SP481_04 Datasheet, PDF (6/10 Pages) Sipex Corporation – Low Power Half-Duplex RS-485 Transceivers

A
R
V_OD
B
R ^VOC
Figure 1. Driver DC Test Load Circuit
3V
DE
DI
A ^RDI^CFFL1
A
RO
B
B
C_L2
15pF
Receiver ^{Test Point}
Output
C_RL
S₁
1K
1K
V_CC
S₂
Figure 2. Receiver Timing Test Load Circuit
Output
500
S₁
V_CC
Under
Test
C_L
S₂
Figure 3. Driver/Receiver Timing Test Circuit
Figure 4. Driver Timing Test Load #2 Circuit
f_SP481/485 = 1MHz; f_SP483 = 100kHz ; t_R < 10ns; t_F < 10ns
+3V
DI
0V
1.5V
B
DRIVER
OUTPUT _A
DIFFERENTIAL V_O⁺
OUTPUT 0V
V_A – V_B ^VO^–
V_O ^1/2VO
t_PLH
t_DPLH
t_R
1.5V
t_PHL
t_DPHL
1/2V_O
t_F
t_{SKEW = |} t_{DPLH -} t_{DPHL |}
Figure 6. Driver Propagation Delays
INPUTS
OUTPUTS
LINE
RE DE DI CONDITION B A
X 1 1 No Fault
01
X 1 0 No Fault
10
X0X
X
ZZ
X 1 X Fault
ZZ
Table 1. Transmit Function Truth Table
INPUTS
RE DE
0
0
0
0
0
0
1
0
OUTPUTS
A-B
R
+0.2V
1
-0.2V
0
Inputs Open
1
X
Z
Table 2. Receive Function Truth Table
Rev. 07/28/04
SP481/483/485 Low Power Half-Duplex RS485 Transceivers
6
© Copyright 2002 Sipex Corporation