MAX491ESD Maxim Integrated Products, MAX491ESD Datasheet - Page 9

• Manufacturer Part Number: MAX491ESD
• Description: RS-422/RS-485 Interface IC
• Manufacturer: Maxim Integrated Products

Specifications of MAX491ESD

• Case: SOP
• Lead Free Status / Rohs Status: No

Figure 4. Driver DC Test Load
Figure 6. Driver/Receiver Timing Test Circuit
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-
_________________________________________________________________Test Circuits
DI
DE
MAX483/MAX487/MAX488/MAX489:
3V
Y
Z
Y
Z
Reduced EMI and Reflections
_______________________________________________________________________________________
V
V
OD
ID
R
C
C
DIFF
L1
L2
R
R
V
OC
A
B
Low-Power, Slew-Rate-Limited
RE
RO
RS-485/RS-422 Transceivers
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.
Figure 5. Receiver Timing Test Load
Figure 7. Driver Timing Test Load
UNDER TEST
RECEIVER
OUTPUT
OUTPUT
15pF
C
TEST POINT
RL
C
L
500Ω
1kΩ
S1
S2
S1
S2
1kΩ
V
CC
V
CC
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