Datasheet

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
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