Copyright © 2008 Future Technology Devices International Limited

9

Document Reference No.: FT_000065

TTL-232R-PCB TTL TO USB SERIAL CONVERTER PCB Datasheet Version 1.01

Clearance No.: FTDI# 54

Name

Type

Description

GND

GND

Device ground supply pin.

CTS#

Input

Clear to Send Control input / Handshake signal.

VCC

Output

+5V output,

TXD

Output

Transmit Asynchronous Data output.

RXD

Input

Receive Asynchronous Data input.

RTS#

Output

Request To Send Control Output / Handshake signal.

Table 4.1 TTL-232R-PCB Signal Descriptions

Selection of whether the UART signal are +3.3V levels or +5V levels is done using resistors. The following

table gives details of what resistors are required for the two different voltage levels. Note that the VCC

output signal will always drive at +5V.

Resistor

R1

Resistor

R2

Description

Fitted

Not Fitted

UART signals are +5V level signals

Not Fitted

Fitted

UART signals are +3.3V level signals

Table 4.2 UART Signal Level Selection

Parameter

Description

Minimum

Typical

Maximum

Units

Conditions

VCC

Output Power Voltage

4.25

5.0

5.25

V

Dependant on the USB

port that the TTL-232R-

PCB is connected to

Output Power Current

-

75

mA

T

Operating Temperature

Range

-40

+85

Table 4.3 TTL-232R-PCB I/O Operating Parameters

Parameter

Description

Minimum

Typical

Maximum

Units

Conditions

Voh

Output Voltage High

3.2

4.1

4.9

V

I source = 6mA

Vol

Output Voltage Low

0.3

0.4

0.6

V

I sink = 6mA

Vin

Input Switching Threshold

1.0

1.2

1.5

V

VHys

Input Switching Hysteresis

20

25

30

mV

Table 4.4 TTL-232R-PCB I/O Pin Characteristics (+5V level signals)