UM3487E Datasheet, PDF (8/14 Pages) Union Semiconductor, Inc. – ±15kV ESD-Protected, Fail-Safe, Hot-Swappable Auto Polarity Reversal RS-485 Transceivers

Typical Operating Circuit
120ohm
DI
L1
B
D
L2
A
DE
RO
R
RE
L1 L2
Master Node
R
D
+5V GND
DI DE RO RE
Slave Node1
UM3487E
L1 L2
R
D
120ohm
L1
L2
DE
D
DI
R
RO
RE
Terminal Slave Node
DI
DE RO RE _{All UM3487E's L1 L2 pin can interchange each other;}
Slave Node N
Test Circuit
Figure 1. Typical Half-Duplex Non-Polarity RS-485 Network
L1
R_LOAD/2
V_OD
R_LOAD/2 ^VOC
L2
Figure 2. Driver DC Test Load
3V
DE
C_L2
DI
L2
V_OD2 ^RDIFF
L1
C_L1
Figure 3. Driver Timing Test Circuit
Driver Output
Under Test
C_L
500ohm
+
S1
V_CC
Receive
Output
Test Point
+
C_RL
1K
VCC
S1
15pF
1K
S2
S2
Figure 4. Driver Enable/Disable Timing Test Load Figure 5. Receiver Enable/Disable Timing Test Load
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http://www.union-ic.com Rev.02 Jan.2014
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