Maxim MAX3464ESA 5v, fail-safe, 20mbps, profibus rs-485/ rs-422 transceiver Datasheet

19-2217; Rev 1; 2/03
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
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/TIA485 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
Ordering Information
Applications
High-Speed RS-485 Communications
PART
TEMP RANGE
PIN-PACKAGE
High-Speed RS-422 Communications
MAX3460CSD
0°C to +70°C
14 SO
Level Translators
MAX3460CPD
0°C to +70°C
14 Plastic DIP
Industrial-Control Local Area Networks
MAX3460ESD
-40°C to +85°C
14 SO
Profibus Applications
MAX3460EPD
-40°C to +85°C
14 Plastic DIP
Ordering Information continued at end of data sheet.
Pin Configurations appear at end of data sheet.
Selector Guide
MAX3460
Full
RECEIVER/
DRIVER
ENABLE
Yes
Yes
RECEIVER/
DRIVER PHASE
SELECT
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
PART
NUMBER
HALF/FULL
DUPLEX
LOWPOWER
SHUTDOWN
Yes
HOT SWAP
INDEPENDENT
SHDN PIN
PIN COUNT
________________________________________________________________ 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
MAX3460–MAX3464
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.
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
ABSOLUTE MAXIMUM RATINGS
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
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.
ELECTRICAL CHARACTERISTICS
(VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1)
PARAMETER
Power-Supply Range
SYMBOL
CONDITIONS
VCC
MIN
TYP
4.75
MAX
UNITS
5.25
V
DRIVER
Differential Driver Output (no load)
VOD
Figure 5, R = ∞
Differential Driver Output
VOD
Figure 5, R = 27Ω
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 27Ω
3
V
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
VIL
DE, DI, RE, SHDN
VHYS
DE, DI, RE, SHDN
Output Leakage (Y and Z) Full
Duplex
IO
DE = GND, VCC =
GND or +5.25V
Input Current
IIN
DI, RE, DE, SHDN
Input Low Voltage
Input Hysteresis
Pulldown Current
VCC
2.1
2.0
0.8
VIN = +12V
RXP = TXP = VCC
Driver Short-Circuit Output
Current (Note 3)
IOSD
Driver Short-Circuit Foldback
Output Current (Note 3)
IOSFD
V
50
VIN = -7V
-100
15
0 ≤ VOUT ≤ 12V, output low
-250
(VCC - 1V) ≤ VOUT ≤ 12V, output low
+25
-7V ≤ VOUT ≤ 1V, output high
µA
30
µA
-25
Thermal Shutdown Threshold
µA
±1
+250
-7V ≤ VOUT ≤ VCC, output high
V
mV
+125
5
V
V
mA
mA
140
°C
8
pF
RECEIVER
2
Differential Input Capacitance
CA, B
Input Current (A and B) Full
Duplex
IA, B
DE = GND,
VCC = GND or 5.25V
Receiver Differential Threshold
Voltage
VTH
-7V ≤ VCM ≤ 12V
VIN = +12V
VIN = -7V
250
-200
-200
-125
_______________________________________________________________________________________
-50
µA
mV
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
(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
V A + VB = 0
Receiver Output High Voltage
VOH
IO = -4mA, VA - VB = VTH
Receiver Output Low Voltage
VOL
IO = 4mA, VB - VA = VTH
0.4
V
Three-State Output Current at
Receiver
IOZR
0 ≤ VO ≤ VCC
±1
µA
Receiver Input Resistance
RIN
-7V ≤ VCM ≤ 12V
48
Receiver Output Short-Circuit
Current
IOSR
0 ≤ VRO ≤ VCC
±7
20
mV
VCC - 1.5
V
kΩ
±95
mA
2.5
4
mA
1
10
µA
Figures 6 and 7, RDIFF = 54Ω,
CL = 50pF
20
ns
Figures 6 and 7, RDIFF = 54Ω,
CL = 50pF
20
ns
Figures 6 and 7, RDIFF = 54Ω,
CL = 50pF, TXP = GND or floating
2
ns
SUPPLY CURRENT
Normal Operation (static condition)
Supply Current in SHDN
IQ
ISHDN
No load, DI = VCC or DI = GND
DE = GND and RE = VCC, or SHDN = VCC
SWITCHING CHARACTERISTICS
Driver Propagation Delay
tPLH
tPHL
Driver Differential Output Rise or
Fall Time
tR
Driver Output Skew |tPLH - tPHL|
tSKEW
tF
Maximum Data Rate
20
Mbps
Driver Enable to Output High
tZH
Figures 8 and 9, S2 closed, RL = 500Ω,
CL = 50pF
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
Figure 10, CL = 15pF (Note 4)
20
ns
Figure 10, CL = 15pF, RXP = GND or
floating (Note 4)
2
ns
Receiver Propagation Delay
Receiver Output Skew |tPLH - tPHL|
tPLH
tPHL
tSKEW
100
ns
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
_______________________________________________________________________________________
3
MAX3460–MAX3464
ELECTRICAL CHARACTERISTICS (continued)
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
Time to Shutdown
CONDITIONS
tSHDN
MIN
(Note 5)
TYP
50
MAX
UNITS
800
ns
Driver Enable from Shutdown to
Output High
tZH (SHDN)
Figures 8 and 9, RL = 500Ω, CL = 50pF,
S2 closed (Note 5)
4
µs
Driver Enable from Shutdown to
Output Low
tZL (SHDN)
Figures 8 and 9, RL = 500Ω, CL = 50pF,
S1 closed (Note 5)
4
µs
Receiver Enable from Shutdown to
Output High
tZH (SHDN)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S2 closed (Notes 4, 5)
4
µs
Receiver Enable from Shutdown to
Output Low
tZL (SHDN)
Figures 8 and 11, RL = 1kΩ, CL = 15pF,
S1 closed (Notes 4, 5)
4
µs
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.
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
NO LOAD SUPPLY CURRENT
vs. TEMPERATURE
2.25
2.20
DE = GND
2.15
2.10
40
30
20
10
2.05
2.00
-20
0
20
40
TEMPERATURE (°C)
60
80
MAX3460-64 toc03
30
25
20
15
10
5
0
0
-40
4
50
35
OUTPUT CURRENT (mA)
2.30
MAX3460-64 toc02
DE = VCC
60
OUTPUT CURRENT (mA)
MAX3460-64 toc01
2.35
OUTPUT CURRENT
vs. RECEIVER OUTPUT HIGH VOLTAGE
OUTPUT CURRENT
vs. RECEIVER OUTPUT LOW VOLTAGE
2.40
NO LOAD SUPPLY CURRENT (mA)
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT LOW VOLTAGE (V)
0
1
2
3
OUTPUT HIGH VOLTAGE (V)
_______________________________________________________________________________________
4
5
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
30
20
10
0
120
100
-15
10
35
60
4.80
4.75
4.70
4.60
-40
-15
10
35
60
-40
85
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
DRIVER PROPAGATION DELAY
vs. TEMPERATURE
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. TEMPERATURE
8
7
-15
10
35
60
4.0
MAX3460-64 toc08
RDIFF = 54Ω
CL = 50pF
10
OUTPUT VOLTAGE (V)
PROPAGATION DELAY (ns)
MAX3460-64 toc07
9
12
8
RDIFF = 54Ω
3.5
3.0
2.5
6
2.0
4
85
MAX3460-64 toc09
TEMPERATURE (°C)
10
-40
-15
10
35
60
-40
85
-15
10
35
60
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
OUTPUT CURRENT
vs. DRIVER OUTPUT LOW VOLTAGE
OUTPUT CURRENT
vs. DRIVER OUTPUT HIGH VOLTAGE
1
120
80
40
0
0.1
1
2
3
4
DIFFERENTIAL OUTPUT VOLTAGE (V)
5
85
MAX3460-64 toc12
MAX3460-64 toc11
160
-160
OUTPUT CURRENT (mA)
10
200
OUTPUT CURRENT (mA)
MAX3460-64 toc10
100
0
IO = -4mA
4.85
4.65
85
11
-40
MAX3460-64 toc06
140
4.90
80
-40
PROPAGATION DELAY (ns)
IO = 4mA
OUTPUT HIGH VOLTAGE (V)
40
MAX3460-64 toc05
MAX3460-64 toc04
SHUTDOWN SUPPLY CURRENT (nA)
50
OUTPUT CURRENT (mA)
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
RECEIVER OUTPUT LOW VOLTAGE (mV)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
-120
-80
-40
0
0
3
6
9
OUTPUT LOW VOLTAGE (V)
12
-7
-5
-3
-1
1
3
5
OUTPUT HIGH VOLTAGE (V)
_______________________________________________________________________________________
5
MAX3460–MAX3464
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
DRIVER AND RECEIVER
PROPAGATION DELAYS
ENABLE RESPONSE TIME
EYE DIAGRAM
MAX3460-64 toc14
MAX3460-64 toc13
MAX3460-64 toc15
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
5V/div
DE
DI 0
5V/div
Y, Z
2V/div
0
1V/div
Y, Z
0
RO 0
0
5V/div
10ns/div
20ns/div
10ns/div
Pin Description
PIN
MAX3460/
MAX3461
MAX3462
FULL DUPLEX
1
6
—
MAX3463/
MAX3464
NAME
FUNCTION
HALF
DUPLEX
—
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
5
3
4
DI
6, 7
4
5
GND
8
—
—
TXP
9
10
11
12
5
6
7
8
—
—
—
—
Y
Z
B
A
13
—
—
RXP
14
1
8
VCC
—
—
—
—
7
6
B
A
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.
Ground
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.
Noninverting Driver Output
Inverting Driver Output
Inverting Receiver Input
Noninverting Receiver Input
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.
Positive Supply: +4.75V ≤ VCC ≤ +5.25V. Bypass VCC to GND with a 0.1µF
capacitor.
Inverting Receiver Input and Inverting Driver Output
Noninverting Receiver Input and Noninverting Driver Output
_______________________________________________________________________________________
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
MAX3460/MAX3461
MAX3462
TRANSMITTING
TRANSMITTING
INPUTS
OUTPUTS
INPUT
OUTPUTS
RE
DE
DI
SHDN
Z
Y
DI
Z
Y
X
1
1
0
0
1
1
0
1
X
1
0
0
1
0
0
1
0
0
0
X
0
High-Z
High-Z
1
0
X
X
Shutdown
X
X
X
1
Shutdown
RECEIVING
RECEIVING
INPUTS
1
≤ -0.2V
0
Open/Shorted
1
A–B
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
1
RO
≥ -0.05V
DE
X
OUTPUT
A–B
OUTPUT
RE
X
INPUTS
Shutdown
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
1
0
X
High-Z
Shutdown
RECEIVING
INPUTS
OUTPUT
RE
DE
A–B
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
_______________________________________________________________________________________
7
MAX3460–MAX3464
Function Tables
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
Pin Configurations and Typical Operating Circuit
VCC
DE
TOP VIEW
4
SHDN 1
VCC RE
2
RE
3
12 A
DE 4
11 B
9
13 RXP
R
DI 5
DI
5
D
GND 7
8
12
RO
Y
TXP
Rt
10
10 Z
9
Y
RO
R
Z
D
GND 6
0.1µF
14
14 VCC
RO
MAX3460
MAX3461
TXP
RXP
2
R
8
A
Rt
11
DI
D
B
13
3 6, 7 GND
DIP/SO
RE
DE
GND
Figure 1. MAX3460/MAX3461 Pin Configuration and Typical Full-Duplex Operating Circuit
0.1µF
TOP VIEW
VCC
MAX3462
VCC 1
5
VCC 1
R
8
A
DI
D
Y
Rt
6
RO
R
Z
RO
2
7
B
DI
3
6
Z
5
Y
A
8
D
GND 4
3
RO
2
R
Rt
7
D
DI
B
DIP/SO
4 GND
GND
Figure 2. MAX3462 Pin Configuration and Typical Full-Duplex Operating Circuit
TOP VIEW
0.1µF
RO 1
R
8 VCC
RO 1
RE 2
7 B
RE 2
DE 3
6 A
DE 3
5 GND
DI 4
DI 4
D
R
VCC
8
7 B
A
5
R
DI
D
RO
B
Rt
6
D
DE
MAX3463
MAX3464
GND
DIP/SO
Rt
A
RE
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH.
Figure 3. MAX3463/MAX3464 Pin Configuration and Typical Full-Duplex Operating Circuit
8
_______________________________________________________________________________________
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
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.
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 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
5.6kΩ 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 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
15µs
TIMER
TIMER
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
5.6kΩ
DE
(HOT SWAP)
EN
100µA
M1
2mA
M2
Figure 4. Simplified Structure of the Driver Enable Pin (DE)
_______________________________________________________________________________________
9
MAX3460–MAX3464
Detailed Description
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
Y
R
OUTPUT
UNDER TEST
VOD
VCC
S1
RL
CL
R
S2
VOC
Z
Figure 8. Enable/Disable Timing Test Load
Figure 5. Driver DC Test Load
3V
DE
1.5V
1.5V
0
tLZ
tZL(SHDN), tZL
Y, Z
2.3V
VOL
OUTPUT NORMALLY HIGH
Y, Z
2.3V
3V
VOH - 0.5V
0
DE
DI
VOL + 0.5V
OUTPUT NORMALLY LOW
tHZ
tZH(SHDN), tZH
Y
VID
RDIFF
CL
Figure 9. Driver Enable and Disable Times
Z
ƒ = 1MHz, tR ≤ 3ns, tF ≤ 3ns
VOH
RO
1.5V
1V
A
-1V
B
1.5V
OUTPUT
VOL
Figure 6. Driver Timing Test Circuit
tPHL
tPLH
INPUT
Figure 10. Receiver Propagation Delays
ƒ = 1MHz, tR ≤ 3ns, tF ≤ 3ns
3V
3V
DI
1.5V
0
1.5V
tPLH
1.5V
RE
1.5V
0
tPHL
1/2 VO
tZL(SHDN), tZL
Z
VO
VCC
RO
1.5V
RO
1.5V
Y
tLZ
OUTPUT NORMALLY LOW
VOL + 0.5V
1/2 VO
OUTPUT NORMALLY HIGH
VDIFF = V (Y) - V (Z)
VO
VDIFF 0
-VO
90%
90%
10%
10%
tR
tF
VOH - 0.5V
0
tZH(SHDN), tZH
tHZ
tSKEW = | tPLH - tPHL |
Figure 7. Driver Propagation Delays
10
Figure 11. Receiver Enable and Disable Times
______________________________________________________________________________________
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
B
ATE
R
VID
RECEIVER
OUTPUT
A
Figure 12. Receiver Propagation Delay Test Circuit
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
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
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 VA-B> 2.1V output.
Chip Information
TRANSISTOR COUNT: 610
PROCESS: BiCMOS
Ordering Information (continued)
PART
TEMP RANGE
PIN-PACKAGE
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
MAX3461CSD
______________________________________________________________________________________
11
MAX3460–MAX3464
high-impedance state if the die temperature exceeds
+140°C.
MAX3460–MAX3464
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
120Ω
120Ω
B
DI
B
DE
D
D
DE
A
B
A
B
A
DI
A
R
RO
R
RO
RE
RE
R
R
D
D
MAX3463
MAX3464
(HALF-DUPLEX)
DI
DE
RO
DI
RE
DE
RO
RE
Figure 13. Typical Half-Duplex RS-485 Network
A
Y
120Ω
120Ω
R
RO
D
B
RE
DE
Z
Z
DI
120Ω
D
DE
RE
B
120Ω
R
Y
A
Y
Z
B
A
B
Y
Z
R
D
DI
R
D
DE RE
RO
DI
DE RE
MAX3460
MAX3461
MAX3462
(FULL-DUPLEX)
RO
NOTE: RE AND DE ON MAX3460/MAX3461/MAX3462 ONLY
Figure 14. Typical Full-Duplex RS-485 Network
12
DI
______________________________________________________________________________________
RO
+5V, Fail-Safe, 20Mbps, Profibus RS-485/
RS-422 Transceivers
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
DIM
A
A1
B
C
e
E
H
L
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
REV.
B
1
1
______________________________________________________________________________________
13
MAX3460–MAX3464
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.)
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
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.