JMicron JMF661

The JMicron JMF661 is a SATA III SSD controller released in 2012, succeeding JMicron's earlier JMF612. Where the JMF612 offered a dual SATA/USB interface, the JMF661 is a conventional SATA III-only design that trades that flexibility for higher throughput and a more capable ECC engine.

The controller uses a 32-bit embedded processor (ARM968 architecture) with 32 KB masked ROM and 128 KB on-chip system RAM. It supports 4 NAND flash channels with up to 16 chip-enables per channel, for a maximum of 32 flash devices and up to 512 GB total capacity. External DDR2 SDRAM (512 Mb to 2 Gb) is required for the firmware buffer. The BCH error correction engine supports 8, 16, 24, or 40 bits of correction per sector, a step up from the JMF612's 16/24-bit engine. Data transfers between the host and flash are handled by dedicated DMA engines without CPU involvement.

The JMF661 explicitly targets Toshiba 24 nm and 32 nm HBL/ABL toggle-mode NAND, and supports page sizes of 4K, 8K, and 16K bytes. It includes NCQ, LBA48, dynamic and static wear-leveling, and online firmware update over SATA. The chip is housed in a 399-ball TFBGA package.