of failure). Lift the LDO, re-test the load: if the short is gone, the LDO killed itself protecting the load. If the load is still shorted, replace it first or the new LDO will fail again immediately.

Q: 1A output — does that match the load?
A: The 3.3V housekeeping rail on a typical Avalon hashboard pulls hundreds of mA — well within the 1A AMS1117 envelope. If the load is closer to 1A, plan on active cooling: the SOT-223 dissipates Vdrop × Iout as heat, which at 12V→3.3V and 1A is ~9W — beyond what a bare SOT-223 can shed.

Q: Rework profile?
A: SOT-223 is straightforward hot-air rework. Preheat the board to 100°C, hot air at 320°C with flux paste, place with tweezers, reflow each lead. Always check the surrounding bypass caps and downstream load for shorts before re-energising.

Q: Bulk pricing for repair benches?
A: Yes — email contact@lys-sz.com for reel-quantity pricing on AMS1117 stock.

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• SPX5205M5 1.8V LDO Voltage Regulator

Avalon hashboard repair benches stocking AMS1117 LDOs by the reel? Email contact@lys-sz.com for bulk pricing. Worldwide shipping from our Shenzhen warehouse.