LTC1334
TEST CIRCUITS
Z
R
V
OD
R
Y
LTC1334 • F01
LTC1334 • F02
LTC1334 • F03
V
CC
3V
D
V
OC
SEL Z
R
L
DE
3V
Y
C
L
A
C
L
B
3V
SEL
R
15pF
500Ω
DR OUT
C
L
S2
S1
Figure 1. RS422/RS485
Driver Test Load
Figure 2. RS485 Driver/Receiver
Timing Test Circuit
Figure 3. RS485 Driver Output
Enable/Disable Timing Test Load
0V
SEL
D
Y, Z
D
0V
SEL
Y, Z
V
IN
A, B
0V
SEL
R
V
OUT
15pF
LTC1334 • F05
C
L
R
L
LTC1334 • F04
Figure 4. RS232 Driver
Swing/Timing Test Circuit
Figure 5. RS232 Receiver
Timing Test Circuit
SWITCHI G WAVEFOR S
3V
D
0V
t
PLH
V
O
Z–Y
–V
O
50%
10%
1.5V
Y
V
O
Z
t
SKEW
t
SKEW
LTC1334 • F06
W
U
f = 1MHz: t
r
≤
10ns: t
f
≤
10ns
1.5V
t
PHL
90%
V
DIFF
= V(Z) – V(Y)
90%
50%
10%
t
f
t
r
1/2 V
O
Figure 6. RS485 Driver Propagation Delays
9