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MAX1487C/D

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17
Low-Power, Slew-Rate-Limited
RS-485/RS-422 Transceivers
Maxim Integrated 7
MAX481/MAX483/MAX485/
MAX487–MAX491/MAX1487
______________________________________________________________Pin Description
MAX481
MAX483
MAX485
MAX487
MAX1487
TOP VIEW
NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH.
TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.
1
2
3
4
8
5
V
CC
GND
DI
DE
RE
RO
R
D
Rt
Rt
7
6
D
R
DE
RE
DI
RO
A
B
1
2
3
4
8
7
6
5
V
CC
B
A
GND
DI
DE
RE
RO
DIP/SO
R
D
1
2
3
4
8
7
6
5
V
CC
A
GND
DE
RE
B
RO
μMAX
B
A
DI
MAX481
MAX483
MAX485
MAX487
MAX1487
Figure 1. MAX481/MAX483/MAX485/MAX487/MAX1487 Pin Configuration and Typical Operating Circuit
µMAX
—
—
5
6
7
8
—
2
—
1
3
—
µMAX
4
5
6
7
—
—
8
—
1
—
2
—
DIP/SO DIP/SO
2 3
Receiver Output Enable. RO is enabled when RE is low; RO is
high impedance when RE is high.
3 4
Driver Output Enable. The driver outputs, Y and Z, are enabled
by bringing DE high. They are high impedance when DE is low. If
the driver outputs are enabled, the parts function as line drivers.
While they are high impedance, they function as line receivers if
RE is low.
DIP/SO
—
4 5
Driver Input. A low on DI forces output Y low and output Z high.
Similarly, a high on DI forces output Y high and output Z low.
5 6, 7 Ground
— 9 Noninverting Driver Output
— 10 Inverting Driver Output
—
3
4
6 — Noninverting Receiver Input and Noninverting Driver Output
— 12 Noninverting Receiver Input
5
6
—
8
RE
DE
DI
GND
Y
Z
A
A
7 — — B Inverting Receiver Input and Inverting Driver Output
— 7 11 B Inverting Receiver Input
8 1 14 V
CC
Positive Supply: 4.75V ≤ V
CC
≤ 5.25V
— — 1, 8, 13 N.C. No Connect—not internally connected
FUNCTION
NAME
431 2
Receiver Output: If A > B by 200mV, RO will be high;
If A < B by 200mV, RO will be low.
2 RO
PIN
FUNCTIONNAME
MAX481/MAX483/
MAX485/MAX487/
MAX1487
MAX488/
MAX490
MAX489/
MAX491
Low-Power, Slew-Rate-Limited
RS-485/RS-422 Transceivers
8 Maxim Integrated
MAX481/MAX483/MAX485/
MAX487–MAX491/MAX1487
__________Applications Information
The MAX481/MAX483/MAX485/MAX487–MAX491 and
MAX1487 are low-power transceivers for RS-485 and RS-
422 communications. The MAX481, MAX485, MAX490,
MAX491, and MAX1487 can transmit and receive at data
rates up to 2.5Mbps, while the MAX483, MAX487,
MAX488, and MAX489 are specified for data rates up to
250kbps. The MAX488–MAX491 are full-duplex trans-
ceivers while the MAX481, MAX483, MAX485, MAX487,
and MAX1487 are half-duplex. In addition, Driver Enable
(DE) and Receiver Enable (RE) pins are included on the
MAX481, MAX483, MAX485, MAX487, MAX489,
MAX491, and MAX1487. When disabled, the driver and
receiver outputs are high impedance.
MAX487/MAX1487:
128 Transceivers on the Bus
The 48kΩ,
1
/
4
-unit-load receiver input impedance of the
MAX487 and MAX1487 allows up to 128 transceivers
on a bus, compared to the 1-unit load (12kΩ input
impedance) of standard RS-485 drivers (32 trans-
ceivers maximum). Any combination of MAX487/
MAX1487 and other RS-485 transceivers with a total of
32 unit loads or less can be put on the bus. The
MAX481/MAX483/MAX485 and MAX488–MAX491 have
standard 12kΩ Receiver Input impedance.
MAX488
MAX490
TOP VIEW
1
2
3
4
RO
DI
GND
8
7
6
5
A
B
Z
Y
V
CC
DIP/SO
R
D
Rt
Rt
V
CC
5
6
7
8
RO
DI
GND
4
GND
DI
RO
3
2
A
B
Y
Z
V
CC
DR
R
D
1
3
V
CC
4
RO
2
A
1
6
5
7
8
GND
DI
Y
Z
B
μMAX
MAX488
MAX490
NOTE: TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE.
MAX489
MAX491
DIP/SO
TOP VIEW
Rt
Rt
DE V
CC
RE GND
V
CC
RE
GND DE
RO
DI
9
10
12
11
B
A
Z
Y
5
RO
NC
DI
2
1, 8, 13
3 6, 7
144
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
CC
N.C.
N.C.
A
B
Z
Y
N.C.
RO
RE
DE
DI
GND
GND
R
D
D
RD
R
Figure 2. MAX488/MAX490 Pin Configuration and Typical Operating Circuit
Figure 3. MAX489/MAX491 Pin Configuration and Typical Operating Circuit
Low-Power, Slew-Rate-Limited
RS-485/RS-422 Transceivers
Maxim Integrated 9
MAX481/MAX483/MAX485/
MAX487–MAX491/MAX1487
MAX483/MAX487/MAX488/MAX489:
Reduced EMI and Reflections
The MAX483 and MAX487–MAX489 are slew-rate limit-
ed, minimizing EMI and reducing reflections caused by
improperly terminated cables. Figure 12 shows the dri-
ver output waveform and its Fourier analysis of a
150kHz signal transmitted by a MAX481, MAX485,
MAX490, MAX491, or MAX1487. High-frequency har-
monics with large amplitudes are evident. Figure 13
shows the same information displayed for a MAX483,
MAX487, MAX488, or MAX489 transmitting under the
same conditions. Figure 13’s high-frequency harmonics
have much lower amplitudes, and the potential for EMI
is significantly reduced.
R
R
Y
Z
V
OD
V
OC
RECEIVER
OUTPUT
TEST POINT
1kΩ
1kΩ
S1
S2
V
CC
C
RL
15pF
DI
DE
3V
Y
Z
C
L1
C
L2
A
B
RO
RE
R
DIFF
V
ID
OUTPUT
UNDER TEST
500Ω
S1
S2
V
CC
C
L
_________________________________________________________________Test Circuits
Figure 4. Driver DC Test Load Figure 5. Receiver Timing Test Load
Figure 6. Driver/Receiver Timing Test Circuit Figure 7. Driver Timing Test Load
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17

MAX1487C/D

Mfr. #:
Buy MAX1487C/D
Manufacturer:
Maxim Integrated
Description:
RS-422/RS-485 Interface IC Low-Power, Slew-Rate-Limited RS-485/RS-422 Transceivers
Lifecycle:
New from this manufacturer.
Delivery:
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