MC2GH256NMCA-2SA00 SAMSUNG [Samsung semiconductor], MC2GH256NMCA-2SA00 Datasheet - Page 7

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MC2GH256NMCA-2SA00

Manufacturer Part Number
MC2GH256NMCA-2SA00
Description
SAMSUNG MultiMediaCard
Manufacturer
SAMSUNG [Samsung semiconductor]
Datasheet
The 512 byte sector size of the SAMSUNG MultiMediaCard is the same as that in an IDE magnetic disk drive. To write or
read a sector (or multiple sectors), the host computer software simply issues a Read or Write command to the MultiMedia
Card. This command contains the address and the number of sectors to write/read. The host software then waits for the
command to complete. The host software does not get involved in the details of how the flash memory is erased, pro-
grammed or read. This is extremely important as flash devices are expected to get more and more complex in the future.
Because the MultiMediaCard uses an intelligent on-board controller, the host system software will not require changing as
new flash memory evolves. In other words, systems that support the MultiMeidaCard today will be able to access future
MultiMediaCards built with new flash technology without having to update or change host software.
The SAMSUNG MultiMediaCards contain a sophisticated defect and error management system. This system is analo-
gous to the systems found in magnetic disk drives and in many cases offers enhancements. For instance, disk drives do
not typically perform a read after write to confirm the data is written correctly because of the performance penalty that
would be incurred. MultiMediaCards do a read after write under margin conditions to verify that the data is written cor-
rectly (except in the case fo a Write without Erase Command). In the rare case that a bit is found to be defective. MultiMe-
diaCards will even replace the entire sector with a spare sector. This is completely transparent to the host and does not
consume any user data space.
The MultiMediaCards soft error rate specification is much better than the magnetic disk drive specification. In the
extremely rare case a read error does occur, MultiMediaCards have innovative algorithms to recover the data. This is sim-
ilar to using retries on a disk drive but is much more sophisticated. The last line of defense is to employ powerful ECC to
correct the data. If ECC is used to recover data, defective bits are replaced with spare bits to ensure they do not cause
any future problems.
These defect and error management systems coupled with the solid-state construction give MultiMediaCards unparal-
leled reliability.
MultiMediaCards have an endurance specification for each sector of 100,000 writes (reading a logical sector is unlimited).
This is far beyond what is needed in nearly all applications of MultiMediaCards. Even very heavy use fo the MultiMedi-
aCard in celluar phone, personal communicators, pagers and voice recorders will use only a fraction of the total endur-
ance over the typical device’s five year lifetime. For instance, it would take over 100 years to wear out an area on the
MultiMediaCard on which a files of any size (from 512bytes to capacity) was rewritten 3 times per hour, 8 hours a day, 365
days per year. With typical applications the endurance limit is not of any practical concern to the vast majority of users.
An important feature of the MultiMediaCard is automatic entrance and exit from sleep mode. Upon completion of an oper-
ation, the MultiMediaCard will enter the sleep mode to conserve power if no further commands are received within 5
msec. The host does not have to take any action for this to occur. In most systems, the MultiMediaCard is in sleep mode
except when the host is acccessing it, thus conserving power. When the host is ready to access the MultiMediaCard and
it is in sleep moed, any command issued to the MultiMediaCard will cause it to exit sleep and respond. The host does not
have to issue a reset first. It may do this if desired, but it is not needed. By not issuing the reset, performance is improved
through the reduction of overhead.
Support for the hot insertion will be required on the host but will be supported through the connector. Connector manufac-
tuers will provide connectors that have power pins long enough to be powered before contact is made with the other pins.
Please see connector data sheets for more details. This approach is similar to that used in PCMCIA to allow for hot inser-
tion. This applies to both MultiMediaCard and SPI modes.
Revision 0.3
3.3 Flash Independent Technology
3.4 Defect and Error Management
3.5 Endurance
3.6 Automatic Sleep Mode
3.7 Hot Insertion
7
MultiMediaCard
Sep.22.2005
TM

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