Full Duplex Rs-485 Transceivers Loopback Test; Iec 61000-4-2 Electrostatic Discharge (Esd) Protection - Analog Devices EVAL-ADM2867EEBZ User Manual

EVAL-ADM2867EEBZ
Insert the LK8 jumper into Position A to bypass the regulator
and power of the ADM2867E
on the P1 connector. In this configuration, the VREG_IN input
on the P1 connector supports a voltage range of 3 V to 5.5 V.
Table 3 lists the supported power supply configurations and the
associated jumper configurations.
FULL DUPLEX RS-485 TRANSCEIVERS
LOOPBACK TEST
To set up a loopback test with the EVAL-ADM2867EEBZ, close
the LK6 and LK7 jumpers. The test details are shown in Table 3
and in Figure 5. A signal generator is connected to the TxD pin,
which allows verification of the bus signals and the receiver output.
Note that the jumper position for LK1 is Position C, LK2 is
Position A, LK4 is Position C, and LK5 is Position C on the
EVAL-ADM2867EEBZ. See Table 3 for the jumper configurations
required for different power supply configurations. The LK11
and LK12 jumpers can be inserted to terminate the transmitter
and the receiver with 120 Ω resistors. Connect both these jumpers
while the EVAL-ADM2867EEBZ is configured for the loopback
test to ensure that the driver is terminated with a standard RS-485
load of 60 Ω (bus terminated at both ends by 120 Ω).
User Guide
directly from the VREG_IN input
4V TO 20V
SIGNAL
POWER
GENERATOR
SUPPLY
P1
LK10
RxD LK9
RE
DE
TxD
TxD
INVD
INVR
Figure 5. Full Duplex RS-485 Loopback Test
IEC 61000-4-2 ELECTROSTATIC DISCHARGE
(ESD) PROTECTION
The EVAL-ADM2867EEBZ is tested to achieve protection
against IEC 61000-4-2 ESD to ±12 kV (contact) and ±15 kV (air)
on Pin A, Pin B, Pin Y, and Pin Z of the ADM2867E.
The IEC 61000-4-2 ESD standard describes testing using two
coupling methods known as contact discharge and air discharge.
Contact discharge implies direct contact between the discharge gun
and the equipment under test (EUT).
During air discharge testing, the charged electrode of the discharge
gun is moved toward the EUT until a discharge occurs as an arc
across the air gap. The discharge gun does not make direct
contact with the EUT.
During testing, Pin A, Pin B, Pin Y, and Pin Z of the
are subjected to at least 10 positive and 10 negative single
discharges with a 1 sec interval between each pulse. The highest
specified IEC 61000-4-2 ESD test is Level 4, which defines a contact
discharge voltage of ±8 kV and an air discharge voltage of ±15 kV.
Figure 4 shows the 8 kV contact discharge current waveform, as
described in the
(I
) of 30 A. The IEC 61000-4-2 waveform parameters include
PEAK
rise times (t ) of <1 ns and pulse widths of ~60 ns.
R
I
PEAK
30A
90%
I 16A
30ns
I 8A
60ns
10%
t
= 0.7ns TO 1ns
R
OSCILLOSCOPE
EVAL-ADM2867EEBZ
P7
A
B
RxD A
Z
B
Z
Y
Y
GND
2
GND
2
P8
Rev. 0 | Page 7 of 12
ADM2867E data sheet, which has a peak current
30ns
Figure 4. IEC 61000-4-2 ESD Waveform (8 kV)
UG-1677
ADM2867E
t
60ns