BM1489

BM1489 is Bitmain's 7 nm Scrypt mining ASIC (silicon part BM1489), the workhorse die behind the Antminer L7 — the current-generation Litecoin and Dogecoin merge-mining machine. Unlike the SHA-256 chips that mine Bitcoin (the BM1368 and BM1370 family), the BM1489 computes the memory-hard Scrypt hash, the proof-of-work that Litecoin and Dogecoin share. It is the current-generation Scrypt workhorse, and understanding it is the key to reading, tuning, or repairing an L7.

Where the BM1489 is used

The BM1489 is purpose-built for one job: it is the chip inside the Antminer L7, Bitmain's flagship Scrypt miner. Because Litecoin and Dogecoin can be produced together through merged mining, an L7 effectively earns two coins from a single Scrypt hashing effort, which is why the BM1489 remains the reference Scrypt die for home and small-facility miners. It is a Scrypt-only part — there is no SHA-256 substitution path, so a BM1489 cannot be repurposed to mine Bitcoin, and a Bitcoin ASIC chip cannot stand in for it.

What the silicon looks like

The BM1489 is fabricated on a 7 nm process and first shipped in 2021. A complete Antminer L7 carries the chip in unusual quantity: 120 BM1489 chips per chain across four chains, for 480 chips in a single machine — far more dies than a typical SHA-256 Antminer, which reflects how much silicon Scrypt's memory-hard design demands per unit of hashrate. Each chip contributes roughly 19.8 MH/s, and 480 of them add up to the L7's nameplate of about 9.5 GH/s. The chips are wired in long serial chains that receive their work over a ribbon interface and pass results back down the line, the same chain topology used across the Antminer family. As on other Antminer hashboards, the chains are organized into voltage domains so the control board can regulate current across groups of chips rather than one chip at a time; the exact per-domain layout for the L7 is not publicly documented, so treat any specific domain count you see quoted online with caution.

Power, efficiency, and tuning

At its factory nameplate the BM1489-based L7 draws about 3,425 W for roughly 9.5 GH/s, an efficiency near 0.36 J/MH (about 360 J/GH). Scrypt efficiency is expressed in joules per megahash rather than the joules-per-terahash used for Bitcoin hardware, because Scrypt hashrates are orders of magnitude lower — a direct consequence of the algorithm's memory requirements. As with other modern Antminer silicon, the chip exposes a tunable clock and a regulated domain voltage, so custom firmware can walk the L7 to a lower-power, higher-efficiency operating point or push it harder within thermal limits.

Repair and diagnostic relevance

For anyone servicing an L7, the BM1489's four-chain, 480-chip architecture is the first thing to understand: a dead or under-performing hashboard is one quarter of the machine, and a single failed chip in a long serial chain can pull an entire chain offline. Because the BM1489 is a high-value Scrypt part, it is also a counterfeiting target — when sourcing replacement boards or chips, verify the genuine four-chain / 120-chip-per-chain layout rather than trusting a printed label. Diagnosing the L7 follows the same logic as a SHA-256 Antminer — check chain enumeration, per-domain voltages, and chip temperatures — but the expected figures differ from the BM1368-class Bitcoin boards, so cross-reference L7-specific values rather than assuming Bitcoin-miner numbers apply.

Why it matters for miners

The BM1489 is, in practical terms, what you are buying when you buy an Antminer L7 to merge-mine Litecoin and Dogecoin. Knowing its node, chip count, and Scrypt-only nature helps you judge whether a low hashrate reading is a tuning issue or a failing chain, and keeps you from confusing it with the Bitcoin SHA-256 chips that share Bitmain's part-number scheme. To compare Scrypt and SHA-256 hardware side by side, see our miner catalog, and review the tuning trade-offs in our firmware comparison.