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MultiMediaCard Product Manual
MultiMediaCard
Host
The R
is switched on and off by the host
OD
synchronously to the open-drain and push-pull
mode transitions. R
DAT
resistors protecting the CMD and the DAT line
against bus floating when no card is inserted or
when all card drivers are in a hi-impedance
mode.
A constant current source can replace the R
order to achieve a better performance (constant
slopes for the signal rising and falling edges). I f
the host does not allow the switchable R
implementation,
a
fix
Consequently the maximum operating frequency in
the open drain mode has to be reduced in this case.
Hot Insertion/Removal
Hot insertion and removal are allowed. The
SanDisk MultiMediaCard will not be damaged by
inserting or removing it into the MultiMediaCard
bus even when the power is up.
•
The inserted card will be properly reset
also when CLK carries a clock frequency
f
.
PP
•
Data
transfer
removal/insertion should be detected by
the bus master using the CRC codes which
suffix every bus transaction.
20
R OD
R
DAT
= max (C , C , C )
C
1
3
2
BUS
Figure 4-1 Bus Circuitry Diagram
and R
are pull-up
CMD
in
OD
OD
R
can
be
used.
CMD
failures
induced
by
SanDisk MultiMediaCard Product Manual Rev. 2 © 2000 SANDISK CORPORATION
R
CMD
C 1 C 2 C 3
MultiMediaCard
4.2.1
Power Protection
Cards can be inserted/removed into/from the bus
without damage. If one of the supply pins (V
V
) is not connected properly, then the current is
SS
drawn through a data line to supply the card.
Every cards output must also be able to withstand
short cuts to either supply.
If the hot insertion feature is implemented in t h e
host, the host has to withstand a shortcut
between V
and V
DD
SS
4.2.2
Programmable Card Output Driver
This
option, defined in chapter
MultiMediaCard standard, is not implemented in
the SanDisk MultiMediaCard.
CMD
DAT
CLK
1 2
3 4 5
6 7
without damage.
6 of t h e
or
DD
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