DS232B Version 1.8

© Future Technology Devices Intl. Ltd. 2005

Page 8 of 25

FT232BM USB UART ( USB - Serial) I.C.

4.1 Signal Descriptions

Table 1 - FT232BM - PINOUT DESCRIPTION

UART INTERFACE GROUP

Pin#

Signal

Type

Description

25

TXD

OUT

Transmit Asynchronous Data Output

24

RXD

IN

Receive Asynchronous Data Input

23

RTS#

OUT

Request To Send Control Output / Handshake signal

22

CTS#

IN

Clear To Send Control Input / Handshake signal

21

DTR#

OUT

Data Terminal Ready Control Output / Handshake signal

20

DSR#

IN

Data Set Ready Control Input / Handshake signal

19

DCD#

IN

Data Carrier Detect Control Input

18

RI#

IN

Ring Indicator Control Input. When the Remote Wakeup option is enabled in the

EEPROM, taking RI# low can be used to resume the PC USB Host controller

from suspend.

16

TXDEN

OUT

Enable Transmit Data for RS485

USB INTERFACE GROUP

Pin#

Signal

Type

Description

7

USBDP

I/O

USB Data Signal Plus ( Requires 1.5k pull-up to 3V3OUT or RSTOUT# )

8

USBDM

I/O

USB Data Signal Minus

EEPROM INTERFACE GROUP

Pin#

Signal

Type

Description

32

EECS

I/O

EEPROM – Chip Select. For 48MHz operation pull EECS to GND using a 10K

resistor. For 6MHz operation no resistor is required. Tri-State during device reset.

**Note 1

1

EESK

OUT

Clock signal to EEPROM. Tri-State during device reset, else drives out. Adding a

10K pull down resistor onto EESK will cause the FT232BM to use USB Product

ID 6004 (hex) instead of 6001 (hex). All of the other USB device descriptors are

unchanged.

**Note 1

2

EEDATA

I/O

EEPROM – Data I/O Connect directly to Data-In of the EEPROM and to Data-

Out of the EEPROM via a 2.2K resistor. Also, pull Data-Out of the EEPROM

to VCC via a 10K resistor for correct operation. Tri-State during device reset.

**Note 1