MAX13448EESD [MAXIM]
80V Fault-Protected Full-Duplex RS-485 Transceiver; 80V故障保护的全双工RS - 485收发器
| 型号： | MAX13448EESD |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 80V Fault-Protected Full-Duplex RS-485 Transceiver |
| 文件： | 总14页 (文件大小：188K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4ꢀ98; Rev ꢀ; 5/ꢀ8
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
General Description
Features
The MAX13448E full-duplex RS-485 transceiver fea-
tures inputs and outputs fault protected up to 8ꢀ0
(with respect to ground). The device operates from a
+3.ꢀ0 to +5.50 supply and features true fail-safe cir-
cuitry, guaranteeing 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-
high when all transmitters are disabled.
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The MAX13448E features a slew-rate limited driver that
minimizes EMI and reduces reflections caused by
improperly terminated cables, allowing error-free data
transmission at data rates up to 5ꢀꢀkbps with a +50
supply, and 25ꢀkbps with a +3.30 supply.
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The MAX13448E includes a hot-swap capability to elimi-
nate false transitions on the bus during power-up or hot
insertion. The driver and receiver feature active-high and
active-low enables, respectively, that can be connected
together externally to serve as a direction control.
The MAX13448E features an 1/8-unit load receiver input
impedance, allowing up to 256 transceivers on the bus.
All driver outputs are protected to 8k0 ESꢁ using the
Human Body Model. The MAX13448E is available in a
14-pin SO package and operates over the extended
-4ꢀ°C to +85°C temperature range.
Ordering Information
ꢀAꢃT
TEꢋꢀVꢃANGE
ꢀꢅNSꢀACKAGE
MAX13448EESꢁ+
-4ꢀ°C to +85°C
14 SO
+ꢁenotes a lead-free package.
Applications
Industrial Control Systems
H0AC Control systems
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Utility Meters
Motor ꢁriver Control Systems
Functional Diagram
V
CC
MAX13448E
DE
RE
V
CC
+
N.C.
RO
1
2
3
4
5
6
7
14
V
CC
1μF
4
14
13 N.C.
R
9
Y
Z
5
RO
DI
R
R
t
D
R
DI
10
RE
12
11
10
9
A
DE
B
12
11
A
B
DI
Z
2
RO
R
D
t
D
1, 8,
13
GND
GND
Y
N.C.
8
N.C.
3
6, 7
GND
GND
DE
RE
R/
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8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
AꢉR/LUTEVꢋAXꢅꢋUꢋVꢃATꢅNGR
(All voltages reference to GNꢁ.)
Continuous Power ꢁissipation (T = +7ꢀ°C)
A
Supply 0oltage (0 ).............................................................+60
14-Pin SO (derate 8.3mW/°C above +7ꢀ°C)................667mW
CC
Control Input 0oltage (RE, ꢁE)...................-ꢀ.30 to (0
ꢁriver Input 0oltage (ꢁI).............................-ꢀ.30 to (0
+ ꢀ.30)
+ ꢀ.30)
Operating Temperature Range ...........................-4ꢀ°C to +85°C
Junction Temperature......................................................+15ꢀ°C
Storage Temperature Range.............................-65°C to +15ꢀ°C
Lead Temperature (soldering, 1ꢀs) .................................+3ꢀꢀ°C
CC
CC
Receiver Input 0oltage (A, B (Note 1)) ................................ 8ꢀ0
ꢁriver Output 0oltage (Y, Z (Note 1)) .................................. 8ꢀ0
Receiver Output 0oltage (RO)....................-ꢀ.30 to (0
+ ꢀ.30)
CC
Short-Circuit ꢁuration (RO, A, B) ...............................Continuous
NrltV1: If the RS-485 transmission lines are unterminated and a short to a voltage 0
occurs at a remote point on the line, an active
SHT
local driver (with ꢁI switching) may see higher voltage than 0
due to inductive kickback at the driver. Terminating the line
MAX1348E
SHT
with a resistor equal to its characteristic impedance minimizes this kickback effect.
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.
ELECTꢃꢅCALVCHAꢃACTEꢃꢅRTꢅCR
(0
= +3.ꢀ to +5.50, T = T
A
to T
, unless otherwise noted. Typical values are at 0
= +3.30 and T = +25°C.) (Notes 2, 3)
CC A
CC
MIN
MAX
ꢀAꢃAꢋETEꢃ
RYꢋꢉ/L
C/NDꢅTꢅ/N
ꢋꢅN
TYꢀ
ꢋAX
5.5
15
UNꢅTR
0
Supply 0oltage Range
0
3.ꢀ
0
CC
CC
No load, ꢁE, ꢁI, RE = ꢀ0 or 0 , 0 = 3.30
CC CC
Supply Current
I
mA
µA
Q
No load, ꢁE, ꢁI, RE = ꢀ0 or 0 , 0
= 50
15
CC CC
ꢁE = GNꢁ, RE = 0 , 0
= 3.30
1ꢀꢀ
1ꢀꢀ
15
CC CC
Supply Current in Shutdown
Mode
I
SHꢁN
ꢁE = GNꢁ, RE = 0 , 0
= 50
CC CC
ꢁE = GNꢁ, RE = GNꢁ, short to +6ꢀ0
ꢁE = GNꢁ, RE = GNꢁ, short to -6ꢀ0
Supply Current with Output
Shorted to 6ꢀ0
I
mA
SHRT
15
Dꢃꢅ0Eꢃ
R = 1ꢀꢀΩ, Figure 1
2
0
0
L
CC
CC
ꢁifferential ꢁriver Output
0
0
0
Oꢁ
R = 54Ω, Figure 1
L
1.5
Change in Magnitude of
ꢁifferential Output 0oltage
Δ0
R = 1ꢀꢀΩ or 54Ω, Figure 1 (Note 4)
L
-ꢀ.2
ꢀ.2
3
Oꢁ
ꢁriver Common-Mode Output
0oltage
0
RL = 1ꢀꢀΩ or 54Ω, Figure 1
0
/2
CC
0
OC
Change in Magnitude of
Common-Mode 0oltage
Δ0
RL = 1ꢀꢀΩ or 54Ω, Figure 1 (Note 4)
-ꢀ.2
+ꢀ.2
0
OC
ꢁI = low, ꢀ0 ≤ 0 or 0 ≤ +120
+25ꢀ
Y
Z
ꢁriver Short-Circuit Output
Current
I
mA
mA
mA
OSꢁ
ꢁI = high, -70 ≤ 0 or 0 ≤ 0 (Note 5)
CC
-25ꢀ
+1ꢀ
Y
Z
ꢁI = low, (0
- 10) ≤ 0 or 0 ≤ +120
Y Z
CC
ꢁriver Short-Circuit Foldback
Output Current
I
I
OSꢁF
OSꢁL
ꢁI = high, -70 ≤ 0 or 0 ≤ +10
-1ꢀ
+6
Y
Z
0 or 0 ≥ + 220, R = 1ꢀꢀΩ
Y
Z
L
ꢁriver-Limit Short-Circuit
Foldback Output Current
0 or 0 ≤ -130, R = 1ꢀꢀΩ
-6
2
Y
Z
L
ꢁriver Input High 0oltage
ꢁriver Input Low 0oltage
ꢁriver Input Current
0
0
0
ꢁIH
0
ꢀ.8
+1
ꢁIL
I
-1
µA
ꢁIN
2
_______________________________________________________________________________________
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
ELECTꢃꢅCALVCHAꢃACTEꢃꢅRTꢅCRV(erolꢁoatꢊ)
(0
= +3.ꢀ to +5.50, T = T
A
to T
, unless otherwise noted. Typical values are at 0
= +3.30 and T = +25°C.) (Notes 2, 3)
CC A
CC
MIN
MAX
ꢀAꢃAꢋETEꢃ
RYꢋꢉ/L
C/NDꢅTꢅ/N
ꢋꢅN
TYꢀ
ꢋAX
UNꢅTR
ꢃECEꢅ0Eꢃ
0
0
= GNꢁ or
= +3.ꢀ0 to +5.50
CC
CC
0 , 0 = +120
+125
µA
A
B
Input Current
I ,
A B
0 , 0 = -70
-1ꢀꢀ
-6
µA
A
B
0 , 0
A
=
8ꢀ0
+6
mA
B
Receiver ꢁifferential Threshold
0oltage
0
-70 ≤ 0
≤ +120
-2ꢀꢀ
-5ꢀ
m0
m0
0
TH
CM
Receiver Input Hysteresis
Output High 0oltage
Output Low 0oltage
Δ0
25
TH
0
-
CC
0
I
I
= -1.6mA
= 1mA
OH
OH
ꢀ.6
0
ꢀ.4
+1
0
OL
OL
Three-State Output Current at
Receiver
I
ꢀ ≤ 0 , 0 ≤ 0
-1
µA
OZR
A
B
CC
Receiver Output Short-Circuit
Current
I
ꢀ ≤ 0
≤ 0
-95
+95
mA
OSR
RO
CC
ERDVꢀꢃ/TECTꢅ/N
All Pins
Human Body Model
Human Body Model
2
8
k0
k0
ESꢁ Protection Level
(A and B, Y and Z)
C/NTꢃ/L
Control Input High 0oltage
Control Input Low 0oltage
0
ꢁE, RE
ꢁE, RE
2
0
0
CIH
0
ꢀ.8
CIL
Input Current Latch ꢁuring First
Rising Edge
I
IN
ꢁE, RE
8ꢀ
µA
ꢀꢃ/TECTꢅ/NVRꢀECꢅ ꢅCATꢅ/NR
Overvoltage Protection
A, B, Y, Z
-8ꢀ
ꢋꢅN
+8ꢀ
0
RWꢅTCHꢅNGVCHAꢃACTEꢃꢅRTꢅCRV(0
=V+3.30V±18ꢌ)
CC
(T = T
A
to T
, unless otherwise noted. Typical values are at 0
MAX
= +3.30 and T = +25°C.)
MIN
CC A
ꢀAꢃAꢋETEꢃ
RYꢋꢉ/L
C/NDꢅTꢅ/N
TYꢀ
ꢋAX
UNꢅTR
Dꢃꢅ0Eꢃ
ꢁriver ꢁifferential Propagation
ꢁelay
t
t
,
ꢁPLH
R = 54Ω, C = 5ꢀpF, Figures 2 and 3
7ꢀꢀ
15ꢀꢀ
12ꢀꢀ
2ꢀꢀ
ns
ns
ns
L
L
ꢁPHL
ꢁriver ꢁifferential Output
Transition Time
t
t
, t
R = 54Ω, C = 5ꢀpF, Figures 2 and 3
25ꢀ
25ꢀ
LH HL
L
L
R = 54Ω, C = 5ꢀpF, t
= [t
-
ꢁPLH
L
L
ꢁSKEW
ꢁifferential ꢁriver Output Skew
15ꢀ
ꢁSKEW
t ], Figures 2 and 3
ꢁPHL
Maximum ꢁata Rate
f
kbps
ns
MAX
ꢁriver Enable Time to Output High
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 4
2ꢀꢀꢀ
ꢁZH
L
L
_______________________________________________________________________________________
3
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
RWꢅTCHꢅNGVCHAꢃACTEꢃꢅRTꢅCRV(0
=V+3.30V±18ꢌ)V(erolꢁoatꢊ)
CC
(T = T
to T
, unless otherwise noted. Typical values are at 0
= +3.30 and T = +25°C.)
A
MIN
MAX
CC A
ꢀAꢃAꢋETEꢃ
RYꢋꢉ/L
C/NDꢅTꢅ/N
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 4
ꢋꢅN
TYꢀ
ꢋAX
UNꢅTR
ꢁriver ꢁisable Time from
Output High
t
1ꢀꢀꢀ
ns
ꢁHZ
L
L
ꢁriver Enable Time from
Shutdown to Output High
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 4
8
µs
ns
ns
ꢁZH(SHꢁN)
L
L
ꢁriver Enable Time to Output Low
t
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 5
15ꢀꢀ
2ꢀꢀꢀ
ꢁZL
L
L
ꢁriver ꢁisable Time from
Output Low
MAX1348E
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 5
ꢁLZ
L
L
ꢁriver Enable Time from
Shutdown to Output Low
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 5
8
µs
µs
ꢁZL(SHꢁN)
L
L
ꢁriver Time to Shutdown
t
R = 5ꢀꢀΩ, C = 5ꢀpF
12
SHꢁN
L
L
ꢃECEꢅ0Eꢃ
t
t
,
C = 2ꢀpF, 0 = 20, 0
Figure 6
= ꢀ0,
CM
RPLH
L
Iꢁ
Receiver Propagation ꢁelay
Receiver Output Skew
2ꢀꢀꢀ
2ꢀꢀ
1ꢀꢀꢀ
15ꢀ
5
ns
ns
ns
ns
µs
ns
RPHL
C = 2ꢀpF, t
L
= [t
- t
],
RSKEW
RPLH RPHL
t
RSKEW
Figure 6
Receiver Enable Time to
Output High
t
t
R = 1kΩ, C = 2ꢀpF, Figure 7
L L
RZH
Receiver ꢁisable Time from
Output High
R = 1kΩ, C = 2ꢀpF, Figure 7
RHZ
L
L
Receiver Wake Time from
Shutdown
t
R = 1kΩ, C = 2ꢀpF, Figure 7
L L
RWAKE
Receiver Enable Time to
Output Low
t
t
R = 1kΩ, C = 2ꢀpF, Figure 7
1ꢀꢀꢀ
RZL
L
L
Receiver ꢁisable Time from
Output Low
R = 1kΩ, C = 2ꢀpF, Figure 7
15ꢀ
2ꢀꢀ
ns
ns
RLZ
L
L
Receiver Time to Shutdown
t
R = 5ꢀꢀΩ, C = 5ꢀpF
SHꢁN
L
L
RWꢅTCHꢅNGVCHAꢃACTEꢃꢅRTꢅCRV(0
=V+ꢄ0V±18ꢌ)
CC
(T = T
to T
, unless otherwise noted. Typical values are at 0
= +50 and T = +25°C.)
A
MIN
MAX
CC A
ꢀAꢃAꢋETEꢃ
RYꢋꢉ/L
C/NDꢅTꢅ/N
ꢋꢅN
TYꢀ
ꢋAX
UNꢅTR
Dꢃꢅ0Eꢃ
ꢁriver ꢁifferential Propagation
ꢁelay
t
t
,
ꢁPLH
R = 54Ω, C = 5ꢀpF, Figure 3
8ꢀꢀ
12ꢀꢀ
2ꢀꢀ
ns
ns
L
L
ꢁPHL
ꢁriver ꢁifferential Output
Transition Time
t
t
, t
R = 54Ω, C = 5ꢀpF, Figure 3
1ꢀꢀ
5ꢀꢀ
LH HL
L
L
R = 54Ω, C = 5ꢀpF, t
= [t
-
ꢁPLH
L
L
ꢁSKEW
ꢁifferential ꢁriver Output Skew
Maximum ꢁata Rate
ns
ꢁSKEW
t ], Figure 3
ꢁPHL
f
kbps
MAX
-
_______________________________________________________________________________________
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
RWꢅTCHꢅNGVCHAꢃACTEꢃꢅRTꢅCRV(0
=V+ꢄ0V±18ꢌ)V(erolꢁoatꢊ)
CC
(T = T
to T
, unless otherwise noted. Typical values are at 0
= +50 and T = +25°C.)
A
MIN
MAX
CC A
ꢀAꢃAꢋETEꢃ
RYꢋꢉ/L
C/NDꢅTꢅ/N
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 4
ꢋꢅN
TYꢀ
ꢋAX
UNꢅTR
ꢁriver Enable Time to Output High
t
15ꢀꢀ
ns
ꢁZH
L
L
ꢁriver ꢁisable Time from
Output High
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 4
1ꢀꢀꢀ
ns
ꢁHZ
L
L
ꢁriver Enable Time from
Shutdown to Output High
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 4
8
1ꢀꢀꢀ
2
µs
ns
µs
ꢁZH(SHꢁN)
L
L
ꢁriver Enable Time to Output Low
t
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 5
L L
ꢁZL
ꢁriver ꢁisable Time from
Output Low
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 5
ꢁLZ
L
L
ꢁriver Enable Time from
Shutdown to Output Low
t
R = 5ꢀꢀΩ, C = 5ꢀpF, Figure 5
8
µs
µs
ꢁZL(SHꢁN)
L
L
ꢁriver Time to Shutdown
t
R = 5ꢀꢀΩ, C = 5ꢀpF
12
SHꢁN
L
L
ꢃECEꢅ0Eꢃ
t
t
,
C = 2ꢀpF, 0 = 20, 0
Figure 6
= ꢀ0,
CM
RPLH
L
Iꢁ
Receiver Propagation ꢁelay
Receiver Output Skew
2ꢀꢀꢀ
2ꢀꢀ
1ꢀꢀꢀ
15ꢀ
8
ns
ns
ns
ns
µs
ns
RPHL
C = 2ꢀpF, t
L
= [t
- t
],
RSKEW
RPLH RPHL
t
RSKEW
Figure 6
Receiver Enable Time to
Output High
t
t
R = 1kΩ, C = 2ꢀpF, Figure 7
L L
RZH
RHZ
Receiver ꢁisable Time from
Output High
R = 1kΩ, C = 2ꢀpF, Figure 7
L
L
Receiver Wake Time from
Shutdown
t
R = 1kΩ, C = 2ꢀpF, Figure 7
L L
RWAKE
Receiver Enable Time to
Output Low
t
t
R = 1kΩ, C = 2ꢀpF, Figure 7
1ꢀꢀꢀ
RZL
RLZ
L
L
Receiver ꢁisable Time from
Output Low
R = 1kΩ, C = 2ꢀpF, Figure 7
15ꢀ
15ꢀ
ns
ns
L
L
Receiver Time to Shutdown
t
R = 5ꢀꢀΩ, C = 5ꢀpF
L L
SHꢁN
NrltV2: Parameters are 1ꢀꢀ% production tested at T = +25°C, unless otherwise noted. Limits over temperature are guaranteed by
A
design.
NrltV3: 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.
NrltV-: Δ0
and Δ0
are the changes in 0 and 0 , respectively, when the ꢁI input changes state.
Oꢁ OC
Oꢁ
OC
NrltVꢄ: 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 recover from bus contention.
_______________________________________________________________________________________
ꢄ
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
Typical Operating Characteristics
(0 = +3.30, T = +25°C, unless otherwise noted.)
CC
A
RECEIVER OUTPUT SINK CURRENT
vs. OUTPUT LOW VOLTAGE
RECEIVER OUTPUT SOURCE CURRENT
vs. OUTPUT HIGH VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
4.20
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
DE = RE = LOW
B - A = HIGH
DE = RE = LOW
A - B = HIGH
DI = FLOATING
-40°C
4.15
4.10
4.05
+85°C
MAX1348E
+25°C
-40°C
+25°C
+85°C
DE = RE = LOW
A - B = HIGH
0
2
4
6
8
10
-40
-15
10
35
60
85
0
2
4
6
8
10
OUTPUT SINK CURRENT (mA)
TEMPERATURE (°C)
OUTPUT SOURCE CURRENT (mA)
RECEIVER OUTPUT LOW VOLTAGE
vs. TEMPERATURE
RECEIVER OUTPUT HIGH VOLTAGE
vs. TEMPERATURE
0.075
3.25
3.24
3.23
3.22
3.21
3.20
DE = RE = LOW
B - A = HIGH
0.070
0.065
0.060
0.055
0.050
0.045
0.040
I
= 1mA
SINK
DE = RE = LOW
A - B = HIGH
I
= 1mA
SOURCE
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE
vs. DIFFERENTIAL OUTPUT CURRENT
DRIVER DIFFERENTIAL OUTPUT
VOLTAGE vs. TEMPERATURE
3.5
3.0
2.5
2.0
1.5
1.0
1.94
1.92
1.90
1.88
1.86
DE = RE = HIGH
DI = HIGH
DE = RE = HIGH
DI = HIGH
R
= 54Ω
LOAD
0
20
40
60
80
100
-40
-15
10
35
60
85
DIFFERENTIAL OUTPUT CURRENT (mA)
TEMPERATURE (°C)
6
_______________________________________________________________________________________
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
Typical Operating Characteristics (continued)
(0 = +3.30, T = +25°C, unless otherwise noted.)
CC
A
SINGLE-ENDED DRIVER SINK CURRENT
SINGLE-ENDED DRIVER OUTPUT
HIGH VOLTAGE vs. SOURCE CURRENT
vs. OUTPUT LOW VOLTAGE
SHUTDOWN CURRENT vs. TEMPERATURE
30
25
20
15
10
5
0.12
0.10
0.08
0.06
0.04
0.02
0
3.35
3.30
3.25
3.20
3.15
3.10
DE = RE = HIGH
DI = HIGH
DE = RE = HIGH
DI = HIGH
0
-40
-15
10
35
60
85
0
2
4
6
8
10
0
2
4
6
8
10
TEMPERATURE (°C)
OUTPUT SINK CURRENT (mA)
OUTPUT SOURCE CURRENT (mA)
RECEIVER PROPAGATION DELAY (500kbsp)
DRIVER PROPAGATION DELAY (500kbsp)
MAX13448E toc12
MAX13448E toc11
2V/div
1V/div
1V/div
2V/div
400ns
400ns
DRIVER PROPAGATION DELAY
vs. TEMPERATURE
RECEIVER PROPAGATION DELAY
vs. TEMPERATURE
500
450
400
350
300
400
375
350
325
300
DE = RE = LOW
C
= 20pF
LOAD
t
DPLH
t
RPLH
t
DPHL
t
RPHL
DE = RE = HIGH
R
C
= 54Ω
= 50pF
LOAD
LOAD
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
7
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
-in Description
ꢀꢅN
1, 8, 13
2
NAꢋE
N.C.
RO
UNCTꢅ/N
No Connection. Not internally connected. Connect N.C. to GNꢁ or leave it unconnected.
Receiver Output. If receiver is enabled and (A - B) ≥ -5ꢀm0, RO = high; if (A - B) ≥ -2ꢀꢀm0, RO = low.
Receiver Output Enable. ꢁrive RE low to enable RO; RO is high impedance when RE is high. ꢁrive
RE high and ꢁE low to enter low-power shutdown mode.
3
4
5
RE
ꢁE
ꢁI
ꢁriver Output Enable. ꢁrive ꢁE high to enable the driver outputs. ꢁrive ꢁE low to put the outputs in
high impedance. ꢁrive RE high and ꢁE low to enter low-power shutdown mode.
ꢁriver Input. ꢁrive ꢁI low to force the noninverting output low and the inverting output high. ꢁrive ꢁI
high to force the noninverting output high and the inverting output low.
MAX1348E
6, 7
9
GNꢁ
Ground
Y
Z
B
A
Noninverting ꢁriver Output
Inverting ꢁriver Output
Inverting Receiver Input
Noninverting Receiver Input
1ꢀ
11
12
Positive Supply. 0
= +3.ꢀ0 to +5.50. Bypass 0
to GNꢁ with a 1µF ceramic capacitor as close
CC
CC
14
0
CC
to 0
as possible. Typical 0
values are at 0
= +3.30 and 0
= +5.ꢀ0.
CC
CC
CC
CC
Y
V
CC
DI
V
V
/2
CC
R /2
L
0
t
t
DPHL
1/2 V
DPLH
O
V
OD
Z
O
V
OC
R /2
L
Y
1/2 V
Z
O
V
OD
= V (Y) - V (Z)
V
O
90%
SKEW
90%
V
OD
0
-V
10%
10%
Figure 1. ꢁriver ꢁC Test Load
O
t
HL
t
LH
V
CC
t
= |t
- t
|
DPLH DPHL
DE
Figure 3. ꢁriver Propagation ꢁelays
C
C
L
Y
DI
R
L
V
O
Z
L
Figure 2. ꢁriver Timing Test Circuit
±
_______________________________________________________________________________________
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
Y
S1
D1
0 OR V
D
OUT
CC
R = 500Ω
L
Z
C
L
50pF
GENERATOR
50Ω
V
0
V
CC
DE
V
CC
/2
t
, t
DZH DZH(SHDN)
0.25V
OH
OUT
V
OM
= (0 + V )/2
OH
0
t
DHZ
Figure 4. ꢁriver Enable and ꢁisable Times (t
, t
, t
)
ꢁHZ ꢁZH ꢁZH(SHꢁN)
V
CC
R = 500Ω
L
Y
Z
S1
D1
0 OR V
D
OUT
CC
C
L
50pF
GENERATOR
50Ω
V
0
CC
DE
V
CC
/2
t
, t
DZL DZL(SHDN)
t
DLZ
V
CC
V
OM
= (V + V )/2
OL CC
OUT
0.25V
V
OL
Figure 5. ꢁriver Enable and ꢁisable Times (t
, t
, t
)
ꢁLZ ꢁZL ꢁZL(SHꢁN)
_______________________________________________________________________________________
9
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
B
A
B
A
RO
V
R
ID
0
C
20pF
L
t
t
RPHL
RPLH
V
OH
V
OH
+ V
OL
2
RO
V
t
= |t
- t
|
OL
SKEW
RPLH RPHL
Figure 6. Receiver Propagation ꢁelays
MAX1348E
S1
S2
+1.5V
-1.5V
S3
A
B
V
CC
1kΩ
RO
V
R
ID
RE
C
L
20pF
GENERATOR
50Ω
S1 OPEN
S2 CLOSED
S3 = +1.5V
S1 CLOSED
S2 OPEN
S3 = -1.5V
V
0
V
0
CC
CC
V
/2
CC
RE
RE
t
, t
*
RZH RWAKE
t
, t
*
RZL SHDN
V
0
V
OH
CC
OL
RO
V
/2
OH
(V + V )/2
OL
CC
RO
V
S1 OPEN
S2 CLOSED
S3 = +1.5V
S1 CLOSED
S2 OPEN
S3 = -1.5V
V
0
CC
V
0
CC
V
/2
CC
V
/2
CC
RE
RE
t
, t
*
RHZ SHDN
t
, t
*
RLZ SHDN
V
V
CC
OL
V
0
OH
*DE =
LOW
0.25V
RO
RO
0.25V
Figure 7. Receiver Enable and ꢁisable Times
18 ______________________________________________________________________________________
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
TFbutV1.V aoelꢁroVTFbut
Detailed Description
The MAX13448E 8ꢀ0 fault-protected RS-485/RS-422
transceiver contains one driver and one receiver. This
device features fail-safe circuitry, guaranteeing 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. The device
has a hot-swap input structure that prevents distur-
bances on the differential signal lines when a circuit
board is plugged into a hot backplane. All receiver
inputs and driver outputs are protected to 8k0 ESꢁ
using the Human Body Model. The MAX13448E
features a reduced slew-rate driver that minimizes
EMI and reduces reflections caused by improperly
terminated cables, allowing error-free data transmis-
sion up to 5ꢀꢀkbps.
TꢃANRꢋꢅTTꢅNG
ꢅNꢀUT
/UTꢀUT
RE
X
ꢁE
1
ꢁI
ꢀ
Z
1
ꢀ
Y
ꢀ
1
X
1
1
High
Impedance
High
ꢀ
1
ꢀ
ꢀ
X
Impedance
X
High Impedance (Shutdown)
ꢃECEꢅ0ꢅNG
ꢅNꢀUT
/UTꢀUT
RE
ꢀ
ꢁE
X
A - B
RO
-5ꢀm0
1
ꢀ
X
-2ꢀꢀm0
ꢀ
Driver
The driver accepts a single-ended, logic-level input
(ꢁI) and converts it to a differential, RS-485/RS-422
level output (A and B). ꢁeasserting the driver enable
places the driver outputs (A and B) into a high-imped-
ance state.
1
1
X
X
ꢁisabled
1
ꢀ
High Impedance (Shutdown)
X = ꢁon’t care; shutdown mode, driver, and receiver outputs are
high impedance.
Receiver
The receiver accepts a differential, RS-485/RS-422
level input (A and B), and translates it to a single-
ended, logic-level output (RO). ꢁeasserting the receiv-
er enable places the receiver outputs (RO) into a
high-impedance state (see Table 1).
To reduce system complexity and the need for external
protection, the driver outputs and receiver inputs of the
MAX13448E withstand voltage faults of up to 8ꢀ0 with
respect to ground without damage (see the Absolute
Maximum Ratings section, Note 1). Protection is guar-
anteed regardless of whether the device is active, in
shutdown, or without power. Certain parasitic effects
present while driving an unterminated cable may cause
the voltage seen at driver outputs to exceed the
absolute maximum limit, while the ꢁI input is switched
during a 8ꢀ0 fault on the A or B input. Therefore, a
termination resistor is recommend in order to maximize
the overvoltage fault protection while the ꢁI input is
being switched. If the ꢁI input does not change state
while the fault voltage is present, the MAX13448E will
withstand up the 8ꢀ0 on the RS-485 inputs, regard-
less of the presence of a termination resistor. While the
MAX13448E is not damaged by up to 8ꢀ0 common-
mode voltages, the RO, Y, and Z outputs will be in an
indeterminate state if the common-mode voltage
exceeds -70 to +120.
Lowꢁ-ower Shutdown
Low-power shutdown is initiated by bringing ꢁE low
and RE high. In shutdown, the device draws a maxi-
mum of 1ꢀꢀµA of supply current.
The device is guaranteed to not enter shutdown if ꢁE is
low and RE is high for 1µs. If the inputs are in this state
for at least 1ms, the device is guaranteed to enter shut-
down. In the shutdown state, the driver outputs (A and
B) as well as the receiver output (RO) are in a high-
impedance state.
8ꢀ0 Fault -rotection
In certain applications, such as industrial control, driver
outputs and receiver inputs of an RS-485 device some-
times experience common-mode voltages in excess of
the -70 to +120 range specified in the EIA/TIA-485
standard. In these applications, ordinary RS-485
devices (typical absolute maximum ratings of -80 to
+12.50) may experience damage without the addition
of external protection devices.
True FailꢁSafe
The MAX13448E guarantees a logic-high receiver out-
put 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
______________________________________________________________________________________ 11
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
R
R
C
D
1MΩ
1500Ω
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
I
100%
90%
I
P
r
DISCHARGE
RESISTANCE
CHARGE-CURRENT-
LIMIT RESISTOR
AMPS
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
36.8%
C
100pF
STORAGE
CAPACITOR
s
10%
0
SOURCE
TIME
0
t
RL
t
DL
MAX1348E
CURRENT WAVEFORM
Figure 8a. Human Body ESꢁ Test Model
Figure 8b. Human Body Current Waveform
receiver threshold between -5ꢀm0 and -2ꢀꢀm0. If the
differential receiver input voltage (A - B) is greater than
or equal to -5ꢀm0, RO is logic-high. If A - B is less than
or equal to -2ꢀꢀm0, RO is logic-low. In the case of a
terminated bus with all transmitters disabled, the
receiver’s differential input voltage is pulled to ꢀ0 by
the termination. With the receiver thresholds of the
MAX13448E, this results in a logic-high with a 5ꢀm0
minimum noise margin. The -5ꢀm0 to -2ꢀꢀm0 threshold
complies with the 2ꢀꢀm0 EIA/TIA-485 standard.
1ꢀꢀpF capacitor charged to the ESꢁ voltage of interest,
which is then discharged into the test device through a
1.5kΩ resistor.
Driver Output -rotection
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
circuits over the whole common-mode voltage range
(see the Typical Operating Characteristics). The sec-
ond, a thermal-shutdown circuit, forces the driver out-
puts into a high-impedance state if the die temperature
exceeds +16ꢀ°C (typ).
8ꢂ0 ESD -rotection
As with all Maxim devices, ESꢁ-protection structures
are incorporated on all pins to protect against electro-
static discharges encountered during handling and
assembly. The driver outputs and receiver inputs of the
MAX13448E have extra protection against static elec-
tricity. Maxim’s engineers have developed state-of-the-
art structures to protect these pins against ESꢁ of 8k0
without damage. The ESꢁ structures withstand high
ESꢁ in all states: normal operation, shutdown, and
powered down. After an ESꢁ event, the MAX13448E
keeps working without latchup or damage. ESꢁ protec-
tion can be tested in various ways. The transmitter out-
puts and receiver inputs of the MAX13448E are
characterized for protection to the following limits:
HotꢁSwap Capability
HrlSRwFpVꢅopalꢆ
When circuit boards are inserted into a powered back-
plane, disturbances to the data bus can lead to data
errors. Upon initial circuit-board insertion, the data
communication processor undergoes its own power-up
sequence. ꢁuring this period, the processor’s logic-
output drivers are high impedance and are unable to
drive the ꢁE input of the device to a defined logic level.
Leakage currents up to 1ꢀµA from the high-imped-
ance state of the processor’s logic drivers could cause
standard CMOS enable inputs of a transceiver to drift to
an incorrect logic level. Additionally, parasitic circuit-
•
8k0 using the Human Body Model
ERDVTtꢆlVCroꢊꢁlꢁroꢆ
board capacitance could cause coupling of 0
or
CC
ESꢁ performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
GNꢁ to the enable inputs. Without the hot-swap capa-
bility, these factors could improperly enable the trans-
ceiver’s driver or receiver.
When 0
rises, an internal pulldown circuit holds ꢁE
CC
HaꢈFoVꢉrꢊdVꢋrꢊtu
Figure 8a shows the Human Body Model, and Figure
8b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of a
low. After the initial power-up sequence, the pulldown
circuit becomes transparent, resetting the hot-swap
tolerable input.
12 ______________________________________________________________________________________
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
MAX1348E
MAX13448E is specified as 1/8 unit loads. This means
a compliant transmitter can drive up to 256 MAX13448E
devices. Reducing the common mode and/or changing
the characteristic impedance of the cable changes the
maximum number of receivers that can be used. Refer
to the TIA/EIA-485 specification for further details.
V
CC
10μs
TIMER
SR LATCH
-roper Termination and Cabling/Wiring
Configurations
TIMER
When the data rates for RS-485 are high relative to its
cable lengths, the system is subject to proper transmis-
sion line design. In most cases, a single, controlled-
impedance cable or trace should be used and should be
properly terminated on both ends with the characteristic
impedance of the cable/trace. RS-485 transceivers
should be connected to the cable/traces with minimum
length wires to prevent stubs. Star configurations and
improperly terminated cables can cause data loss. Refer
to the Applications section of the Maxim website or to
TIA/EIA publication TSB89 for further information.
5kΩ
DE
DE
(HOT SWAP)
100μA
500μA
M1
M2
Reduced EMI and Reflections
The MAX13448E features reduced slew-rate drivers
that minimize EMI and reduce reflections caused by
improperly terminated cables, allowing error-free data
transmission up to 5ꢀꢀkbps.
Figure 9. Simplified Structure of the ꢁriver Enable Pin (ꢁE)
Line Length
The Telecommunications Industry Association (TIA)
publishes the document TSB-89: Application
Guidelines for TIA/EIA-485-A that is a good reference
for determining maximum data rate vs. line length.
HrlSRwFpVꢅopalVCꢁPeaꢁlPd
The enable inputs feature hot-swap capability. At the
input there are two NMOS devices, M1 and M2 (Figure
9). When 0
ramps from zero, an internal 7µs timer
CC
turns on M2 and sets the SR latch that also turns on M1.
Transistor M2, a 1.5mA current sink, and M1, a 1ꢀꢀµA
current sink, pull ꢁE to GNꢁ through a 5kΩ resistor. M2
is designed to pull ꢁE to the disabled state against an
external parasitic capacitance up to 1ꢀꢀpF that can
drive ꢁE high. After 7µs, the timer deactivates M2 while
M1 remains on, holding ꢁE low against three-state leak-
ages that can drive ꢁE 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, ꢁE reverts to a standard, high-impedance
CMOS input.
Typical Applications
The MAX13448E transceivers are designed for bidirec-
tional data communications on multipoint bus transmis-
sion lines. Figure 1ꢀ shows a typical network application
circuit. To minimize reflections, terminate the line at both
ends in its characteristic impedance, and keep stub
lengths off the main line as short as possible.
Applications Information
256 Transceivers on the Bus
The RS-485 standard specifies the load each receiver
places on the bus in terms of unit loads. An RS-485
compliant transmitter can drive 32 one-unit loads when
used with a 12ꢀΩ cable that is terminated on both ends
over a common-mode range of -70 to +120. The
______________________________________________________________________________________ 13
8ꢀ0 Faultꢁ-rotected FullꢁDuplex
RSꢁ485 Transceiver
A
Y
120Ω
120Ω
120Ω
R
RO
RE
DE
D
DI
B
Z
DE
RE
Z
B
120Ω
D
DI
R
RO
Y
A
Y
Z
B
A
Y
Z
B
A
MAX1348E
R
R
MAX13448E
D
D
DI
DI
DE
DE
RE RO
RE RO
Figure 1ꢀ. Typical Full-ꢁuplex RS-485 Network
-in Configuration
Chip Information
PROCESS: BiCMOS
TOP VIEW
+
N.C.
RO
1
2
3
4
5
6
7
14 V
CC
13 N.C.
12 A
RE
MAX13448E
DE
11 B
DI
10 Z
-acꢂage Information
GND
GND
9
8
Y
For the latest package outline information and land patterns, go
to www.ꢈFxꢁꢈSꢁe.erꢈIpFeꢇFgtꢆ.
N.C.
ꢀACKAGEVTYꢀE ꢀACKAGEVC/DE D/CUꢋENTVN/.
R/
14 SO
S14-5
21S88-1
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.
1- ____________________Maxim Integrated -roducts, 12ꢀ San Gabriel Drive, Sunnyvale, CA 94ꢀ86 4ꢀ8ꢁ737ꢁ76ꢀꢀ
© 2ꢀꢀ8 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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