Page 1
General Description
The MAX3460–MAX3464 are high-speed differential
bus transceivers for RS-485 and RS-422 communications. They are designed to meet TIA/EIA-422-B,
TIA/EIA-485-A, V.11, and X.27 standards. The transceiver complies with the Profibus specification providing +2.1V output level with a 54Ω load, 20Mbps data
rate, and output skew less than 2ns. Each part contains
one three-state differential line driver and one differential input line receiver. The devices operate from a +5V
supply and feature true fail-safe circuitry, which guarantees 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 guaranteed 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, respectively, 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
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.
Pin Configurations appear 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
HOT SWAP
SHUTDOWN
Page 2
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= +5V ±5%, TA= T
MIN
to T
MAX
, 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 (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
= +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
Power-Supply Range V
DRIVER
Differential Driver Output (no load) V
Differential Driver Output V
Change in Magnitude of
Differential Output Voltage
Driver Common-Mode Output
Voltage
Change in Magnitude of
Common-Mode Voltage
Input High Voltage V
Input Low Voltage V
Input Hysteresis V
Output Leakage (Y and Z) Full
Duplex
Input Current I
Pulldown Current RXP = TXP = V
Driver Short-Circuit Output
Current (Note 3)
Driver Short-Circuit Foldback
Output Current (Note 3)
Thermal Shutdown Threshold 140 °C
RECEIVER
Differential Input Capacitance C
Input Current (A and B) Full
Duplex
Receiver Differential Threshold
Voltage
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
CC
OD
OD
∆V
V
OC
∆V
HYS
I
IN
I
OSD
I
OSFD
A, B
I
A, B
V
TH
Figure 5, R = ∞ V
Figure 5, R = 27Ω 2.1 V
Figure 5, R = 50Ω or 27Ω
OD
(Note 2)
Figure 5, R = 50Ω or 27Ω 3V
Figure 5, R = 50Ω or 27Ω
OC
(Note 2)
DE, DI, RE, SHDN 2.0 V
IH
DE, DI, RE, SHDN 0.8 V
IL
DE, DI, RE, SHDN 50 mV
V
= +12V +125
DE = GND, VCC =
O
GND or +5.25V
DI, RE, DE, SHDN ±1µA
CC
0 ≤ V
-7V ≤ V
(VCC - 1V) ≤ V
-7V ≤ V
DE = GND,
V
-7V ≤ VCM ≤ 12V -200 -125 -50 mV
≤ 12V, output low +250
OUT
≤ V
OUT
OUT
= GND or 5.25V
CC
, output high -250
CC
≤ 12V, output low +25
OUT
≤ 1V, output high -25
IN
V
= -7V -100
IN
VIN = +12V 250
V
= -7V -200
IN
4.75 5.25 V
CC
0.2 V
0.2 V
51530µA
8pF
V
µA
mA
mA
µA
Page 3
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +5V ±5%, TA= T
MIN
to T
MAX
, 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 ∆V
Receiver Output High Voltage V
Receiver Output Low Voltage V
Three-State Output Current at
Receiver
Receiver Input Resistance R
Receiver Output Short-Circuit
Current
SUPPLY CURRENT
N or m al O p er ati on ( stati c cond i ti on) I
Supply Current in SHDN I
SWITCHING CHARACTERISTICS
Driver Propagation Delay
Driver Differential Output Rise or
Fall Time
Driver Output Skew |t
Maximum Data Rate 20 Mbps
Driver Enable to Output High t
Driver Enable to Output Low t
Driver Disable Time from Low t
Driver Disable Time from High t
Receiver Propagation Delay
Recei ver O utp ut S kew |t
Receiver Enable to Output Low t
Receiver Enable to Output High t
Receiver Disable Time from Low t
Receiver Disable Time from High t
PLH
PLH
- t
PHL
- t
P H L
VA + VB = 0 20 mV
TH
OH
OL
I
OZR
IN
I
OSR
Q
SHDN
t
PLH
t
PHL
t
R
t
F
|t
| t
SKEW
ZH
ZL
LZ
HZ
t
PLH
t
PHL
SKEW
ZL
ZH
LZ
HZ
IO = -4mA, VA - VB = V
IO = 4mA, VB - VA = V
0 ≤ VO ≤ V
CC
TH
TH
-7V ≤ VCM ≤ 12V 48 kΩ
0 ≤ VRO ≤ V
CC
No load, DI = VCC or DI = GND 2.5 4 mA
DE = GND and RE = VCC, or SHDN = V
Figures 6 and 7, R
= 50pF
C
L
Figures 6 and 7, R
= 50pF
C
L
Figures 6 and 7, R
C
= 50pF, TXP = GND or floating
L
DIFF
DIFF
DIFF
= 54Ω,
= 54Ω,
= 54Ω,
Figures 8 and 9, S2 closed, RL = 500Ω,
C
= 50pF
L
Figures 8 and 9, S1 closed, RL = 500Ω,
C
= 50pF
L
Figures 8 and 9, S1 closed, RL = 500Ω,
= 50pF
C
L
Figures 8 and 9, S2 closed, RL = 500Ω,
C
= 50pF
L
Figure 10, CL = 15pF (Note 4) 20 ns
Figure 10, CL = 15pF, RXP = GND or
floating (Note 4)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S1 closed (Note 4)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Note 4)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S1 closed (Note 4)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Note 4)
VCC - 1.5 V
±7 ±95 mA
CC
110µA
0.4 V
±1µA
20 ns
20 ns
2ns
100 ns
100 ns
100 ns
100 ns
2ns
100 ns
100 ns
100 ns
100 ns
Page 4
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 ∆VOCare the changes in VODand 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= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VCC= +5V and TA= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Time to Shutdown t
SHDN
(Note 5) 50
ns
Driver Enable from Shutdown to
Output High
)
Figures 8 and 9, RL = 500Ω, CL = 50pF,
S2 closed (Note 5)
4µs
Driver Enable from Shutdown to
Output Low
)
Figures 8 and 9, RL = 500Ω, CL = 50pF,
S1 closed (Note 5)
4µs
Receiver Enable from Shutdown to
Output High
)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Notes 4, 5)
4µs
Receiver Enable from Shutdown to
Output Low
)
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 = V
CC
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.)
t
ZH (SHDN
t
ZL (SHDN
t
ZH (SHDN
t
ZL (SHDN
800
Page 5
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VCC= +5V, TA = +25°C, unless otherwise noted.)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
50
40
30
20
10
SHUTDOWN SUPPLY CURRENT (nA)
0
-40 10-15 35 60 85
TEMPERATURE (°C)
MAX3460-64 toc04
RECEIVER OUTPUT LOW VOLTAGE (mV)
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
11
10
MAX3460-64 toc07
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
IO = 4mA
140
120
100
80
-40 10-15 35 60 85
TEMPERATURE (°C)
DRIVER PROPAGATION DELAY
vs. TEMPERATURE
12
R
= 54Ω
DIFF
= 50pF
C
L
10
MAX3460-64 toc05
MAX3460-64 toc08
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
4.90
IO = -4mA
4.85
4.80
4.75
4.70
OUTPUT HIGH VOLTAGE (V)
4.65
4.60
-40 85
10-15 35 60
TEMPERATURE (°C)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
4.0
R
= 54Ω
DIFF
3.5
MAX3460-64 toc06
MAX3460-64 toc09
9
PROPAGATION DELAY (ns)
8
7
-40 10-15 35 60 85
TEMPERATURE (°C)
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
100
10
1
OUTPUT CURRENT (mA)
0.1
021345
DIFFERENTIAL OUTPUT VOLTAGE (V)
8
PROPAGATION DELAY (ns)
6
4
200
160
MAX3460-64 toc10
120
80
OUTPUT CURRENT (mA)
40
0
3.0
OUTPUT VOLTAGE (V)
2.5
2.0
-40 10-15 35 60 85
TEMPERATURE (°C)
-40 10-15 35 60 85
OUTPUT CURRENT
vs. DRIVER OUTPUT LOW VOLTAGE
-160
MAX3460-64 toc11
-120
-80
OUTPUT CURRENT (mA)
-40
063912
OUTPUT LOW VOLTAGE (V)
0
TEMPERATURE (°C)
OUTPUT CURRENT
vs. DRIVER OUTPUT HIGH VOLTAGE
MAX3460-64 toc12
-7 -3-5 -1 1 3 5
OUTPUT HIGH VOLTAGE (V)
Page 6
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
6 _______________________________________________________________________________________
Pin Description
Typical Operating Characteristics (continued)
(VCC= +5V, TA = +25°C, 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
MAX3460/
MAX3461
FULL DUPLEX
PIN
MAX3462
MAX3463/
MAX3464
HALF
DUPLEX
1 ——SHDN Shutdown. Drive SHDN high to enter low-power shutdown mode.
221RO
3 — 2 RE
4 — 3DE
534DI
6, 7 4 5 GND Ground
8 ——TXP
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
14 1 8 V
—— 7 B Inverting Receiver Input and Inverting Driver Output
—— 6 A Noninverting Receiver Input and Noninverting Driver Output
NAME FUNCTION
Receiver Output. When RE is low and (A - B) ≥ -50mV, RO is high; if (A - B) ≤
-200mV, RO is low.
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.
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 lowpower shutdown mode.
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.
Transmitter Phase. Connect TXP to GND, or leave unconnected for normal
transmitter phase/polarity. Connect TXP to V
phase/polarity. TXP has an internal 15µA pulldown.
Receiver Phase. Connect RXP to GND, or leave unconnected for normal
receiver phase/polarity. Connect RXP to V
CC
phase/polarity. RXP has an internal 15µA pulldown.
Positive Supply: +4.75V ≤ VCC ≤ +5.25V. Bypass VCC to GND with a 0.1µF
CC
capacitor.
to invert the transmitter
CC
to invert the receiver
Page 7
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
_______________________________________________________________________________________ 7
MAX3460/MAX3461
Function Tables
MAX3462
MAX3463/MAX3464
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
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
TRANSMITTING
INPUTS OUTPUTS
RECEIVING
INPUTS OUTPUT
TRANSMITTING
INPUT OUTPUTS
DI Z Y
101
010
RECEIVING
INPUTS OUTPUT
A–BRO
≥ -0.05V 1
≤ -0.2V 0
Open/Shorted 1
INPUTS OUTPUTS
RE DE DI B A
X11 0 1
X10 1 0
0 0 X High-Z High-Z
1 0 X Shutdown
TRANSMITTING
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
Page 8
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
8 _______________________________________________________________________________________
Pin Configurations and Typical Operating Circuit
Figure 1. MAX3460/MAX3461 Pin Configuration and Typical Full-Duplex Operating Circuit
Figure 2. MAX3462 Pin Configuration and Typical Full-Duplex Operating Circuit
Figure 3. MAX3463/MAX3464 Pin Configuration and Typical Full-Duplex Operating Circuit
TOP VIEW
SHDN
GND
GND
DE
1
RO
2
R
RE
3
4
DI
5
D
6
7
14
V
CC
RXP
13
A
12
BDE
11
Z
10
9
Y
TXP
8
TXP
RXP
5
DI
2
RO
8
13
DIP/SO
CC
414
9ZY
D
R
3 GND
6, 7
RE
10
12
11
A
B
0.1µF
R
t
V
TOP VIEW
V
GND
V
1
CC
3
D
1
CC
RO
DI
R
2
3
D
4
8
A
7
B
6
Z
5
Y
DI
2
RO
DIP/SO
4 GND
0.1µF
5ZY
6
8
A
R
R
7
t
B
MAX3460
MAX3461
MAX3462
V
RE
CC
R
t
R
t
GND
R
V
GND
R
CC
D
RO
D
DI
DE
RO
DI
TOP VIEW
0.1µF
R
1
RO
2
RE
3
DE
D
4
DI
8
RO
V
CC
7
B
RE
6
A
DE
5
GND
DI
R
1
2
3
D
4
V
8
CC
B
7
6
5
A
GND
R
t
MAX3463
MAX3464
B
R
t
A
DIP/SO
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH.
DE
R
D
RE
DI
RO
Page 9
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 circuitry, 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 section). The MAX3460–MAX3464’s driver slew rates allow
transmit speeds up to 20Mbps.
The MAX3463 and MAX3464 are half-duplex transceivers, while the MAX3460, MAX3461, and MAX3462
are full-duplex transceivers. All of these parts operate
from a single +5V supply. Drivers are output short-circuit current limited. Thermal shutdown circuitry protects
drivers against excessive power dissipation. When activated, the thermal shutdown circuitry places the driver
outputs into a high-impedance state. 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” backplane (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 receiver output when the receiver inputs are shorted or open,
or when they are connected to a terminated transmission line with all drivers disabled. This is done by setting the receiver threshold between -50mV and
-200mV. If the differential receiver input voltage (A - B)
is greater than or equal to -50mV, RO is logic high. If A
- B is less than or equal to -200mV, RO is logic low. In
the case of a terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled
to 0V by the termination. With the receiver thresholds of
the 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 complies with the ±200mV EIA/TIA-485 standard.
Hot-Swap Capability
Hot-Swap Inputs
When circuit boards are inserted into a “hot” or powered backplane, disturbances to the enable and differential 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 highimpedance output could cause DE to drift to an incorrect 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 VCCrises, 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 VCCramps 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 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 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 VCC.
Figure 4. Simplified Structure of the Driver Enable Pin (DE)
V
CC
TIMER
15µs
TIMER
EN
5.6kΩ
M1 M2
100µA
(HOT SWAP)
2mA
DE
Page 10
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
10 ______________________________________________________________________________________
Figure 5. Driver DC Test Load
Figure 6. Driver Timing Test Circuit
Figure 7. Driver Propagation Delays
Figure 8. Enable/Disable Timing Test Load
Figure 9. Driver Enable and Disable Times
Figure 10. Receiver Propagation Delays
Figure 11. Receiver Enable and Disable Times
Y
R
V
OD
R
V
OC
Z
3V
DE
Y
DI
R
DIFF
V
ID
C
L
Z
S1
OUTPUT
R
L
UNDER TEST
C
L
S2
3V
DE
Y, Z
V
OL
Y, Z
1.5V
0
, t
t
ZL(SHDN)
ZL
2.3V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
0
2.3V
t
ZH(SHDN)
, t
ZH
ƒ = 1MHz, tR ≤ 3ns, tF ≤ 3ns
V
OH
RO
V
OL
A
1V
B
-1V
1.5V 1.5V
t
PHL
INPUT
OUTPUT
t
PLH
V
CC
1.5V
t
LZ
V
+ 0.5V
OL
V
- 0.5V
OH
t
HZ
3V
DI
V
DIFF
1.5V
0
Z
V
O
Y
1/2 V
V
O
0
-V
10%
O
t
R
ƒ = 1MHz, tR ≤ 3ns, tF ≤ 3ns
O
90%
1.5V
t
PLH
V
= V (Y) - V (Z)
DIFF
t
SKEW
= | t
t
PHL
90%
t
F
- t
|
PLH
PHL
10%
1/2 V
O
3V
RE
V
CC
RO
RO
1.5V
0
t
, t
ZL(SHDN)
ZL
1.5V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
0
1.5V
t
ZH(SHDN)
, t
ZH
1.5V
t
LZ
V
+ 0.5V
OL
- 0.5V
V
OH
t
HZ
Page 11
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 transceivers has a 1/4-unit-load receiver input impedance
(48kΩ), allowing up to 128 transceivers to be connected in parallel on one communication line. Any combination 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 simultaneously; the parts 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 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 contention. The first, a foldback current limit on the output
stage, provides immediate protection against short circuits over the whole common-mode voltage range (see
Typical Operating Characteristics). The second, a thermal 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, |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 MAX3460–MAX3464 transceivers are designed for
bidirectional data communications on multipoint bus
transmission lines. Figures 13 and 14 show typical network applications circuits. To minimize reflections, the
line should be terminated at both ends in its characteristic 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 loading of two termination networks with 220Ω termination
impedance and 390Ω pullups and pulldowns, the drivers can drive V
A-B
> 2.1V output.
Chip Information
TRANSISTOR COUNT: 610
PROCESS: BiCMOS
Figure 12. Receiver Propagation Delay Test Circuit
Ordering Information (continued)
B
RECEIVER
ATE
V
ID
R
OUTPUT
A
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
Page 12
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
12 ______________________________________________________________________________________
Figure 13. Typical Half-Duplex RS-485 Network
Figure 14. Typical Full-Duplex RS-485 Network
120Ω 120Ω
DI
D
B
B
D
DE
DE
RO
RE
R
MAX3463
A
D
MAX3464
(HALF-DUPLEX)
DI DE RO
A
RO
RE
DE
DI
R
D
120Ω
B
Z
120Ω
Y
YZB A B
AABAB
R
R
RE
YZ
D
DI DE RO
R
RE
120Ω
120Ω
Y
D
Z
B
R
A
DI
RO
RE
DI
DE
RE
RO
D
R
D
R
(FULL-DUPLEX)
DI DE RORE
NOTE: RE AND DE ON MAX3460/MAX3461/MAX3462 ONLY
DI DE RORE
MAX3460
MAX3461
MAX3462
Page 13
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
______________________________________________________________________________________ 13
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
.)
N
1
TOP VIEW
D
e
FRONT VIEW
INCHES
DIM
MIN
0.053A
0.004
A1
0.014
B
0.007
C
e 0.050 BSC 1.27 BSC
0.150
HE
A
B
A1
C
L
E
H 0.2440.228 5.80 6.20
0.016L
VARIATIONS:
INCHES
MINDIM
D
0.189 0.197 AA5.004.80 8
0.337 0.344 AB8.758.55 14
D
0-8
SIDE VIEW
MAX
0.069
0.010
0.019
0.010
0.157
0.050
MAX
0.3940.386D
MILLIMETERS
MAX
MIN
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
3.80 4.00
0.40 1.27
MILLIMETERS
MAX
MIN
9.80 10.00
N MS012
16
AC
SOICN .EPS
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
REV.DOCUMENT CONTROL NO.APPROVAL
21-0041
1
B
1
Page 14
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.
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
.)
PDIPN.EPS
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