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LTC2872IUHF#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28
LTC2872
13
2872f
TesT circuiTs
Figure 8. RS485 Termination Resistance and Timing Measurements (Note 5)
Figure 9. RS232 Driver Timing and Slew Rate Measurements
Figure 10. RS232 Driver Enable and Disable Times
2872 F08
RECEIVER
V
AB
A
B
V
AB
I
A
R
TERM
=
V
B
½V
L
½V
L
TE485
I
A
I
A
90%
10%
t
RTZ485
t
RTEN485
0V
V
L
TE485
+
–
+
–
2872 F09
DRIVER
INPUT
DRIVER
OUTPUT
C
L
R
L
t
PHLD232
t
PLHD232
t
SKEWD232
= |t
PHLD232
– t
PLHD232
|
t
F
t
R
DRIVER
INPUT
DRIVER
INPUT
SLEW RATE =
6V
t
F
OR t
R
3V
–3V
0V
V
OLD
V
L
½V
L
½V
L
0V
3V
–3V
0V
V
OHD
2872 F10
0V OR V
L
DXEN
DRIVER
OUTPUT
C
L
R
L
t
HZD232
t
LZD232
DXEN
DRIVER
OUTPUT
DRIVER
OUTPUT
0.5V
t
ZHD232
t
ZLD232
5V
5V
0.5V
0V
0V
0V
V
OHD
V
L
½V
L
½V
L
V
OLD
LTC2872
14
2872f
TesT circuiTs
Figure 11. RS232 Receiver Timing Measurements
Figure 12. RS232 Receiver Enable and Disable Times
2872 F11
t
PHLR232
t
SKEWR232
= |t
PLHR232
– t
PHLR232
|
t
PLHR232
t
RR232
90%
1.5V 1.5V
½V
L
10%
t
FR232
90%
0V
–3V
V
L
+3V
½V
L
10%
0V
V
L
RECEIVER
OUTPUT
RECEIVER
OUTPUT
RECEIVER
INPUT
RECEIVER
INPUT
C
L
2872 F12
–3V OR +3V
RXEN
RECEIVER
OUTPUT
GND
OR V
L
C
L
R
L
t
HZR232
t
LZR232
RXEN
RECEIVER
OUTPUT
RECEIVER
OUTPUT
0.5V
t
ZHR232
t
ZLR232
½V
L
½V
L
0.5V
0V
0V
V
L
V
OHR
V
L
½V
L
½V
L
V
OLR
LTC2872
15
2872f
FuncTion Tables
Table 1. Shutdown and Fast Enable Modes
FEN
485/232_1 AND
485/232_2
RXEN1 AND
RXEN2
DXEN1 AND
DXEN2
TE485_1 AND
TE485_2 H/F LB
DC/DC
CONVERTER MODE AND COMMENTS
0 X 1 0 0 X X OFF Shutdown: All Main Functions Off
1 X 1 0 0 X X ON Fast-Enable: DC/DC Converter On Only
Table 2. Mode Selection Table for a Given Port (FEX = X)
485/232 RXEN DXEN TE485 H/F LB DC/DC CONVERTER MODE AND COMMENTS
0 X 1 X X 0 ON RS232 Drivers On
0 0 X X X 0 ON RS232 Receivers On
1 X 1 X X 0 ON RS485 Driver On
1 0 X X X 0 ON RS485 Receiver On
1 X X 1 X X ON RS485 Termination Mode (See Table 7)
1 X X X 0 0 X RS485 Full Duplex Mode
1 X X X 1 0 X RS485 Half Duplex Mode
1 0 X X X 1 ON RS485 Loopback Mode
0 0 X X X 1 ON RS232 Loopback Mode
Table 3. RS232 Receiver Mode for a Given Port (485/232 = 0)
RXEN RECEIVER INPUT (A, B) CONDITIONS RECEIVER OUTPUTS (RA, RB) RECEIVER INPUTS (A, B)
1 X No Fault Hi-Z 125kΩ
0 0 No Fault 1 5kΩ
0 1 No Fault 0 5kΩ
0 X Thermal Fault Hi-Z 5kΩ
Table 4. RS232 Driver Mode for a Given Port (485/232 = 0)
DXENX DRIVER INPUT (DY, DZ) CONDITIONS DRIVER OUTPUT (Y, Z)
0 X No Fault 125kΩ
1 0 No Fault 1
1 1 No Fault 0
X X Thermal Fault 125kΩ
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28

LTC2872IUHF#PBF

Mfr. #:
Buy LTC2872IUHF#PBF
Manufacturer:
Analog Devices Inc.
Description:
RS-232 Interface IC RS232/RS485 Dual Port Multiprotocol Transceiver with Integrated Termination (Shared I/O)
Lifecycle:
New from this manufacturer.
Delivery:
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