{"product_id":"lmh6644-operational-amplifier-soic14-antminer-s21-plus-hydro-hashboard-repair","title":"LMH6644 Quad Op-Amp SOIC14 – Antminer S21+ Hydro Hashboard Repair","description":"\u003ch2\u003eLMH6644 Quad Operational Amplifier – SOIC14 Op-Amp for Antminer S21+ Hydro Hash Board Signal Conditioning\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eLMH6644\u003c\/strong\u003e is a \u003cstrong\u003efour-channel voltage-feedback high-speed rail-to-rail output operational amplifier\u003c\/strong\u003e used on the \u003cstrong\u003eAntminer S21+ Hydro hash board\u003c\/strong\u003e. It integrates \u003cstrong\u003efour independent op-amps in a single SOIC14 SMD package\u003c\/strong\u003e, purpose-built for the \u003cstrong\u003ehigh-speed signal sampling, current detection and signal buffering circuits\u003c\/strong\u003e around the ASIC hash chips. On the S21+ Hydro board it sits in the signal-conditioning path — a core component for \u003cstrong\u003evoltage sampling, feedback control and signal amplification\u003c\/strong\u003e back to the main control MCU.\u003c\/p\u003e\n\u003cp\u003eKey electrical strengths: \u003cstrong\u003e130 MHz gain-bandwidth\u003c\/strong\u003e, \u003cstrong\u003e135 V\/μs slew rate\u003c\/strong\u003e, \u003cstrong\u003e75 mA linear output current per channel\u003c\/strong\u003e, and a wide \u003cstrong\u003e2.7–12.8 V single-supply range\u003c\/strong\u003e that matches the 5 V rails on the mining board. Rail-to-rail output stays within \u003cstrong\u003e40 mV of either supply rail\u003c\/strong\u003e, so weak sampling signals from the hash chip are transmitted without attenuation.\u003c\/p\u003e\n\u003ch3\u003eRole on the S21+ Hydro Hash Board Circuit\u003c\/h3\u003e\n\u003cp\u003eOn the S21+ Hydro board, the LMH6644 is responsible for \u003cstrong\u003ebuffering, amplifying and filtering the current and voltage sampling signals of the ASIC chip\u003c\/strong\u003e. It acquires the real-time operating-voltage and load-current analogue signals coming off the hash chip, normalises them into standard-level voltage signals, and returns them to the main control MCU to complete \u003cstrong\u003eclosed-loop voltage regulation, overvoltage and overcurrent protection, and computing-power monitoring\u003c\/strong\u003e. A single LMH6644 covers up to four independent sampling channels — meaning one failed device can silently disable four feedback paths at once.\u003c\/p\u003e\n\u003ch3\u003eWhen to Replace the LMH6644 — Fault Symptoms \u0026amp; Diagnosis\u003c\/h3\u003e\n\u003cp\u003eAn LMH6644 failure — \u003cstrong\u003einternal channel breakdown, excessive offset drift, or open \/ short circuits in the output\u003c\/strong\u003e — drives \u003cstrong\u003eabnormal signal voltages on the S21+ Hydro ASIC chip\u003c\/strong\u003e, which typically manifests as overall system instability: hash-rate decay, board offline events in the kernel log, or the miner shutting down under protection when it should be running normally.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFault diagnosis procedure:\u003c\/strong\u003e use a multimeter to measure the LMH6644's power-supply pins and its input \/ output pins on the board. If the \u003cstrong\u003eoutput level is fixed and no longer correlated with the input signal\u003c\/strong\u003e, the chip is failed and should be replaced.\u003c\/p\u003e\n\u003ch3\u003eReplacement Standard — Original LMH6644 Only\u003c\/h3\u003e\n\u003cp\u003eSubstitution is not an option. \u003cstrong\u003eOnly original LMH6644 devices must be used\u003c\/strong\u003e. Low-speed general-purpose op-amps \u003cstrong\u003ecannot be substituted\u003c\/strong\u003e: they lack the bandwidth (130 MHz) and the output current (75 mA \/ channel) required to condition the S21+ Hydro sampling signals cleanly, and installing one will continue to cause abnormal ASIC chip signal voltages — the exact symptom you were trying to fix. The replacement device we supply matches the original in all electrical and package specifications.\u003c\/p\u003e\n\u003ch3\u003eSoldering \u0026amp; Post-Replacement Verification\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eAnti-static handling\u003c\/strong\u003e is mandatory throughout — wrist strap grounded, ESD-safe bench mat, ionised tools. Desolder the failed LMH6644 with a \u003cstrong\u003elow-temperature SOIC14 SMD hot-air-rework profile\u003c\/strong\u003e to avoid damaging the fine PCB traces of the S21+ Hydro hash board. Clean the pads with flux and braid, place the new LMH6644 aligned to pin 1, and re-flow at the same low-temperature profile.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePost-replacement verification:\u003c\/strong\u003e bring the miner back online and test the sampling-signal voltage of the ASIC chips under full load. If the signal returns to its standard range and the hash rate stabilises at spec, the repair is complete.\u003c\/p\u003e\n\u003ch4\u003eLMH6644 Core Electrical Specifications\u003c\/h4\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth style=\"text-align: left; padding: 6px 12px;\"\u003eParameter\u003c\/th\u003e\n\u003cth style=\"text-align: left; padding: 6px 12px;\"\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003ePart Number\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eLMH6644\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003ePackage\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eSOIC14 surface-mount\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eChannels\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e4 independent voltage-feedback op-amps\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eGain-Bandwidth Product\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e130 MHz (unity gain)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eSlew Rate\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e135 V\/μs — no waveform distortion at speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eLinear Output Current\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e75 mA per channel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003ePeak Short-Circuit Current\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e115 mA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eSupply Voltage\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e2.7 V – 12.8 V single supply (5 V mining-board compatible)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eOutput Swing\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eWithin 40 mV of either supply rail (rail-to-rail)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eQuiescent Current\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e2.7 mA per channel — low heat generation\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eInput Offset Voltage\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e5 mV max — controlled sampling error\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eTotal Harmonic Distortion\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e-62 dBc — low-interference weak-signal amplification\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003e-40 °C to +85 °C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eFunction\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eVoltage \/ current sampling, feedback control, signal amplification for ASIC chip signals\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eCompatibility\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eAntminer S21+ Hydro hash board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eSubstitution\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eOriginal LMH6644 only — low-speed general-purpose op-amps not compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eCondition\u003c\/td\u003e\n\u003ctd style=\"text-align: left; padding: 6px 12px;\"\u003eBrand new\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003c\/h3\u003e\n\u003ch3\u003eRelated Antminer S21+ Hydro Hash Board Repair Parts\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/products\/sgm8304yts14-100mhz-high-voltage-output-amplifiers-antminer-repair\"\u003eSGM8304YTS14 100MHz Quad Op-Amp – Antminer S21 (Sister Signal-Conditioning IC)\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/bitmain-bm1370bc-asic-chip-antminer-s21pro-s21xp-s21hydro\"\u003eBM1370BC ASIC Chip – Antminer S21+ \/ S21 Pro \/ S21 XP \/ S21 Hydro\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/antminer-s21-hyd-thermal-grease-stencil-stainless-steel-positioning-frame\"\u003eAntminer S21+ Hyd Thermal Grease Stencil – Hashboard Repair Tool\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/products\/antminer-test-fixture-hashboard-asic-universal-tester-s19-s21-s19hyd-t21-all-series\"\u003eUniversal Antminer Hashboard Test Fixture – Post-Repair Verification\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eRepairing S21+ Hydro hash boards in volume or stocking op-amp spares for a repair bench? \u003ca href=\"mailto:contact@lys-sz.com\"\u003eContact us at contact@lys-sz.com\u003c\/a\u003e for tray-quantity LMH6644 pricing. Worldwide shipping from our Shenzhen warehouse.\u003c\/p\u003e","brand":"LYS Shenzhen","offers":[{"title":"Default Title","offer_id":45626918207667,"sku":null,"price":1.2,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0627\/6710\/4179\/files\/lmh6644-quad-op-amp-soic14-antminer-s21-plus-hydro.webp?v=1782867584","url":"https:\/\/lys-sz.com\/products\/lmh6644-operational-amplifier-soic14-antminer-s21-plus-hydro-hashboard-repair","provider":"LYS Shenzhen","version":"1.0","type":"link"}