Ultra Fast USB 2.0 SD/MMC Flash Media Controller

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.

5.1Pin Descriptions

Table 5.2 USB2244/2244i 36-Pin QFN Pin Descriptions

 

 

 

36-PIN

BUFFER

 

 

NAME

 

SYMBOL

QFN

TYPE

 

DESCRIPTION

 

 

 

 

 

 

 

 

 

SECURE DIGITAL INTERFACE

 

 

 

 

 

 

SD Data

 

SD_D[7:0]

7

I/O12PU

 

The bi-directional signals should have weak

 

 

 

8

 

 

pull-up resistors. The register can be

 

 

 

10

 

 

controlled by: SD_MMC_INTF_EN bit of

 

 

 

20

 

 

SDC_MODE_CTL

 

 

 

23

 

 

 

 

 

 

25

 

 

 

 

 

 

4

 

 

 

 

 

 

5

 

 

 

 

 

 

 

 

 

 

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

 

GPIO15

26

I/O12

 

This is a GPIO designated as the Secure

GPIO

 

(SD_nCD)

 

 

 

Digital card detection pin.

 

 

 

 

 

 

 

 

 

 

USB INTERFACE

 

 

 

 

 

 

 

USB Bus Data

 

USB+

2

I/O-U

 

These pins connect to the USB bus data

 

 

USB-

3

 

 

signals.

 

 

 

 

 

 

 

USB Transceiver

 

RBIAS

35

I-R

 

A 12.0k , 1.0% resistor is attached from VSSA

Bias

 

 

 

 

 

to this pin in order to set the transceiver's

 

 

 

 

 

 

internal bias currents.

 

 

 

 

 

 

 

Revision 1.0 (05-27-08)

 

 

10

 

SMSC USB2244/USB2244i

DATASHEET