Datasheet ST491ACN, ST491ACDR, ST491ACD, ST491ABN, ST491ABD Datasheet (SGS Thomson Microelectronics)

ST491A

LOW POWER HIGH SPEED RS-485/RS-422 TRANSCEIVER

■ LOW SUPPLY CURRENT: 5mA MAX

■ DESIGNED FOR RS485 INTERFACE

APPLICATIONS

■ -7 TO 12 COMMON MODE INPUT VOLTAGE

RANGE

■ 70mV TYPICAL INPUT HYSTERESIS

■ DESIGNED FOR 25Mbps OPERATION

■ OPERATE FROM SINGLE 5 SUPPLY

■ ±4kV ESD PROTECTION

■ CURRENT LIMITING AND T HER MAL

SHUTDOWN FOR DRIVER OVERLOAD
PROTECTION

DESCRIPTION

The ST491A is a low power transceiver for
RS-485 and RS-422 communications. The device
contains one driver and one receiver in full duplex
configuration. The ST491A draws 5mA (typ.) of
supply current when unloaded a nd operates from
a single 5V supply.

Driver is short-circuit current limited and is
protected against ex cessive power dissipation by
thermal shutdown circuitry that place the driver
outputs into a high-impedance state. The receiver
input has a fail-safe feature that guarantees a
logic high out put if both inputs are open circuit.

DIP SOP

ORDERING CODES

Type

ST491ACN 0 to 70 °C DIP-14 25parts per tube /40tube per box
ST491ABN -40 to 85 °C DIP-14 25parts per tube / 40tube per box
ST491ACD 0 to 70 °C SO-14 (Tube) 50parts per tube / 20tube per box

ST491ABD -40 to 85 °C SO-14 (Tube) 50parts per tube / 20tube per box
ST491ACDR 0 to 70 °C SO-14 (Tape & Reel) 2500 parts per reel
ST491ABDR -40 to 85 °C SO-14 (Tape & Reel) 2500 parts per reel

Temperature

Range

Package Comments

1/12July 2003

ST491A

PIN CONFIGURA TION

PIN DESCRIPTION

PlN N° SYMBOL NAME AND FUNCTION

1 NC Not Connected
2 RO Receiver Output.
3 RE Receiver Output Enable
4 DE Driver Output Enable
5 DI Inverting Driver Input.
6 GND Ground
7 GND Ground
8 NC Not Connected

9 Y Non-inverting Driver Output
10 Z Inverting Driver Output
11 B Inverting Receiver Input
12 A Non-inverting Receiver Input
13 NC Not Connected
14

V

CC

Supply Voltage

TRUTH TABLE (DRIVER)

INPUT OUTPUTS

DI DE Y Z

LHLH
HHHL
XLZZ

X= Don’t Care; Z=High Impedance

2/12

TRUTH TABLE (RECEIVER)

INPUT OUTPUT

A-B RE RO

≥ -0.2V L H

between -0.2V to 0.2V L ?

≤ -0.2V L L

OPEN L H

XHZ

?= Irrelevant; X= Don’t Care; Z=High Impedance

ST491A

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

V

V

Y,VZ

V

A,VB

V

RO

ESD Human Body Model 3.5 KV

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is
not implied.

ELECTRICAL CHARACTERISTICS

V

=4.5Vto5.5V,TA=-40to85°C, unless otherwise specified.TypicalvaluesarereferredtoTA=25°C)

CC

Symbol Parameter Test Conditions Min. Typ. Max. Unit

I

SUPPLY

C

IN

C

YZ

C

OUT

Supply Voltage

CC

Driver Input Voltage

DI

Driver Output Voltage
Receiver Input Voltage

7V

-0.5 to 7 V

-7.5 to 12.5 V

-7.5 to 12.5 V

Receiver Output Voltage -0.3 to (VCC+ 0.3)

No Load Supply Current 2 5 mA
Input Capacitance 1.8 pF
Driver Output Capacitance 1.2 pF
Output Capacitance 2.3 pF

V

TRANSMITTER ELECTRICAL CHARACTERISTICS

V

=4.5Vto5.5V,TA= -40 to 85°C,unless oth erwise specified. Typical v alues arereferred to Ta= 25°C)

CC

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

V

V

∆V

V

∆V

I

I

OSD

V

Differential Drive Output

OD1

(No load)
Differential Drive Output

OD2

(With Load)
Differential Drive Output

OD3

(With Load)
Change in magnitude of

OD

Driver Differential Output

RL=54Ω(RS-422) (Figure 1) 1.5 2.6 5 V

RL= 100Ω (RS-422) (Figure 1) 2 3 V

=54Ωor 100Ω (Figure 1) 0 0.2 V

R

L

Voltage for Complementary
Output States (Note1)

Driver Common Mode

OC

Output Voltage
Change in magnitude of

OC

Driver Common Mode

RL=54Ω(Figure 1) 1 3 V

=54Ω(Figure 1) 0 0.2 V

R

L

Output Voltage (Note1)
Power Off Output Current VCC=0V VO=-7V to 12V ± 100 µA

OFF

Driver Short Circuit Output

VO=-7V to 12V ± 35 ± 250 mA

Current

V

Input Logic Threshold Low 0.8 V

IL

Input Logic Threshold High 2 V

IH

V

CC

V

3/12

ST491A

RECEIVER ELECTRICAL CHARACTERISTICS

V

=4.5Vto5.5V,TA= -40 to 85°C,unless oth erwise specified. Typical v alues arereferred to Ta= 25°C)

CC

Symbol Parameter Test Conditions Min. Typ. Max. Unit

I

Input Current (A, B) other input=0V

V

∆V

V

V

R

IN

Receiver Differential

TH

Threshold Voltage
Receiver Input Hysteresis VCM=0V 70 mV

TH

Receiver Output High

OH

Voltage
Receiver Output Low

OL

Voltage
Receiver Input Resistance VCM= -7V to 12V 12 24 KΩ

RIN

= 0 or 5.25V

V

CC

VCM= -7V to 12V -0.2 0.2 V

I

= -8mA, VID= 200mV 3.5 4.7 V

OUT

I

= 8mA, VID= -200mV 0.3 0.5 V

OUT

DRIVER SWITCHING CHARACTERISTICS

=4.5Vto5.5V,TA=-40to 85°C, unlessotherwise specified. Typicalvalues are referred toTa=25°C)

V

CC

Symbol Parameter Test Conditions Min. Typ. Max. Unit

Maximum Data Rate Jitter <5% 25 50 Mbps

D

R

t

PLH

t

PHL

t

SKEW

t

TLH

t

THL

t

PZL

t

PZH

t

PHZ

t

PLZ

Propagation Delay Input to
Output

Differential Output Delay
Skew

Rise or Fall Differential
Time

Output Enable Time CL= 50pF S1 Closed 14 25 ns
Output Enable Time CL= 50pF S2 Closed 14 25 ns
Output Disable Time CL= 15pF S2 Closed 10 25 ns
Output Disable Time CL= 15pF S1 Closed 16 25 ns

RL=54Ω CL1=CL2=50pF, (Figure 1) 10 16 ns

RL=54Ω CL1=CL2=50pF, (Figure 1) 1 3 ns

RL=54Ω CL1=CL2=50pF, (Figure 1) 8 12 ns

V

=12V 0.5 1 mA

IN

=-7V -0.35 -0.8 mA

V

IN

RECEIVER SWITCHING CHARACTERISTICS

=4.5Vto5.5V,TA=-40to85°C, unless otherwisespecified.Typicalvalues are ref erred toTa=25°C)

V

CC

Symbol Parameter Test Conditions Min. Typ. Max. Unit

Propagation Delay Input to

t

PLH

Output

t

PHL

t

SKD|tPLH -tPHL

Skew

t
t

t
t

Rise or Fall Time CL= 15pF (Figures 2,4) 6 ns

TLH
THL

Output Enable Time CRL= 15pF S1 Closed 6 12 ns

t

PZL

Output Enable Time CRL= 15pF S2 Closed 7 12 ns

PZH

Output Disable Time CRL= 15pF S2 Closed 6 12 ns

PHZ

Output Disable Time CRL= 15pF S1 Closed 6 12 ns

t

PLZ

4/12

| Receiver Output

CL= 15pF (Figures 2,4) 19 30 ns

CL= 15pF (Figures 2,4) 1 3 ns

TEST CIRCUITS AND TYPICAL CHARA CTERISTICS
Figure1 : Driver DC Test Load

Figure2 : Receiver Timing Test Load

ST491A

Figure3 : Driver/Receiver Timing Test Circuit

5/12

ST491A

Figure4 : Driver Timing Test Load

Figure5 : Driver Propagation Delay

6/12

Figure6 : Receiver Propagation Delay

ST491A

Figure7 : Receiver Output Current vs Output

Voltage (Output Low)

Figure8 : Receiver Output Current vs Output
Voltage (Outpu t High)

Figure9 : Driver Diff. Output Voltage vs Common
Mode Voltage (Diff. Output Low)

Figure10 : Driver Diff. Output Voltage vs
Common Mode Voltage (Diff. Output High)

7/12

ST491A

Figure11 : Driver Short Circuit Current vs Line

Voltage (Outpu t High)

Figure12 : Driver Short Circuit Current vs. Li ne
Voltage (Output Low)

Figure13 : Receiver Input Current vs Input
Voltage

8/12

Plastic DIP-14 MECHANICAL DATA

mm. inch

DIM.

MIN. TYP MAX. MIN. TYP. MAX.

a1 0.51 0.020

B 1.39 1.65 0.055 0.065

b 0.5 0.020

b1 0.25 0.010

D 20 0.787
E 8.5 0.335

e 2.54 0.100

e3 15.24 0.600

F 7.1 0.280

ST491A

I 5.1 0.201

L 3.3 0.130

Z 1.27 2.54 0.050 0.100

P001A

9/12

ST491A

SO-14 MECHANICAL DATA

DIM.

A 1.75 0.068
a1 0.1 0.2 0.003 0.007
a2 1.65 0.064

b 0.35 0.46 0.013 0.018

b1 0.19 0.25 0.007 0.010

C 0.5 0.019
c1 45˚ (typ.)

D 8.55 8.75 0.336 0.344

E 5.8 6.2 0.228 0.244

e 1.27 0.050

e3 7.62 0.300

F 3.8 4.0 0.149 0.157

G 4.6 5.3 0.181 0.208

L 0.5 1.27 0.019 0.050
M 0.68 0.026
S ˚ (max.)

MIN. TYP MAX. MIN. TYP. MAX.

mm. inch

8

10/12

PO13G

ST491A

Tape & Reel SO-14 MECHANICAL DATA

mm. inch

DIM.

MIN. TYP MAX. MIN. TYP. MAX.

A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 60 2.362
T 22.4 0.882

Ao 6.4 6.6 0.252 0.260
Bo 9 9.2 0.354 0.362
Ko 2.1 2.3 0.082 0.090
Po 3.9 4.1 0.153 0.161

P 7.9 8.1 0.311 0.319

11/12

ST491A

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use o f suc h inf ormat ion n or f or an y infr ingeme nt of paten ts or oth er ri gh ts of third part ies whic h may resul t f rom
its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of STMicroelectronics.

Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco

© The ST logo is a registered trademark of STMicroelectronics

© 2003 STMicroelectronics - Printed in Italy - All Rights Reserved

STMicroelectronics GROUP OF COMPANIES

Singapore - Spain - Sweden - Switzerland - United Kingdom - United States.

© http://www.st.com

12/12