Datasheet ST485ERB Datasheet (ST)

Features

■ Low quiescent current: 300 µA

■ Designed for RS-485 interface application

■ - 7 V to 12 V common mode input voltage range

■ Driver maintains high impedance in 3-state or

with the power OFF

■ 70 mV typical input hysteresis

■ 30 ns propagation delay, 5 ns skew

■ Operate from a single 5 V supply

■ Current limiting and thermal shutdown for

driver overload protection

■ ESD protection:

– ± 15 kV (HBM)
– ± 8 kV (IEC-1000-4-2 contact discharge)

■ Allows up to 256 transceivers on the bus

ST485ERB

±15 kV ESD protected, low power

RS-485/RS-422 transceiver

DIP-8 SO-8

The ST485ERB is designed for bi-directional data
communications on multipoint bus transmission
line (half-duplex applications).

Description

The ST485ERB is al low power transceiver for
RS-485 and RS-422 communication. Each driver
output and receiver input is protected against ±15
kV electrostatic discharge (HBM) ± 8 kV (IEC­1000-4-2 contact discharge) shocks, without
latch-up. These parts contain one driver and one
receiver.

This transceiver draws 300 µA (typ.) of supply
current when unloaded or fully loaded with
disabled drivers.

It operates from a single 5 V supply.

Driver is short-circuit current limited and is
protected against excessive power dissipation by
thermal shutdown circuitry that places the driver
outputs into a high-impedance state.

Table 1. Device summary

Order code Temperature range Package Packaging

ST485ERBN - 40 to 85 °C DIP-8 50 parts per tube / 40 tube per box

ST485ERBDR - 40 to 85 °C SO-8 (tape and reel) 2500 parts per reel

February 2009 Rev 7 1/19

www.st.com

19

Contents ST485ERB

Contents

1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Test circuit and typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2/19

ST485ERB Pin settings

1 Pin settings

Figure 1. Pin configuration

Table 2. Pin description

Pin n° Symbol Name and function

1 RO Receiver output

2REReceiver output enable

3 DE Driver output enable

4 DI Driver input

5 GND Ground

6 A Non-inverting receiver input and non-inverting driver output

7 B Inverting receiver input and inverting driver output

8V

CC

Supply voltage

3/19

Truth tables ST485ERB

2 Truth tables

Table 3. Truth table (driver)

Inputs Outputs

RE

XHHLH

XHLHL

XLXZZ

DE DI B A

Note: X = Don’t care; Z = High impedance

Table 4. Truth table (receiver)

Inputs Outputs

RE

LL

LL

L L Inputs open H

HLX Z

DE A-B RO

Note: X = Don’t care; Z = High impedance

≥ +0.2V H

≤ -0.2V L

4/19

ST485ERB Maximum ratings

3 Maximum ratings

Table 5. Absolute maximum ratings

Symbol Parameter Value Unit

V

V

V

V

V

Supply voltage 7 V

CC

V

Control input voltage (RE, DE) -0.5 to (VCC + 0.5) V

I

Driver input voltage (DI) -0.5 to (VCC + 0.5) V

DI

Driver output voltage (A, B) ± 14 V

DO

Receiver input voltage (A, B) ± 14 V

RI

Receiver output voltage (RO) -0.5 to (VCC + 0.5) V

RO

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

Functional operation under these condition is not implied.

5/19

Electrical characteristics ST485ERB

4 Electrical characteristics

Table 6. ESD performance: transmitter outputs, receiver inputs

Symbol Parameter Test conditions Min. Typ. Max. Unit

ESD ESD protection voltage Human body model ±15 kV

ESD ESD protection voltage IEC-1000-4-2 ±8kV

VCC = 5 V ± 5 %, TA = T
to T

= 25 °C

A

Table 7. DC electrical characteristics

MIN

to T

, unless otherwise specified. Typical values are referred

MAX

Symbol Parameter Test conditions

V

V

Differential driver output (no

OD1

load)

Differential driver output

OD2

(with load)

RL = 27Ω (RS-485) (Figure 2)

= 50Ω (RS-422) (Figure 2)

R

L

Change in magnitude of

ΔV

driver differential output

OD

voltage for complementary

= 27Ω or 50Ω (Figure 2)0.2V

R

L

output states

V

Driver common-mode

OC

output voltage

= 27Ω or 50Ω (Figure 2)3V

R

L

Change in magnitude of

ΔV

driver common-mode output

OC

voltage for complementary

= 27Ω or 50Ω (Figure 2)0.2V

R

L

output states

V

Input high voltage RE, DE, DI 2.0 V

IH

V

Input low voltage RE, DE, DI 0.8 V

IL

I

I

V

ΔV

V

V

I

R

Input current RE, DE, DI ± 2µA

IN1

V

= 0V or 5.25V, VDE = 0V

Input current (A, B)

IN2

Receiver differential

TH

threshold voltage

Receiver input hysteresis VCM = 0V 70 mV

TH

Receiver output high

OH

voltage

Receiver output low voltage IO = 4mA, VID = -200mV 0.4 V

OL

3-State (high impedance)

OZR

output current at receiver

Receiver input resistance VCM = -7 to 12V 24 kΩ

IN

CM

= 12V

V

IN

V

= -7V

IN

= -7 to 12V -0.2 0.2 V

V

CM

= -4mA, VID = 200mV 3.5 V

I

O

= 0.4 to 2.4V ± 1µA

V

O

(1)

Min. Typ. Max. Unit

5V

5

1.5

V

5

V

1

-0.8mAmA

6/19

ST485ERB Electrical characteristics

Table 7. DC electrical characteristics (continued)

Symbol Parameter Test conditions

(1)

Min. Typ. Max. Unit

VRE = 0V or V

I

No load supply current

CC

(2)

VDE = V
VDE = 0V

I

OSD1

I

OSD2

I

1. All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are

2. Supply current specification is valid for loaded transmitters when V

3. Applies to peak current. See typical Operating Characteristics.

(VCC = 5 V ± 5 %, TA = T
to T

Table 8. Driver switching characteristics

Driver short-circuit current,

=High

V

O

Driver short-circuit current,
VO=Low

Receiver short-circuit

OSR

current

referenced to device ground unless specified.

to T

= 25 °C)

A

MIN

V

= -7 to 12V

O

= -7 to 12V

V

O

= 0V to V

V

O

, unless otherwise specified. Typical values are referred

MAX

Symbol Parameter Test conditions

t
t

t
t

t

PLH

t

TLH

THL

PZH

Propagation delay input to
output

PHL

Output skew to output

SK

Rise or fall time

Output enable time

R

= 54Ω, CL1 = CL2 = 100pF

DIFF

(see Figure 4 and Figure 6)

R

= 54Ω, CL1 = CL2 = 100pF

DIFF

(see Figure 4 and Figure 6)

= 54Ω, CL1 = CL2 = 100pF

R

DIFF

(see Figure 4 and Figure 6)

= 100pF, S2 = Closed

C

L

(see Figure 5 and Figure 7)

CC

CC

CC

(3)

(3)

DE

(1)

= 0 V

400

900

300

500µAµA

35 250 mA

35 250 mA

795mA

Min. Typ. Max. Unit

10 30 60 ns

510ns

31540ns

70 90 ns

C

= 100pF, S1 = Closed

t

t

t

PHZ

C

1. All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are
referenced to device ground unless specified.

Output enable time

PZL

Output disable time

PLZ

Output disable time

Output AB capacitance 43 pF

AB

L

(see Figure 5 and Figure 7)

= 15pF, S1 = Closed

C

L

(see Figure 5 and Figure 7)

= 15pF, S2 = Closed

C

L

(see Figure 5 and Figure 7)

70 90 ns

70 90 ns

70 90 ns

7/19

Electrical characteristics ST485ERB

(VCC = 5 V ± 5 %, TA = T
to T

= 25 °C)

A

Table 9. Receiver switching characteristics

Symbol Parameter Test conditions

t

PLH

t

PHL

t

SKD

t

PZH

t

PZL

t

PLZ

t

PHZ

f

MAX

1. All currents into device pins are positive; all cuttents out of device pins are negative; all voltages are
referenced to device ground unless specified

Propagation delay input
to output

Differential receiver
skew

Output enable time

Output enable time

Output disable time

Output disable time

Maximum data rate 2.5 Mbps

MIN

to T

, unless otherwise specified. Typical values are referred

MAX

(1)

R

= 54Ω,CL1 = CL2 = 100pF

DIFF

(see Figure 4 and Figure 8)

R

= 54Ω, CL1 = CL2 = 100pF

DIFF

(see Figure 4 and Figure 8)

= 15pF, S1 = Closed (see

C

RL

Figure 2 and Figure 9)

= 15pF, S2 = Closed

C

RL

(see Figure 2 and Figure 9)

C

= 15pF, S1 = Closed

RL

(see Figure 2 and Figure 9)

= 15pF, S2 = Closed

C

RL

(see Figure 2 and Figure 9)

Min. Typ. Max. Unit

20 130 210 ns

13 ns

20 50 ns

20 50 ns

20 50 ns

20 50 ns

8/19

ST485ERB Test circuit and typical characteristics

5 Test circuit and typical characteristics

Figure 2. Driver DC test load Figure 3. Receiver timing test load

Figure 4. Drive/receiver timing test

circuit

Figure 5. Driver timing test load

9/19

Test circuit and typical characteristics ST485ERB

Figure 6. Driver propagation delay

Figure 7. Driver enable and disable time

10/19

ST485ERB Test circuit and typical characteristics

Figure 8. Receiver propagation delay

Figure 9. Receiver enable and disable time

11/19

Test circuit and typical characteristics ST485ERB

Figure 10. Receiver output current vs. output

low voltage

Figure 12. Driver output current vs. output low

voltage

Figure 11. Receiver output current vs. output

high voltage

Figure 13. Driver output current vs. output

high voltage

Figure 14. Supply current vs. temperature Figure 15. Receiver high level output voltage

12/19

vs. temperature

ST485ERB Test circuit and typical characteristics

Figure 16. Receiver low level output voltage

vs. temperature

Figure 17. Differential driver output voltage vs.

temperature

13/19

Package mechanical data ST485ERB

6 Package mechanical data

In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK
specifications, grade definitions and product status are available at: www.st.com. ECOPACK
is an ST trademark.

®

packages, depending on their level of environmental compliance. ECOPACK®

14/19

ST485ERB Package mechanical data

Plastic DIP-8 mechanical data

Dim.

Min. Typ. Max. Min. Typ. Max.

A 3.3 0.130

a1 0.7 0.028

B1.39 1.65 0.055 0.065

B1 0.91 1.04 0.036 0.041

b 0.5 0.020

b10.38 0.5 0.015 0.020

D 9.8 0.386

E 8.8 0.346

e 2.54 0.100

e3 7.62 0.300

e4 7.62 0.300

F 7.1 0.280

I4.8 0.189

L 3.3 0.130

Z 0.44 1.6 0.017 0.063

mm. inch.

P001F

15/19

Package mechanical data ST485ERB

SO-8 mechanical data

Dim.

A1.35 1.75 0.053 0.069

A1 0.10 0.25 0.04 0.010

A2 1.10 1.65 0.043 0.065

B0.33 0.51 0.013 0.020

C0.19 0.25 0.007 0.010

D4.80 5.00 0.189 0.197

E 3.80 4.00 0.150 0.157

e 1.27 0.050

H5.80 6.20 0.228 0.244

h 0.25 0.50 0.010 0.020

L 0.40 1.27 0.016 0.050

k 8° (max.)

ddd 0.1 0.04

Min. Typ. Max. Min. Typ. Max.

mm. inch.

16/19

0016023/C

ST485ERB Package mechanical data

Tape & reel SO-8 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

N60 2.362

T 22.4 0.882

Ao 8.1 8.5 0.319 0.335

Bo 5.5 5.9 0.216 0.232

Ko 2.1 2.3 0.082 0.090

Po 3.9 4.1 0.153 0.161

P7.98.1 0.311 0.319

17/19

Revision history ST485ERB

7 Revision history

Table 10. Document revision history

Date Revision Changes

21-Mar-2006 3 Order codes has been updated and new template.

01-Aug-2006 4 Mistake in cover page description 300 mA ==> 300 µA.

25-Oct-2006 5 Order codes updated.

02-Dec-2008 6 Modified: device name Table 1 on page 1.

16-Feb-2008 7 Modified Note: on page 5.

18/19

ST485ERB

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