Full Duplex Rs-485 Transceivers Loopback Test - Analog Devices EVAL-ADM2463EEBZ User Manual

UG-1715
ADP7104 LDO Regulator
The EVAL-ADM2463EEBZ/EVAL-ADM2763EEBZ feature two
on-board ADP7104 LDO regulators that allow flexible power
supply configurations during evaluation.
The V regulator, U1, is powered from the VDD1 terminal on
DD1
Connector P5, and is configured using the LK8 jumper. This
jumper position selects the regulator output to the V
Options of 1.8 V, 2.5 V, 3.3 V, and 5 V are available. To bypass
the V ADP7104 regulator, U1, and power the V
DD1
from the VDD1 terminal, insert the LK8 jumper into Position E.
The V regulator, U3, is powered from the VDD2 terminal on
DD2
Connector P6, and is configured using the LK9 jumper. This
jumper position selects the regulator output to the
or ADM2763E V pin. Options of 3.3 V and 5 V are available.
DD2
To bypass the V regulator, U3, and power the V
DD2
directly from the VDD2 terminal, insert the LK9 jumper into
Position C.
Table 2 and Table 3 lists the supported power supply
configurations and the associated jumper configurations.
Table 2. Primary Side Input Supply Configurations
Jumper LK8 VDD1 Input Voltage Range
A 2.2 V to 20 V
B 2.9 V to 20 V
C 3.7 V to 20 V
D 5.4 V to 20 V
E 1.7 V to 5.5 V
Table 3. Secondary Side Input Supply Configurations
Jumper LK9 VDD2 Input Voltage Range
A 3.7 V to 20 V
B 5.4 V to 20 V
C 3 V to 5.5 V
SIGNAL
GENERATOR
INVR
EVAL-ADM2463EEBZ/EVAL-ADM2763EEBZ
pin.
DD1
pin directly
DD1
ADM2463E
pin
DD2
4V TO 20V
POWER
SUPPLY
P5
P1
LK8
RxD
RE
A
RxD
DE B
RE
DE
Z
TxD
Y
INVR
TxD
P2
Figure 2. Full Duplex RS-485 Loopback Test
FULL DUPLEX RS-485 TRANSCEIVERS
LOOPBACK TEST
A loopback test can be set up with the EVAL-ADM2463EEBZ/
EVAL-ADM2763EEBZ by closing the LK4 and LK5 jumpers.
The details of this test are shown in Table 1 and in Figure 2. A
signal generator is connected to the TxD pin, which allows
verification of the bus signals and the receiver output. Note that
during the test, the jumper position for LK1 is Position C, LK2 is
Position A, and LK3 is Position C. See Table 2 for the jumper
configurations for different power supply configurations. The
LK6 and LK7 jumpers can be inserted to terminate the
transmitter and receiver with 120 Ω resistors. Connect both
jumpers when the board is configured in parallel by the loopback
to ensure that the test is conducted with a standard RS-485 load
of 60 Ω (bus terminated at both ends by 120 Ω).
V
Regulator provides 1.8 V
Regulator provides 2.5 V
Regulator provides 3.3 V
Regulator provides 5 V
Supplied directly from the VDD1 terminal on P5
V
Regulator provides 3.3 V
Regulator provides 5 V
Supplied directly from the VDD2 terminal on P6
4V TO 20V
POWER
SUPPLY
P6
P3
LK9
A
B
Z
Y
GND2
GND2
P4
EVAL-ADM2463EEBZ/
EVAL-ADM2763EEBZ
Rev. 0 | Page 6 of 11
Supply
DD1
Supply
DD2
OSCILLOSCOPE
User Guide