BM1485

BM1485 is Bitmain's 28 nm Scrypt mining ASIC (part marking BM1485), the die that powered the Antminer L3+ generation of Litecoin and Dogecoin miners. Unlike the SHA-256 silicon that dominates Bitcoin mining, the BM1485 computes the memory-hard Scrypt proof-of-work, which makes it a fundamentally different chip from the BM1368 and the rest of Bitmain's double-SHA-256 line. Introduced in 2017, it remains the reference Scrypt ASIC chip that most home and small-scale Litecoin/Dogecoin operations were built around.

Where the BM1485 is used

The BM1485 is the chip inside the Antminer L3+ and the slightly faster L3++ — Bitmain's long-running Scrypt workhorses. A stock L3+ is rated at roughly 504 MH/s for about 800 W, while the L3++ pushes to around 580 MH/s at correspondingly higher draw. Because Litecoin and Dogecoin both use Scrypt and are routinely merge-mined, a single L3+ packed with BM1485 dies can earn both coins from one proof-of-work effort, which is a large part of why this hardware stayed in service long after newer Bitcoin ASICs eclipsed it.

One point matters before you shop: the BM1485 is a Scrypt-only chip and is not interchangeable with any SHA-256 Bitcoin miner. It will never appear in an S9, S19, or S21, and a Scrypt hashboard can never be cross-populated with chips from a Bitcoin board. Treat the L3 family as its own ecosystem.

What the silicon looks like

Each L3+ hashboard carries 72 BM1485 chips, and a complete L3+ runs four hashboards for 288 chips total — a wider, lower-frequency layout than the long serial chains of modern Bitcoin miners. Every board is divided into 12 voltage domains of 6 chips each, with each domain held near ~0.80 V, so the control board manages current across groups of chips rather than one chip at a time. Spread across 288 dies, the unit's ~504 MH/s works out to only about 1.7 MH/s per chip — modest throughput per die that reflects both the 28 nm process and the nature of the algorithm.

That algorithm is the key architectural story. Scrypt is deliberately memory-hard: each hash requires building and randomly reading a scratchpad of memory, so every BM1485 integrates on-die SRAM to hold that scratchpad. This embedded memory makes a Scrypt die physically larger per unit of hashrate than a comparable SHA-256 chip, and it is why Scrypt ASICs like the BM1485 deliver hashrates in megahashes per second rather than the tera-scale numbers a Bitcoin chip produces.

Servicing and counterfeit notes

For anyone repairing an L3+, the BM1485's 12-domain layout is the unit of diagnosis: a dead or under-performing hashboard is best traced domain by domain, checking the ~0.80 V rails and the serial chain through each group of six chips. Because these are aging units, supply matters too — older L3+ stock is frequently refurbished and re-sold, so it is worth confirming the genuine 72-chip Scrypt layout on each board rather than assuming a listing is accurate. The chip carries no published hexadecimal silicon ID in our records (it is catalogued as a named die for completeness), so physical board inspection is the most reliable verification.

Why it matters for miners

The BM1485 is, in practical terms, the chip you are dealing with whenever you run or service an Antminer L3+ or L3++ for Litecoin and Dogecoin. Understanding its Scrypt foundations, its 72-chips-per-board architecture, and its domain-level power layout helps you reason about realistic hashrate, plan board-level repairs, and avoid the common mistake of treating Scrypt and SHA-256 hardware as interchangeable. It is a useful reference point for seeing how the same ASIC design principles — serial chains, voltage domains, and per-domain power management — adapt to a different proof-of-work than the one Bitcoin uses.