Backward compatible with USB 2.0 and supports SuperSpeed (5Gbps), High-Speed (480Mbps), and Full-Speed (12Mbps) operation.
The chip supports SATA III (6Gbps). If you put a fast SATA SSD (like a Samsung 870 EVO) into a JMS579 enclosure, you can realistically see sequential read/write speeds of . That is effectively the maximum speed the SATA interface allows, proving that the chip itself is not a bottleneck.
The is a single-chip bridge controller from JMicron Technology that enables connectivity between a USB 3.0 host and a SATA 6Gb/s storage device. It is primarily used in external hard drive enclosures, SSD adapters, docking stations, and optical drive enclosures. The device is known for its low power consumption, UASP (USB Attached SCSI Protocol) support, and stable performance for both HDDs and SSDs. jmicron jms579
If you see an external enclosure advertising "USB 3.1" speeds but it uses the JMS579, do not expect speeds above 500MB/s. It is limited by the USB 3.0 pipeline. For SATA drives, this is fine (since SATA caps at 600MB/s anyway), but don't buy this expecting gigabit speeds.
The JMS579 bridges USB transactions to ATA/SCSI commands: Backward compatible with USB 2
Almost always, this is a firmware or driver issue with the specific enclosure brand, not the chip itself. Ensuring your USB drivers are up to date usually resolves this.
The JMS579 is technically a controller. If you remember the confusing naming conventions, "USB 3.1 Gen 1" is actually just USB 3.0 (5Gbps). That is effectively the maximum speed the SATA
The JMS579 is designed with power-saving modes. It supports SATA link power management and USB selective suspend. For laptop users, this means your external drive won't drain your battery as aggressively when it's idle but plugged in.
Includes hardware acceleration for sequential and random data rates and support for external SPI NVRAM. Known Implementation Details & Issues
Would you like a firmware configuration guide, a schematic checklist, or a performance comparison table with ASM1153E and JMS578?
If you are shopping for a $15-$25 enclosure on Amazon, look for "JMS579" in the specs or "UASP Support" in the features. It is the assurance you need that you are getting the maximum speed your drive can offer.