19-0497; Rev 0; 2/98
1.6µA, RS-485/RS-422, Half-Duplex,
Differential Transceiver for Battery-Powered Systems
________________General Description
The MAX3471 half-duplex transceiver is intended for
lithium battery-powered RS-485/RS-422 applications. It
draws only 1.6µA (typical) supply current from a 3.6V
supply with the receiver enabled and the driver dis-
abled. Its wide 2.5V to 5.5V supply voltage guarantees
operation over the lifetime of a lithium battery.
This device features true fail-safe operation that guar-
antees a logic-high receiver output when the receiver
inputs are open or shorted. This means that the receiv-
er output will be a logic high if all transmitters on a ter-
minated bus are disabled (high impedance). The
MAX3471 has a 1/8-unit load input resistance. When
driver outputs are enabled and pulled above V
CC
or
below GND, internal circuitry prevents battery back-
charging.
The MAX3471 is available in an 8-pin µMAX package.
____________________________Features
o
1.6µA Supply Current with Receiver Enabled
o
+2.5V to +5.5V Single-Supply Operation
o
True Fail-Safe Receiver Input
o
Available in µMAX Package
o
1/8-Unit-Load Receiver Input
o
-7V to +10V Common-Mode Input Voltage Range
MAX3471
_______________Ordering Information
PART
MAX3471CUA
MAX3471EUA
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
8 µMAX
________________________Applications
Remote Meter Reading
Battery-Powered Differential Communications
Level Translators
___________________Pin Configuration
TOP VIEW
RO
RE
DE
DI
1
2
3
4
8
V
CC
B
A
GND
MAX3471
7
6
5
µMAX
Typical Application Circuit
V
CC
DI
D
DE
RO
RE
R
GND
REMOTE UNIT
DI
V
CC
D
DE
R
A
B
A
GND
V
CC
D
DI
DE
R
CENTRAL UNIT
RO RE
B
A
GND
A
R
B
B
D
DI
RO
RE
V
CC
DE
V
CC
0.1µF
RO RE
MAX3471
REMOTE UNIT
REMOTE UNIT
TYPICAL HALF-DUPLEX RS-485 NETWORK
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
1.6µA, RS-485/RS-422, Half-Duplex,
Differential Transceiver for Battery-Powered Systems
MAX3471
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (V
CC
) ..............................................................7V
Control Input Voltage (RE,
DE)...................-0.3V to (V
CC
+ 0.3V)
Driver Input Voltage (DI).............................-0.3V to (V
CC
+ 0.3V)
Driver Output/Receiver Input Voltage (A, B).....................±10.5V
Receiver Output Voltage (RO)....................-0.3V to (V
CC
+ 0.3V)
Continuous Power Dissipation
µMAX (derate 4.5mW/°C above +70°C) ......................362mW
Operating Temperature Ranges
MAX3471CUA .....................................................0°C to +70°C
MAX3471EUA ..................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Note 1:
All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device
ground unless otherwise noted.
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.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= +2.5V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +3.6V and T
A
= +25°C.) (Note 1)
PARAMETER
Differential Driver Output (no load)
Differential Driver Output
(with load)
SYMBOL
V
OD1
CONDITIONS
Figure 1 (R = open)
R = 750Ω (RS-422)
V
OD2
Figure 1
R = 27Ω (RS-485)
R = 27Ω (RS-485),
V
CC
= 5V, T
A
= +25°C
Figure 1, R = 750Ω or 27Ω
1.5
0.2
3.28
0.83
1.5
V
MIN
TYP
MAX
V
CC
UNITS
V
Change in Magnitude of
Differential Output Voltage
(Note 2)
Driver Common-Mode Output
Voltage
Change in Magnitude of
Common-Mode Voltage (Note 2)
Input High Voltage
Input Low Voltage
DI Input Hysteresis
Input Current
Input Current (A and B),
Half Duplex
Driver Short-Circuit Output
Current (Note 3)
Receiver Differential Threshold
Voltage
Receiver Input Hysteresis
Receiver Output High Voltage
Receiver Output Low Voltage
Three-State Current at Receiver
Output
Receiver Input Resistance
∆V
OD
0.2
V
V
OC
∆V
OC
V
IH
V
IL
V
HYS
I
IN1
I
IN2
I
OSD
V
TH
∆V
TH
V
OH
V
OL
I
OZR
R
IN
Figure 1, R = 750Ω or 27Ω
Figure 1, R = 750Ω or 27Ω
DE, DI,
RE
DE, DI,
RE
100
DE, DI,
RE
DE = GND,
V
CC
= GND or 5.5V
-7V
≤
V
OUT
≤
10V
-7V
≤
V
CM
≤
10V
V
CM
= 0
I
O
= -0.8mA, V
ID
= -50mV
I
O
= 2.2mA, V
ID
= -450mV
0
≤
V
O
≤
V
CC
-7V
≤
V
CM
≤
10V
96
V
CC
- 0.4
V
IN
= 10V
V
IN
= -7V
V
CC
≤
3.6V
V
CC
≤
5.5V
-60
-130
-450
-250
32
±0.001
0.7 x V
CC
0.6 x V
CC
0.2
V
V
V
0.3 x V
CC
±1
0.105
-0.075
60
130
-50
V
mV
µA
mA
mA
mV
mV
V
0.4
±1
V
µA
kΩ
2
_______________________________________________________________________________________
1.6µA, RS-485/RS-422, Half-Duplex,
Differential Transceiver for Battery-Powered Systems
DC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.5V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +3.6V and T
A
= +25°C.) (Note 1)
PARAMETER
Receiver Output Short-Circuit
Current
SYMBOL
I
OSR
0
≤
V
RO
≤
V
CC
V
CC
≤
3.6V, no load,
RE
= DI = GND or V
CC
,
V
A
= V
B
= 0
V
CC
≤
5.5V, no load,
RE
= DI = GND or V
CC
,
V
A
= V
B
= 0
CONDITIONS
V
CC
≤
3.6V
V
CC
≤
5.5V
DE = V
CC
DE = GND
DE = V
CC
DE = GND
MIN
-20
-40
50
1.6
83
2.8
TYP
MAX
50
110
60
2
µA
100
4
UNITS
mA
MAX3471
Supply Current
I
CC
SWITCHING CHARACTERISTICS
(V
CC
= +2.5V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +3.6V and T
A
= +25°C.)
PARAMETER
Driver Input to Output
Propagation Delay
Driver Output Skew
(t
DPLH
- t
DPHL
)
Driver Rise or Fall Time
Driver Enable Time to Output
High
Driver Enable Time to Output
Low
Driver Disable Time from Low
Driver Disable Time from High
Receiver Input to Output
Propagation Delay
Differential Receiver Skew
(t
RPLH
- t
RPHL
)
Data Rate
Receiver Enable Time to
Output Low
Receiver Enable Time to
Output High
Receiver Disable Time from Low
Receiver DisableTime from High
SYMBOL
t
DPLH,
t
DPHL
t
DSKEW
t
DR
, t
DF
t
DZH
t
DZL
t
DLZ
t
DHZ
t
RPLH
t
RPHL
t
RSKEW
f
MAX
t
RZL
t
RZH
t
RLZ
t
RHZ
CONDITIONS
Figures 3 and 5, R
DIFF
= 1.5kΩ,
C
L1
= C
L2
= 100pF
Figures 3 and 5, R
DIFF
= 1.5kΩ,
C
L1
= C
L2
= 100pF
Figures 3 and 5, R
DIFF
= 1.5kΩ,
C
L1
= C
L2
= 100pF
Figures 4 and 6, C
L
= 100pF, S2 closed, S1 open
Figures 4 and 6, C
L
= 100pF, S1 closed, S2 open
Figures 4 and 6, C
L
= 15pF, S1 closed, S2 open
Figures 4 and 6, C
L
= 15pF, S2 closed, S1 open
Figures 7 and 9, C
L
= 15pF,
|
V
ID
|
= 2V
Figures 7 and 9,
|
V
ID
|
= 2V
Figure 9, C
L
= 100pF
Figures 2 and 8, C
L
= 15pF, S1 closed, S2 open
Figures 2 and 8, C
L
= 15pF, S2 closed, S1 open
Figures 2 and 8, C
L
= 15pF, S1 closed, S2 open
Figures 2 and 8, C
L
= 15pF, S2 closed, S1 open
64
70
85
50
35
500
500
200
200
0.75
MIN
TYP
1.40
0.025
1.34
1.5
0.86
0.4
0.6
5.2
6.4
1.2
1.75
6.00
4.00
1.5
1.5
12
12
MAX
2.00
UNITS
µs
µs
µs
µs
µs
µs
µs
µs
µs
kbps
ns
ns
ns
ns
Note 1:
All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device
ground unless otherwise noted.
Note 2:
∆V
OD
and
∆V
OC
are the changes in magnitude of V
OD
and V
OC
, respectively, when the DI input changes state.
Note 3:
Maximum and minimum current levels apply to peak current just prior to foldback-current limiting.
_______________________________________________________________________________________
3
1.6µA, RS-485/RS-422, Half-Duplex,
Differential Transceiver for Battery-Powered Systems
MAX3471
__________________________________________Typical Operating Characteristics
(V
CC
= +3.6V, T
A
= +25°C, unless otherwise noted.)
OUTPUT CURRENT
vs. RECEIVER OUTPUT LOW VOLTAGE
MAX3471toc01
OUTPUT CURRENT vs. RECEIVER
OUTPUT HIGH VOLTAGE
MAX3471toc02
RECEIVER OUTPUT HIGH
VOLTAGE vs. TEMPERATURE
LOAD = 0.8mA
RECEIVER OUTPUT VOLTAGE (V)
5.0
V
CC
= 5V
4.5
MAX3471toc03
45
40
OUTPUT CURRENT (mA)
35
30
25
20
15
10
5
0
0
V
CC
= 3.6V
V
CC
= 5V
20
18
16
OUTPUT CURRENT (mA)
14
12
10
8
6
4
2
0
V
CC
= 3.6V
V
CC
= 5V
5.5
4.0
V
CC
= 3.6V
3.5
3.0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT HIGH VOLTAGE (V)
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
OUTPUT LOW VOLTAGE (V)
RECEIVER OUTPUT LOW
VOLTAGE vs. TEMPERATURE
MAX3471toc04
DRIVER OUTPUT CURRENT
vs. DIFFERENTIAL OUTPUT VOLTAGE
MAX3471toc05
DRIVER DIFFERENTIAL
OUTPUT VOLTAGE vs. TEMPERATURE
DIFFERENTIAL OUTPUT VOLTAGE (V)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
R
DIFF
= 54Ω
-50
-25
0
25
50
75
100
125
V
CC
= 3.6V
V
CC
= 5V
MAX3471toc06
140
LOAD = 2.2mA
RECEIVER OUTPUT VOLTAGE (mV)
120
100
80
60
V
CC
= 5V
40
20
0
-50
-25
0
25
50
75
100
V
CC
= 3.6V
40
DRIVER OUTPUT CURRENT (mA)
35
30
25
20
15
10
5
0
0
V
CC
= 3.6V
V
CC
= 5V
2.0
125
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
DRIVER DIFFERENTIAL
OUTPUT VOLTAGE vs. TEMPERATURE
MAX3471toc07
OUTPUT CURRENT vs. DRIVER
OUTPUT LOW VOLTAGE (V
CC
= 5V)
MAX3471toc08
OUTPUT CURRENT vs. DRIVER
OUTPUT LOW VOLTAGE (V
CC
= 3.6V)
V
CC
= 3.6V
25
OUTPUT CURRENT (mA)
20
15
10
5
0
MAX3471toc09
5.0
DIFFERENTIAL OUTPUT VOLTAGE (V)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-50
R
DIFF
= 1.5kΩ
V
CC
= 3.6V
V
CC
= 5V
60
V
CC
= 5V
50
OUTPUT CURRENT (mA)
40
30
20
10
0
30
-25
0
25
50
75
100
125
0
1
2
3
4
5
6
7
8
9
10
0
2
4
6
8
10
12
TEMPERATURE (°C)
OUTPUT LOW VOLTAGE (V)
OUTPUT LOW VOLTAGE (V)
4
_______________________________________________________________________________________
1.6µA, RS-485/RS-422, Half-Duplex,
Differential Transceiver for Battery-Powered Systems
Typical Operating Characteristics (continued)
(V
CC
= +3.6V, T
A
= +25°C, unless otherwise noted.)
OUTPUT CURRENT vs. DRIVER
OUTPUT HIGH VOLTAGE (V
CC
= 3.6V)
MAX3471toc11
MAX3471toc10
MAX3471
OUTPUT CURRENT vs. DRIVER
OUTPUT HIGH VOLTAGE (V
CC
= 5V)
45
40
OUTPUT CURRENT (mA)
35
30
25
20
15
10
5
0
-12 -10
-8
-6
-4
-2
0
2
4
6
OUTPUT HIGH VOLTAGE (V)
0
V
CC
= 5V
25
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE (DE = V
CC
)
80
SUPPLY CURRENT (µA)
70
60
50
40
30
20
10
0
DE = V
CC
-50
-25
0
25
50
75
100
125
V
CC
= 2.5V
V
CC
= 3.6V
V
CC
= 5.5V
V
CC
= 5.0V
MAX3471toc12
90
V
CC
= 3.6V
20
OUTPUT CURRENT (mA)
15
10
5
-12
-10
-8
-6
-4
-2
0
2
4
OUTPUT HIGH VOLTAGE (V)
TEMPERATURE (°C)
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE (DE = GND)
MAX3471toc13
DRIVER PROPAGATION DELAY
(t
DPHL
, t
DPLH
) vs. TEMPERATURE
1.4
PROPAGATION DELAY (µs)
1.3
1.2
1.1
1.0
0.9
0.8
C
L1
= C
L2
= 100pF
0.7
V
CC
= 5V, R
DIFF
= 54Ω
V
CC
= 3.6V, R
DIFF
= 54Ω
V
CC
= 3.6V, R
DIFF
= 1.5kΩ
V
CC
= 5V, R
DIFF
= 1.5kΩ
MAX3471toc14
3.0
2.5
SUPPLY CURRENT (µA)
2.0
V
CC
= 3.6V
1.5
1.0
0.5
DE = GND
0
-50
-25
0
25
50
75
100
V
CC
= 2.5V
V
CC
= 5.5V
V
CC
= 5.0V
1.5
125
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
RECEIVER PROPAGATION
DELAY (t
PLH
) vs. TEMPERATURE
MAS3471toc15
RECEIVER PROPAGATION
DELAY (t
PHL
) vs. TEMPERATURE
7.0
PROPAGATION DELAY (µs)
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
V
CC
= 5V
V
CC
= 3.6V
MAX3471toc16
6
V
CC
= 3.6V
5
PROPAGATION DELAY (µs)
4
V
CC
= 5V
3
2
1
0
-40
CIRCUIT OF FIGURE 9
C
L
= 100pF
|
V
ID
|
= 2V
-20
0
20
40
60
80
7.5
|
V
ID
|
= 2V
C
L
= 100pF
-40
-20
0
20
40
60
80
100
100
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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