5

temperature. The transmitters have an internally limited output

slew rate which is less than 30V/

µs. The outputs are short

circuit protected and can be shorted to ground indefinitely. The

powered down output impedance is a minimum of 300

Ω with

Receivers

The receiver inputs accept up to

±30V while presenting the

required 3k

Ω to 7kΩ input impedance even if the power is off

which is within the

±3V limits, known as the transition region, of

The output will be low whenever the input is greater than 2.4V

and high whenever the input is floating or driven between +0.8V

and -30V. The receivers feature 0.5V hysteresis (except during

shutdown) to improve noise rejection.

Application Information

The HIN232A may be used for all RS-232 data terminal and

communication links. It is particularly useful in applications

where

±12V power supplies are not available for

conventional RS-232 interface circuits. The applications

presented represent typical interface configurations.

A simple duplex RS-232 port with CTS/RTS handshaking is

illustrated in Figure 7. Fixed output signals such as DTR

(data terminal ready) and DSRS (data signaling rate select)

is generated by driving them through a 5k

Ω resistor

connected to V+.

In applications requiring four RS-232 inputs and outputs

(Figure 8), note that each circuit requires two charge pump

capacitors (C1 and C2) but can share common reservoir

capacitors (C3 and C4). The benefit of sharing common

reservoir capacitors is the elimination of two capacitors and

the reduction of the charge pump source impedance which

effectively increases the output swing of the transmitters.

300

Ω

400k

Ω

V-

V+

FIGURE 4. TRANSMITTER

5k

Ω

GND

FIGURE 5. RECEIVER

AVERAGE PROPAGATION DELAY =

2

OR

OR

FIGURE 6. PROPAGATION DELAY DEFINITION

-

+

-

+

-

+

CTR (20) DATA

TERMINAL READY

DSRS (24) DATA

SIGNALING RATE

RS-232

INPUTS AND OUTPUTS

TD (2) TRANSMIT DATA

RTS (4) REQUEST TO SEND

RD (3) RECEIVE DATA

CTS (5) CLEAR TO SEND

SIGNAL GROUND (7)

15

8

13

7

14

16

-

+

6

R2

R1

T2

T1

9

12

10

11

4

5

3

1

HIN232A

C1

0.1

µF

C2

0.1

µF

TD

RTS

RD

CTS

SELECT

+5V

INPUTS

OUTPUTS

TTL/CMOS

FIGURE 7. SIMPLE DUPLEX RS-232 PORT WITH CTS/RTS HANDSHAKING

HIN232A