EVAL-ADM3062EEBZ/EVAL-ADM3062EEB1Z User Guide UG-1220
Rev. 0 | Page 3 of 9
EVALUATION BOARD HARDWARE
SETTING UP THE EVALUATION BOARD
The E VA L -ADM3062EEBZ and E VA L -ADM3062EEB1Z
evaluation boards are powered by connecting a 3.0 V or 5.5 V
power supply to the J1 screw terminals at the top of the evaluation
board for the ADM3062E V
CC
pin and GND pin. A 10 µF
decoupling capacitor, C3, is fitted at the connector between V
CC
and GND. The V
CC
pin of the RS-485 transceiver is fitted with a
100 nF decoupling capacitor, C1, with a second footprint for an
optional additional capacitor, C2. The V
IO
pin can be connected
with V
CC
or a separate 1.8 V power supply.
Corresponding labeled test points allow monitoring of the power
supply to the evaluation board and the probe reference to ground.
INPUT AND OUTPUT CONNECTIONS
Digital input and output signals are connected via the J3 screw
terminal block, allowing wire connections from the evaluation
boards to a signal generator or UART. The EVAL-ADM3062EEBZ
and EVA L -ADM3062EEB1Z include connections for data input
(DI), receiver output (RO), receiver enable (
RE
), and driver enable
(DE). Alternatively, jumper connections can drive these inputs
and/or connect them to the VCC and GND pins (see Table 1).
Connections to an RS-485 bus are made via a screw terminal block,
J5. For the E VAL -ADM3062EEBZ or EVA L-ADM3062EEB1Z
half-duplex boards, there are two bus input/output signals, A and B,
for noninverting and inverting signals, respectively. The bus cable
can include a common ground connection or shield and can
also be connected to the J5 screw terminal block of the evaluation
boards. Test points are available on the evaluation boards and
are appropriately labeled for all digital and bus input/output
signals.
OTHER BOARD COMPONENTS
The E VA L -ADM3062EEBZ and EVA L-ADM3062EEB1Z
evaluation boards include footprints for termination resistors,
RT1 and RT2, as well as pull-up and pull-down resistors, R1 and
R2. Termination resistors of 120 Ω are fitted to the evaluation
board; these resistors can be removed or replaced with a different
value resistor as needed. Inserting both LK3 and LK4 adds a
60 Ω load to the RS-485 driver.
Biasing Resistors for Bus Idle Fail-Safe
Although the ADM3062E has a built in receiver fail-safe for the
bus idle condition, there are footprints on the evaluation boards
for fitting the R2 pull-up resistor to the V
CC
pin on A, as well as
the R1 pull-down resistor to GND on B. These resistors can be
fitted if the user is connecting to other devices that require such
external biasing resistors on the bus. The exact value required
for a 200 mV minimum differential voltage in the bus idle con-
dition depends on the supply voltage (for example, 960 Ω for
3.3 V and 1440 Ω for 5 V).
For more information about the bus idle fail-safe, see the
AN-960 Application Note, RS-485/RS-422 Circuit Implemen-
tation Guide.
Table 1. Jumper Configurations
Link Connection Description
LK1 A Connects the receiver enable (
RE
) input of the ADM3062E to the VCC
pin. This setting disables the receiver.
B Connects the
RE
input of the ADM3062E to GND. This setting enables the receiver.
C Connects the
RE
input of the ADM3062E to the J3-2 terminal block connector.
D Connects the
RE
input of the ADM3062E to the J3-3 terminal block connector; that is, the input for both
RE
and DE
is set by LK1. This setting ensures that when the driver is enabled, the receiver is disabled, or when the driver is
disabled, the receiver is enabled.
LK2 A Connects the DE input of the ADM3062E to the VCC
pin. This setting enables the driver.
B Connects the DE input of the ADM3062E to GND. This setting disables the driver.
C Connects the DE input of the ADM3062E to the J3-2 terminal block connector.
LK3 Inserted Connects the 120 Ω RT1 termination resistor across the RS-485 A and B pins.
Not inserted Disconnects the 120 Ω RT1 termination resistor across the RS-485 A and B pins.
LK4 Inserted Connects the 120 Ω RT2 termination resistor across the RS-485 A and B pins.
Disconnects the 120 Ω RT2 termination resistor across the RS-485 A and B pins.
LK6 Inserted Connects Pin V
CC
with Pin V
IO
on the ADM3062E device.
Not inserted Disconnects Pin V
CC
with Pin V
IO
on the ADM3062E device.
