Filter
Top Products
5-6 PXA250 and PXA210 Applications Processors Design Guide
MultiMediaCard (MMC)
5.1.4 Pull-up and Pull-down
Table 5-4 and Table 5-5 show the pull-up and pull-down resistors required for SDCard and MMC
devices according to their respective specifications.
5.2 Utilized Features
The applications processor MultiMediaCard controller has these features:
• Data transfer rates as fast as 20 Mbps
• A16 bit response FIFO
• Dual receive data FIFOs
• Dual transmit FIFOs
• Support for two MMCs in either MMC or SPI mode
The sample schematics in this section support MMC and SDCard and are configured to use MMC
or SPI mode.
The applications processor MultiMediaCard controller and the MMC device have the same
maximum data rate, 20 Mbps, so their communication rates are compatible. However, because the
maximum applications processor MultiMediaCard controller data rate is 20 Mbps and the
maximum SDCard data rate is 25 Mbps, SDCard devices are not utilized to their fullest extent.
The circuit designs presented in this guide (Figure 5-1 and Figure 5-2) only show support for one
SDCard or MMC device, but the applications processor MultiMediaCard controller handles as
many as two devices.
Table 5-4. SDCard Pull-up and Pull-down Resistors
Signal Pull-up or Pull-down Min Max Remark
CMD pull-up 10kΩ 100kΩ Prevents bus floating
DAT0-DAT3 pull-up 10kΩ 100kΩ Prevents bus floating
WP
1
pull-up — — Any value sufficient to prevent bus floating
NOTE: 1. This resistor is shown in the specification but the value is not specified
Table 5-5. MMC Pull-up and Pull-down Resistors
Signal Pull-up or Pull-down Min Max Remark
CMD pull-up 4.7kΩ 100kΩ Prevents bus floating
DAT pull-up 50kΩ 100kΩ Prevents bus floating