UM3491 Datasheet, PDF (10/14 Pages) Union Semiconductor, Inc. – +3.3V Low Power，±15kV ESD-Protected, Fail-Safe, RS-422 Transceivers in SOP14/DIP14

Test Circuit
Y
R
VOD
R ^VOC
Z
Figure 3. Driver DC Test Load
3V
DE
DI
Y
VOD2
Z
CL1
RDIFF
CL2
UM3491
Receive ^{Test Point}
Output
+
S1
CRL
15pF
1K
S2
1K
VCC
Figure 4. Receiver Enable/Disable Timing Test Load
Output
500ohm
Under
Test
+
CL
VCC
S1
S2
Figure 5. Driver Timing Test Circuit
Figure 6. Driver Enable and Disable Timing Test Load
3.3V
1.5V
DI 0V
Z
VO
Y
1/2VO
tDPLH
VO
VDIFF 0
－VO
10％
tDR
90％
VDIFF=V(Y)-V(Z)
tSKEW=tDPLH-tDPHL
1.5V
tDPHL
1/2VO
90％
10％
tDF
Figure 7. Driver Propagation Delays
RO ^VOH
VOL
1V A
-1V B
tRPHL
1.5V OUTPUT
INPUT
1.5V
tRPLH
3.3V
DE 0V
Y,Z
VOL
1.5V
Y,Z
0
1.5V
tDZL(SHDN), tDZL
tDLZ
2.3V Output Normally Low
Output Normally High
2.3V
tDZH(SHDN), tDZH
tDHZ
VOL+0.5V
VOH-0.5V
Figure 8. Driver Enable and Disable Times
3.3V
RE
0V
1.5V
VCC
RO
0
tRZL(SHDN), tRZL
tRLZ
1.5V Output Normally Low
Output Normally High
1.5V
tRZH(SHDN), tRZH
tRHZ
1.5V
VOL+0.5V
VOH-0.5V
Figure 9. Receiver Propagation Delays
Figure 10. Receiver Enable and Disable Times
A
RO
R
RE
120ohm
B
B
ATE
VD
R ^Receiver
DE
Output
A
Z
DI
D
120ohm
Y
DATA IN
DATA OUT
Figure 11. Receiver Propagation Delay Test Circuit
Figure 12: Line Repeater
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http://www.union-ic.com Rev.02 Jun.2012
10/14