Datasheet

LTC2872

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