USB Disk Module
APHAxxxXAX0XG-XTX
3
©2016 Apacer Technology, Inc. Rev. 1.6
1. General Description
Apacer USB3.0 Handy FLASH Drive EH353 is a ultra high-performance flash disk drive designed offering
portable storage solutions or external memory expansion. This new generation USB flash drive is
compatible with the latest USB specification – USB3.0 Super Speed, with a maximum transfer rate of 5.0
Gbps. The connector is backward employable with USB2.0 and USB1.1 interfaces as well. With
compliance with USB3.0 specification, this USB drive can deliver up to 205 MB/s outstanding performance.
Reliability wise, the USB comes with various implementations including powerful hardware ECC engine,
power saving modes, wear leveling and flash block management. This product is well suited for portable
flash storage applications while operating at minimal power consumption.
1.1 Performance-Optimized USB Controller
1.1.1 Power Saving Implemented
The internal controller of the USB model is designed with power saving implementations, allowing the
device to operate at low power consumption.
1.1.2 Program RAM Architect
The internal Program RAM implementation allows the host to upgrade firmware codes anytime when
needed.
1.1.3 Error Correction Code (ECC)
The UFD utilizes 1-bit Error Detection Code (EDC) and Error Correction Code (ECC).
1.1.4 Flash Block Management
Current production technology is unable to guarantee total reliability of NAND flash memory array. When a
flash memory device leaves factory, it comes with a minimal number of initial bad blocks during production
or out-of-factory as there is no currently known technology that produce flash chips free of bad blocks. In
addition, bad blocks may develop during program/erase cycles. When host performs program/erase
command on a block, bad block may appear in Status Register. Since bad blocks are inevitable, the
solution is to keep them in control. Apacer flash devices are programmed with ECC and block mapping
technique to reduce invalidity or error. Once bad blocks are detected, data in those blocks will be
transferred to free blocks and error will be corrected by designated algorithms.
1.1.5 Wear-Leveling Algorithms
Flash memory devices differ from Hard Disk Drives (HDDs) in terms of how blocks are utilized. For HDDs,
when a change is made to stored data, like erase or update, the controller mechanism on HDDs will
perform overwrites on blocks. Unlike HDDs, flash blocks cannot be overwritten and each P/E cycle wears
down the lifespan of blocks gradually. Repeatedly program/erase cycles performed on the same memory
cells will eventually cause some blocks to age faster than others. This would bring flash storages to their
end of service term sooner. Wear leveling is an important mechanism that level out the wearing of blocks
so that the wearing-down of blocks can be almost evenly distributed. This will increase the lifespan of flash
drives. Commonly used wear leveling types are Static and Dynamic.
