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232ACB

High Speed +5V Powered RS-232 Transmitters/Receivers

Intersil 

HIN232A

impedance, VCC = 4.5V, and maximum allowable operating

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 300Ω with

±2V applied to the outputs and VCC = 0V.

Receivers

The receiver inputs accept up to ±30V while presenting the

required 3kΩ to 7kΩ input impedance even if the power is off

(VCC = 0V). The receivers have a typical input threshold of 1.3V

which is within the ±3V limits, known as the transition region, of

the RS-232 specifications. The receiver output is 0V to VCC.

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.

V+

VCC

400kΩ

TXIN

GND < TXIN < VCC

300Ω

TOUT

V- < VTOUT < V+

V-

FIGURE 4. TRANSMITTER

VCC

RXIN

-30V < RXIN < +30V

5kΩ

GND

ROUT

GND < VROUT < VCC

FIGURE 5. RECEIVER

TIN

OR

RIN

TOUT

OR

ROUT

tPHL

tPLH

VOH

VOL

tPHL + tPLH

AVERAGE PROPAGATION DELAY =

2

FIGURE 6. PROPAGATION DELAY DEFINITION

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 5kΩ 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.

+5V

C1 +

0.1µF -

C2 +

0.1µF -

TD

INPUTS RTS

OUTPUTS

TTL/CMOS RD

CTS

1

16

3

HIN232A

4

5

11 T1

T2

10

12

9 R2 R1

-

+

CTR (20) DATA

TERMINAL READY

DSRS (24) DATA

SIGNALING RATE

6

SELECT

-

+

RS-232

INPUTS AND OUTPUTS

14

TD (2) TRANSMIT DATA

7 RTS (4) REQUEST TO SEND

13

RD (3) RECEIVE DATA

8 CTS (5) CLEAR TO SEND

15

SIGNAL GROUND (7)

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

5

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