UM3491
+3.3V Low Power
，
±15kV ESD-Protected, Fail-Safe, RS-422
Transceivers in SOP14/DIP14
General Description
The UM3491 is ±15kV electrostatic discharge (ESD)-protected, high-speed transceivers for
RS-422 communication that contain one driver and one receiver. The device features fail-safe
circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or
shorted. This means that the receiver output will be a logic high if all transmitters on a terminated
bus are disabled (high impedance). The UM3491 allowing transmit speeds up to 10Mbps. The
device features enhanced ESD protection. All transmitter outputs and receiver inputs are
protected to ±15kV using the Human Body Model.
These transceivers typically draw 180µA of supply current when unloaded, or when fully
loaded with the drivers disabled.
The device has a 1/8-unit-load receiver input impedance that allows up to 256 transceivers on the
bus. The UM3491 is intended for full-duplex communications.
Applications
RS-422 Communications
Level Translators
Transceivers for EMI-Sensitive
Applications
Industrial-Control Local Area
Networks
Features
ESD Protection for RS-422 I/O Pins
±15kV, Human Body Model
True Fail-Safe Receiver While Maintaining
EIA/TIA-422 Compatibility
Maximum Data Rate up to 10Mbps
Error-Free Data Transmission
1nA Low-Current Shutdown Mode
Allow Up to 256 Transceivers on the Bus
Pin Configurations
Top View
NC
RO
RE
DE
DI
GND
GND
1
2
3
4
5
6
7
D
R
14
13
12
11
10
9
8
VCC
NC
A
B
Z
Y
NC
XX: Week Code
UM3491EESE
SOP14
XX: Week Code
UM3491EEPE
DIP14
Selector Guide
Part
Number
UM3491
Half/Full
Duplex
full
Data
Rate
(Mbps)
10
Slew-
Rate
Limited
Yes
Low-
Power
Shutdown
Yes
Receiver/
Driver
Enable
Yes
Quiescent
Current
(µA)
180
Transceivers
Pin
On
Count
Bus
256
14
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UM3491
Ordering Information
Part Number
UM3491EESE
UM3491EEPE
Temperature Range
-40°C to +85°C
-40°C to +85°C
Packaging Type
SOP14
DIP14
Shipping Qty
2500pcs/13 Inch Tape & Reel
25pcs Tube
Absolute Maximum Ratings
Symbol
V
CC
Parameter
Supply Voltage
Control Input Voltage (RE, DE)
Driver Input Voltage (DI)
Driver Output Voltage (A, B, Y, Z)
Receiver Input Voltage (A, B)
Receiver Output Voltage (RO)
P
D
T
A
T
STG
T
L
14-Pin Plastic DIP (derate 10.0mW/°C above +70°C)
14-Pin SO (derate 8.33mW/°C above +70°C)
Ambient Temperature
Storage Temperature Range
Lead Temperature for Soldering 10 seconds
Value
+7
-0.3V to (VCC + 0.3V)
-0.3V to (VCC + 0.3V)
±13
±25
-0.3V to (VCC + 0.3V)
800
667
-40 to +85
-65 to +150
+300
Unit
V
V
V
V
V
V
mW
°C
°C
°C
DC Electrical Characteristics
(V
CC
= +3.3V ± 5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +3.3V
and T
A
= +25°C.) (Note 1)
Parameter
DRIVER
Differential Driver Output
(No Load)
Differential Driver Output
Differential Driver Output
Change-in-Magnitude of
Differential Output Voltage
(Note 2)
Driver Common-Mode
Output Voltage
Input High Voltage
Input Low Voltage
DI Input Hysteresis
Symbol
V
OD1
V
OD2
V
OD3
ΔV
OD
V
OC
V
IH
V
IL
V
HYS
Test Conditions
Figure 3
Figure 3, R = 50Ω
Figure 3, R = 27Ω
Figure 3, R = 50Ω
Figure 3, R = 50Ω
DE, DI, R E
DE, DI, R E
______
Min
Typ
Max
Unit
V
V
V
V
V
V
Vcc
1.8
1.3
Vcc
Vcc
0.2
3.0
2.0
0.8
100
______
V
mV
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UM3491
DC Electrical Characteristics (Continued)
(V
CC
= +3.3V ± 5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +3.3V
and T
A
= +25°C.) (Note 1)
Parameter
DRIVER
Driver Short-Circuit Output
Current (Note 3)
RECEIVER
Input Current (A and B)
I
IN
DE = GND,
V
CC
= GND or
3.465V
V
IN
= 12V
V
IN
= -7V
-200
-125
25
I
O
= -4mA, V
ID
= -50mV
I
O
= 4mA, V
ID
= -200mV
0.4V
≤
V
O
≤
2.4V
-7V≤V
CM
≤12V
0V≤V
RO
≤V
CC
96
±7
±95
VCC
-0.4
0.4
±1
125
-75
-50
mV
mV
V
V
µA
kΩ
mA
µA
V
OD1
-7V≤V
OUT
≤V
CC
0V≤V
OUT
≤12V
-250
250
mA
Symbol
Test Conditions
Min
Typ
Max
Unit
Receiver Differential
Threshold Voltage
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State Output Current at
Receiver
Receiver Input Resistance
Receiver Output Short Circuit
Current
SUPPLY CURRENT
Supply Current
V
TH
Δ
V
TH
V
OH
V
OL
I
OZR
R
IN
I
OSR
-7V≤V
CM
≤12V
I
CC
RE = V
CC
No load,
DE =DI=GND
or V
CC
RE =GND
DE = GND, V
RE
= V
CC
Human Body Model
20
180
0.001
±15
60
µA
300
10
µA
kV
Supply Current in Shutdown
Mode
ESD Protection for Y, Z, A, B
I
SHDN
Note 1: All currents into the device are positive; all currents out of the device are negative. All
voltages are referred to device ground unless otherwise noted.
Note 2:
ΔV
OD
and
ΔV
OC
are the changes in V
OD
and V
OC
, respectively, when the DI input
changes state.
Note 3: Maximum current level applies to peak current just prior to foldback-current limiting;
minimum current level applies during current limiting.
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UM3491
Switching Characteristics
(V
CC
= +3.3V ± 5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +3.3V
and T
A
= +25°C.)
Parameter
Driver Input-to-Output
Driver Output Skew
| t
DPLH
- t
DPH
L |
Driver Rise or Fall Time
Maximum Data Rate
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from
Low
Driver Disable Time from
High
Receiver Input to Output
| t
RPLH
- t
RPHL
| Differential
Receiver Skew
Receiver Enable to Output
Low
Receiver Enable to Output
High
Receiver Disable Time from
Low
Receiver Disable Time from
High
Time to Shutdown
Driver Enable from
Shutdown to Output High
Driver Enable from
Shutdown to Output Low
Receiver Enable from
Shutdown- to-Output High
Receiver Enable from
Shutdown- to-Output Low
Symbol
t
DPLH
t
DPHL
t
DSKEW
t
DR
, t
DF
f
MAX
t
DZH
t
DZL
t
DLZ
t
DHZ
t
RPLH
,
t
RPHL
t
RSKD
t
RZL
t
RZH
t
RLZ
t
RHZ
t
SHDN
t
DZH(SHDN
)
Test Conditions
Figures 5 and 7, R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 5 and 7, R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Figures 5 and 7, R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF
Min
10
10
Typ
30
30
10
Max
60
60
25
30
10
Unit
ns
ns
ns
Mbps
ns
ns
ns
ns
ns
ns
5
15
Figures 6 and 8, C
L
= 100pF,
S2 closed
Figures 6 and 8, C
L
= 100pF,
S1 closed
Figures 6 and 8, C
L
= 15pF,
S1 closed
Figures 6 and 8, C
L
= 15pF,
S2 closed
Figures 9 and 11; | V
ID
|
≥
2.0V;
rise and fall time of V
ID
≤
15ns
Figures 9 and 11; | V
ID
|
≥
2.0V;
rise and fall time of V
ID
≤
15ns
Figures 4 and 10, C
L
= 100pF,
S1 closed
Figures 4 and 10, C
L
= 100pF,
S2 closed
Figures 4 and 10, C
L
= 100pF,
S1 closed
Figures 4 and 10, C
L
= 100pF,
S2 closed
(Note 4)
Figures 6 and 8, C
L
= 15pF,
S2 closed
Figures 6 and 8, C
L
= 15pF,
S1 closed
Figures 4 and 10, C
L
= 100pF,
S2 closed
Figures 4 and 10, C
L
= 100pF,
S1 closed
_______
40
40
40
40
20
100
13
40
40
40
40
50
200
40
40
150
150
70
70
70
70
180
100
100
100
100
600
200
200
500
500
ns
ns
ns
ns
ns
ns
ns
ns
ns
t
DZL(SHDN)
t
RZH(SHDN)
t
RZL(SHDN)
Note 4:
The device is put into shutdown by bringing R E high and DE low. If the enable inputs are
in this state for less than 50ns, the device is guaranteed not to enter shutdown. If the enable inputs are in
this state for at least 600ns, the device is guaranteed to have entered shutdown.
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UM3491
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
No Load Supply Current vs.
Temperature
250
225
200
175
150
125
100
-60
-40
-20
0
20
40
60
80
100
Temperature(
℃
)
RE=L,DE=H
Output Current vs.Receiver Output
High Voltage
30
25
Output Current (μA)
20
15
10
5
0
0
1
2
3
4
Output High Voltage (V)
No Load Supply Current(μA)
Output Current vs. Receiver Output
Low Voltage
60
50
Output Current (μA)
40
30
20
10
0
0
1
2
3
4
Output Low Voltage (V)
Receiver Output High Voltage(V)
3
2.95
2.9
2.85
2.8
2.75
2.7
2.65
2.6
2.55
2.5
-60
Receiver Output High Voltage vs.
Temperature
I
RO
=8mA
-40
-20
0
20
40
60
80
100
Temperature(
℃
)
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