ltc2871fe Linear Technology Corporation, ltc2871fe Datasheet - Page 18

• Manufacturer Part Number: ltc2871fe
• Description: Ltc2870/ltc2871 - Rs232/rs485 Multiprotocol Transceivers With Integrated Termination
• Manufacturer: Linear Technology Corporation

FUNCTION TABLES
LTC2870/LTC2871
Table 5. LTC2871 CH2 CONTROL
Table 6. RS485 Driver Mode (TE485 = 0)
Table 7. RS485 Receiver Mode (LB = 0)
Table 8. RS485 Termination (485/232 = 1 for LTC2870)
Table 9. RS485 Duplex Control (485/232 = 1 for LTC2870)
Table 10. LTC2870 Loopback Functions
18
CH2
RXEN OR RX485
DX485 OR DXEN
X
0
0
0
1
1
1
LB
X
0
1
TE485
H/F
1
0
0
0
X
0
1
1
X
0
1
X
0
1
DX232
RXEN
0
0
1
1
0
1
1
X
1
0
Loopback (RA = DY, RB = DZ)
RX232
Inputs Open or Shorted Together (DC)
RS485 DRIVER OUTPUTS
DI
X
0
1
X
1
0
1
0
0
1
0
H/F, LB
Not Loopback
Not Loopback
X
X
X
Thermal Fault
CONDITIONS
MODE
A - B (NOTE 5)
No Fault
No Fault
No Fault
Y, Z
Y, Z
RS232 RECEIVER INPUTS
< –200mV
RIN1
> 200mV
Hi-Z
5kΩ
Hi-Z
5kΩ
5kΩ
Hi-Z
5kΩ
X
X
Thermal Fault
CONDITIONS
No Fault
No Fault
125kΩ
125kΩ
RIN2
Hi-Z
5kΩ
Hi-Z
5kΩ
Hi-Z
Hi-Z
Hi-Z
Y
0
1
RS485 RECEIVER INPUTS
Table 11. LTC2871 Loopback Functions
125kΩ
125kΩ
LB
Z
1
0
X
0
1
1
1
RS232 DRIVER OUTPUTS
A, B
Y, Z
Thermal Fault
DOUT1
CONDITIONS
Driven
Driven
Driven
Driven
Hi-Z
Hi-Z
Hi-Z
No Fault
No Fault
No Fault
Failsafe
R (A TO B)
RX232
120Ω
X
1
0
1
0
Hi-Z
Hi-Z
RX485
DOUT2
Driven
Driven
X
1
1
0
0
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
R (Y TO Z)
RA, RO
120Ω
Hi-Z
Hi-Z
Hi-Z
Hi-Z
0
1
1
Loopback All (ROUT1 = DIN1, ROUT2 = DIN2, RO = DI)
Loopback RS232 (ROUT1 = DIN1, ROUT2 = DIN2)
COMMENTS
Both Drivers and Receivers Disabled
Both Receivers Enabled, Both Drivers Disabled
Both Receivers Disabled, Both Drivers Enabled
Both Receivers and Drivers Enabled
Channel 2 Drivers and Receivers Disabled
Channel 2 Drivers and Receivers Disabled
Channel 2 Drivers and Receivers Disabled
Loopback RS485 (R0 = DI)
Not Loopback
Not Loopback
MODE
28701f