SMSC USB2242i 사용자 설명서

Ultra Fast USB 2.0 Memory Stick Flash Media Controller

SMSC USB2242/USB2242i

11

Revision 1.0 (05-27-08)

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.

24MHz Crystal or 
external clock 
input

XTAL1 (CLKIN)

33

ICLKx

This pin can be connected to one terminal 
of the crystal or it can be connected to an 
external 24 clock when a crystal is not 
used.

24MHz Crystal

XTAL2

32

OCLKx

This is the other terminal of the crystal, or 
it can be left open when an external clock 
source is used to drive XTAL1(CLKIN).  It 
may not be used to drive any external 
circuitry other than the crystal circuit.

3.3V Analog 
Power 

VDDA33

36

3.3V Analog Power 

1.8V PLL Power 

VDD18PLL

34

This pin is the 1.8V Power for the PLL.

+1.8V Filtered analog power for internal 
PLL. This pin must have a 1.0

μ

F(or 

greater) ±20% (ESR <0.1

Ω) capacitor to 

VSS.

General Purpose 
I/O

GPIO1  (LED1)

1

I/O12

This pin may be used either as input, edge 
sensitive interrupt input, or output.

In addition, as an output, the GPIO1 can 
use output controlled by the LED1_GPIO1 
register.

General Purpose 
I/O

GPIO2 / RXD / 
SDA

27

I/O12

GPIO: This pin may be used either as 
input, edge sensitive interrupt input, or 
output.

I

RXD: In addition to the above, the signal 
can be used as input to the RXD of UART 
in the device, when the TXD_RXD_SEL 
bit in UTIL_CONFIG1 register is cleared to 
"0".

I/O12

SDA: This is the data pin when used with 
an external serial EEPROM.

General Purpose 
I/O

GPIO4

29

I/O12

This pin may be used either as input, edge 
sensitive interrupt input, or output.