STMICROELECTRONICS ST491ACN

ST491A
Low power high speed
RS-485/RS-422 transceiver
Features
■
Low supply current: 5mA max
■
Designed for RS485 interface applications
■
-7V to 12V common mode input voltage range
■
70mV typical input hysteresis
■
Designed for 25Mbps operation
■
Operate from a single 5V supply
■
±4kV ESD protection
■
Current limiting and thermal shutdown for
driver overload protection
DIP-14
Description
The ST491A is a low power transceiver for RS485 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 and 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 receiver
input has a fail-safe feature that guarantees a
logic high output if both inputs are open circuit.
Order code
Part number
Temperature range
Package
Packaging
ST491ACN
0 to 70 °C
DIP-14
25parts per tube / 40tube per box
May 2007
Rev 6
1/17
www.st.com
17
Contents
ST491A
Contents
1
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5
Test circuit and typical characteristics
6
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2/17
......................... 9
ST491A
Pin configuration
1
Pin configuration
Figure 1.
Pin connections
Table 1.
Pin description
Pin 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
9
Y
Non-inverting driver output
10
Z
Inverting driver output
11
A
Inverting receiver input
12
B
Non-inverting receiver input
13
VCC
Supply voltage
14
VCC
Supply voltage
Not connected
3/17
Truth tables
ST491A
2
Truth tables
Table 2.
Truth table (driver)
Inputs
Outputs
DI
DE
Y
Z
L
H
L
H
H
H
H
L
X
L
Z
Z
Note:
X = Don’t care; Z = High impedance
Table 3.
Truth table (receiver)
Inputs
Note:
4/17
Outputs
A-B
RE
RO
≥ -0.2V
L
H
between -0.2V to 0.2V
L
?
≤-0.2V
L
L
OPEN
L
H
X
H
Z
?=Irrelevant; X = Don’t care; Z = High impedance
ST491A
Maximum ratings
3
Maximum ratings
Table 4.
Absolute maximum ratings
Symbol
Parameter
VCC
Supply voltage
VDI
Driver input voltage
Value
Unit
7
V
-0.5 to 7
V
VY, VZ
Driver output voltage
-7.5 to 12.5
V
VA, VB
Receiver input voltage
-7.5 to 12.5
V
-0.3 to (VCC + 0.3)
V
3.5
KV
VRO
Receiver output voltage
ESD
Human body model
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.
5/17
Electrical characteristics
ST491A
4
Electrical characteristics
Table 5.
Electrical characteristics
(VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are
referred to TA=25°C)
Symbol
ISUPPLY
Parameter
Min.
No load supply current
Typ.
Max.
Unit
2
5
mA
CIN
Input capacitance
1.8
pF
CYZ
Driver output capacitance
1.2
pF
Output capacitance
2.3
pF
COUT
Table 6.
Transmitter electrical characteristics
(VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are
referred to TA=25°C)
Symbol
Parameter
VOD1
Differential drive output (no load)
VOD2
Differential drive output (with
load)
RL= 54Ω (RS-422) (Figure 1.)
1.5
2.6
VOD3
Differential drive output (with
load)
RL= 100Ω (RS-422) (Figure 1.)
2
3
ΔVOD
Change in magnitude of driver
differential output voltage for
complementary output states
RL= 54Ω or 100Ω (Figure 1.)
VOC
Driver common mode output
voltage
RL= 54Ω (Figure 1.)
ΔVOC
Change in magnitude of driver
common mode output voltage
RL= 54Ω (Figure 1.)
IOFF
Power off output current
VCC = 0V, VO=-7V to 12V
IOSD
Driver short circuit output current VO=-7V to 12V
6/17
VIL
Input logic threshold low
VIH
Input logic threshold high
Test conditions
Min.
Typ.
0
1
0
± 35
2
Max.
Unit
VCC
V
5
V
V
0.2
V
3
V
0.2
V
± 100
μA
± 250
mA
0.8
V
V
ST491A
Table 7.
Symbol
IIN
Electrical characteristics
Receiver electrical characteristics
(VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are
referred to TA=25°C)
Parameter
Test conditions
Other input = 0V
VCC = 0 or 5.25V
Input current (A, B)
Typ.
Max.
VIN=12V
0.5
1
VIN=-7V
-0.35
-0.8
VTH
Receiver differential threshold
voltage
VCM = -7V to 12V
ΔVTH
Receiver input hysteresis
VCM = 0V
VOH
Receiver output high voltage
IOUT = -8mA, VID = 200mV
VOL
Receiver output low voltage
IOUT = 8mA, VID = -200mV
RRIN
Receiver input resistance
VCM = -7V to 12V
Table 8.
Symbol
Min.
Unit
mA
-0.2
3.5
0.2
70
mV
4.7
V
0.3
12
V
0.5
24
V
KΩ
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)
Parameter
Test conditions
Min.
Typ.
25
50
Max.
Unit
DR
Maximum data rate
Jitter <5%
tPLH
tPHL
Propagation delay input
to output
RL= 54Ω, CL1=CL2=50pF, (Figure 1.)
10
16
ns
tSKEW
Differential output delay
skew
RL= 54Ω, CL1=CL2=50pF, (Figure 1.)
1
3
ns
tTLH
tTHL
Rise or fall differential
time
RL= 54Ω, CL1=CL2=50pF, (Figure 1.)
8
12
ns
tPZL
Output enable time
CL= 50pF, S1 Closed
14
25
ns
tPZH
Output enable time
CL= 50pF, S2 Closed
14
25
ns
tPHZ
Output disable time
CL= 15pF, S2 Closed
10
25
ns
tPLZ
Output disable time
CL= 15pF, S1 Closed
16
25
ns
Mbps
7/17
Electrical characteristics
Table 9.
Symbol
8/17
ST491A
Receiver switching characteristics
(VCC = 4.5V to 5.5V, TA = -40 to 85°C, unless otherwise specified. Typical values are
referred to TA=25°C)
Parameter
Test conditions
Min.
Typ.
Max.
Unit
tPLH
tPHL
Propagation delay input
to output
CL = 15pF, (Figure 2., Figure 4.)
19
30
ns
tSKD
|tPLH - tPHL| Receiver
output skew
CL = 15pF, (Figure 2., Figure 4.)
1
3
ns
tTLH
tTHL
Rise or fall time
CL = 15pF, (Figure 2., Figure 4.)
6
tPZL
Output enable time
CRL= 15pF, S1 Closed
6
12
ns
tPZH
Output enable time
CRL= 15pF, S2 Closed
7
12
ns
tPHZ
Output disable time
CRL= 15pF, S2 Closed
6
12
ns
tPLZ
Output disable time
CRL= 15pF, S1 Closed
6
12
ns
ns
ST491A
Test circuit and typical characteristics
5
Test circuit and typical characteristics
Figure 2.
Driver DC test load
Figure 3.
Receiver timing test load
9/17
Test circuit and typical characteristics
Figure 4.
Driver/receiver timing test circuit
Figure 5.
Driver timing test load
10/17
ST491A
ST491A
Test circuit and typical characteristics
Figure 6.
Driver propagation delay
Figure 7.
Receiver propagation delay
11/17
Test circuit and typical characteristics
Figure 8.
Receiver output current vs. output
low voltage (output low)
ST491A
Figure 9.
Receiver output current vs. output
high voltage (output high)
Figure 10. Driver diff. output voltage vs
Figure 11. Driver diff. output voltage vs
common mode voltage (diff. output
common mode voltage (diff. output
low)
high)
Figure 12. Driver short circuit current vs line
voltage (output high)
12/17
Figure 13. Receiver high level output voltage
vs. temperature
ST491A
Test circuit and typical characteristics
Figure 14. Receiver input current vs input
voltage
13/17
Package mechanical data
6
ST491A
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
14/17
ST491A
Package mechanical data
Plastic DIP-14 MECHANICAL DATA
mm.
inch
DIM.
MIN.
a1
0.51
B
1.39
TYP
MAX.
MIN.
TYP.
MAX.
0.020
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
I
5.1
0.201
L
Z
3.3
1.27
0.130
2.54
0.050
0.100
P001A
15/17
Revision history
ST491A
7
Revision history
Table 10.
Revision history
Date
Revision
10-May-2005
3
Mistake on Figure 1.
04-Jul-2005
4
Mistake on Figure 1 and Table 1 (Pin 13).
28-Apr-2006
5
Order codes has been updated and new template.
28-May-2007
6
Order codes has been updated.
16/17
Changes
ST491A
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