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dc1851af
DEMO MANUAL DC1851A
The LTC2872 may be made to self-oscillate as a ring
oscillator by connecting the drivers and receivers in one
all-encompassing loop, and adding one inversion. The
inversion may be introduced with a logic inverter, or by
cross-connecting the RS485 driver and receiver in full-
duplex mode (connect Y to B and Z to A). The connection
arrangement shown in Figure 2 forms a ring oscillator
when used with the default jumper conditions. With V
CC
=
V
L
= 3.3V, the frequency of oscillation is typically 260kHz.
QUICK START PROCEDURE
LOGIC SUPPLY, V
L
1.7V TO V
CC
–
+
MAIN SUPPLY, V
CC
3.0V TO 5.5V
–
+
dc1851 F01
LOGIC
SIGNALS
I/O
SIGNALS
CONTROL LINES
Figure 1. Basic Test Setup. As Shown, Channel 1 is Configured for Full-Duplex RS485, While Channel 2 Is Configured for 2 + 2 RS232.
