19-2756; Rev 1; 4/03
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
Features
♦ ±80V Fault Protection
♦ ±12kV ESD Protection
♦ +3.3V Operation
♦ Internal Slew-Rate Limiting
♦ 250kbps Data Rate
♦ Allows Up to 128 Transceivers on the Bus
♦ -7V to +12V Common-Mode Input Voltage Range
♦ True Fail-Safe Inputs
♦ Hot-Swap Input Structure on DE
♦ Available in 8-Pin SO and PDIP Packages
Hot-swap circuitry eliminates false transitions on the
data cable during circuit initialization or connection to a
live backplane. Short-circuit current limiting and thermal-shutdown circuitry protect the driver against excessive power dissipation.
Ordering Information
The MAX3430 is available in 8-pin SO and 8-pin PDIP
packages, and is specified over commercial and industrial temperature ranges.
PART
Applications
RS-422/RS-485 Communications
TEMP RANGE
PIN-PACKAGE
MAX3430CPA
0°C to +70°C
8 Plastic DIP
MAX3430CSA
0°C to +70°C
8 SO
MAX3430EPA
-40°C to +85°C
8 Plastic DIP
MAX3430ESA
-40°C to +85°C
8 SO
Lighting Systems
Industrial-Control Local Area Networks
Profibus Applications
Multimaster RS-485 Networks
Pin Configuration and Typical Operating Circuit
TOP VIEW
VCC
RO
1
RE
2
R
DE 3
DI
4
D
8
VCC
7
B
6
A
5
GND
RO
1
RE 2
3
DE
4
DI
R
DE
0.1µF
MAX3430
8
D
7 B
6
D
5
DI
B
Rt
A
Rt
A
RO
R
GND
RE
DIP/SO
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX3430
General Description
The MAX3430 fault-protected RS-485 transceiver features
±80V protection from overvoltage signal faults on communication bus lines. Each device contains one driver and
one receiver, and the output pins can withstand faults,
with respect to ground, of up to ±80V. Even if the faults
occur when the transceiver is active, shut down, or powered off, the device will not be damaged. The MAX3430
operates from a 3.3V supply and features a slew-rate-limited driver that minimizes EMI and reduces reflections
caused by improperly terminated cables, allowing errorfree data transmission at data rates up to 250kbps. The
MAX3430 has a 1/4-unit-load receiver input impedance
allowing up to 128 transceivers on a single bus and features fail-safe circuitry, which guarantees a logic-high
receiver output when the receiver inputs are open.
MAX3430
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
ABSOLUTE MAXIMUM RATINGS
(All voltages are referenced to GND.)
VCC ........................................................................................+5V
RE, DE, DI...................................................-0.3V to (VCC + 0.3V)
Driver Output Voltage (A, B) (Note 1) ..................................±80V
Receiver Input Voltage (A, B) (Note 1) ................................±80V
RO ..............................................................-0.3V to (VCC + 0.3V)
Continuous Power Dissipation (TA = +70°C)
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ...727mW
Operating Temperature Ranges
MAX3430C_ _ .....................................................0°C to +70°C
MAX3430E_ _ ..................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: A, B must be terminated with 54Ω or 100Ω to guarantee ±80V fault protection.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(VCC = +3.3V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DRIVER
Figure 1, RL = 100Ω
2.0
VCC
Figure 1, RL = 54Ω
1.5
VCC
Differential Driver Output
VOD
Change in Magnitude of
Differential Output Voltage
∆VOD
Figure 1, RL = 100Ω or 54Ω (Note 2)
Driver Common-Mode Output
Voltage
VOC
Figure 1, RL = 100Ω or 54Ω
Change in Magnitude of
Common-Mode Voltage
∆VOC
Figure 1, RL = 100Ω or 54Ω (Note 2)
VCC / 2
V
0.2
V
3
V
0.2
V
DRIVER LOGIC
Driver Input High Voltage
VIH
DI
Driver Input Low Voltage
VIL
DI
0.8
V
Driver Input Current
IIN
DI
±1
µA
Driver Short-Circuit Output
Current
IOSD
Driver Short-Circuit Foldback
Output Current
IOSDF
2.0
V
0 ≤ VOUT ≤ 12V (Note 3)
+250
-7V ≤ VOUT ≤ VCC (Note 3)
-250
(VCC - 1V) ≤ VOUT ≤ 12V (Note 3)
+10
-7V ≤ VOUT ≤ 1V (Note 3)
-10
mA
mA
RECEIVER
Input Current (A, B)
IA, B
DE = GND, RE = GND, VIN = +12V
250
DE = GND, RE = GND, VIN = -7V
-200
VIN = -80V to +80V
Receiver Differential Threshold
Voltage
VTH
-7V ≤ VCM ≤ 12V
Receiver Input Hysteresis
∆VTH
V A + VB = 0
2
µA
-6
+6
mA
-200
-50
mV
25
_______________________________________________________________________________________
mV
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
MAX3430
DC ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.3V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RECEIVER LOGIC
VCC 0.6
V
RO Output High Voltage
VOH
IO = -1.6mA
RO Output Low Voltage
VOL
IO = 1mA
0.4
V
Three-State Output Current at
Receiver
IOZR
0 ≤ VO ≤ VCC
±1
µA
Receiver Input Resistance
RIN
-7V ≤ VCM ≤ 12V
Receiver Output Short-Circuit
Current
IOSR
0 ≤ VRO ≤ VCC
Control Input High Voltage
VCIH
DE, RE
Control Input Low Voltage
VCIL
DE, RE
48
kΩ
±95
mA
CONTROL
2.0
V
0.8
V
Input Current DE Current Latch
During First DE Rising Edge
80
µA
Input Current RE Current Latch
During First RE Rising Edge
80
µA
PROTECTION SPECIFICATIONS
(VCC = +3.3V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
SYMBOL
ESD Protection
CONDITIONS
A, B
Human Body Model
MIN
TYP
MAX
±12
UNITS
kV
SUPPLY CURRENT
Supply Current
ICC
Supply Current in Shutdown
Mode
ISHDN
No load, RE = 0, DE = VCC, DI = 0 or VCC
3.5
10
No load, RE = VCC, DE = VCC,
DI = 0 or VCC
3.0
8
RE = VCC, DE = 0
200
mA
µA
_______________________________________________________________________________________
3
MAX3430
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
DRIVER SWITCHING CHARACTERISTICS
(VCC = +3.3V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
Driver Propagation Delay
SYMBOL
tDPLH
tDPHL
CONDITIONS
MIN
Figures 2 and 3, RL = 54Ω, CL = 50pF
Driver Differential Output Rise or
Fall Time
tDR, tDF
Figures 2 and 3, RL = 54Ω, CL = 50pF
Differential Driver Output Skew,
|tDPLH - tDPHL|
tDSKEW
Figures 2 and 3, RL = 54Ω, CL = 50pF
Maximum Data Rate
TYP
MAX
700
1500
700
1500
250
150
UNITS
ns
1200
ns
200
ns
250
kbps
Driver Enable to Output Low
tDZL
Figure 4, CL = 50pF
5200
ns
Driver Disable Time from Output
Low
tDLZ
Figure 4, CL = 50pF
1000
ns
tDZL(SHDN) Figure 4, CL = 50pF
8000
ns
Driver Output Enable Time from
Shutdown
Driver Enable to Output High
tDZH
Figure 5, CL = 50pF
5200
ns
Driver Disable Time from Output
High
tDHZ
Figure 5, CL = 50pF
1000
ns
tDZH(SHDN) Figure 5, CL = 50pF
8000
ns
1000
ns
Driver Output Enable Time from
Shutdown
Driver Time to Shutdown
tSHDN
RECEIVER SWITCHING CHARACTERISTICS
(VCC = +3.3V ±10%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
Receiver Propagation Delay
Receiver Output Skew,
|tRPLH - tRPHL|
SYMBOL
tRPLH
tRPHL
tSKEW
CONDITIONS
MIN
TYP
Figure 6, CL = 20pF, VID = 2V, VCM = 0
MAX
120
120
UNITS
ns
Figure 6, CL = 20pF
40
ns
Receiver Enable to Output Low
tRZL
Figure 7, R = 1kΩ, CL = 20pF
80
ns
Receiver Enable to Output High
tRZH
Figure 7, R = 1kΩ, CL = 20pF
80
ns
Receiver Disable Time from Low
tRLZ
Figure 7, R = 1kΩ, CL = 20pF
80
ns
tRHZ
Figure 7, R = 1kΩ , CL = 20pF
80
ns
5000
ns
1000
ns
Receiver Disable Time form High
Receiver Output Enable Time
from Shutdown
Receiver Time to Shutdown
tRZH(SHND),
Figure 7, R = 1kΩ, CL = 20pF
tRZL(SHND)
tSHDN
Note 2: ∆VOD and ∆VOC are the changes in VOD and VOC, respectively, when the DI input changes state.
Note 3: The short-circuit output current applies to peak current just prior to foldback current limiting; the short-circuit foldback output
current applies during current limiting to allow a recovery from bus contention.
4
_______________________________________________________________________________________
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
SHUTDOWN CURRENT
vs. TEMPERATURE
175
3
2
150
16
OUTPUT CURRENT (mA)
SHUTDOWN CURRENT (µA)
4
20
MAX3430 toc02
RE = 0
DE = VCC
SUPPLY CURRENT (mA)
200
MAX3430 toc01
5
OUTPUT CURRENT
vs. RECEIVER OUTPUT LOW VOLTAGE
125
100
75
50
MAX3430 toc03
SUPPLY CURRENT
vs. TEMPERATURE
12
8
4
1
25
0
0
-40
-20
0
20
40
60
80
0
20
40
60
0
80
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT
vs. RECEIVER OUTPUT HIGH VOLTAGE
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
IO = -1.6mA
6
3
OUTPUT LOW VOLTAGE (V)
3.25
OUTPUT HIGH VOLTAGE (V)
9
0.5
MAX3430 toc05
MAX3430 toc04
3.30
3.20
3.15
3.10
3.05
0
3.00
0.5
1.0
1.5
2.0
2.5
3.0
3.5
IO = +1mA
0.4
0.3
0.2
0.1
0
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
OUTPUT HIGH VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
A, B CURRENT
vs. A, B VOLTAGE (TO GROUND)
60
40
20
MAX3430 toc09
3.0
2
RL = 100Ω
2.5
2.0
A, B CURRENT (mA)
80
3
MAX3430 toc08
100
3.5
DIFFERENTIAL OUTPUT VOLTAGE (V)
MAX3430 toc07
120
3.5
MAX3430 toc06
OUTPUT LOW VOLTAGE (V)
12
0
0.5
TEMPERATURE (°C)
15
OUTPUT CURRENT (mA)
-20
TEMPERATURE (°C)
18
OUTPUT CURRENT (mA)
0
-40
RL = 54Ω
1.5
1.0
1
0
-1
0.5
-2
0
-3
RE = DE = GND
0
0
0.5
1.0
1.5
2.0
2.5
3.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
3.5
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
-80
-60
-40
-20
0
20
40
60
80
A, B VOLTAGE (V)
_______________________________________________________________________________________
5
MAX3430
Typical Operating Characteristics
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
MAX3430
Test Circuits/Timing Diagrams
A
3V
RL
2
CL
DE
A
DI
VOD
VO
RL
B
RL
CL
VOC
2
B
Figure 2. Driver Timing Test Circuit
Figure 1. Driver DC Test Load
VCC
RL = 500Ω
VCC
DI
0
S1
VCC/2
0 OR +3V
tDPLH
OUT
D
CL
50pF
tDPHL
1/2 VO
GENERATOR
B
50Ω
VO
A
1/2 VO
VOD = V (A) - V (B)
80%
VO
80%
20%
VCC
20%
tDR
DE
tDF
VCC/2
tDZL, tDZL(SHDN)
0
tDLZ
VCC
tSKEW = |tDPLH - tDPHL|
OUT
VOM = (VOL + VCC)/2
0.25V
VOL
Figure 4. Driver Enable and Disable Times (tDZL, tDLZ,
tDLZ(SHDN))
Figure 3. Driver Propagation Delays
S1
0 OR +3V
VCC
OUT
D
CL
50pF
DE
RL = 500Ω
VCC/2
tDZH, tDZH(SHDN)
0
0.25V
GENERATOR
50Ω
OUT
VOH
VOM = (0 + VOH)/2
0
tDHZ
Figure 5. Driver Enable and Disable Times (tDHZ, tDZH, tDZH(SHDN))
6
_______________________________________________________________________________________
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
B
VID
R
A
CL
20pF
VOH
tRPHL
tRPLH
1.5V
0
RO
VOL
Figure 6. Receiver Propagation Delays
+1.5V
S3
-1.5V
VID
R
S1
R
1kΩ
RO
VCC
S2
CL
20pF
GENERATOR
50Ω
3V
RE
0
3V
S1 OPEN
S2 CLOSED
S3 = +1.5V
RE
1.5V
0
tRZH, tRZH(SHDN)
tRZL, tRZL (SHDN)
VOH
RO
VCC
RO
VOH/2
(VOL + VCC)/2
0
VOL
3V
RE
1.5V
0
S1 CLOSED
S2 OPEN
S3 = -1.5V
3V
S1 OPEN
S2 CLOSED
S3 = +1.5V
RE
1.5V
0
S1 CLOSED
S2 OPEN
S3 = -1.5V
tRHZ
RO
tRLZ
VOH
0.25V
VCC
RO
0
0.25V
VOL
Figure 7. Receiver Enable and Disable Times
_______________________________________________________________________________________
7
MAX3430
Test Circuits/Timing Diagrams (continued)
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
MAX3430
Pin Description
PIN
NAME
1
RO
Receiver Output
FUNCTION
2
RE
Receiver Output Enable. RO is enabled when RE is low; RO is high impedance when RE is high. The
device enters a low-power shutdown mode if RE is high and DE is low.
3
DE
Driver Output Enable. Driving DE high enables the driver outputs. Pulling DE low puts the driver
outputs in a high-impedance state. If RE is high and DE is low, the device enters a low-power
shutdown mode. If the driver outputs are enabled, the device functions as a line driver, and when
they are high impedance it functions as a line receiver if RE is low.
4
DI
Driver Input. A logic low on DI forces output A low and output B high, while a logic high on DI forces
output A high and output B low.
5
GND
6
A
Ground
Noninverting Receiver Input/Driver Output
7
B
8
VCC
Inverting Receiver Input/Driver Output
Positive Supply, VCC = +3.3V ±10%. Bypass VCC to GND with a 0.1µF ceramic capacitor.
Function Tables
Table 1. Transmitting
INPUTS
Table 2. Receiving
OUTPUTS
MODE
RE
DE
Normal
0
Normal
0
0
RE
DE
DI
B
A
X
1
1
0
1
X
1
0
1
0
0
0
X
High-Z
High-Z
Normal
1
0
X = Don’t care.
X
High-Z
High-Z
Shutdown
8
INPUTS
1
X = Don’t care.
OUTPUTS
MODE
(A - B)
RO
0
≥ -50mV
1
Normal
0
≤ -200mV
0
Normal
0
Inputs
open
1
Normal
0
X
High-Z
Shutdown
_______________________________________________________________________________________
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
Driver
The driver accepts a single-ended, logic-level input
(DI) and transfers it to a differential, RS-485 level output
(A and B). Driving DE high enables the driver, while
pulling DE low places the driver outputs (A and B) into
a high-impedance state.
Receiver
The receiver accepts a differential, RS-485 level input
(A and B), and transfers it to a single-ended, logic-level
output (RO). Pulling RE low enables the receiver, while
driving RE high and DE low places the receiver inputs
(A and B) into a high-impedance state.
Low-Power Shutdown
Force DE low and RE high to shut down the MAX3430. A
time delay of 1µs prevents the device from accidentally
entering shutdown due to logic skews when switching
between transmit and receive modes. Holding DE low
and RE high for at least 1ms guarantees that the
MAX3430 enters shutdown. In shutdown, the device
consumes 100µA supply current.
±80V Fault Protection
The driver outputs/receiver inputs of RS-485 devices in
industrial network applications often experience voltage
faults resulting from transients that exceed the -7V to
+12V range specified in the EIA/TIA-485 standard. In
these applications, ordinary RS-485 devices (typical
absolute maximum ratings -8V to +12.5V) require costly
external protection devices. To reduce system complexity and the need for external protection, the driver
outputs/receiver inputs of the MAX3430 withstand voltage faults of up to ±80V with respect to ground without
damage (see the Absolute Maximum Ratings section,
Note 1). Protection is guaranteed regardless of whether
the device is active, shut down, or without power.
RC
1MΩ
CHARGE-CURRENTLIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
Cs
100pF
RD
1.5kΩ
±12kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against ESD
encountered during handling and assembly. The
MAX3430 receiver inputs/driver outputs (A, B) have
extra protection against static electricity found in normal operation. Maxim’s engineers have developed
state-of-the-art structures to protect these pins against
±12kV ESD without damage. After an ESD event, the
MAX3430 continues working without latchup.
ESD protection can be tested in several ways. The
receiver inputs are characterized for protection up to
±12kV using the Human Body Model.
ESD Test Conditions
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
Human Body Model
Figure 8a shows the Human Body Model, and Figure
8b shows the current waveform it generates when discharged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the device through a
1.5kΩ resistor.
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or bus contention.
The first, a foldback current limit on the driver output
IP 100%
90%
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
True Fail-Safe
The MAX3430 uses a -50mV to -200mV differential
input threshold to ensure true fail-safe receiver inputs.
This threshold guarantees the receiver outputs a logic
high for shorted, open, or idle data lines. The -50mV to
-200mV threshold complies with the ±200mV threshold
EIA/TIA-485 standard.
Ir
AMPERES
DEVICE
UNDER
TEST
36.8%
10%
0
0
Figure 8a. Human Body ESD Test Model
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
tRL
TIME
tDL
CURRENT WAVEFORM
Figure 8b. Human Body Model Current Waveform
_______________________________________________________________________________________
9
MAX3430
Detailed Description
MAX3430
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
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 exceeds +160°C. Normal operation resumes when
the die temperature cools by +140°C, resulting in a
pulsed output during continuous short-circuit conditions.
VCC
15µs
TIMER
TIMER
5.6kΩ
DE
(HOT SWAP)
DE
2mA
100µA
M1
M2
Figure 9. Simplified Structure of the Driver Enable Pin (DE)
Hot-Swap Capability
Hot-Swap Inputs
Inserting circuit boards into a hot, or powered backplane
may cause voltage transients on DE, RE, and receiver
inputs A and B that can lead to data errors. For example,
upon initial circuit board insertion, the processor undergoes a power-up sequence. During this period, the highimpedance state of the output drivers makes them
unable to drive the MAX3430 enable inputs to a defined
logic level. Meanwhile, leakage currents of up to 10µA
from the high-impedance output, or capacitively coupled
noise from VCC or GND, could cause an input to drift to
an incorrect logic state. To prevent such a condition from
occurring, the MAX3430 features hot-swap input circuitry
on DE to safeguard against unwanted driver activation
during hot-swap situations. When VCC rises, an internal
pulldown circuit holds DE low for at least 10µs, and until
the current into DE exceeds 200µA. After the initial
power-up sequence, the pulldown circuit becomes
transparent, resetting the hot-swap tolerable input.
Hot-Swap Input Circuitry
At the driver enable input (DE), there are two NMOS
devices, M1 and M2 (Figure 9). When VCC ramps from
0, an internal 15µs timer turns on M2 and sets the SR
latch, which also turns on M1. Transistors M2, a 2mA
current sink, and M1, a 100µA current sink, pull DE to
GND through a 5.6kΩ resistor. M2 pulls DE to the disabled state against an external parasitic capacitance
up to 100pF that may drive DE high. After 15µs, the
timer deactivates M2 while M1 remains on, holding DE
low against three-state leakage currents that may drive
DE high. M1 remains on until an external current source
overcomes the required input current. At this time, the
SR latch resets M1 and turns off. When M1 turns off, DE
reverts to a standard, high-impedance CMOS input.
Whenever VCC drops below 1V, the input is reset.
120Ω
120Ω
DE
B
B
DI
D
D
DI
DE
RO
RE
A
B
A
B
A
A
R
R
RE
R
R
D
D
MAX3430
DI
DE
RO RE
DI
DE
RO RE
Figure 10. Typical RS-485 Network
10
RO
______________________________________________________________________________________
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
128 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12kΩ
(one-unit load), and a standard driver can drive up to
32-unit loads. The MAX3430 transceiver 1/4-unit-load
receiver input impedance (48kΩ) allows up to 128
transceivers connected in parallel on one communication line. Connect any combination of these devices,
and/or other RS-485 devices, for a maximum of 32 unit
loads to the line.
RS-485 Applications
The MAX3430 transceiver provides bidirectional data
communications on multipoint bus transmission lines.
Figure 10 shows a typical network applications circuit.
The RS-485 standard covers line lengths up to 4000ft.
The signal line must be terminated at both ends in its
characteristic impedance, and stub lengths off the
main line kept as short as possible.
Chip Information
TRANSISTOR COUNT: 300
PROCESS: BiCMOS
______________________________________________________________________________________
11
MAX3430
Applications Information
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
DIM
A
A1
B
C
e
E
H
L
N
E
H
INCHES
MILLIMETERS
MAX
MIN
0.069
0.053
0.010
0.004
0.014
0.019
0.007
0.010
0.050 BSC
0.150
0.157
0.228
0.244
0.016
0.050
MAX
MIN
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
1.27 BSC
3.80
4.00
5.80
6.20
0.40
SOICN .EPS
MAX3430
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
1.27
VARIATIONS:
1
INCHES
TOP VIEW
DIM
D
D
D
MIN
0.189
0.337
0.386
MAX
0.197
0.344
0.394
MILLIMETERS
MIN
4.80
8.55
9.80
MAX
5.00
8.75
10.00
N MS012
8
AA
14
AB
16
AC
D
A
B
e
C
0 -8
A1
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
21-0041
12
______________________________________________________________________________________
REV.
B
1
1
±80V Fault-Protected, Fail-Safe,
1/4-Unit Load, +3.3V RS-485 Transceiver
PDIPN.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
MAX3430
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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