SP301 Datasheet, PDF (14/18 Pages) Sipex Corporation – RS-232/RS-422 Line Drivers/Receivers

shown in these figures, the loopback function
internally connects the driver outputs to the
corresponding receiver inputs, and switches the
output pin to a resistive divider of 10kΩ nominal
impedance from V_EE to ground. Receiver out-
puts are left active for signal verification.
During loopback, the receiver inputs are tied to
ground via a 5kΩ pulldown resistor. To mini-
mize loopback errors, the receiver inputs must
be limited to ±10V swings.
SP301 CONFIGURATIONS IN LOOPBACK MODE
One-Channel Full Duplex RS-232 &
One-Channel Full Duplex RS-422
Opposite Drivers
Two-Channel Full Duplex RS-422
10k
V_{EE 10k}
TIA
RS-422 LINE DRIVER
RS-422 RECEIVER
ROA
TOA₂
TOA₁
10k
10k _VEE
RIA₁
RIA₂
TIB
RS-232 LINE DRIVER
RS-232 RECEIVER
ROB
TOB₁
10k
V_EE
10k
RIB₁
SELECT A = 1
SELECT B = 0
LB = 0 ^(ACTIVE)
10k
V_{EE 10k}
TIB
RS-422 LINE DRIVER
RS-422 RECEIVER
ROB
10k
V_EE
10k
TIA
RS-422 LINE DRIVER
RS-422 RECEIVER
ROA
SELECT A = 1
SELECT B = 1
LB = 0 (ACTIVE)
TOB₁
TOB₂
10k
10k _VEE
RIB₂
RIB₁
TOA₁
TOA₂
10k
10k _VEE
RIA₂
RIA₁
64
Corporation
SIGNAL PROCESSING EXCELLENCE