FT232R USB UART I.C. Datasheet Version 1.04

© Future Technology Devices International Ltd. 2005

Page 8

4.2 SSOP-28 Package Signal Descriptions

Table 1 - SSOP Package Pin Out Description

Pin No. Name

Type Description

USB Interface Group

15

USBDP

I/O

USB Data Signal Plus, incorporating internal series resistor and 1.5kΩ pull up resistor to 3.3V

16

USBDM

I/O

USB Data Signal Minus, incorporating internal series resistor.

Power and Ground Group

4

VCCIO

PWR

+1.8V to +5.25V supply to the UART Interface and CBUS group pins (1...3, 5, 6, 9...14, 22, 23). In USB bus

powered designs connect to 3V3OUT to drive out at 3.3V levels, or connect to VCC to drive out at 5V CMOS

level. This pin can also be supplied with an external 1.8V - 2.8V supply in order to drive out at lower levels. It

should be noted that in this case this supply should originate from the same source as the supply to Vcc. This

means that in bus powered designs a regulator which is supplied by the 5V on the USB bus should be used.

7, 18, 21

GND

PWR

Device ground supply pins

17

3V3OUT

Output 3.3V output from integrated L.D.O. regulator. This pin should be decoupled to ground using a 100nF capacitor.

The prime purpose of this pin is to provide the internal 3.3V supply to the USB transceiver cell and the internal

1.5kΩ pull up resistor on USBDP. Up to 50mA can be drawn from this pin to power external logic if required.

This pin can also be used to supply the FT232R’s VCCIO pin.

20

VCC

PWR

3.3V to 5.25V supply to the device core.

25

AGND

PWR

Device analog ground supply for internal clock multiplier

Miscellaneous Signal Group

8, 24

NC

NC

No internal connection.

19

RESET#

Input

Can be used by an external device to reset the FT232R. If not required can be left unconnected, or pulled up

to VCCIO.

26

TEST

Input

Puts the device into I.C. test mode. Must be tied to GND for normal operation.

27

OSCI

Input

Input to 12MHz Oscillator Cell. Optional - Can be left unconnected for normal operation. *

28

OSCO

Output Output from 12MHz Oscillator Cell. Optional - Can be left unconnected for normal operation if internal oscilla-

tor is used. *

UART Interface and CBUS Group **

1

TXD

Output Transmit Asynchronous Data Output.

2

DTR#

Output Data Terminal Ready Control Output / Handshake signal.

3

RTS#

Output Request To Send Control Output / Handshake signal.

5

RXD

Input

Receive Asynchronous Data Input.

6

RI#

Input

Ring Indicator Control Input. When remote wake up is enabled in the internal EEPROM taking RI# low can be

used to resume the PC USB host controller from suspend.

9

DSR#

Input

Data Set Ready Control Input / Handshake signal.

10

DCD#

Input

Data Carrier Detect Control input.

11

CTS#

Input

Clear to Send Control input / Handshake signal.

12

CBUS4

I/O

Configurable CBUS I/O Pin. Function of this pin is configured in the device internal EEPROM. Factory Default

function is SLEEP#. See CBUS Signal Options, Table 3.

13

CBUS2

I/O

Configurable CBUS I/O Pin. Function of this pin is configured in the device internal EEPROM. Factory Default

function is TXDEN. See CBUS Signal Options, Table 3.

14

CBUS3

I/O

Configurable CBUS I/O Pin. Function of this pin is configured in the device internal EEPROM. Factory Default

function is PWREN#. See CBUS Signal Options, Table 3.

22

CBUS1

I/O

Configurable CBUS I/O Pin. Function of this pin is configured in the device internal EEPROM. Factory Default

function is RXLED#. See CBUS Signal Options, Table 3.

23

CBUS0

I/O

Configurable CBUS I/O Pin. Function of this pin is configured in the device internal EEPROM. Factory Default

function is TXLED#. See CBUS Signal Options, Table 3.

* Contact FTDI technical support for details on how to use an external crystal, ceramic resonator, or oscillator with the

FT232R.

** When used in Input Mode, these pins are pulled to VCCIO via internal 200kΩ resistors. These pins can be

programmed to gently pull low during USB suspend ( PWREN# = “1” ) by setting an option in the internal EEPROM.