General Description
The MAX3460–MAX3464 are high-speed differential
bus transceivers for RS-485 and RS-422 communica-
tions. They are designed to meet TIA/EIA-422-B,
TIA/EIA-485-A, V.11, and X.27 standards. The trans-
ceiver complies with the Profibus specification provid-
ing +2.1V output level with a 54Ωload, 20Mbps data
rate, and output skew less than 2ns. Each part contains
one three-state differential line driver and one differen-
tial input line receiver. The devices operate from a +5V
supply and feature true fail-safe circuitry, which guaran-
tees a logic-high receiver output when the receiver
inputs are open or shorted. This enables all receiver
outputs on a terminated bus to output logic highs when
all transmitters are disabled.
All devices feature a 1/4 standard unit load receiver
input impedance that allows 128 transceivers on the
bus. Driver and receiver propagation delays are guar-
anteed under 20ns for multidrop, clock distribution
applications. Drivers are short-circuit current limited
and are protected against excessive power dissipation
by thermal shutdown circuitry. The driver and receiver
feature active-high and active-low enables, respective-
ly, that can be connected together externally to serve
as a direction control.
Applications
High-Speed RS-485 Communications
High-Speed RS-422 Communications
Level Translators
Industrial-Control Local Area Networks
Profibus Applications
Features
♦Recommended for Profibus Applications
♦Guaranteed 20Mbps Data Rate
♦20ns Transmitter and Receiver Propagation Delay
♦2ns Transmitter and Receiver Skew
♦High Differential Driver Output Level (2.1V on 54Ω)
♦Hot-Swap Versions
♦1µA Shutdown Supply Current
♦Low Supply Current Requirements (2.5mA typ)
♦Allow Up to 128 Transceivers on the Bus
♦True Fail-Safe Receiver while Maintaining EIA/TIA-
485 Compatibility
♦Designed for Multipoint Transmissions on Long
or Noisy Bus Lines
♦Full Duplex and Half Duplex Versions Available
♦Phase Controls to Correct for Twisted-Pair
Reversal for 14-Pin Versions
♦Current-Limiting and Thermal Shutdown for
Driver Overload Protection
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
PART
NUMBER
HALF/FULL
DUPLEX
RECEIVER/
DRIVER
ENABLE
LOW-
POWER
SHUTDOWN
HOT SWAP
RECEIVER/
DRIVER PHASE
SELECT
INDEPENDENT
SHDN PIN
PIN COUNT
MAX3460 Full Yes Yes Yes Yes Yes 14
MAX3461 Full Yes Yes No Yes Yes 14
MAX3462 Full No No No No No 8
MAX3463 Half Yes Yes Yes No No 8
MAX3464 Half Yes Yes No No No 8
Selector Guide
19-2217; Rev 1; 2/03
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.
Ordering Information continued at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX3460CSD 0°C to +70°C 14 SO
MAX3460CPD 0°C to +70°C 14 Plastic DIP
MAX3460ESD -40°C to +85°C 14 SO
MAX3460EPD -40°C to +85°C 14 Plastic DIP
Pin Configurations appear at end of data sheet.
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +5V ±5%, TA= TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA= +25°C.) (Note 1)
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.
Supply Voltage (VCC) to GND ..................................-0.3V to +6V
Control Input Voltage (RE, DE, DI, SHDN, TXP, RXP)
to GND....................................................-0.3V to (VCC + 0.3V)
Driver Output Voltage (Y, Z) to GND .........................-8V to +13V
Receiver Input Voltage (A, B) to GND.......................-8V to +13V
Differential Driver Output Voltage (Y - Z) ...............................±8V
Differential Receiver Input (A - B) ..........................................±8V
Receiver Output Voltage (RO) to GND.......-0.3V to (VCC + 0.3V)
Output Driver Current (Y, Z) ...........................................±250mA
Continuous Power Dissipation (TA= +70°C)
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
8-Pin DIP (derate 9.09mW/°C above +70°C)...............727mW
14-Pin SO (derate 8.33mW/°C above +70°C)..............667mW
14-Pin DIP (derate 10mW/°C above +70°C)................800mW
Operating Temperature Range
MAX346_C__ ......................................................0°C to +70°C
MAX346_E__....................................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Power-Supply Range VCC 4.75 5.25 V
DRIVER
Differential Driver Output (no load) VOD Figure 5, R = ∞VCC V
Differential Driver Output VOD Figure 5, R = 27Ω2.1 V
Change in Magnitude of
Differential Output Voltage ∆VOD Figure 5, R = 50Ω or 27Ω
(Note 2) 0.2 V
Driver Common-Mode Output
Voltage VOC Figure 5, R = 50Ω or 27Ω3V
Change in Magnitude of
Common-Mode Voltage ∆VOC Figure 5, R = 50Ω or 27Ω
(Note 2) 0.2 V
Input High Voltage VIH DE, DI, RE, SHDN 2.0 V
Input Low Voltage VIL DE, DI, RE, SHDN 0.8 V
Input Hysteresis VHYS DE, DI, RE, SHDN 50 mV
VIN = +12V +125
Output Leakage (Y and Z) Full
Duplex IODE = GND, VCC =
GND or +5.25V VIN = -7V -100 µA
Input Current IIN DI, RE, DE, SHDN ±1µA
Pulldown Current RXP = TXP = VCC 51530µA
0 ≤ VOUT ≤ 12V, output low +250
Driver Short-Circuit Output
Current (Note 3) IOSD -7V ≤ VOUT ≤ VCC, output high -250 mA
(VCC - 1V) ≤ VOUT ≤ 12V, output low +25
Driver Short-Circuit Foldback
Output Current (Note 3) IOSFD -7V ≤ VOUT ≤ 1V, output high -25 mA
Thermal Shutdown Threshold 140 °C
RECEIVER
Differential Input Capacitance CA, B 8pF
VIN = +12V 250
Input Current (A and B) Full
Duplex IA, B DE = GND,
VCC = GND or 5.25V VIN = -7V -200 µA
Receiver Differential Threshold
Voltage VTH -7V ≤ VCM ≤ 12V -200 -125 -50 mV
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V ±5%, TA= TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Receiver Input Hysteresis ∆VTH VA + VB = 0 20 mV
Receiver Output High Voltage VOH IO = -4mA, VA - VB = VTH VCC - 1.5 V
Receiver Output Low Voltage VOL IO = 4mA, VB - VA = VTH 0.4 V
Three-State Output Current at
Receiver IOZR 0 ≤ VO ≤ VCC ±1µA
Receiver Input Resistance RIN -7V ≤ VCM ≤ 12V 48 kΩ
Receiver Output Short-Circuit
Current IOSR 0 ≤ VRO ≤ VCC ±7 ±95 mA
SUPPLY CURRENT
N or m al O p er ati on ( stati c cond i ti on) IQNo load, DI = VCC or DI = GND 2.5 4 mA
Supply Current in SHDN ISHDN DE = GND and RE = VCC, or SHDN = VCC 110µA
SWITCHING CHARACTERISTICS
tPLH
Driver Propagation Delay tPHL
Figures 6 and 7, RDIFF = 54Ω,
CL = 50pF 20 ns
tR
Driver Differential Output Rise or
Fall Time tF
Figures 6 and 7, RDIFF = 54Ω,
CL = 50pF 20 ns
Driver Output Skew |tPLH - tPHL|t
SKEW Figures 6 and 7, RDIFF = 54Ω,
CL = 50pF, TXP = GND or floating 2ns
Maximum Data Rate 20 Mbps
Driver Enable to Output High tZH Figures 8 and 9, S2 closed, RL = 500Ω,
CL = 50pF 100 ns
Driver Enable to Output Low tZL Figures 8 and 9, S1 closed, RL = 500Ω,
CL = 50pF 100 ns
Driver Disable Time from Low tLZ Figures 8 and 9, S1 closed, RL = 500Ω,
CL = 50pF 100 ns
Driver Disable Time from High tHZ Figures 8 and 9, S2 closed, RL = 500Ω,
CL = 50pF 100 ns
tPLH
Receiver Propagation Delay tPHL
Figure 10, CL = 15pF (Note 4) 20 ns
Recei ver O utp ut S kew |tPLH - tP H L
| tSKEW Figure 10, CL = 15pF, RXP = GND or
floating (Note 4) 2ns
Receiver Enable to Output Low tZL Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S1 closed (Note 4) 100 ns
Receiver Enable to Output High tZH Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Note 4) 100 ns
Receiver Disable Time from Low tLZ Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S1 closed (Note 4) 100 ns
Receiver Disable Time from High tHZ Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Note 4) 100 ns
Note 1: All currents into the device are positive; all currents out of the device are negative. All voltages are referenced to device
ground, unless otherwise noted.
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.
Note 4: Capacitive load includes test probe and fixture capacitance.
Note 5: Shutdown is enabled by bringing RE high and DE low or by bringing SHDN high. 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 800ns, the device
is guaranteed to have entered shutdown.
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V ±5%, TA= TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
Time to Shutdown tSHDN (Note 5) 50
800
ns
Driver Enable from Shutdown to
Output High
tZH
(
SHDN
)
Figures 8 and 9, RL = 500Ω, CL = 50pF,
S2 closed (Note 5) 4µs
Driver Enable from Shutdown to
Output Low
tZL
(
SHDN
)
Figures 8 and 9, RL = 500Ω, CL = 50pF,
S1 closed (Note 5) 4µs
Receiver Enable from Shutdown to
Output High
tZH
(
SHDN
)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Notes 4, 5) 4µs
Receiver Enable from Shutdown to
Output Low
tZL
(
SHDN
)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S1 closed (Notes 4, 5) 4µs
NO LOAD SUPPLY CURRENT
vs. TEMPERATURE
MAX3460-64 toc01
2.00
2.05
2.15
2.10
2.30
2.35
2.25
2.20
2.40
NO LOAD SUPPLY CURRENT (mA)
-40 0 20-20 40 60 80
TEMPERATURE (°C)
DE = VCC
DE = GND
0
30
20
10
40
50
60
0 2.01.50.5 1.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT CURRENT
vs. RECEIVER OUTPUT LOW VOLTAGE
MAX3460-64 toc02
OUTPUT LOW VOLTAGE (V)
OUTPUT CURRENT (mA)
0
10
5
20
15
30
25
35
021345
OUTPUT CURRENT
vs. RECEIVER OUTPUT HIGH VOLTAGE
MAX3460-64 toc03
OUTPUT HIGH VOLTAGE (V)
OUTPUT CURRENT (mA)
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 5
11
10
9
8
7
-40 10-15 35 60 85
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
MAX3460-64 toc07
TEMPERATURE (°C)
PROPAGATION DELAY (ns)
12
10
8
6
4
-40 10-15 35 60 85
DRIVER PROPAGATION DELAY
vs. TEMPERATURE
MAX3460-64 toc08
TEMPERATURE (°C)
PROPAGATION DELAY (ns)
RDIFF = 54Ω
CL = 50pF
4.0
3.5
3.0
2.5
2.0
-40 10-15 35 60 85
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
MAX3460-64 toc09
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
RDIFF = 54Ω
0.1
10
1
100
021345
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX3460-64 toc10
DIFFERENTIAL OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
0
40
120
80
160
200
OUTPUT CURRENT
vs. DRIVER OUTPUT LOW VOLTAGE
MAX3460-64 toc11
OUTPUT LOW VOLTAGE (V)
OUTPUT CURRENT (mA)
063912
0
-40
-120
-80
-160
OUTPUT CURRENT
vs. DRIVER OUTPUT HIGH VOLTAGE
MAX3460-64 toc12
OUTPUT HIGH VOLTAGE (V)
OUTPUT CURRENT (mA)
-7 -3-5 -1 1 3 5
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
0
10
30
20
40
50
-40 10-15 35 60 85
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX3460-64 toc04
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (nA)
80
120
100
140
-40 10-15 35 60 85
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
MAX3460-64 toc05
TEMPERATURE (°C)
RECEIVER OUTPUT LOW VOLTAGE (mV)
IO = 4mA
4.60
4.70
4.65
4.80
4.75
4.85
4.90
-40 85
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
MAX3460-64 toc06
TEMPERATURE (°C)
OUTPUT HIGH VOLTAGE (V)
10-15 35 60
IO = -4mA
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
6 _______________________________________________________________________________________
Pin Description
PIN
MAX3460/
MAX3461 MAX3462 MAX3463/
MAX3464
FULL DUPLEX HALF
DUPLEX
NAME FUNCTION
1——SHDN Shutdown. Drive SHDN high to enter low-power shutdown mode.
221RO
Receiver Output. When RE is low and (A - B) ≥ -50mV, RO is high; if (A - B) ≤
-200mV, RO is low.
3—2RE Receiver Output Enable. Drive RE low to enable RO; RO is high impedance
when RE is high. Drive RE high and DE low to enter low-power shutdown mode.
4—3DE
Driver Output Enable. Drive DE high to enable driver output. These outputs
are high impedance when DE is low. Drive RE high and DE low to enter low-
power shutdown mode.
534DI
Driver Input. With DE high, a low on DI forces the noninverting output low and
the inverting output high. Similarly, a high on DI forces the noninverting output
high and the inverting output low.
6, 7 4 5 GND Ground
8——TXP
Transmitter Phase. Connect TXP to GND, or leave unconnected for normal
transmitter phase/polarity. Connect TXP to VCC to invert the transmitter
phase/polarity. TXP has an internal 15µA pulldown.
95—Y Noninverting Driver Output
10 6 —Z Inverting Driver Output
11 7 —B Inverting Receiver Input
12 8 —A Noninverting Receiver Input
13 ——RXP
Receiver Phase. Connect RXP to GND, or leave unconnected for normal
receiver phase/polarity. Connect RXP to VCC to invert the receiver
phase/polarity. RXP has an internal 15µA pulldown.
14 1 8 VCC Positive Supply: +4.75V ≤ VCC ≤ +5.25V. Bypass VCC to GND with a 0.1µF
capacitor.
—— 7 B Inverting Receiver Input and Inverting Driver Output
—— 6 A Noninverting Receiver Input and Noninverting Driver Output
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
05V/div
2V/div
5V/div
0
0
DRIVER AND RECEIVER
PROPAGATION DELAYS
MAX3460-64 toc13
DI
Y, Z
RO
10ns/div
0
0
ENABLE RESPONSE TIME
MAX3460-64 toc14
DE
Y, Z
20ns/div
1V/div
5V/div
EYE DIAGRAM
MAX3460-64 toc15
10ns/div
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 7
MAX3460/MAX3461
Function Tables
TRANSMITTING
INPUTS OUTPUTS
RE DE DI SHDN Z Y
X11001
X10010
0 0 X 0 High-Z High-Z
1 0 X X Shutdown
X X X 1 Shutdown
RECEIVING
INPUTS OUTPUT
RE DE A–B SHDN RO
0X≥ -0.05V 0 1
0X≤ -0.2V 0 0
0 X Open/Shorted 0 1
1 1 X 0 High-Z
1 0 X X Shutdown
X X X 1 Shutdown
MAX3462
TRANSMITTING
INPUT OUTPUTS
DI Z Y
101
010
RECEIVING
INPUTS OUTPUT
A–BRO
≥ -0.05V 1
≤ -0.2V 0
Open/Shorted 1
MAX3463/MAX3464
TRANSMITTING
INPUTS OUTPUTS
RE DE DI B A
X11 0 1
X10 1 0
0 0 X High-Z High-Z
1 0 X Shutdown
RECEIVING
INPUTS OUTPUT
RE DE A–BRO
0X ≥ -0.05V 1
0X ≤ -0.2V 0
0 X Open/Shorted 1
1 1 X High-Z
1 0 X Shutdown
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
8 _______________________________________________________________________________________
Pin Configurations and Typical Operating Circuit
TOP VIEW
14
13
12
11
10
9
8
1
2
3
4
5
6
7
VCC
VCC VCC
RXP
A
BDE
DE
RE
RE
RO
SHDN
MAX3460
MAX3461
Z
Y
TXP RXP
TXP
RO
RO
DI
DI
GND
GND
DI
DIP/SO
R
R
6, 7
3 GND
12
10
9
Z
Y
11
A
B
0.1µF
5
414
2
13
8
D
DR
Rt
Rt
DE
GND
D
RE
Figure 1. MAX3460/MAX3461 Pin Configuration and Typical Full-Duplex Operating Circuit
TOP VIEW
8
7
6
5
1
2
3
4
VCC
VCC
A
B
RO
VCC
MAX3462
Z
YRO
RO
DI
DI
GND
DI
DIP/SO
R
R
4 GND
8
6
5
Z
Y
7
A
B
0.1µF
3
1
2
D
DR
Rt
Rt
GND
D
Figure 2. MAX3462 Pin Configuration and Typical Full-Duplex Operating Circuit
TOP VIEW
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH.
8
7
6
5
1
2
3
4
VCC
B
RE
RO
MAX3463
MAX3464
A
GND RO
DI
DI
DE
DIP/SO
R
0.1µF
D
Rt
Rt
8
7
6
5
1
2
3
4
VCC
B
RE
RO
A
B
A
GND
DI
DE
DE
R
D
R
D
RE
Figure 3. MAX3463/MAX3464 Pin Configuration and Typical Full-Duplex Operating Circuit
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 9
Detailed Description
The MAX3460–MAX3464 high-speed transceivers for
RS-485/RS-422 communication contain one driver and
one receiver. These devices feature true fail-safe cir-
cuitry, which guarantees a logic-high receiver output
when the receiver inputs are open or shorted, or when
they are connected to a terminated transmission line
with all drivers disabled (see the True Fail-Safe sec-
tion). The MAX3460–MAX3464’s driver slew rates allow
transmit speeds up to 20Mbps.
The MAX3463 and MAX3464 are half-duplex trans-
ceivers, while the MAX3460, MAX3461, and MAX3462
are full-duplex transceivers. All of these parts operate
from a single +5V supply. Drivers are output short-cir-
cuit current limited. Thermal shutdown circuitry protects
drivers against excessive power dissipation. When acti-
vated, the thermal shutdown circuitry places the driver
outputs into a high-impedance state. The MAX3460
and MAX3463 devices have a hot-swap input structure
that prevents disturbances on the differential signal
lines when a circuit board is plugged into a “hot” back-
plane (see Hot Swap section). All devices have output
levels that are compatible with Profibus standards.
True Fail-Safe
The MAX3460–MAX3464 guarantee a logic-high receiv-
er output when the receiver inputs are shorted or open,
or when they are connected to a terminated transmis-
sion line with all drivers disabled. This is done by set-
ting 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 dis-
abled, the receiver’s differential input voltage is pulled
to 0V by the termination. With the receiver thresholds of
the MAX3460–MAX3464, this results in a logic high with
a 50mV minimum noise margin. Unlike previous true
fail-safe devices, the -50mV to -200mV threshold com-
plies with the ±200mV EIA/TIA-485 standard.
Hot-Swap Capability
Hot-Swap Inputs
When circuit boards are inserted into a “hot” or pow-
ered backplane, disturbances to the enable and differ-
ential receiver inputs can lead to data errors. Upon
initial circuit board insertion, the processor undergoes
its power-up sequence. During this period, the output
drivers are high impedance and are unable to drive the
DE input of the MAX3460/MAX3463 to a defined logic
level. Leakage currents up to 10µA from the high-
impedance output could cause DE to drift to an incor-
rect logic state. Additionally, parasitic circuit board
capacitance could cause coupling of VCC or GND to
DE. These factors could improperly enable the driver.
When VCC rises, an internal pulldown circuit holds DE
low for around 15µs. After the initial power-up
sequence, the pulldown circuit becomes transparent,
resetting the hot-swap tolerable input.
Hot-Swap Input Circuitry
The MAX3460/MAX3463 enable inputs feature hot-swap
capability. At the input there are two NMOS devices, M1
and M2 (Figure 4). 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
5.6kΩresistor. M2 is designed to pull DE to the disabled
state against an external parasitic capacitance up to
100pF that can drive DE high. After 15µs, the timer
deactivates M2 while M1 remains on, holding DE low
against three-state leakages that can drive DE high. M1
remains on until an external source overcomes the
required input current. At this time, the SR latch resets
and M1 turns off. When M1 turns off, DE reverts to a
standard, high-impedance CMOS input. Whenever VCC
drops below 1V, the hot-swap input is reset.
For RE there is a complimentary circuit employing two
PMOS devices pulling RE to VCC.
VCC
TIMER
TIMER
EN
DE
(HOT SWAP)
15µs
100µA
M1 M2
5.6kΩ
2mA
Figure 4. Simplified Structure of the Driver Enable Pin (DE)
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
10 ______________________________________________________________________________________
Y
Z
VOD
R
RVOC
Figure 5. Driver DC Test Load
DI
DE
3V
Y
VID CL
RDIFF
Z
Figure 6. Driver Timing Test Circuit
DI
3V
0
Z
Y
VO
0
-VO
VO
1.5V
1/2 VO
1/2 VO
tPLH
tF
tR
tPHL
10%
90% 90%
1.5V
10%
VDIFF = V (Y) - V (Z)
tSKEW = | tPLH - tPHL |
VDIFF
ƒ = 1MHz, tR ≤ 3ns, tF ≤ 3ns
Figure 7. Driver Propagation Delays
S1
S2
OUTPUT
UNDER TEST
VCC
CL
RL
Figure 8. Enable/Disable Timing Test Load
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
3V
0
Y, Z
VOL
Y, Z
0
1.5V 1.5V
VOL + 0.5V
VOH - 0.5V
2.3V
2.3V
tZL(SHDN), tZL tLZ
tZH(SHDN), tZH tHZ
DE
Figure 9. Driver Enable and Disable Times
VOH
VOL
A
B
1V
-1V
1.5V 1.5V
OUTPUT
INPUT
RO
tPLH
tPHL
ƒ = 1MHz, tR ≤ 3ns, tF ≤ 3ns
Figure 10. Receiver Propagation Delays
3V
0
VCC
RO
RO
0
1.5V
1.5V
RE
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
1.5V 1.5V
VOL + 0.5V
VOH - 0.5V
tZL(SHDN), tZL tLZ
tZH(SHDN), tZH tHZ
Figure 11. Receiver Enable and Disable Times
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
______________________________________________________________________________________ 11
Applications Information
128 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 MAX3460–MAX3464 family of trans-
ceivers has a 1/4-unit-load receiver input impedance
(48kΩ), allowing up to 128 transceivers to be connect-
ed in parallel on one communication line. Any combina-
tion of these devices and/or other RS-485 transceivers
with a total of 32 unit loads or less can be connected to
the line.
Low-Power Shutdown Mode
(except MAX3462)
Low-power shutdown mode is initiated by bringing
SHDN high (MAX3460/MAX3461), or both RE high and
DE low. In shutdown, the devices typically draw only
1µA of supply current. RE and DE can be driven simul-
taneously; the parts are guaranteed not to enter shut-
down if RE is high and DE is low for less than 50ns. If
the inputs are in this state for at least 800ns, the parts
are guaranteed to enter shutdown.
Driver Output Protection
Two mechanisms prevent excessive output current and
power dissipation caused by faults or by bus con-
tention. The first, a foldback current limit on the output
stage, provides immediate protection against short cir-
cuits over the whole common-mode voltage range (see
Typical Operating Characteristics). The second, a ther-
mal shutdown circuit, forces the driver outputs into a
high-impedance state if the die temperature exceeds
+140°C.
Propagation Delay
Many digital encoding schemes depend on the difference
between the driver and receiver propagation delay times.
Typical propagation delays are shown in the Typical
Operating Characteristics. The difference in receiver delay
times, |tPLH - tPHL|, is a maximum of 2ns. The driver skew
time |tPLH - tPHL| is also a maximum of 2ns.
Typical Applications
The MAX3460–MAX3464 transceivers are designed for
bidirectional data communications on multipoint bus
transmission lines. Figures 13 and 14 show typical net-
work applications circuits. To minimize reflections, the
line should be terminated at both ends in its character-
istic impedance, and stub lengths off the main line
should be kept as short as possible.
Profibus Termination
The MAX3460–MAX3464 are designed for driving
Profibus termination networks. With a worst-case load-
ing of two termination networks with 220Ωtermination
impedance and 390Ωpullups and pulldowns, the dri-
vers can drive VA-B> 2.1V output.
Chip Information
TRANSISTOR COUNT: 610
PROCESS: BiCMOS
VID
ATE RECEIVER
OUTPUT
B
A
R
Figure 12. Receiver Propagation Delay Test Circuit
Ordering Information (continued)
PART TEMP RANGE PIN-PACKAGE
MAX3461CSD 0°C to +70°C 14 SO
MAX3461CPD 0°C to +70°C 14 Plastic DIP
MAX3461ESD -40°C to +85°C 14 SO
MAX3461EPD -40°C to +85°C 14 Plastic DIP
MAX3462CSA 0°C to +70°C 8 SO
MAX3462CPA 0°C to +70°C 8 Plastic DIP
MAX3462ESA -40°C to +85°C 8 SO
MAX3462EPA -40°C to +85°C 8 Plastic DIP
MAX3463CSA 0°C to +70°C 8 SO
MAX3463CPA 0°C to +70°C 8 Plastic DIP
MAX3463ESA -40°C to +85°C 8 SO
MAX3463EPA -40°C to +85°C 8 Plastic DIP
MAX3464CSA 0°C to +70°C 8 SO
MAX3464CPA 0°C to +70°C 8 Plastic DIP
MAX3464ESA -40°C to +85°C 8 SO
MAX3464EPA -40°C to +85°C 8 Plastic DIP
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
12 ______________________________________________________________________________________
MAX3463
MAX3464
(HALF-DUPLEX)
DI
DE
RO
RE
RE
D
R
B
A
B
AABAB
120Ω120Ω
D
R
DI DE RO RE
D
R
DI DE RO
D
R
DE
DI
RO
RE
Figure 13. Typical Half-Duplex RS-485 Network
MAX3460
MAX3461
MAX3462
(FULL-DUPLEX)
D
R
R
D
D
R
DI DE RORE
YZB A B
D
R
DI DE RORE
YZ
120Ω
120Ω
120Ω
120Ω
Y
Z
B
A
DI
DE
RO
RE
NOTE: RE AND DE ON MAX3460/MAX3461/MAX3462 ONLY
RO
DE
DI
RE
A
B
Z
Y
Figure 14. Typical Full-Duplex RS-485 Network
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
______________________________________________________________________________________ 13
SOICN .EPS
PACKAGE OUTLINE, .150" SOIC
1
1
21-0041 B
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
TOP VIEW
FRONT VIEW
MAX
0.010
0.069
0.019
0.157
0.010
INCHES
0.150
0.007
E
C
DIM
0.014
0.004
B
A1
MIN
0.053A
0.19
3.80 4.00
0.25
MILLIMETERS
0.10
0.35
1.35
MIN
0.49
0.25
MAX
1.75
0.050
0.016L0.40 1.27
0.3940.386D
D
MINDIM
D
INCHES
MAX
9.80 10.00
MILLIMETERS
MIN MAX
16 AC
0.337 0.344 AB8.758.55 14
0.189 0.197 AA5.004.80 8
N MS012
N
SIDE VIEW
H 0.2440.228 5.80 6.20
e 0.050 BSC 1.27 BSC
C
HE
eBA1
A
D
0-8
L
1
VARIATIONS:
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.)
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
PDIPN.EPS
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.)