SLUFD128MU1U-A STEC, SLUFD128MU1U-A Datasheet - Page 7

• Manufacturer Part Number: SLUFD128MU1U-A
• Manufacturer: STEC
• Type: USB Flash Driver

Specifications of SLUFD128MU1U-A

• Density: 128MByte
• Operating Supply Voltage (typ): 5V
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Package Type: Not Required
• Mounting: Socket
• Pin Count: 4
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (max): 5.25V
• Programmable: Yes
• Lead Free Status / RoHS Status: Compliant

SLUFDxxx(M/G)U1U(I)-y
Datasheet
3.1.2 Controller external components
In addition to the functional blocks shown in Figure 4, the Industrial Grade UFD has the following
external components:
3.2
Since the Industrial Grade UFD provides a standard USB interface to the host, no software
integration is required, providing the shortest time-to-market for design engineers.
The firmware of the embedded USB 2.0 controller contains STEC’s advanced flash memory
management algorithms to ensure the most optimum device performance, reliability and endurance.
It was designed to maximize the benefits of flash memory, while at the same time overcoming
inherent NAND flash limitations. Implemented in firmware are the below features:
3.2.1 Bad Block Management
Inherent to NAND flash technology are areas (blocks) on the media that cannot be used for storage
because of their high error rate. These so-called “bad blocks” are already identified by the flash
vendor during manufacturing, but can also be accumulated over time during device operation.
The Mach1 controller contains a table that lists all the bad blocks on the device (Bad Block Table),
and automatically maps out these blocks upon system initialization. During device operation it
ensures that newly accumulated bad blocks are also mapped out and added to the Bad Block Table.
Bad block management is 100% transparent to the host application, which will not be aware of the
location or existence of bad blocks on the media.
3.2.2 Wear Leveling
The SLC NAND flash devices that are being used in the USB Flash Drive are guaranteed for 100,000
Write/Erase cycles per block. This means that after approximately 100,000 erase cycles, the erase
block has a higher probability for errors than the error rate that is typical to the flash. While 100,000
write/erase cycles may be good for consumer data storage, such as digital cameras, MP3 players,
etc., it is not sufficient for industrial and embedded applications where data is constantly written to
the device and long product life is required.
For example, operating systems that use a file system, will update the File Allocation Table (FAT)
every time a write is done to the device. Without any wear leveling in place, the area on the flash
where the FAT table is located would wear out faster than other areas, reducing the lifetime of the
entire flash device.
To overcome this limitation, the flash management algorithm needs to make sure that each block in
the device ages, i.e. is “worn out”, at the same rate. The built-in wear leveling scheme makes sure
SLC NAND Flash for the most reliable data storage.
Crystal Oscillator 12Mhz, as the main clock source.
Flash file system management
Bad-block management
Wear-leveling
Power failure management
Performance optimization
Flash Management
61000-04536-105, May 2007
Industrial Grade USB Flash Drive
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