SMSC USB2244 - Manual (Page 10)

Ultra Fast USB 2.0 SD/MMC Flash Media Controller
Datasheet
Revision 1.0 (05-27-08) 10 SMSC USB2244/USB2244i
DATASHEET
Chapter 5 Pin Descriptions
This section provides a detailed description of each signal. The signals are arranged in functional
groups according to their associated interface.
The “n” symbol in the signal name indicates that the active, or asserted, state occurs when the signal
is at a low voltage level. When “n” is not present before the signal name, the signal is asserted at the
high voltage level.
The terms assertion and negation are used exclusively. This is done to avoid confusion when working
with a mixture of “active low” and “active high” signals. The term assert, or assertion, indicates that a
signal is active, independent of whether that level is represented by a high or low voltage. The term
negate, or negation, indicates that a signal is inactive.
5.1 Pin Descriptions
Table 5.2 USB2244/2244i 36-Pin QFN Pin Descriptions
NAME SYMBOL
36-PIN
QFN
BUFFER
TYPE DESCRIPTION
SECURE DIGITAL INTERFACE
SD Data SD_D[7:0] 7
8
10
20
23
25
4
5
I/O12PU The bi-directional signals should have weak
pull-up resistors. The register can be
controlled by: SD_MMC_INTF_EN bit of
SDC_MODE_CTL
SD Clock SD_CLK 9 O12 This is an output clock signal to SD/MMC
device.
The clock frequency is software configurable.
SD Command SD_CMD 11 I/O12PU This is a bi-directional signal that connects to
the CMD signal of SD/MMC device. The bi-
directional signal should have an internal weak
pull-up resistor.
The pull-up register can be controlled by:
SD_MMC_INTF_EN bit of SDC_MODE CTL
SD Write Protect SD_nWP 30 I/O12 This pin is designated as the Secure Digital
card mechanical write detect pin.
SD Card Detect
GPIO GPIO15
(SD_nCD) 26 I/O12 This is a GPIO designated as the Secure
Digital card detection pin.
USB INTERFACE
USB Bus Data USB+
USB- 2
3 I/O-U These pins connect to the USB bus data
signals.
USB Transceiver
Bias RBIAS 35 I-R A 12.0k , 1.0% resistor is attached from VSSA
to this pin in order to set the transceiver's
internal bias currents.