APCFA032GTAHS-ETAC Apacer, APCFA032GTAHS-ETAC Datasheet - Page 10

• Manufacturer Part Number: APCFA032GTAHS-ETAC
• Description: Memory Cards CFAST2 SLC EXT 32GB COMPACT FLASH CARD
• Manufacturer: Apacer

Specifications of APCFA032GTAHS-ETAC

• Rohs: yes
• Product: Compact Flash
• Memory Size: 32 GB
• Sustained Read: 160 MB/s
• Sustained Write: 150 MB/s
• Active Mode Current: 335 mA
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Dimensions: 36.4 mm x 42.8 mm x 3.6 mm
• Connector Type: 7 + 17 Pin Female
• Minimum Operating Temperature: - 40 C

CFast2
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5. Flash Management
5.1 Error Correction/Detection
CFast implements a hardware ECC scheme, based on the BCH algorithm. It can detect and correct up to
16 bits or 24 bits error in 1K bytes.
5.2 Bad Block Management
Although bad blocks on the flash media are already identified by the flash manufacturer, they can also be
accumulated over time during operation. CFast’s controller maintains a table that lists those normal
blocks with disk data, the free blocks for wear leveling, and bad blocks with errors. When a normal block
is detected broken, it is replaced with a free block and listed as a bad block. When a free block is
detected broken, it is then removed from the free block list and marked as a bad block.
During device operation, this ensures that newly accumulated bad blocks are transparent to the host. The
device will stop file write service once there are only two free blocks left such that the read function is still
available for copying the files from the disk into another.
5.3 Wear Leveling
The NAND flash devices are limited by a certain number of write cycles. When using a FAT-based file
system, frequent FAT table updates are required. If some area on the flash wears out faster than others, it
would significantly reduce the lifetime of the whole SSD, even if the erase counts of others are far from
the write cycle limit. Thus, if the write cycles can be distributed evenly across the media, the lifetime of the
media can be prolonged significantly. This scheme is called wear leveling.
Apacer’s wear-leveling scheme is achieved both via buffer management and Apacer-specific
dynamic/static global wear leveling to ensure the lifetime of the flash media can be increased and the disk
access performance is optimized as well.
5.4 Power Failure Management
The Low Power Detection on the controller initiates cached data saving before the power supply to the
device is too low. This feature prevents the device from crash and ensures data integrity during an
unexpected blackout. Once power was failure before cached data writing back into flash, data in the
cache will lost. The next time the power is on, the controller will check these fragmented data segment,
and, if necessary, replace them with old data kept in flash until programmed successfully.
5.5 ATA Secure Erase
Accomplished by the Secure Erase (SE) command, which added to the open ANSI standards that control
disk drives, “ATA Secure Erase” is built into the disk drive itself and thus far less susceptible to malicious
software attacks than external software utilities. It is a positive easy-to-use data destroy command,
amounting to electronic data shredding. Executing the command causes a drive to internally completely
erase all possible user data. This command is carried out within disk drives, so no additional software is
required. Once executed, neither data nor the erase counter on the device would be recoverable, which
blurs the accuracy of device lifespan. The process to erase will not be stopped until finished while
encountering power failure, and will be continued when power is back on.
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© 2012 Apacer Technology Inc.
Rev. 1.0