XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
FEBRUARY 2014
REV. 1.0.0
GENERAL DESCRIPTION
FEATURES
The XR33032/35/38 family of high performance half
duplex RS-485 transceivers are optimized to operate
over a wide range of supply voltage, from +2.8V to
+5.5V. The analog bus pins can withstand direct shorts
up to ±18V, and are protected against ESD events up
to ±15kV.
+2.8V to +5.5V Operating Range
±18V Fault Tolerance on Analog Bus pins
Robust ESD (ElectroStatic Discharge) Protection:
In an isolated application it may be more efficient to
use a remote power supply rather than generating an
isolated supply at every node. The XR33032/35/38
transceivers can operate with more than 2V IR drop in
the cable when utilizing a remote 5V power supply.
The transceivers draw less than 600µA, and typically
only 300µA when idling with the receivers active.
The receivers include full fail-safe circuitry, guaranteeing a logic-high receiver output when the receiver
inputs are open, shorted, or undriven. The receiver
input impedance is 96k (1/8 unit load), allowing up to
256 devices on the bus while preserving the full signal
margin.
The drivers are protected by short circuit detection as
well as thermal shutdown, and maintain high impedance in shutdown or when powered off. The XR33032
and XR33035 drivers are slew limited for reduced EMI
and error-free communication over long or unterminated data cables.
The DE and RE pins include hot swap circuitry to prevent false transitions on the bus during power-up or
live insertion, and can enter a low current shutdown
mode (40nA typically) for extreme power savings.
RO
1
RE
R
8
VCC
2
7
B/Z
DE
3
6
A/Y
DI
4
5
GND
D
■
±15kV IEC 61000-4-2 Air Gap Discharge
■
± 8kV IEC 61000-4-2 Contact Discharge
■
±15kV Human Body Model
■
± 4kV Human Body Model on non-bus pins
300µA Idle Current, 40nA Shutdown Current
Enhanced Receiver Fail-Safe Protection for Open,
Shorted, or Terminated but Idle Data Lines
Hot-Swap Glitch Protection on DE and RE Pins
Driver Short Circuit Current Limit and Thermal
Shutdown for Overload Protection
1/8th Unit Load Allows up to 256 Devices on Bus
Industry Standard 8 NSOIC Half Duplex Package
TYPICAL APPLICATIONS
Isolated Multipoint RS-485 Data Buses
Remote Nodes Powered by the Host
Building Automation and HVAC
Industrial Process Control Networks
Remote Utility Meter Reading
Energy Monitoring and Control
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at these ratings or any other above those
indicated in the operation sections to the specifications below is not implied.
VCC
-0.3V to +7.0V
Input Voltage at Control and Driver Input (RE, DE, and DI)
-0.3V to +7.0V
-0.3V to (VCC + 0.3V)
Receiver Output Voltage (RO)
Driver Output Voltage (A and B)
±18V
Receiver Input Voltage (A and B)
±18V
Transient Voltage Pulse, through 100
Figure 5
±70V
Driver Output Current
±250mA
Storage Temperature Range
-65°C to +150°C
Lead Temperature (soldering, 10s)
+300°C
Package Power Dissipation
8-Pin SO
JA = 128.4°C/W
Maximum Junction Temperature = +150°C
14-Pin SO JA = 86°C/W
ORDERING INFORMATION
PART NUMBER
DUPLEX
DATA RATE
PACKAGE
TEMPERATURE RANGE
XR33032ID-F
Half
250kbps
8-pin Narrow SOIC
-40°C to +85°C
XR33032IDTR-F
Half
250kbps
8-pin Narrow SOIC
-40°C to +85°C
XR33035ID-F
Half
1Mbps
8-pin Narrow SOIC
-40°C to +85°C
XR33035IDTR-F
Half
1Mbps
8-pin Narrow SOIC
-40°C to +85°C
XR33038ID-F
Half
10Mbps
8-pin Narrow SOIC
-40°C to +85°C
XR33038IDTR-F
Half
10Mbps
8-pin Narrow SOIC
-40°C to +85°C
NOTE: TR = Tape and Reel part numbers, -F = Green / RoHS Compliant
2
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
ELECTRICAL CHARACTERISTICS
Unless otherwise noted: VCC = +2.8V to +5.5V, TA = -40C to +85C. Typical values are at VCC = 3.3V, TA = +25°C.
SYMBOL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
2.8
5.5
V
2
VCC
V
RL = 100 (RS-422), Figure 2
1.5
VCC
V
RL = 54 (RS-485), Figure 2
1.5
VCC
V
-7V VCM +12V, Figure 3
1.8
VCC
V
RL = 100 (RS-422), Figure 2
1.4
VCC
V
RL = 54 (RS-485), Figure 2
1.1
VCC
V
-7V VCM +12V, Figure 3
-0.2
+0.2
V
RL = 100 (RS-422), or
RL = 54 (RS-485),
Figure 2, Note 1
3
V
+0.2
V
DRIVER DC CHARACTERISTICS
VCC
VOD
VOD
Supply Voltage Range
Differential Driver Output,
+3.0V VCC +5.5V
Differential Driver Output,
+2.8V VCC +3.0V
VOD
Change in Magnitude of
Differential Output Voltage
VCM
Driver Common-Mode Output
Voltage (Steady State)
VCM
Change in Magnitude of
Common-Mode Output Voltage
VIH
VIL
VHYS
IIN
IA, B
Logic High Threshold (DI, DE, RE)
VCC / 2
-0.2
2.8
V
+4.5V VCC 5.5V
2.3
V
+4.0V VCC 4.5V
2.0
V
+2.8V VCC +4.0V
Logic Low Threshold (DI, DE, RE)
0.8
Input Hysteresis (DI, DE, RE)
100
Logic Input Current (DI, DE, RE)
-1
Logic Input Current (DE and RE)
-200
100
mV
+1
µA
+200
µA
125
µA
Input Current (A and B)
-100
µA
125
IOL
µA
Output Leakage (Y and Z)
Full Duplex (Note 2)
-100
IOSD
V
Driver Short-Circuit Output Current
-250
3
+250
0V VIN VCC,
After first transition, Note 2
Until first transition, Note 2
VOUT = +12V, DE = 0V,
VCC = 0V or +5.5V
VOUT = -7V, DE = 0V,
VCC = 0V or +5.5V
VOUT = +12V, DE = 0V,
VCC = 0V or +5.5V
µA
VOUT = -7V, DE = 0V,
VCC = 0V or +5.5V
mA
-7V VOUT +12V, Figure 4
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
Unless otherwise noted: VCC = +2.8V to +5.5V, TA = -40C to +85C. Typical values are at VCC = 3.3V, TA = +25°C.
SYMBOL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
DRIVER THERMAL CHARACTERISTICS
TTS
Thermal Shutdown Temperature
175
°C
TTSH
Thermal Shutdown Hysteresis
15
°C
Junction temperature
RECEIVER DC CHARACTERISTICS
VTH
Receiver Differential Input Threshold
Voltage (VA - VB)
VOH
Receiver Input Hysteresis
VOH
Receiver Output High Voltage (RO)
VOL
Receiver Output Low Voltage (RO)
IOZR
High-Z Receiver Output Current
RIN
Receiver Input Resistance
IOSC
Receiver Output Short-Circuit
Current
-200
-125
-50
25
mV
-7V VCM +12V
mV
VCM = 0V
V
IOUT = -1mA
0.4
V
IOUT = 1mA
±1
µA
0V VOUT VCC
k
-7V VCM +12V
±120
mA
0V VRO VCC
400
600
µA
300
600
µA
300
500
µA
No Load, RE = 0V, DE = 0V
Receiver A and B inputs open
0.040
1
µA
RE = VCC, DE = 0V
±15
kV
Human Body Model
±15
kV
IEC 61000-4-2 Airgap
±8
kV
IEC 61000-4-2 Contact
±4
kV
Human Body Model
VCC-0.6
96
SUPPLY CURRENT
ICC
ISHDN
Supply Current
Supply Current in Shutdown Mode
No Load, RE = 0V, DE = VCC
DI = 0V
No Load, RE = VCC, DE = VCC
DI = 0V
ESD PROTECTION
ESD Protection for A, B, Y, and Z
ESD Protection for all other pins
4
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
Unless otherwise noted: VCC = +2.8V to +5.5V, TA = -40C to +85C. Typical values are at VCC = 3.3V, TA = +25°C.
SYMBOL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
DRIVER AC CHARACTERISTICS
XR33032 (250kbps)
tDPLH
Driver Prop. Delay (Low to High)
250
1500
ns
tDPHL
Driver Prop. Delay (High to Low)
250
1500
ns
CL = 50pF, RL = 54,
200
ns
Figure 6
1600
ns
|tDPLH-tDPHL|
tDR, tDF
Differential Driver Output Skew
20
Driver Differential Output
Rise or Fall Time
350
Maximum Data Rate
250
kbps
1/tUI, Duty Cycle 40 to 60%
tDZH
Driver Enable to Output High
200
2500
ns
tDZL
Driver Enable to Output Low
200
2500
ns
CL = 50pF, RL = 500,
tDHZ
Driver Disable from Output High
6
100
ns
Figure 7
tDLZ
Driver Disable from Output Low
6
100
ns
tDZH(SHDN)
Driver Enable from Shutdown to
Output High
5500
ns
tDZL(SHDN)
Driver Enable from Shutdown to
Output Low
5500
ns
600
ns
tSHDN
Time to Shutdown
50
200
CL = 50pF, RL = 500,
Figure 7
Notes 3
RECEIVER AC CHARACTERISTICS
XR33032 (250kbps)
tRPLH
Receiver Prop. Delay (Low to High)
200
ns
tRPHL
Receiver Prop. Delay (High to Low)
200
ns
|tRPLH-tRPHL|
Receiver Propagation Delay Skew
30
ns
Maximum Data Rate
250
kbps
CL = 15pF, VID = ±2V,
VID Rise and Fall times < 15ns
Figure 8
1/tUI, Duty Cycle 40 to 60%
tRZH
Receiver Enable to Output High
50
ns
tRZL
Receiver Enable to Output Low
50
ns
CL = 15pF, RL = 1k,
tRHZ
Receiver Disable from Output High
50
ns
Figure 9
tRLZ
Receiver Disable from Output Low
50
ns
tRZH(SHDN)
Receiver Enable from Shutdown
to Output High
3500
ns
tRZL(SHDN)
Receiver Enable from Shutdown
to Output Low
3500
ns
600
ns
tSHDN
Time to Shutdown
50
200
5
CL = 15pF, RL = 1k,
Figure 9
Notes 3
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
Unless otherwise noted: VCC = +2.8V to +5.5V, TA = -40C to +85C. Typical values are at VCC = 3.3V, TA = +25°C.
SYMBOL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
DRIVER AC CHARACTERISTICS
XR33035 (1Mbps)
tDPLH
Driver Prop. Delay (Low to High)
150
300
ns
tDPHL
Driver Prop. Delay (High to Low)
150
300
ns
CL = 50pF, RL = 54,
5
50
ns
Figure 6
200
350
ns
|tDPLH-tDPHL|
tDR, tDF
Differential Driver Output Skew
Driver Differential Output
Rise or Fall Time
Maximum Data Rate
100
Mbps 1/tUI, Duty Cycle 40 to 60%
1
tDZH
Driver Enable to Output High
1000
2500
ns
tDZL
Driver Enable to Output Low
1000
2500
ns
CL = 50pF, RL = 500,
tDHZ
Driver Disable from Output High
60
100
ns
Figure 7
tDLZ
Driver Disable from Output Low
60
100
ns
tDZH(SHDN)
Driver Enable from Shutdown to
Output High
3500
ns
tDZL(SHDN)
Driver Enable from Shutdown to
Output Low
3500
ns
600
ns
tSHDN
Time to Shutdown
50
200
CL = 50pF, RL = 500,
Figure 7
Notes 3
RECEIVER AC CHARACTERISTICS
XR33035 (1Mbps)
tRPLH
Receiver Prop. Delay (Low to High)
200
ns
tRPHL
Receiver Prop. Delay (High to Low)
200
ns
|tRPLH-tRPHL|
Receiver Propagation Delay Skew
30
ns
Maximum Data Rate
CL = 15pF, VID = ±2V,
VID Rise and Fall times < 15ns
Figure 8
Mbps 1/tUI, Duty Cycle 40 to 60%
1
tRZH
Receiver Enable to Output High
50
ns
tRZL
Receiver Enable to Output Low
50
ns
CL = 15pF, RL = 1k,
tRHZ
Receiver Disable from Output High
50
ns
Figure 9
tRLZ
Receiver Disable from Output Low
50
ns
tRZH(SHDN)
Receiver Enable from Shutdown
to Output High
3500
ns
tRZL(SHDN)
Receiver Enable from Shutdown
to Output Low
3500
ns
600
ns
tSHDN
Time to Shutdown
50
200
6
CL = 15pF, RL = 1k,
Figure 9
Notes 3
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
Unless otherwise noted: VCC = +2.8V to +5.5V, TA = -40C to +85C. Typical values are at VCC = 3.3V, TA = +25°C.
SYMBOL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
DRIVER AC CHARACTERISTICS
XR33038 (10Mbps)
tDPLH
Driver Prop. Delay (Low to High)
30
ns
tDPHL
Driver Prop. Delay (High to Low)
30
ns
CL = 50pF, RL = 54,
Differential Driver Output Skew
5
ns
Figure 6
Driver Differential Output
Rise or Fall Time
25
ns
|tDPLH-tDPHL|
tDR, tDF
Maximum Data Rate
Mbps 1/tUI, Duty Cycle 40 to 60%
10
tDZH
Driver Enable to Output High
50
ns
tDZL
Driver Enable to Output Low
50
ns
CL = 50pF, RL = 500,
tDHZ
Driver Disable from Output High
50
ns
Figure 7
tDLZ
Driver Disable from Output Low
50
ns
tDZH(SHDN)
Driver Enable from Shutdown to
Output High
250
ns
tDZL(SHDN)
Driver Enable from Shutdown to
Output Low
250
ns
600
ns
tSHDN
Time to Shutdown
50
200
CL = 50pF, RL = 500,
Figure 7
Notes 3
RECEIVER AC CHARACTERISTICS
XR33038 (10Mbps)
tRPLH
Receiver Prop. Delay (Low to High)
50
ns
tRPHL
Receiver Prop. Delay (High to Low)
50
ns
|tRPLH-tRPHL|
Receiver Propagation Delay Skew
5
ns
Maximum Data Rate
CL = 15pF, VID = ±2V,
VID Rise and Fall times < 15ns
Figure 8
Mbps 1/tUI, Duty Cycle 40 to 60%
10
tRZH
Receiver Enable to Output High
50
ns
tRZL
Receiver Enable to Output Low
50
ns
CL = 15pF, RL = 1k,
tRHZ
Receiver Disable from Output High
50
ns
Figure 9
tRLZ
Receiver Disable from Output Low
50
ns
tRZH(SHDN)
Receiver Enable from Shutdown
to Output High
2200
ns
tRZL(SHDN)
Receiver Enable from Shutdown
to Output Low
2200
ns
600
ns
tSHDN
Time to Shutdown
50
200
7
CL = 15pF, RL = 1k,
Figure 9
Notes 3
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
NOTE:
1.
Change in Magnitude of Differential Output Voltage and Change in Magnitude of Common Mode Output Voltage
are the changes in output voltage when DI input changes state.
2.
The hot swap feature disables the DE and RE inputs for the first 10µs after power is applied. Following this time
period these inputs are weakly pulled to their disabled state (low for DE, high for RE) until the first transition, after
which they become high impedance inputs.
3.
The transceivers are put into shutdown by bringing RE High and DE Low simultaneously for at least 600ns. If the
control inputs are in this state for less than 50ns, the device is guaranteed to not enter shutdown. If the enable
inputs are held in this state for at least 600ns the device is assured to be in shutdown. Note that the receiver and
driver enable times increase significantly when coming out of shutdown.
BLOCK DIAGRAMS
FIGURE 1. HALF DUPLEX 8 NSOIC
RO
1
RE
R
8
VCC
2
7
B/Z
DE
3
6
A/Y
DI
4
5
GND
D
8
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
TEST FIGURES
FIGURE 2. DIFFERENTIAL DRIVER OUTPUT VOLTAGE
Z
RL
2
DI = 0V or VCC
VOD
D
VCM
RL
2
Y
DE = VCC
FIGURE 3. DIFFERENTIAL DRIVER OUTPUT VOLTAGE OVER COMMON MODE
Z
375æ
DI = 0V or VCC
VOD
D
VCM
60æ
375æ
Y
DE = VCC
FIGURE 4. DRIVER OUTPUT SHORT CIRCUIT CURRENT
Z
DI = 0V or VCC
IOSD
D
-7V to +12V
Y
DE = 0V or VCC
9
V
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
FIGURE 5. TRANSIENT OVER-VOLTAGE TEST CIRCUIT
Device powered on or powered off
A or Z
Transceiver,
Generator, or
Receiver
100
VTEST
15us duration
15 duty cycle
B or Y
FIGURE 6. DRIVER PROPAGATION DELAY TEST CIRCUIT & TIMING DIAGRAM
DI
3V
1.5V
0V
Z
tSKEW = |tDPHL è tDPLH|
1.5V
tDPLH
tDPHL
VOD
Y
VOD
(VY - VZ)
VOD+
0V
VOD-
90%
90%
10%
10%
tDR
tDF
Z
DI
D
VOD
RL
CL
Y
DE = VCC
10
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
FIGURE 7. DRIVER ENABLE AND DISABLE TIMING TEST CIRCUITS & TIMING DIAGRAMS
Z
Testing Z: DI = 0V
VOUT
D
Testing Y: DI = VCC
RL
DE
CL
Y
3V
DE
1.5V
1.5V
0V
tDZH
VOH
tDHZ
VOH + VOL
2
VOUT
VOH - 0.25V
VOL
VCC
Z
RL
Testing Z: DI = VCC
VOUT
D
Testing Y: DI = 0V
CL
DE
Y
3V
DE
1.5V
1.5V
0V
tDZL
VOH
VOUT
tDLZ
VOH + VOL
2
VOL + 0.25V
VOL
11
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
FIGURE 8. RECEIVER PROPAGATION DELAY TEST CIRCUIT & TIMING DIAGRAM
B
RO
R
CL
A
RE = 0V
B
+1V
0V
-1V
A
tRPLH
tRPHL
VOH
1.5V
1.5V
VOL
RO
12
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
FIGURE 9. RECEIVER ENABLE AND DISABLE TEST CIRCUITS & TIMING DIAGRAMS
B
RO
R
RE
A
RL
CL
3V
RE
1.5V
1.5V
0V
tRZH
VA = VCC
VB = 0V
VOH
tRHZ
VOH
2
RO
VOH - 0.25V
0V
VCC
B
RL
RO
R
CL
RE
A
3V
RE
1.5V
1.5V
0V
tRZL
VA = 0V
VB = VCC
VCC
RO
tRLZ
VCC + VOL
2
VOL + 0.25V
VOL
13
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
PIN DESCRIPTIONS
PIN NUMBER
PIN NAME
TYPE
1
RO
Out
2
3
RE
DE
DESCRIPTION
Receiver Output. When RE is low and
if (A-B) -50mV, RO is high.
If (A-B) -200mV, RO is Low.
In
Receiver Output Enable (Hot Swap).
When RE is low, RO is enabled. When RE is High,
RO is high impedance. When RE is high and DE is
low, shutdown mode is enabled.
In
Driver Output Enable (Hot Swap).
When DE is high, outputs are enabled. When DE is
low, outputs are high impedance. When DE is low
and RE is high, shutdown mode is enabled.
Driver Input.
With DE high, a low level on DI forces non-Inverting
output low and inverting output high. Similarly, a
high level on DI forces non-Inverting output high
and inverting output low.
4
DI
In
5
GND
Pwr
Ground.
6
A
I/O
Non-Inverting Receiver Input and
Non-Inverting Driver Output.
7
B
I/O
Inverting Receiver Input and
Inverting Driver Output.
8
VCC
Pwr
Power Supply Input.
Bypass to ground with 0.1 µF capacitor.
14
REV. 1.0.0
XR33032/35/38
REV. 1.0.0
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
PRODUCT DESCRIPTION
The XR33032/35/38 RS-485/422 devices are part of Exar’s high performance serial interface product line. The
analog bus pins can survive direct shorts up to ±18V, and are protected against ESD events up to ±15kV.
ENHANCED FAILSAFE
Standard RS-485 differential receivers will be in an indeterminate state whenever the analog bus pins are not
being driven. The enhanced failsafe feature of the XR33032/35/38 family guarantees a logic-high receiver
output when the receiver inputs are open, shorted, or when they are connected to a terminated transmission
line with all drivers disabled. In a terminated bus with all transmitters disabled, the receivers’ differential input
voltage is pulled to 0V by the termination. The XR33032/35/38 family interprets 0V differential as a logic high
with a minimum 50mV noise margin while maintaining compliance with the EIA/TIA-485 standard of ±200mV.
Although the XR33032/35/38 family does not need failsafe biasing resistors, it can operate without issue if
biasing is used.
RECEIVER INPUT FILTERING
XR33032 and XR33035 receivers incorporate internal filtering in addition to input hysteresis. This filtering
enhances noise immunity by ignoring signals that do not meet a minimum pulse width of 30ns. Receiver
propagation delay increases slightly due to this filtering. The high speed XR33038 device does not have this
input filtering.
HOT-SWAP CAPABILITY
When VCC is first applied the driver enable and receiver enable (DE and RE) are held inactive for
approximately 10 microseconds. During power ramp-up other system ICs may drive unpredictable values, or
tristated lines may be influenced by stray capacitance. The hot-swap feature prevents these devices from
driving any output signal until power has stabilized. After the initial 10µs, the driver and receiver enable pins are
weakly pulled to their disabled states (low for DE, high for RE) until the first transition. After the first transition,
the DE and RE pins operate as high impedance inputs.
If circuit boards are inserted into an energized backplane (commonly called "live insertion" or "hot-swap")
power may suddenly be applied to all circuits. Without the hot-swap capability, this situation could improperly
enable the transceiver’s driver or receiver, driving invalid data onto shared busses and possibly causing driver
contention or device damage.
DRIVER OUTPUT PROTECTION
Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus
contention. First, a driver current limit on the output stage provides immediate protection against short circuits
over the whole common-mode voltage range. Second, a thermal-shutdown circuit forces the driver outputs into
a high-impedance state if junction temperature becomes excessive.
LINE LENGTH and TERMINATIONS
The RS-485/RS-422 standard covers line lengths up to 4000ft. Maximum achievable line length is a function of
the data rate, cable characteristics and environmental noise. Termination prevents signal reflections by
eliminating the impedance mismatches on a transmission line. Line termination is generally used if rise and fall
times are shorter than the round-trip signal propagation time. Higher supply voltage will allow longer cables to
be used.
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XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
±15kV ESD PROTECTION
ESD protection structures are incorporated on all pins to protect against electrostatic discharges encountered
during handling, assembly and operation. The driver outputs and receiver inputs of the XR33032/35/38 have
extra protection against static electricity. Exar uses state of the art structures to protect these pins against ESD
of ±15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown
and powered down. After an ESD event, the XR33032/35/38 keep operating without latch-up or damage.
ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the XR33032/35/
38 are characterized for protection to the following limits:
■
±15kV using the Human Body Model
■
± 8kV Contact Discharge Model
■
±15kV Air-gap Discharge Model
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. However, it does not
specifically refer to integrated circuits. The XR33032/35/38 family helps you design equipment to meet
IEC 61000-4-2, without sacrificing board-space and cost for external ESD-protection components.
The major differences between tests done using the Human body model and IEC 61000-4-2 is a higher peak
current in IEC 61000-4-2. Series resistance is lower in the IEC 61000-4-2 model. Hence, the ESD withstand
voltage measured to IEC 61000-4-2 is generally lower than that of human body model.
The air-gap test involves approaching the device with a charged probe. The contact discharge method
connects the probe to the device before the probe is energized.
256 TRANSCEIVERS ON THE BUS
The standard RS-485 receiver input impedance is 12k Ohms (1 unit load). A standard driver can drive up to 32
unit loads. The XR33032/35/38 transceivers have a 1/8th unit load receiver input impedance of 96k, allowing
up to 256 transceivers to be connected in parallel on a communication line. Any combination of these devices
and other RS-485 transceivers up to a total of 32 unit loads may be connected to the line.
LOW POWER SHUTDOWN MODE
Low-power shutdown mode is initiated by bringing both RE high and DE low simultaneously. While in shutdown
devices draw less than 1µA of supply current. DE and RE may be tied together and driven by a single control
signal. Devices are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the
inputs are in this state for at least 600ns, the parts will enter shutdown.
Enable times tZH and tZL apply when the part is not in low-power shutdown state. Enable times tZH(SHDN) and
tZL(SHDN) apply when the parts are shutdown. The drivers and receivers take longer to become enabled from
low-power shutdown tZH(SHDN) and tZL(SHDN) than from driver / receiver disable mode (tZH and tZL).
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XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
FUNCTION TABLES
TABLE 1: HALF DUPLEX 8 PIN
TRANSMITTING
Inputs
Outputs
RE
DE
DI
A
B
X
1
1
1
0
X
1
0
0
1
0
0
X
High-Z
1
0
X
Shutdown
TABLE 2: HALF DUPLEX 8 PIN
RECEIVING
Inputs
Output
RE
DE
VA - VB
RO
0
X
-50mV
1
0
X
-200mV
0
0
X
Open/Shorted
1
1
1
X
High-Z
1
0
X
Shutdown
Note: Receiver inputs -200mV VA - VB -50mV are considered indeterminate.
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XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
PACKAGE DRAWINGS
FIGURE 10. 8 NSOIC
18
REV. 1.0.0
XR33032/35/38
WIDE SUPPLY 18V TOLERANT RS-485/RS-422 TRANSCEIVERS
REV. 1.0.0
REVISION HISTORY
DATE
REVISION
February 2014
1.0.0
DESCRIPTION
Initial release [ECN 1411-03]
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to
improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any
circuits described herein, conveys no license under any patent or other right, and makes no representation that
the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration
purposes and may vary depending upon a user’s specific application. While the information in this publication
has been carefully checked; no responsibility, however, is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the
failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to
significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless
EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has
been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately
protected under the circumstances.
Copyright 2014 EXAR Corporation
Datasheet February 2014.
For technical support please email Exar’s Serial Technical Support group at: serialtechsupport@exar.com.
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
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