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.