Other Board Components - Analog Devices EVAL-ADM2867EEBZ User Manual

UG-1677
Link Jumper Connection
LK5 A
B
C
LK6 Inserted
Not inserted
LK7 Inserted
Not inserted
LK8 A
B
C
LK9 Inserted
Not inserted
LK10 Inserted
Not inserted
LK11 Inserted
Not inserted

OTHER BOARD COMPONENTS

The EVAL-ADM2867EEBZ has footprints for the RT1 and RT2
termination resistors. Two 120 Ω termination resistors are fitted to
the EVAL-ADM2867EEBZ, but these resistors can be removed or
replaced with a resistor of a different value as needed. Insert the
LK11 jumper to add a 120 Ω load to the RS-485 driver. When LK6,
LK7, and LK10 are inserted, an additional 120 Ω termination
resistor is connected, resulting in a 60 Ω load on the RS-485 driver.
Biasing Resistors for Bus Idle Fail-Safe
The ADM2867E has a built in receiver fail-safe for the bus idle
condition, but there are footprints on the EVAL-ADM2867EEBZ
for fitting the R10 and R11 pull-up resistors to the V
Pin A and Pin Y of the ADM2867E, as well as the R12 and R13
pull-down resistors to the GND
These resistors can be fitted if the user is connecting to other
devices that require external biasing resistors on the bus. The exact
value required for a 200 mV minimum differential voltage in bus
idle condition depends on the minimum supply voltage and the
termination scheme. For 5 V transceiver operation, 1140 Ω is
recommended. For 3.3 V transceiver operation, 900 Ω is
recommended.
See the AN-960 Application
Implementation Guide for more information about the bus idle
fail-safe.
On-Board LTC6900 Oscillator
An LTC6900 clock oscillator is provided on the EVAL-
ADM2867EEBZ to allow efficient evaluation of the device
without the need for an external signal source.
Description
Connects the INVR input of the
Connects the INVR input of the
Connects the INVR input of the
Connects the Pin B of the
Disconnects the Pin B of the
Connects the Pin A of the
Disconnects the Pin A of the
Connects the V pin of the
CC
ADP7104 regulator and allows an external power supply to connect directly to the V
Powers the V pin of the
CC
must be supplied with at least 4 V through the VREG_IN terminal on the P1 connector.
Powers the V pin of the
CC
must be supplied with at least 6 V through the VREG_IN terminal on the P1 connector.
Connects the V pin of the
CC
Disconnects the V pin of the
CC
on the P1 connector.
Connects the 120 Ω RT2 termination resistor across the Pin A and Pin B of the ADM2867E.
Disconnects the 120 Ω RT2 termination resistor across the Pin A and Pin B of the ADM2867E.
Connects the 120 Ω RT1 termination resistor across the Pin Y and Pin Z of the ADM2867E.
Disconnects the 120 Ω RT1 termination resistor across the Pin Y and Pin Z of the ADM2867E.
supply on
ISO
supply pins on Pin B and Pin Z.
2
Note, RS-485/RS-422 Circuit
ADM2867E to the V pin. This setting enables the receiver inversion feature.
IO
ADM2867E to the INVR terminal on the P3 connector.
ADM2867E to the GND
1
ADM2867E to Pin Z.
ADM2867E from Pin Z.
ADM2867E to Pin Y.
ADM2867E from Pin Y.
ADM2867E to the VREG_IN terminal on the P1 connector. This option bypasses the
ADM2867E with a regulated 3.3 V power supply from the ADP7104. The
ADM2867E with a regulated 5 V power supply from the ADP7104. The
ADM2867E to the V pin.
IO
ADM2867E from the V
To use the LTC6900
into Position BC. This setting connects the clock oscillator output
to the TxD input pin of the ADM2867E.
The R2 and R3 resistors can be used to configure the switching
frequency of the clock oscillator within the 100 kHz to 12.5 MHz
range. Calculate the frequency using the following equation:
f = 10 MHz
OSC
where f is the output frequency of the
OSC
The LTC6900
must only be used when the V
and 5.5 V.
ADP7104
The EVAL-ADM2867EEBZ features an on-board
LDO regulator that allows flexible power supply configurations
during evaluation.
To use the on-board regulator, insert the LK8 jumper into
Position B or Position C. This setting connects the regulator output
to the V pin of the ADM2867E. In this configuration, power
CC
must be supplied to the VREG_IN input on the P1 connector.
The ADP7104
regulated 3.3 V or 5 V power to the V
the LK8 jumper. When using the
LK8 jumper at Position C to provide a regulated 5 V power supply
to the V pin of the ADM2867E. Insert the LK8 jumper at
CC
Position B to provide a 3.3 V power supply to the V
ADM2867E. Note that when LK8 is inserted at Position B, 5 V
transceiver operation is not supported.
Rev. 0 | Page 6 of 12
EVAL-ADM2867EEBZ
pins. This setting is used for normal receiver operation.
CC
pin. The V pin is powered from the VIO terminal
IO IO
oscillator for evaluation, insert the LK3 jumper
 
20 kΩ
  16 kΩ (R2 + R3) 2 MΩ
 
(R2 + R3)
 
oscillator is powered from the V
supply voltage is between 2.7 V
IO
LDO Regulator
LDO regulator can be configured to provide
pin of the
CC
ADP7104
User Guide
pin of the ADM2867E.
ADP7104
ADP7104
≤ ≤
LTC6900 oscillator.
supply, and
IO
ADP7104
ADM2867E via
regulator, insert the
pin of the
CC