UM3352E
±15kV ESD-Protected, Slew-Rate-Limited, Fail-Safe,
True RS-485 Transceivers
UM3352E SOP8/DIP8
General Description
The UM3352E series are ±15kV ESD-protected, high-speed, half-duplex transceivers for RS-485
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, shorted or idle.
This means that the receiver output will be logic high if all transmitters on a terminated bus are
disabled (high impedance). The UM3352E features reduced slew-rate driver that minimizes EMI
and reduces reflections caused by improperly terminated cables, allowing error-free data
transmission up to 500kbps. It also features enhanced ESD protection. All transmitter outputs and
receiver inputs incorporate advanced structures allowing them to survive ESD events in excess of
±15kV Human Body Mode and IEC61000-4-2 Air Discharge Mode, ±8kV IEC61000-4-2 Contact
Discharge Mode. New ESD structures protect the device whether or not it is powered up and
without degrading the RS-485 common mode range of -7V to 12V. The UM3352E includes a hot
swap circuit inside, which allows live cable insertion and removal. Proprietary protection circuit
built on A and B ports, can dissipate high surge current up to 6A to ground.
The transceivers typically draw 450μA 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 and are intended for half-duplex communications.
Applications
Features
RS-485 Transceivers
Intelligent Meters and Sensors
Industrial Control
Lighting Systems
Security Systems
HVAC Application
ESD Protection for RS-485 I/O Pins
±15kV—Human Body Mode
±15kV—IEC61000-4-2, Air Discharge Mode
±8kV—IEC61000-4-2, Contact Discharge Mode
True Fail-Safe Receiver
Enhanced Slew-Rate Limiting Facilitates Error-Free
Data Transmission
2µA Low-Current Shutdown Mode
-7V to +12V Common-Mode Input Voltage Range
Allows up to 256 Transceivers on the Bus
Thermal Shutdown
Current-Limiting for Driver Overload Protection
Hot Swap Capability
Ordering Information
Part Number
Operating
Temperature
Mark Code
Package Type
UM3352EESA
-40°C to +85°C
UM3352EESA
SOP8
UM3352EEPA
-40°C to +85°C
UM3352EEPA
DIP8
Shipping Qty
3000pcs/13 Inch
Tape & Reel
50pcs/Tube
Device Electrical Characteristic Summary
Part
Number
UM3352E
Guaranteed
Date Rate
(Mbps)
0.5
Low-Power
Shutdown
Slew-Rate
Limited
Yes
Yes
Driver/
Receiver
Enable
Yes
Shutdown
Current
(µA)
2
Transceivers
On Bus
256
±15kV
ESD
Protection
Yes
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UM3352E
Pin Configurations
Top View
RO 1
8
VCC
RE
2
7
B
DE
3
6
A
DI
4
5
GND
XX: Week Code
UM3352EESA
SOP8
RO 1
8
VCC
RE
2
7
B
DE
3
6
A
DI
4
5
GND
XX: Week Code
UM3352EEPA
DIP8
Pin Description
Pin Number
Symbol
1
RO
2
______
RE
Function
Receiver Output. If A＞B by -50mV, RO will be high; if A＜B by
200mV, RO will be low.
______
Receiver Output Enable.
Drive RE low to______
enable Receiver, RO is
______
high impedance when RE is high. Drive RE high and DE low to
enter low-power shutdown mode.
Driver Enable. Drive DE high to enable
______drivers. The outputs are high
impedance when DE is low. Drive RE high and DE low to enter
low-power shutdown mode.
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.
Ground.
3
DE
4
DI
5
GND
6
A
Non-Inverting Receiver Input and Non-Inverting Driver Output.
7
B
Inverting Receiver Input and Inverting Driver Output.
8
VCC
Power Supply for RS-485 Transceiver.
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UM3352E
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
VCC
Supply Voltage
+7
V
Control Input Voltage (R E , DE)
-0.3V to (VCC + 0.3V)
V
Driver Input Voltage (DI)
-0.3V to (VCC + 0.3V)
V
Driver Output Voltage (A, B)
-7.5 to +12.5
V
Receiver Input Voltage (A, B)
-7.5 to +12.5
V
Receiver Output Voltage (RO)
-0.3V to (VCC + 0.3V)
V
TA
Ambient Temperature
-40 to +85
°C
TSTG
Storage Temperature Range
-65 to +160
°C
TL
Lead Temperature for Soldering 10 seconds
+300
°C
______
DC Electrical Characteristics
(VCC=+5V ± 5%, TA=-40°C to +85°C, unless otherwise noted. Typical values are at VCC=+5V and
TA =+25°C.) (Note 1)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
SUPPLY CURRENT
Supply Current
Supply Current in Shutdown
Mode
ICC
ISHDN
No Load,
DI=GND
or VCC
DE=VCC,
R E =0V or VCC
0.45
DE=0V,
______
R E =0V
0.45
______
mA
______
DE = GND, R E = VCC
µA
2
LOGIC
Input High Voltage
Input Low Voltage
VIH
VIL
______
DE, DI, R E
V
2.0
______
DE, DI, R E
______
Input Hysteresis
VHYS
DE, DI, R E
Input Leakage Current
ILEAK
DE, DI, R E
0.8
V
mV
100
______
±2
µA
5
V
DRIVER
Differential Driver Output
VOD1
No Load, Figure 2
Differential Driver Output
VOD2
Figure 2, RLOAD=50Ω
Change-in-Magnitude of
Differential Output Voltage
ΔVOD
Figure 2, RLOAD=50Ω
(Note 2)
0.2
V
Driver Common-Mode
Output Voltage
VOC
Figure 2, RLOAD=50Ω
3.0
V
Change-in-Magnitude of
Common-Mode Voltage
ΔVOC
Figure 2, RLOAD=50Ω
(Note 2)
0.2
V
Driver Short-Circuit Output
Current (Note 3)
IOSD
1.5
V
VOUT=-7V
-250
VOUT=12V
250
mA
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UM3352E
DC Electrical Characteristics (Continued)
(VCC=+5V ± 5%, TA=-40°C to +85°C, unless otherwise noted. Typical values are at VCC=+5V and
TA=+25°C.) (Note 1)
Parameter
Symbol
Test Conditions
Min
-200
Typ
Max
Unit
-50
mV
RECEIVER
Receiver Differential Threshold
Voltage
VTH
-7V≤VCM≤12V
Receiver Input Hysteresis
ΔVTH
VCM=0V
Receiver Input Resistance
RIN
-7V≤VCM≤12V
Input Current (A and B)
IIN2
DE=GND,
VCC=GND or
5V
25
mV
96
kΩ
VIN=12V
1.0
VIN=-7V
-0.8
mA
VCC -1.5
V
Receiver Output High Voltage
VOH
IO=-1.5mA, VID=+200mV
Receiver Output Low Voltage
VOL
IO=2.5mA, VID=-200mV
0.4
V
Three-State Output Current at
Receiver
IOZR
VCC=5V, 0V≤VO≤VCC
±1
µA
Receiver Output Short Circuit
Current
IOSR
0V≤VRO≤VCC
±60
mA
±8
ESD Protection
ESD Protection for A, B
Human Body Mode
IEC61000-4-2
Air Discharge Mode
IEC61000-4-2
Contact Discharge Mode
±15
±15
kV
±8
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: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes
state.
Note 3: Maximum current level applies to peak current just prior to fold back current limiting;
minimum current level applies during current limiting.
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UM3352E
Switching Characteristics
(VCC=+5V ± 5%, TA=-40°C to +85°C, unless otherwise noted. Typical values are at VCC=+5V and
TA=+25°C.)
Parameter
Maximum Data Rate
Driver Input-to-Output
Symbol
fMAX
tDPLH
tDPHL
Test Conditions
Figures 3 and 7, RDIFF=54Ω,
CL1=CL2=100pF
Min
Typ
500
50
Max
1000
50
1000
Unit
kbps
ns
Driver Output Skew
| tDPLH - tDPHL |
tDSKEW
Figures 3 and 7, RDIFF=54Ω,
CL1=CL2=100pF
15
100
ns
Driver Rise or Fall Time
tDR, tDF
Figures 3 and 7, RDIFF=54Ω,
CL1=CL2=100pF
100
750
ns
Driver Enable to Output High
tDZH
Figures 4 and 8, CL=100pF,
S2 Closed
30
2500
ns
Driver Enable to Output Low
tDZL
Figures 4 and 8, CL=100pF,
S1 Closed
30
2500
ns
Driver Disable Time from
Low
tDLZ
Figures 4 and 8, CL=15pF,
S1 Closed
60
200
ns
Driver Disable Time from
High
tDHZ
Figures 4 and 8, CL=15pF,
S2 Closed
100
200
ns
Receiver Input to Output
tRPLH,
tRPHL
|VID| ≥2.0V,
Rise and Fall Time of VID≤ 1 5ns
75
200
ns
tRSKD
Figures 6 and 9, |VID| ≥2.0V,
Rise and Fall Time of VID≤ 1 5ns
0
30
ns
tRZL
Figures 5 and 10, CL=100pF,
S1 Closed
20
50
ns
Receiver Enable to Output
High
tRZH
Figures 5 and 10, CL=100pF,
S2 Closed
20
50
ns
Receiver Disable Time from
Low
tRLZ
Figures 5 and 10, CL=100pF,
S1 Closed
20
50
ns
Receiver Disable Time from
High
tRHZ
Figures 5 and 10, CL=100pF,
S2 Closed
20
50
ns
Time to Shutdown
tSHDN
(Note 4)
200
600
ns
Driver Enable from
Shutdown to Output High
tDZH(SHDN)
Figures 4 and 8, CL=15pF,
S2 Closed
700
4500
ns
Driver Enable from
Shutdown to Output Low
tDZL(SHDN)
Figures 4 and 8, CL=15pF,
S1 Closed
700
4500
ns
Receiver Enable from
Shutdown to Output High
tRZH(SHDN)
700
3500
ns
Receiver Enable from
Shutdown to Output Low
tRZL(SHDN)
700
3500
ns
Differential
Receiver Skew
| tRPLH - tRPHL |
Receiver Enable to Output
Low
Figures 5 and 10, CL=100pF,
S2 Closed
Figures 5 and 10, CL=100pF,
S1 Closed
______
Note 4: The device is put into shutdown by bringing RE 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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UM3352E
Typical Operating Characteristics
(VCC=+5.0V, TA=+25ºC, unless otherwise noted.)
DriverDifferential
Differential Output
Temperature
Driver
OutputVoltage
Voltagevs.
vs.
Temperature
DI=1,
RLOAD
=54Ω
RLOAD
=54Ω
Supply
vs. Temperature
Temperature
SupplyCurrent
Current vs.
0.50
Driver Differential Output Voltage (V)
Supply Current (mA)
0.55
DE=0,
RE=0
DE=0,
/RE=0
0.45
DE=1,
RE=1
DE=1, /RE=1
0.40
0.35
0.30
-50
-25
0
25
50
Temperature (℃ )
75
4.95
4.9
4.85
4.8
A B Short-Circuit Current (mA)
90
0
25
50
Temperature (℃ )
75
2.45
2.4
2.35
2.3
2.25
2.2
2.15
2.1
-50
-25
0
25
50
Temperature (℃ )
75
100
Receiver
vs.Temperature
Temperature
ReceiverOutput
OutputLow
Low Voltage
Voltage vs.
Receiver Output Low Voltage (mV)
Receiver Output High Voltage (V)
5
-25
2.5
100
Receiver
vs.Temperature
Temperature
ReceiverOutput
Output High
High Voltage
Voltage vs.
-50
2.55
0.06
0.05
0.04
0.03
0.02
0.01
0
100
-50
Short-Circuit Current
Current vs.
AABBShort-Circuit
vs.Temperature
Temperature
DI=1
-25
0
25
50
Temperature (℃ )
75
100
A B Pin I-V Snap Back Characteristic
80
70
60
VCLAMP
10V/div
VSB
50
40
30
ISURGE
20
5A/div
ISB
5µs/div
10
0
-50
-25
0
25
50
Temperature (℃ )
75
100
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UM3352E
Typical Operating Characteristics (Continued)
(VCC=+5.0V, TA=+25ºC, unless otherwise noted.)
Receiver Propagation Delay
RL=54Ω, CL=100pF
Transmitter Propagation Delay
RL=54Ω, CL=100pF
A-B
DI
2V/div
2V/div
A-B
2V/div
RO
400ns/div
2V/div
400ns/div
RS-485 Communication Function Table
Table1. Transmitting
INPUTS
RE
DE
X
1
X
1
0
0
1
0
X=Don’t care; High-Z=High impedance
______
OUTPUTS
DI
1
0
X
X
B
0
1
High-Z
A
1
0
High-Z
Shutdown
Table2. Receiving
INPUTS
RE
DE
0
X
0
X
0
X
1
1
1
0
X=Don’t care; High-Z=High impedance
______
A-B
≥-50mV
≤-200mV
Open/Shorted
X
X
OUTPUTS
RO
1
0
1
High-Z
Shutdown
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UM3352E
Typical Operating Circuit
120ohm
120ohm
B
DI
DE
B
B
D
D
A
DE
A
A
B
RO
RE
A
B
A
R
RO
RE
R
Master Node
D
DI
R
DI
Terminal Slave Node
R
D
DE
RO RE
Slave Node1
DI
DE
RO RE
Slave Node N
Figure 1. Typical Half-Duplex RS-485 Network
Test Circuit
B
3V
DE
RLOAD/2
CL2
A
DI
VOD2
RDIFF
B
VOD
CL1
RLOAD/2 VOC
A
Figure 2. Driver DC Test Load
Driver Output
Under Test
CL
500ohm
S1
Figure 3. Driver Timing Test Circuit
VCC
CRL
15pF
+
1K
Test Point
Receive
Output
S1
+
VCC
1K
S2
S2
Figure 4. Driver Enable/Disable Timing Test Load
Figure 5. Receiver Enable/Disable Timing Test Load
Figure 6. Receiver Propagation Delay Test Circuit
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UM3352E
Figure 7. Driver Propagation Delays
Figure 9. Receiver Propagation Delays
Figure 8. Driver Enable and Disable Times
Figure 10. Receiver Enable and Disable Times
Detail Description
The UM3352E high-speed transceivers for RS-485 communication contain one driver and one
receiver. The device features fail-safe circuitry, which guarantees a logic-high receiver output when
the receiver input is open or shorted, or when it is connected to a terminated transmission line with
all drivers disabled. The UM3352E features reduced slew-rate driver that minimizes EMI and
reduces reflections caused by improperly terminated cables, allowing error-free data transmission up
to 500kbps. It operates from a single +5V supply. Drivers are output short-circuit current limited.
Thermal shutdown circuitry protects drivers against excessive power dissipation. When activated,
the thermal shutdown circuitry places the driver outputs into a high impedance state.
Fail-Safe
The UM3352E guarantees a logic-high receiver output when the receiver inputs are shorted or open,
or when they are connected to a terminated transmission line with all drivers disabled. This is done
by setting the receiver threshold between -50mV and -200mV. If the differential receiver input
voltage (A-B) is greater than or equal to -50mV, RO is logic high. If A-B is less than or equal to
-200mV, RO is logic low. In the case of a terminated bus with all transmitters disabled, the
receiver’s differential input voltage is pulled to 0V by the termination. With the receiver thresholds
of the UM3352E, this results in a logic high with a 50mV minimum noise margin. Unlike previous
fail-safe devices, the -50mV to -200mV threshold complies with the ±200mV EIA/TIA-485
standard.
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UM3352E
Applications Information
256 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12kΩ (one unit load), and the standard driver can
drive up to 32 unit loads. The Union family of transceivers have a 1/8 unit load receiver input
impedance (96kΩ), allowing up to 256 transceivers to be connected in parallel on one
communication line. Any combination of these devices, as well as other RS-485 transceivers with a
total of 32 unit loads or fewer, can be connected to the line.
Reduced EMI and Reflections
The UM3352E is slew-rate limited, minimizing EMI and reducing reflections caused by improperly
terminated cables. In general, a transmitter’s rise time relates directly to the length of an
unterminated stub, which can be driven with only minor waveform reflections. The following
equation expresses this relationship conservatively:
Length=tRISE/(10×1.5ns/ft)
Where tRISE is the transmitter’s rise time.
A system can work well with longer unterminated stubs, even with severe reflections, if the
waveform settles out before the receiver’s UART samples them.
Low-Power Shutdown Mode
______
Low-power shutdown mode is initiated by bringing______
both R E high and DE low. In shutdown, the
device typically draws only 2µA of supply current.
R E and DE may be driven simultaneously; the
______
parts are guaranteed not to enter shutdown if R E is high and DE is low for less than 50ns. If the
inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown. Enable times tZH
and tZL in the Switching Characteristics tables assume the part was not in a low-power shutdown
state. Enable times tZH(SHDN) and tZL(SHDN) assume the parts were shut down. It takes drivers and
receivers longer to become enabled from low-power shutdown mode (tZH(SHDN), tZL(SHDN)) than from
driver/receiver-disable mode (tZH, tZL).
Driver Output Protection
Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus
contention. The first, a foldback current limit on the output stage, provides immediate protection
against short circuits over the whole common-mode voltage range. The second, a thermal shutdown
circuit, forces the driver outputs into a high-impedance state if the die temperature becomes
excessive.
Line Length vs. Data Rate
The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000
feet, repeater is required.
ESD Protection
All pins on these devices include class 2 (>2kV) Human Body Model (HBM) ESD protection
structures, but the RS-485 pins (driver outputs and receiver inputs) incorporate advanced structures
allowing them to survive ESD events in excess of ±15kV HBM, ±15kV IEC61000-4-2 Air
Discharge Mode and ±8kV IEC61000-4-2 Contact Discharge Mode. The RS-485 pins are
particularly vulnerable to ESD strikes because they typically connect to an exposed port on the
exterior of the finished product. Simply touching the port pins, or connecting a cable, can cause an
ESD event that might destroy unprotected ICs.
These new ESD structures protect the device whether or not it is powered up, and without degrading
the RS-485 common mode range of -7V to +12V. This built-in ESD protection cuts the need for
board level protection structures (e.g., transient suppression diodes), and the associated, undesirable
capacitive load they present.
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UM3352E
IEC61000-4-2 Testing
The IEC61000 test method applies to finished equipments, rather than to an individual IC. Therefore,
the pins most likely to suffer an ESD event are those that are exposed to the outside world (the
RS-485 pins in this case), and the IC is tested in its typical application configuration (power applied)
rather than testing each pin-to-pin combination. The IEC61000 standard’s lower current limiting
resistor coupled with the larger charge storage capacitor yields a test that is much more severe than
the HBM test.
Air-Gap Discharge Test Method
For this test method, a charged probe tip moves toward the IC pin until the voltage arcs to it. The
current waveform delivered to the IC pin depends on approach speed, humidity, temperature, etc., so
it is difficult to obtain repeatable results. The UM3352E RS-485 pins withstand ±15kV air-gap
discharges.
Contact Discharge Test Method
During the contact discharge test, the probe contacts the tested pin before the probe tip is energized,
thereby eliminating the variables associated with the air-gap discharge. The result is a more
repeatable and predictable test, but equipment limits prevent testing devices at voltages higher than
±8kV. The RS-485 pins of all the UM3352E versions survive ±8kV contact discharges.
Typical Applications
The UM3352E transceivers are designed for bidirectional data communications on multipoint bus
transmission lines. To minimize reflections, the line should be terminated at both ends in its
characteristic impedance, and stub lengths of the main line should be kept as short as possible.
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UM3352E
Package Information
UM3352EESA SOP8
Outline Drawing
D
c
Symbol
1
2
θ
e
Top View
End View
b
Side View
A
A1
A2
b
c
D
E
E1
e
L
θ
DIMENSIONS
MILLIMETERS
INCHES
Min
Typ
Max
Min
Typ
Max
1.35
1.55
1.75
0.053 0.061 0.069
0.10
0.25
0.004
0.010
1.25
1.65
0.049
0.065
0.30
0.51
0.012
0.020
0.15
0.25
0.006
0.010
4.70
4.90
5.10
0.185 0.193 0.200
3.80
3.90
4.00
0.150 0.154 0.157
5.80
6.00
6.20
0.228 0.236 0.244
1.27BSC
0.050 BSC
0.40
1.27
0.016
0.050
0°
8°
0°
8°
Land Pattern
1.27
0.60
NOTES:
1. Compound dimension: 4.90×3.90;
2. Unit: mm;
3. General tolerance ±0.05mm unless otherwise specified;
4. The layout is just for reference.
Tape and Reel Orientation
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UM3352E
UM3352EEPA DIP8
Outline Drawing
Symbol
A
A1
A2
b
b1
c
D
E
E1
E2
e
L
DIMENSIONS
MILLIMETERS
INCHES
Min Typ Max Min
Typ
Max
3.71
4.80 0.146
0.189
0.38
0.015
3.20 3.40 3.60 0.126 0.134 0.142
0.38
0.57 0.015
0.022
1.52BSC
0.060BSC
0.20 0.28 0.36 0.008 0.011 0.014
9.00 9.20 9.50 0.354 0.362 0.374
6.20 6.40 6.60 0.244 0.252 0.260
7.32
7.92 0.288
0.312
8.40
9.05 0.331
0.356
2.54TYP
0.100TYP
3.00 3.30 3.60 0.118 0.130 0.142
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UM3352E
GREEN COMPLIANCE
Union Semiconductor is committed to environmental excellence in all aspects of its
operations including meeting or exceeding regulatory requirements with respect to the use
of hazardous substances. Numerous successful programs have been implemented to reduce
the use of hazardous substances and/or emissions.
All Union components are compliant with the RoHS directive, which helps to support
customers in their compliance with environmental directives. For more green compliance
information, please visit:
http://www.union-ic.com/index.aspx?cat_code=RoHSDeclaration
IMPORTANT NOTICE
The information in this document has been carefully reviewed and is believed to be accurate.
Nonetheless, this document is subject to change without notice. Union assumes no
responsibility for any inaccuracies that may be contained in this document, and makes no
commitment to update or to keep current the contained information, or to notify a person or
organization of any update. Union reserves the right to make changes, at any time, in order
to improve reliability, function or design and to attempt to supply the best product possible.
Union Semiconductor, Inc
Add: Unit 606, No. 570 Shengxia Road, Shanghai 201210
Tel: 021-51093966
Fax: 021-51026018
Website: www.union-ic.com
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http://www.union-ic.com Rev.10 May.2020
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