General Description
The MAX3460MAX3464 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 54
load, 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
o Recommended for Profibus Applications
o Guaranteed 20Mbps Data Rate
o 20ns Transmitter and Receiver Propagation Delay
o 2ns Transmitter and Receiver Skew
o High Differential Driver Output Level (2.1V on 54)
o Hot-Swap Versions
o 1A Shutdown Supply Current
o Low Supply Current Requirements (2.5mA typ)
o Allow Up to 128 Transceivers on the Bus
o True Fail-Safe Receiver while Maintaining EIA/TIA-
485 Compatibility
o Designed for Multipoint Transmissions on Long
or Noisy Bus Lines
o Full Duplex and Half Duplex Versions Available
o Phase Controls to Correct for Twisted-Pair
Reversal for 14-Pin Versions
o Current-Limiting and Thermal Shutdown for
Driver Overload Protection
MAX3460MAX3464
+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
0C to +70C
14 SO
MAX3460CPD
0C to +70C
14 Plastic DIP
MAX3460ESD
-40C to +85C
14 SO
MAX3460EPD
-40C to +85C
14 Plastic DIP
Pin Configurations appear at end of data sheet.
MAX3460MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= +5V 5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V and T
A
= +25C.) (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 (V
CC
) to GND ..................................-0.3V to +6V
Control Input Voltage (RE, DE, DI, SHDN, TXP, RXP)
to GND....................................................-0.3V to (V
CC
+ 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 (V
CC
+ 0.3V)
Output Driver Current (Y, Z) ...........................................250mA
Continuous Power Dissipation (T
A
= +70C)
8-Pin SO (derate 5.88mW/C above +70C)................471mW
8-Pin DIP (derate 9.09mW/C above +70C) ...............727mW
14-Pin SO (derate 8.33mW/C above +70C)..............667mW
14-Pin DIP (derate 10mW/C above +70C) ................800mW
Operating Temperature Range
MAX346_C__ ......................................................0C to +70C
MAX346_E__....................................................-40C to +85C
Junction Temperature ......................................................+150C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10s) .................................+300C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Power-Supply Range
V
CC
4.75
5.25
V
DRIVER
Differential Driver Output (no load)
V
OD
Figure 5, R =
V
CC
V
Differential Driver Output
V
OD
Figure 5, R = 27
2.1
V
Change in Magnitude of
Differential Output Voltage
V
OD
Figure 5, R = 50
or 27
(Note 2)
0.2
V
Driver Common-Mode Output
Voltage
V
OC
Figure 5, R = 50
or 27
3
V
Change in Magnitude of
Common-Mode Voltage
V
OC
Figure 5, R = 50
or 27
(Note 2)
0.2
V
Input High Voltage
V
IH
DE, DI, RE, SHDN
2.0
V
Input Low Voltage
V
IL
DE, DI, RE, SHDN
0.8
V
Input Hysteresis
V
HYS
DE, DI, RE, SHDN
50
mV
V
IN
= +12V
+125
Output Leakage (Y and Z) Full
Duplex
I
O
DE = GND, V
CC
=
GND or +5.25V
V
IN
= -7V
-100
A
Input Current
I
IN
DI, RE, DE, SHDN
1
A
Pulldown Current
RXP = TXP = V
CC
5
15
30
A
0
V
OUT
12V, output low
+250
Driver Short-Circuit Output
Current (Note 3)
I
OSD
-7V
V
OUT
V
CC
, output high
-250
mA
(V
CC
- 1V)
V
OUT
12V, output low
+25
Driver Short-Circuit Foldback
Output Current (Note 3)
I
OSFD
-7V
V
OUT
1V, output high
-25
mA
Thermal Shutdown Threshold
140
C
RECEIVER
Differential Input Capacitance
C
A, B
8
pF
V
IN
= +12V
250
Input Current (A and B) Full
Duplex
I
A, B
DE = GND,
V
CC
= GND or 5.25V
V
IN
= -7V
-200
A
Receiver Differential Threshold
Voltage
V
TH
-7V
V
CM
12V
-200
-125
-50
mV
MAX3460MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V 5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V and T
A
= +25C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Receiver Input Hysteresis
V
TH
V
A
+ V
B
= 0
20
mV
Receiver Output High Voltage
V
OH
I
O
= -4mA, V
A
- V
B
= V
TH
V
CC
- 1.5
V
Receiver Output Low Voltage
V
OL
I
O
= 4mA, V
B
- V
A
= V
TH
0.4
V
Three-State Output Current at
Receiver
I
OZR
0
V
O
V
CC
1
A
Receiver Input Resistance
R
IN
-7V
V
CM
12V
48
k
Receiver Output Short-Circuit
Current
I
OSR
0
V
RO
V
CC
7
95
mA
SUPPLY CURRENT
N or m al O p er ati on ( stati c cond i ti on) I
Q
No load, DI = V
CC
or DI = GND
2.5
4
mA
Supply Current in SHDN
I
SHDN
DE = GND and RE = V
CC
, or SHDN = V
CC
1
10
A
SWITCHING CHARACTERISTICS
t
PLH
Driver Propagation Delay
t
PHL
Figures 6 and 7, R
DIFF
= 54
,
C
L
= 50pF
20
ns
t
R
Driver Differential Output Rise or
Fall Time
t
F
Figures 6 and 7, R
DIFF
= 54
,
C
L
= 50pF
20
ns
Driver Output Skew |t
PLH
- t
PHL
|
t
SKEW
Figures 6 and 7, R
DIFF
= 54
,
C
L
= 50pF, TXP = GND or floating
2
ns
Maximum Data Rate
20
Mbps
Driver Enable to Output High
t
ZH
Figures 8 and 9, S2 closed, R
L
= 500
,
C
L
= 50pF
100
ns
Driver Enable to Output Low
t
ZL
Figures 8 and 9, S1 closed, R
L
= 500
,
C
L
= 50pF
100
ns
Driver Disable Time from Low
t
LZ
Figures 8 and 9, S1 closed, R
L
= 500
,
C
L
= 50pF
100
ns
Driver Disable Time from High
t
HZ
Figures 8 and 9, S2 closed, R
L
= 500
,
C
L
= 50pF
100
ns
t
PLH
Receiver Propagation Delay
t
PHL
Figure 10, C
L
= 15pF (Note 4)
20
ns
Recei ver O utp ut S kew |t
PLH
- t
P H L
| t
SKEW
Figure 10, C
L
= 15pF, RXP = GND or
floating (Note 4)
2
ns
Receiver Enable to Output Low
t
ZL
Figures 8 and 11, R
L
= 1k
, C
L
= 15pF,
S1 closed (Note 4)
100
ns
Receiver Enable to Output High
t
ZH
Figures 8 and 11, R
L
= 1k
, C
L
= 15pF,
S2 closed (Note 4)
100
ns
Receiver Disable Time from Low
t
LZ
Figures 8 and 11, R
L
= 1k
, C
L
= 15pF,
S1 closed (Note 4)
100
ns
Receiver Disable Time from High
t
HZ
Figures 8 and 11, R
L
= 1k
, C
L
= 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:
V
OD
and
V
OC
are the changes in V
OD
and V
OC
, 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.
MAX3460MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
4
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V 5%, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V and T
A
= +25C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Time to Shutdown
t
SHDN
(Note 5)
50
800
ns
Driver Enable from Shutdown to
Output High
t
ZH (SHDN)
Figures 8 and 9, R
L
= 500
, C
L
= 50pF,
S2 closed (Note 5)
4
s
Driver Enable from Shutdown to
Output Low
t
ZL (SHDN)
Figures 8 and 9, R
L
= 500
, C
L
= 50pF,
S1 closed (Note 5)
4
s
Receiver Enable from Shutdown to
Output High
t
ZH (SHDN)
Figures 8 and 11, R
L
= 1k
, C
L
= 15pF,
S2 closed (Notes 4, 5)
4
s
Receiver Enable from Shutdown to
Output Low
t
ZL (SHDN)
Figures 8 and 11, R
L
= 1k
, C
L
= 15pF,
S1 closed (Notes 4, 5)
4
s
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 = V
CC
DE = GND
0
30
20
10
40
50
60
0
2.0
1.5
0.5 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
0
2
1
3
4
5
OUTPUT CURRENT
vs. RECEIVER OUTPUT HIGH VOLTAGE
MAX3460-64 toc03
OUTPUT HIGH VOLTAGE (V)
OUTPUT CURRENT (mA)
Typical Operating Characteristics
(V
CC
= +5V, T
A
= +25C, unless otherwise noted.)
MAX3460MAX3464
+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)
R
DIFF
= 54
C
L
= 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)
R
DIFF
= 54
0.1
10
1
100
0
2
1
3
4
5
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)
0
6
3
9
12
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)
(V
CC
= +5V, T
A
= +25C, 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)
I
O
= 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
I
O
= -4mA
MAX3460MAX3464
+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.
2
2
1
RO
Receiver Output. When RE is low and (A - B)
-50mV, RO is high; if (A - B)
-200mV, RO is low.
3
--
2
RE
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
--
3
DE
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.
5
3
4
DI
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 V
CC
to invert the transmitter
phase/polarity. TXP has an internal 15A pulldown.
9
5
--
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 V
CC
to invert the receiver
phase/polarity. RXP has an internal 15A pulldown.
14
1
8
V
CC
Positive Supply: +4.75V
V
CC
+5.25V. Bypass V
CC
to GND with a 0.1F
capacitor.
--
--
7
B
Inverting Receiver Input and Inverting Driver Output
--
--
6
A
Noninverting Receiver Input and Noninverting Driver Output
Typical Operating Characteristics (continued)
(V
CC
= +5V, T
A
= +25C, unless otherwise noted.)
0
5V/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
MAX3460MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________
7
MAX3460/MAX3461
Function Tables
TRANSMITTING
INPUTS
OUTPUTS
RE
DE
DI
SHDN
Z
Y
X
1
1
0
0
1
X
1
0
0
1
0
0
0
X
0
High-Z
High-Z
1
0
X
X
Shutdown
X
X
X
1
Shutdown
RECEIVING
INPUTS
OUTPUT
RE
DE
AB
SHDN
RO
0
X
-0.05V
0
1
0
X
-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
1
0
1
0
1
0
RECEIVING
INPUTS
OUTPUT
AB
RO
-0.05V
1
-0.2V
0
Open/Shorted
1
MAX3463/MAX3464
TRANSMITTING
INPUTS
OUTPUTS
RE
DE
DI
B
A
X
1
1
0
1
X
1
0
1
0
0
0
X
High-Z
High-Z
1
0
X
Shutdown
RECEIVING
INPUTS
OUTPUT
RE
DE
AB
RO
0
X
-0.05V
1
0
X
-0.2V
0
0
X
Open/Shorted
1
1
1
X
High-Z
1
0
X
Shutdown
MAX3460MAX3464
+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
V
CC
V
CC
V
CC
RXP
A
B
DE
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
0.1
F
5
4
14
2
13
8
D
D
R
R
t
R
t
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
V
CC
V
CC
A
B
RO
V
CC
MAX3462
Z
Y
RO
RO
DI
DI
GND
DI
DIP/SO
R
R
4 GND
8
6
5
Z
Y
7
A
B
0.1
F
3
1
2
D
D
R
R
t
R
t
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
V
CC
B
RE
RO
MAX3463
MAX3464
A
GND
RO
DI
DI
DE
DIP/SO
R
0.1
F
D
R
t
R
t
8
7
6
5
1
2
3
4
V
CC
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
MAX3460MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________
9
Detailed Description
The MAX3460MAX3464 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 MAX3460MAX3464'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 MAX3460MAX3464 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 MAX3460MAX3464, 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 10A 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 V
CC
or GND to
DE. These factors could improperly enable the driver.
When V
CC
rises, an internal pulldown circuit holds DE
low for around 15s. 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 V
CC
ramps from 0, an internal
15s timer turns on M2 and sets the SR latch, which
also turns on M1. Transistors M2, a 2mA current sink,
and M1, a 100A current sink, pull DE to GND through a
5.6k
resistor. M2 is designed to pull DE to the disabled
state against an external parasitic capacitance up to
100pF that can drive DE high. After 15s, 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 V
CC
drops below 1V, the hot-swap input is reset.
For RE there is a complimentary circuit employing two
PMOS devices pulling RE to V
CC
.
V
CC
TIMER
TIMER
EN
DE
(HOT SWAP)
15
s
100
A
M1
M2
5.6k
2mA
Figure 4. Simplified Structure of the Driver Enable Pin (DE)
MAX3460MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
10
______________________________________________________________________________________
Y
Z
V
OD
R
R
V
OC
Figure 5. Driver DC Test Load
DI
DE
3V
Y
V
ID
C
L
R
DIFF
Z
Figure 6. Driver Timing Test Circuit
DI
3V
0
Z
Y
V
O
0
-V
O
V
O
1.5V
1/2 V
O
1/2 V
O
t
PLH
t
F
t
R
t
PHL
10%
90%
90%
1.5V
10%
V
DIFF
= V (Y) - V (Z)
t
SKEW
= | t
PLH
- t
PHL
|
V
DIFF
= 1MHz, t
R
3ns, t
F
3ns
Figure 7. Driver Propagation Delays
S1
S2
OUTPUT
UNDER TEST
V
CC
C
L
R
L
Figure 8. Enable/Disable Timing Test Load
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
3V
0
Y, Z
V
OL
Y, Z
0
1.5V
1.5V
V
OL
+ 0.5V
V
OH
- 0.5V
2.3V
2.3V
t
ZL(SHDN)
, t
ZL
t
LZ
t
ZH(SHDN)
, t
ZH
t
HZ
DE
Figure 9. Driver Enable and Disable Times
V
OH
V
OL
A
B
1V
-1V
1.5V
1.5V
OUTPUT
INPUT
RO
t
PLH
t
PHL
= 1MHz, t
R
3ns, t
F
3ns
Figure 10. Receiver Propagation Delays
3V
0
V
CC
RO
RO
0
1.5V
1.5V
RE
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
1.5V
1.5V
V
OL
+ 0.5V
V
OH
- 0.5V
t
ZL(SHDN)
, t
ZL
t
LZ
t
ZH(SHDN)
, t
ZH
t
HZ
Figure 11. Receiver Enable and Disable Times
MAX3460MAX3464
+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 12k
(one-unit load), and the standard driver can drive up to
32 unit loads. The MAX3460MAX3464 family of trans-
ceivers has a 1/4-unit-load receiver input impedance
(48k
), 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
1A 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
+140C.
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, |t
PLH
- t
PHL
|, is a maximum of 2ns. The driver skew
time |t
PLH
- t
PHL
| is also a maximum of 2ns.
Typical Applications
The MAX3460MAX3464 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 MAX3460MAX3464 are designed for driving
Profibus termination networks. With a worst-case load-
ing of two termination networks with 220
termination
impedance and 390
pullups and pulldowns, the dri-
vers can drive V
A-B
> 2.1V output.
Chip Information
TRANSISTOR COUNT: 610
PROCESS: BiCMOS
V
ID
ATE
RECEIVER
OUTPUT
B
A
R
Figure 12. Receiver Propagation Delay Test Circuit
Ordering Information (continued)
PART
TEMP RANGE
PIN-PACKAGE
MAX3461CSD
0C to +70C
14 SO
MAX3461CPD
0C to +70C
14 Plastic DIP
MAX3461ESD
-40C to +85C
14 SO
MAX3461EPD
-40C to +85C
14 Plastic DIP
MAX3462CSA
0C to +70C
8 SO
MAX3462CPA
0C to +70C
8 Plastic DIP
MAX3462ESA
-40C to +85C
8 SO
MAX3462EPA
-40C to +85C
8 Plastic DIP
MAX3463CSA
0C to +70C
8 SO
MAX3463CPA
0C to +70C
8 Plastic DIP
MAX3463ESA
-40C to +85C
8 SO
MAX3463EPA
-40C to +85C
8 Plastic DIP
MAX3464CSA
0C to +70C
8 SO
MAX3464CPA
0C to +70C
8 Plastic DIP
MAX3464ESA
-40C to +85C
8 SO
MAX3464EPA
-40C to +85C
8 Plastic DIP
MAX3460MAX3464
+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
A
A
B
A
B
120
120
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
RO
RE
Y
Z
B
A
B
D
R
DI
DE
RO
RE
Y
Z
120
120
120
120
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
MAX3460MAX3464
+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
0.053
A
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
0.016
L
0.40
1.27
0.394
0.386
D
D
MIN
DIM
D
INCHES
MAX
9.80
10.00
MILLIMETERS
MIN
MAX
16
AC
0.337
0.344
AB
8.75
8.55
14
0.189
0.197
AA
5.00
4.80
8
N MS012
N
SIDE VIEW
H
0.244
0.228
5.80
6.20
e
0.050 BSC
1.27 BSC
C
H
E
e
B
A1
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
.)
MAX3460MAX3464
+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
.)
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