ST ST75185C User Manual

Multiple RS-232 drivers and receivers

Features

■ Meets and exceeds the requirements of

EIA/TIA-232-E and ITUV.28 standard

■ Single chip with easy interface between UART

and serial port connector of IBM PC/AT™ and
compatibles

■ Designed to support data rates up to 120 kbps

■ Pinout compatible with ST75C185

Description

SO-20

ST75185C

TSSOP20

The ST75185C contains three drivers and five
receivers. The pinout matches the DB9S
connector design in order to decrease the part
count, reduce the board space required and allow
easy interconnection of the UART and serial port
connector of IBM PC/AT™ and compatibles. The
bipolar circuits and processing of the ST75185C
provides a rugged low-cost solution for this
function at the expense of quiescent power and
external passive components relative to the
ST75C185.

The ST75185C complies with the requirements of
the EIA/TIA 232-E and ITU (formally CCITT) v.28
standards. These standards are for data
interchange between a host computer and
peripheral at signalling rates up to 20 k-bits/s. The
switching speeds of the ST75185C are fast
enough to support rates up to 120 K-bits/s with
lower capacitive loads (shorter cables). Inter­operability at the higher signalling rates cannot be
assured unless the designer has design control of
the cable and the interface circuits at the both
ends. For inter-operability at signalling rates to

120 k-bits/s, use of EIA/ITA-423-B (ITU v.10) and
EIA/ITA-422-B (ITU v.11) standards are
recommended.

The ST75185C is characterized for operation over
the range of 0°C to 70 °C

.

Table 1. Device summary

Order codes Temperature range Packages Packaging

ST75185CTR 0 to 70 °C TSSOP20 (tape and reel) 2500 parts per reel

ST75185CDR 0 to 70 °C SO-20 (tape and reel) 1000 parts per reel

April 2009 Doc ID 6228 Rev 18 1/22

www.st.com

22

Contents ST75185C

Contents

1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6 Application information: diodes on power supply . . . . . . . . . . . . . . . . 15

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2/22 Doc ID 6228 Rev 18

ST75185C Pin configuration

1 Pin configuration

Figure 1. Pin connection IEC logic symbol and logic diagram

Table 2. Pin description

Pin n° Symbol Name and function

1V

2 RA1 First receiver input

3 RA2 Second receiver input

4 RA3 Third receiver input

5 DY1 First driver output

6 DY2 Second driver output

7 RA4 Fourth receiver input

8 DY3 Third driver output

9 RA5 Fifth receiver input

10 V

11 GND Ground

12 RY5 Fifth receiver output

13 DA3 Third driver input

14 RY4 Fourth receiver output

15 DA2 Second driver input

16 DA1 First driver input

17 RY3 Third receiver output

DD

SS

Supply voltage (+12 V)

Supply voltage (-12V)

18 RY2 Second receiver output

19 RY1 First receiver output

20 V

CC

Supply voltage (+5 V)

Doc ID 6228 Rev 18 3/22

Maximum ratings ST75185C

2 Maximum ratings

Table 3. Absolute maximum ratings over operating free-air temperature range

Symbol Parameter Value Unit

(1)

(1)

(1)

15 V

-15 V

10 V

T

V

V

V

V

V

V

I

P

T

STG

T

DD

SS

CC

O

O

D

A

L

Supply voltage

Supply voltage

Supply voltage

Input voltage range (Driver) -15 to 7 V

I

Input voltage range (Receiver) -30 to 30 V

I

Output voltage range (Driver) -15 to 15 V

Receiver low level output current 20 mA

Continuous total power dissipation See dissipation rating table

Operating free-air temperature range 0 to 70 °C

Storage temperature range -65 to + 150 °C

Lead temperature 1.6 mm. from case for 10 sec. 260 °C

1. All voltage are with respect to the network ground terminal.

Note: Absolute maximum ratings are those values beyond which damage to the device may occur.

Functional operation under these condition is not implied.

Table 4. Dissipation rating table

MICROPACKAGE (D) 1125 mW 9.0 mW/°C 720 mW

Package

Power rating

≤ 25°C

at T

A

Derating factor

above TA = 25°C

Power rating

at TA ≤ 70°C

Table 5. Thermal data

Symbol Parameter TSSOP20 Unit

R

thJC

R

thJA

1. This value is referred to single-layer PCB, JEDEC standard test board.

Thermal resistance junction-case 27.22 °C/W

Thermal resistance junction-ambient 114.5

(1)

°C/W

4/22 Doc ID 6228 Rev 18

ST75185C Maximum ratings

Table 6. Recommended operating conditions

Symbol Parameter Min. Max. Unit.

DD

SS

CC

Supply voltage 7.5 15 V

Supply voltage -7.5 -15 V

Supply voltage 4.5 5.5 V

Driver input voltage 0 V

I

CC

V

V

V

V

Driver -6

I

OH

High level output current

Receiver -0.5

Driver 6

I

OL

T

Low level output current

Receiver 16

Operating free-air temperature range 0 70 °C

A

V

mA

mA

Doc ID 6228 Rev 18 5/22

Electrical characteristics ST75185C

3 Electrical characteristics

Table 7. Supply currents

Test conditions Value

Symbol Parameter

I

Supply current from V

DD

DD

V

DD

V

SS

9-9

No load.

Min. Typ. Max.

all inputs at

15 -15 25

9-9

1.9V

No load.

all inputs at

15 -15 9

0.8V

15

4.5

Unit

mA12 -12 19

mA12 -12 5.5

9-9

No load.

all inputs at

I

Supply current from V

SS

SS

9-9

15 -15 -25

1.9V

No load.

all inputs at

15 -15 -3.2

I

Supply current from V

CC

CC

No load. All inputs at 5V

VCC = 5V

0.8V

-15

mA12 -12 -19

-3.2

mA12 -12 -3.2

30 mA

6/22 Doc ID 6228 Rev 18

ST75185C Electrical characteristics

VDD = 9 V, VSS = -9 V, VCC = 5 V, unless otherwise specified.

Table 8. Driver electrical characteristics over operating free-air temperature range

Symbol Parameter Test conditions

V

OH

High level output voltage

= 0.8 V, RL = 3kΩ

V

IL

(See Figure 3)

Val ue

Unit

Min. Typ. Max.

67.5 V

V

OL

I

IH

I

IL

I

OS(H)

I

OS(L)

R

Low level output voltage
(Note 3)

High level input current VI = 5 V (See Figure 4)10µA

Low level input current VI = 0 V (See Figure 4) −1.6 mA

High level short circuit
output current (Note 4)

Low level short circuit output
current

Output resistance

O

VIH = 1.9 V, RL = 3kΩ
(See Figure 3)

VIL = 0.8 V, VO = 0 V
(See Figure 3)

VIH = 2 V VO = 0 V
(See Figure 3)

= VSS = VCC = 0 V

V

DD

= -2 to 2 V (Note 3)

V

O

-7.5 -6 V

-4.5 −12 −19.5 mA

4.5 12 19.5 mA

300 Ω

Note: 1 The algebraic convention, where the more positive (less negative) limits designated as

maximum, is used in this datasheet for logic levels only (e.g. if - 10 V is a maximum, the
typical value is a more negative voltage).

2 Output short circuit conditions must maintain the total power dissipation below absolute

maximum ratings.

3 Test conditions are those specified by EIA-232-E and as listed above.

V

= 12 V, VSS = -12 V, VCC = 5 V, TA = 25 °C

DD

Table 9. Driver switching characteristics

Symbol Parameter Test conditions

Val ue

Min. Typ. Max.

Unit

t

PLH

t

PHL

t

TLH

t

THL

Propagation Delay Time, Low to
High Level Output

Propagation Delay Time, High to
Low Level Output

Transition Time Low to High Level
Output

Transition Time High to Low Level
Output

RL = 3 to 7 kΩ CL = 15 pF
(See Figure 5, Figure 6)

RL = 3 to 7 kΩ CL = 15 pF
(See Figure 5, Figure 6)

= 3 to 7 kΩ CL = 15 pF

R

L

(See Figure 5, Figure 6)

= 3 to 7 kΩ CL = 2500 pF

R

L

(Note 4, Figure 5, Figure 6)

= 3 to 7 kΩ CL = 15 pF

R

L

(See Figure 5, Figure 6)

R

= 3 to 7 kΩ CL = 2500 pF

L

(Note 4, Figure 5, Figure 6)

315 500 ns

75 175 ns

60 100 ns

1.7 2.5 µs

40 7.5 ns

1.5 2.5 µs

4 Measured between -3 V and 3 V points of output waveform (EIA-232-E conditions), all

unused inputs are tied.

Doc ID 6228 Rev 18 7/22