SDP3B FlashDisk Product Manual
SanDisk SDP3B FlashDisk Product Manual © 1998 SANDISK CORPORATION 13
1.7.5.2 Limitations and Issues
The advantage of the Write without Erase and
Erase Sector commands is that they shift the bulk
of the erase and write time to the Erase Sector
command. The Erase Sector command performs
most of the normal tasks needed. To increase the
speed of the Write without Erase command, the
final margin verify done in a normal write
command is skipped for the first 16K writes.
When the cycle count (hot count) of a sector
exceeds 16K, the system controller automatically
reverts to a full write, including the final margin
verify. Since the erase is not required in this case,
a write to a pre-erased sector with a hot count of
over 16K is still faster than to a sector that has
not been pre-erased. The Translate Sector
command can be used to determine the “hot count”
of a sector.
1.7.6 Automatic Sleep Mode
A unique feature of the SanDisk SDP3B
FlashDisk (and other SanDisk products) is
automatic entrance and exit from sleep mode.
Upon completion of a command, the SDP3B
FlashDisk 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 SDP3B
FlashDisk is in sleep mode except when the host
is accessing it, thus conserving power. Note that
the delay from command completion to entering
sleep mode can be adjusted.
When the host is ready to access the SDP3B
FlashDisk and it is in sleep mode, any command
issued to the SDP3B FlashDisk will cause it to
exit sleep and respond. The host does not have to
follow the ATA protocol of issuing 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 but this must be
done only for the SanDisk products as other ATA
products may not support this feature.
1.7.7 Dynamic Adjustment of Performance
versus Power Consumption
A very unique and valuable feature of the SDP3B
FlashDisk is the ability of the host to control the
power the card consumes. This allows SDP3B
FlashDisks to work across a broad cross section of
platforms without compromising performance. For
instance, it can operate in a platform that
provides only 32 mA at 3.3 volts average current
(of course at reduced performance) or in a platform
that provides 90 mA at full performance. Please
see the Set Features command for details.
1.7.8 Power Supply Requirements
This is a dual voltage product which means it
will operate at a voltage range of 3.30 volts ± 5%
or 5.00 volts ± 10% (± 5% for industrial versions).
Per the PCMCIA specification section 2.1.1, the
host system must apply 0 volts in order to change a
voltage range. This same procedure of providing 0
volts to the card is required if the host system
applies an input voltage outside the desired
voltage by more than 20%. This means less than
4.0 volts for the 5.00 volt range and less than 2.70
volts for the 3.30 volt range.
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