1/13
September 2003
s
LOW QUIESCENT CURRENT: 300
A
s
DESIGNED FOR RS-485 INTERFACE
APPLICATIONS
s
-7V TO 12V COMMON MODE INPUT
VOLTAGE RANGE
s
DRIVER MAINTAINS HIGH IMPEDANCE IN
3-STATE OR WITH THE POWER OFF
s
70mV TYPICAL INPUT HYSTERESIS
s
30ns PROPAGATION DELAYS, 5ns SKEW
s
OPERATE FROM A SINGLE 5V SUPPLY
s
CURRENT LIMITING AND THERMAL
SHUTDOWN FOR DRIVER OVERLOAD
PROTECTION
s
ESD PROTECTION:
15KV (H.B.M.)
8KV (IEC-1000-4-2 CONTACT
DISCHARGE)
s
ALLOWS UP TO 64 TRANSCEIVERS ON
THE BUS
DESCRIPTION
The ST485E is al low power transceiver for
RS-485 and RS-422 communication. Each driver
output and receiver input is protected against
15KV electrostatic discharge (H.B.M.) (ESD)
shocks, without latcup. These parts contain one
driver
and
one
receiver
in
half
duplex
configuration.
This transceiver draw 300
A (typ.) of supply
current when unloaded or fully loaded with
disabled drivers.
It operates from a single 5V supply.
Driver is short-circuit current limited and is
protected against excessive power dissipation by
thermal shutdown circuitry that place the driver
outputs into a high-impedance state.
The ST485E is designed for bi-directional data
communications on multipoint bus transmission
line (half-duplex applications).
ORDERING CODES
Type
Temperature
Range
Package
Comments
ST485ECN
0 to 70 C
DIP-8
50parts per tube / 40tube per box
ST485EBN
-40 to 85 C
DIP-8
50parts per tube / 40tube per box
ST485EXN
-55 to 125 C
DIP-8
50parts per tube / 40tube per box
ST485ECD
0 to 70 C
SO-8 (Tube)
100parts per tube / 20tube per box
ST485EBD
-40 to 85 C
SO-8 (Tube)
100parts per tube / 20tube per box
ST485EXD
-55 to 125 C
SO-8 (Tube)
100parts per tube / 20tube per box
ST485ECDR
0 to 70 C
SO-8 (Tape & Reel)
2500 parts per reel
ST485EBDR
-40 to 85 C
SO-8 (Tape & Reel)
2500 parts per reel
ST485EXDR
-55 to 125 C
SO-8 (Tape & Reel)
2500 parts per reel
ST485E
15KV ESD PROTECTED, LOW POWER
RS-485/RS-422 TRANSCEIVER
DIP
SOP
ST485E
2/13
PIN CONFIGURATION
PIN DESCRIPTION
TRUTH TABLE (DRIVER)
X= Don't Care; Z=High Impedance
TRUTH TABLE (RECEIVER)
X= Don't Care; Z=High Impedance
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is
not implied.
PlN N
SYMBOL
NAME AND FUNCTION
1
RO
Receiver Output
2
RE
Receiver 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
8
V
CC
Supply Voltage
INPUTS
OUTPUTS
RE
DE
DI
B
A
X
H
H
L
H
X
H
L
H
L
X
L
X
Z
Z
INPUTS
OUTPUT
RE
DE
A-B
RO
L
L
+0.2V
H
L
L
-0.2V
L
L
L
INPUTS OPEN
H
H
L
X
Z
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
7
V
V
I
Control Input Voltage (RE, DE)
-0.5 to (V
CC
+ 0.5)
V
V
DI
Driver Input Voltage (DI)
-0.5 to (V
CC
+ 0.5)
V
V
DO
Driver Output Voltage (A, B)
14
V
V
RI
Receiver Input Voltage (A, B)
14
V
V
RO
Receiver Output Voltage (RO)
-0.5 to (V
CC
+ 0.5)
V
ST485E
3/13
ESD PERFORMANCE: TRANSMITTER OUTPUTS, RECEIVER INPUTS
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 5V
5%, T
A
= T
MIN
to T
MAX
, unless otherwise specified. Typical values are referred to T
A
= 25C)
(See Note 1)
Note 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.
Note 2: Supply current specification is valid for loaded transmitters when V
DE
= 0V
Note 3: Applies to peak current. See typical Operating Characteristics.
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
8
KV
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
V
OD1
Differential Driver Output
(No Load)
5
V
V
OD2
Differential Driver Output
(With Load)
R
L
= 27
(RS-485) (See Fig. 1)
R
L
= 50
(RS-422) (See Fig. 1)
1.5
5
5
V
V
V
OD
Change in Magnitude of
Driver Differential Output
Voltage for Complementary
Output States
R
L
= 27
or 50
(See Fig. 1)
0.2
V
V
OC
Driver Common-Mode
Output Voltage
R
L
= 27
or 50
(See Fig. 1)
3
V
V
OC
Change in Magnitude of
Driver Common-Mode
Output Voltage for
Complementary Output
States
R
L
= 27
or 50
(See Fig. 1)
0.2
V
V
IH
Input High Voltage
RE, DE, DI
2.0
V
V
IL
Input Low Voltage
RE, DE, DI
0.8
V
I
IN1
Input Current
RE, DE, DI
2
A
I
IN2
Input Current (A, B)
V
CM
= 0V or 5.25V
V
DE
= 0V
V
IN
= 12V
V
IN
= -7V
1
-0.8
mA
mA
V
TH
Receiver Differential
Threshold Voltage
V
CM
= -7 to 12V
-0.2
0.2
V
V
TH
Receiver Input Hysteresis
V
CM
= 0V
70
mV
V
OH
Receiver Output High
Voltage
I
O
= -4mA
V
ID
= 200mV
3.5
V
V
OL
Receiver Output Low
Voltage
I
O
= 4mA
V
ID
= -200mV
0.4
V
I
OZR
3-State (High Impedance)
Output Current at Receiver
V
O
= 0.4 to 2.4V
1
A
R
IN
Receiver Input Resistance
V
CM
= -7 to 12V
24
K
I
CC
No Load Supply Current
(Note 2)
V
RE
= 0V or V
CC
V
DE
= V
CC
V
DE
= 0V
400
300
900
500
A
A
I
OSD1
Driver Short-Circuit Current,
V
O
=High
V
O
= -7 to 12V (Note 3)
35
250
mA
I
OSD2
Driver Short-Circuit Current,
V
O
=Low
V
O
= -7 to 12V (Note 3)
35
250
mA
I
OSR
Receiver Short-Circuit
Current
V
O
= 0V to V
CC
7
95
mA
ST485E
4/13
DRIVER SWITCHING CHARACTERISTICS
(V
CC
= 5V
5%, T
A
= T
MIN
to T
MAX
, unless otherwise specified. Typical values are referred to T
A
= 25C)
(See Note 1)
Note 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.
RECEIVER SWITCHING CHARACTERISTICS
(V
CC
= 5V
5%, T
A
= T
MIN
to T
MAX
, unless otherwise specified. Typical values are referred to T
A
= 25C)
(See Note 1)
Note 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.
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
t
PLH
t
PHL
Propagation Delay Input to
Output
R
DIFF
= 54
C
L1
= C
L2
= 100pF
(See Fig. 3 and 5)
25
45
ns
t
SK
Output Skew to Output
R
DIFF
= 54
C
L1
= C
L2
= 100pF
(See Fig. 3 and 5)
2
5
ns
t
TLH
t
THL
Rise or Fall Time
R
DIFF
= 54
C
L1
= C
L2
= 100pF
(See Fig. 3 and 5)
15
40
ns
t
PZH
Output Enable Time
C
L
= 100pF
S2 = Closed
(See Fig. 4 and 6)
35
50
ns
t
PZL
Output Enable Time
C
L
= 100pF
S1 = Closed
(See Fig. 4 and 6)
25
40
ns
t
PLZ
Output Disable Time
C
L
= 15pF
S1 = Closed
(See Fig. 4 and 6)
25
40
ns
t
PHZ
Output Disable Time
C
L
= 15pF
S2 = Closed
(See Fig. 4 and 6)
35
50
ns
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
t
PLH
t
PHL
Propagation Delay Input to
Output
R
DIFF
= 54
C
L1
= C
L2
= 100pF
(See Fig. 3 and 7)
110
130
ns
t
SKD
Differential Receiver Skew
R
DIFF
= 54
C
L1
= C
L2
= 100pF
(See Fig. 3 and 7)
5
10
ns
t
PZH
Output Enable Time
C
RL
= 15pF
S2 = Closed
(See Fig. 2 and 8)
11
35
ns
t
PZL
Output Enable Time
C
RL
= 15pF
S1 = Closed
(See Fig. 2 and 8)
13
35
ns
t
PLZ
Output Disable Time
C
RL
= 15pF
S1 = Closed
(See Fig. 2 and 8)
13
35
ns
t
PHZ
Output Disable Time
C
RL
= 15pF
S2 = Closed
(See Fig. 2 and 8)
11
35
ns
f
MAX
Maximum Data Rate
5
Mbps
ST485E
5/13
TEST CIRCUITS AND TYPICAL CHARACTERISTICS
Figure 1 : Driver DC Test Load
Figure 2 : Receiver Timing Test Load
Figure 3 : Drive/Receiver Timing Test Circuit
Figure 4 : Driver Timing Test Load
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