STMICROELECTRONICS ST485AB

ST485AB
Very high speed
low power RS-485/RS-422 transceiver
Features
■
Low supply current: 5 mA max
■
High data rate > 30 Mbps
■
Designed for RS 485 interface applications
■
-7 to 12 common mode input voltage range
■
Driver maintains high impedance in 3-state or
with the power off
■
70mV typical input hysteresis
■
Operate from single 5 supply
■
±4 kV ESD protection
■
Current limiting and thermal shutdown for
driver overload protection
■
DIP-8
SO-8
The ST485A is designed for bi-directional data
communications or multipoint bus transmission
lines.
Latch-up free up to 500 mA
Description
The ST485A is a low power, high speed
transceiver for RS-485 and RS-422
communications. The device contains one driver
and one receiver in half duplex configuration. The
ST485A draws 3 mA (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 place the driver
outputs into a high-impedance state. The receiver
input has a fail-safe feature that guarantees a
logic high output if both inputs are open circuit.
Table 1.
Device summary
Order code
Temperature
range
Package
Packaging
ST485ABN
-40 to 85 °C
DIP-8
50parts per tube / 40tube per box
ST485ABDR
-40 to 85 °C
SO-8 (Tape & reel)
2500 parts per reel
August 2007
Rev. 3
1/19
www.st.com
19
Contents
ST485AB
Contents
1
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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
ST485AB
Pin configuration
1
Pin configuration
Figure 1.
Pin configuration
Table 2.
Pin description
Pin n°
Symbol
Name and function
1
RO
Receiver output. If A>B by 200 mV, RO will be high; if A<B by 200 mV, RO will be low
2
RE
Receiver output enable. RO is enabled when RE is low; RO is high impedance when RE is
high. If RE is high and DE is low, the device will enter a low power shutdown mode.
3
DE
Driver output enable. The driver outputs are enabled by bringing DE high. They are high
impedance when DE is low. If RE is high DE is low, the device will enter a low-power shutdown
mode. If the driver outputs are enabled, the part functions as line driver, while they are high
impedance, it functions as line receivers if RE is low.
4
DI
Driver input. A low on DI forces output A low and output B high. Similarly, a high on DI forces
output A high and output B low
5
GND
6
A
Non-inverting receiver input and non-inverting driver output
7
B
Inverting receiver input and inverting driver output
8
VCC
Ground
Supply voltage: VCC= 4.75 V to 5.25 V
3/19
Truth tables
ST485AB
2
Truth tables
Table 3.
Truth table (driver)
Inputs
Outputs
Mode
RE
DE
DI
B
A
A
X
H
H
L
H
Normal
X
H
L
H
L
Normal
L
L
X
Z
Z
Normal
Note:
X = Don’t care; Z = High impedance
Table 4.
Truth table (receiver)
Inputs
Outputs
Mode
Note:
4/19
RE
DE
A-B
L
L
≥
L
L
≤-0.2
L
L
-0.2 V
V
Inputs open
X = Don’t care; Z = High impedance
RO
H
Normal
L
Normal
H
Normal
ST485AB
Maximum ratings
3
Maximum ratings
Table 5.
Absolute maximum ratings
Symbol
VCC
Parameter
Supply voltage
Value
Unit
7
V
VI
Control input voltage (RE, DE)
-0.3 to 7
V
VDI
Driver input voltage (DI)
-0.3 to 7
V
VDO
Driver output voltage (A, B)
-7.5 to 12.5
V
VRI
Receiver input voltage (A, B)
-7.5 to 12.5
V
VRO
Receiver output voltage (RO)
-0.3 to (VCC + 0.3)
V
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
ST485AB
4
Electrical characteristics
Table 6.
DC electrical characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85°C, unless otherwise
specified. Typical values are referred to TA = 25°C, VCC = 5 V) (Note: 1)
Symbol
Parameter
ISUPPLY VCC Power supply current
Test conditions
No load, VRE=0 V or VCC
Min.
Typ.
Max.
Unit
VDE = VCC
2.3
5
mA
VDE = 0 V
2.6
5
mA
CI/O
Input/output capacitance
10
pF
CAB
Driver output capacity
10
pF
Table 7.
Symbol
Logic input electrical characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85°C, unless
otherwise specified. Typical values are referred to TA = 25°C, VCC = 5 V) (Note: 1)
Parameter
Test conditions
VIL
Input logic threshold low
DE, DI, RE
VIH
Input logic threshold high
DE, DI, RE
IIN1
Logic input current
DE, DI, RE
IIN2
Input current (A, B)
VDE=0 V,
VCC= 0 or 5.25 V
Table 8.
Symbol
Typ.
Max.
Unit
0.8
V
2
V
± 2.0
µA
VIN=12 V
1
mA
VIN=-7 V
-0.8
mA
Transmitter electrical characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85°C, unless
otherwise specified. Typical values are referred to TA = 25°C, VCC = 5 V) (Note: 1)
Parameter
Test conditions
VOD1
Differential driver output (No load)
VOD2
Differential driver output (with load)
RL= 54 Ω (RS-422)
VCM= -7 V to 12 V
ΔVOD
Change in magnitude of driver
differential output voltage for
complementary output states
(Note: 1)
RL= 27 Ω or 50 Ω
VOC
Driver common mode output
voltage
RL= 27 Ω or 50 Ω
ΔVOC
Change in magnitude of driver
common mode output voltage
(Note: 1)
RL= 54 Ω or 100 Ω
IOSD
Driver short circuit output current
VO= -7 V to 12 V
6/19
Min.
Min.
1.5
Typ.
Max.
Unit
5
V
2.7
5
V
0
0.2
V
3
V
0.2
V
± 250
mA
1
0
ST485AB
Table 9.
Symbol
Electrical characteristics
Receiver electrical characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85°C, unless
otherwise specified. Typical values are referred to TA = 25°C, VCC = 5 V) (Note: 1)
Parameter
Test conditions
Min.
VTH
Receiver Differential Threshold
Voltage
VCM = -7 V to 12 V
ΔVTH
Receiver Input Hysteresis
VCM = 0 V
VOH
Receiver Output High Voltage
IOUT = -4 mA, VID = 200 mV
VOL
Receiver Output Low Voltage
IOUT = 4 mA, VID = -200 mV
IOZR
3-State (High Impedance) Output
Current at Receiver
VO = 0.4 V to 2.4 V
RRIN
Receiver Input Resistance
VCM = -7 V to 12 V
12
IOSR
Receiver Short-Circuit Current
VO = 0 V to VCC
7
Table 10.
Symbol
Typ.
-0.2
3.5
Max.
Unit
0.2
V
70
mV
4.7
V
0.2
0.4
V
±1
μA
24
KΩ
95
mA
Driver switching characteristics (VCC = 4.5 V to 5.5 V, TA = -40 to 85°C, unless otherwise
specified. Typical values are referred to TA = 25°C, VCC = 5 V) (See Note: 1, Note 3)
Parameter
Test conditions
Min.
Typ.
30
50
Max.
Unit
DR
Maximum data rate
Jitter < 5%
tPLH
tPHL
Propagation delay input to output
RL= 54 Ω, CL1=CL2=50 pF,
(Figure 8.)
18
30
ns
Differential output delay skew
RL= 54Ω, CL1=CL2=50 pF,
(Figure 6.)
0.5
2
ns
tTLH
tTHL
Rise or fall differential time
RL= 54Ω, CL1=CL2=50 pF,
(Figure 6.)
8
12
ns
tPZL
Output enable time
CL= 50 pF, S1 Closed
30
ns
tPZH
Output enable time
CL= 50 pF, S2 Closed
30
ns
tPHZ
Output disable time
CL= 15 pF, S2 Closed
30
ns
tPLZ
Output disable time
CL= 15 pF, S1 Closed
30
ns
2
ns
6
ns
tSKEW
tSK(EN)
Synchronous driver operation a-b at
enable
tSK(DS)
Synchronous driver operation A-B
at disable
4
Mbps
7/19
Electrical characteristics
Table 11.
Symbol
Driver switching characteristics (VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise
specified. Typical values are referred to TA = 25°C, VCC = 5V) (See Note: 1, Note 3)
Parameter
tPLH
tPHL
Typ.
Max.
Unit
CL = 15 pF
18
30
ns
|tPLH - tPHL| Propagation delay skew CL = 15 pF
0.5
2
ns
Propagation Delay
tRPDS
ST485AB
Test conditions
Min.
tPZL
Output enable time
CRL = 15 pF, S1 Closed
7
12
ns
tPZH
Output enable time
CRL = 15 pF, S2 Closed
7
12
ns
tPHZ
Output disable time
CRL = 15 pF, S2 Closed
7
12
ns
tPLZ
Output disable time
CRL = 15 pF, S1 Closed
7
12
ns
Note:
8/19
1
All currents into device pins are positive; all currents out of device pins are negative; all
voltages are referenced to device ground unless specified.
2
Applies to peak current. See typical Operating Characteristics.
3
tr=tf ≤6 ms.
ST485AB
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.
Driver/receiver timing test circuit
9/19
Test circuit and typical characteristics
Figure 5.
Driver timing test load
Figure 6.
Driver timing test load
10/19
ST485AB
ST485AB
Test circuit and typical characteristics
Figure 7.
Driver enable and disable time
Figure 8.
Receiver propagation delay
11/19
Test circuit and typical characteristics
Figure 9.
Receiver enable and disable time
Figure 10. Receiver output current vs. output
voltage (output low)
12/19
ST485AB
Figure 11. Receiver output current vs. output
voltage (output high)
ST485AB
Test circuit and typical characteristics
Figure 12. Driver diff. output voltage vs
Figure 13. Driver diff. output voltage vs
common mode voltage (diff. output
common mode voltage (diff. output
low)
low)
Figure 14. Driver short circuit current vs line
voltage (output high)
Figure 15. Driver short circuit current vs. line
voltage (output low)
Figure 16. Receiver input current vs input
voltage
13/19
Package mechanical data
6
ST485AB
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a Lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
14/19
ST485AB
Package mechanical data
Plastic DIP-8 mechanical data
mm.
inch.
Dim.
Min.
A
Typ.
Max.
Min.
3.3
Typ.
Max.
0.130
a1
0.7
B
1.39
1.65
0.055
0.065
B1
0.91
1.04
0.036
0.041
b
b1
0.028
0.5
0.38
0.020
0.5
D
0.015
0.020
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
I
4.8
0.189
L
Z
3.3
0.44
0.130
1.6
0.017
0.063
P001F
15/19
Package mechanical data
ST485AB
SO-8 mechanical data
Dim.
mm.
Min.
Typ.
inch.
Max.
Min.
Typ.
Max.
A
1.35
1.75
0.053
0.069
A1
0.10
0.25
0.04
0.010
A2
1.10
1.65
0.043
0.065
B
0.33
0.51
0.013
0.020
C
0.19
0.25
0.007
0.010
D
4.80
5.00
0.189
0.197
E
3.80
4.00
0.150
0.157
e
1.27
0.050
H
5.80
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
ddd
8° (max.)
0.1
0.04
0016023/C
16/19
ST485AB
Package mechanical data
Tape & reel SO-8 mechanical data
mm.
inch.
Dim.
Min.
A
Typ.
Max.
Min.
330
Max.
12.992
C
12.8
D
20.2
0.795
N
60
2.362
T
13.2
Typ.
0.504
22.4
0.519
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
P
7.9
8.1
0.311
0.319
17/19
Revision history
ST485AB
7
Revision history
Table 12.
Revision history
Date
Revision
28-Mar-2006
2
Order codes updated and new template.
24-Aug-2007
3
Added Table 1. in cover page.
18/19
Changes
ST485AB
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