Chapter 1 – Introduction
Revision 3.1
SanDisk iNAND Product Manual
© 2006 SanDisk Corporation
1-4
12/07/06
1.7
Defect and Error Management
The SanDisk iNAND contains a sophisticated defect and error management system. This
system is analogous to the systems found in magnetic disk drives and in many cases offers
enhancements. If necessary, iNAND will rewrite data from a defective sector to a good
sector. This is completely transparent to the host and does not consume any user data space.
The soft error rate specification for iNAND is much better than the magnetic disk drive
specification. In the extremely rare case that a read error does occur, iNAND has
innovative algorithms to recover the data. These defect and error management systems,
coupled with the solid state construction, give SanDisk iNAND unparalleled reliability.
1.8 Wear
Leveling
Wear-leveling is an intrinsic part of the erase pooling functionality of iNAND.
1.9
Automatic Sleep Mode
A unique feature of iNAND is automatic entrance and exit from sleep mode. Upon
completion of an operation, cards enter sleep mode to conserve power if no further
commands are received in less than 5 milliseconds (ms). The host does not have to take any
action for this to occur. However, in order to achieve the lowest sleep current, the host
needs to shut down its clock to the card. In most systems, cards are in sleep mode except
when accessed by the host, thus conserving power.
When the host is ready to access a card in sleep mode, any command issued to it will cause
it to exit sleep, and respond.
1.10 iNAND — SD Bus Mode
The following sections provide valuable information on SanDisk iNAND in SD Bus mode.
SanDisk iNAND devices are fully compliant with the SDA
Physical Layer Specification
,
Version 2.00
. Card Specific Data (CSD) Register structures are compliant with CSD
Structure 1.0 and 2.0.
This section covers Negotiating Operating Conditions, Card Acquisition and Identification,
Card Status, Memory Array Partitioning, Read/Write Operations, Data Transfer Rate, Data
Protection in Flash Cards, Write Protection, Copy Bit, and CSD Register.
Additional practical card detection methods can be found in application notes pertaining to
the SDA
Physical Layer Specification
,
Version 2.00
.
