UG-534 Datasheet, PDF (3/8 Pages) Analog Devices – Isolated error amplifier

Evaluation Board User Guide
EVALUATION BOARD HARDWARE
ADuM3190 ISOLATED ERROR AMPLIFIER
The EVAL-ADuM3190EBZ board, shown in Figure 1, can
be used to evaluate the performance and data sheet specifica-
tions of the ADuM3190. Figure 2 shows the schematic of the
EVAL-ADuM3190EBZ circuit which can be used to test the
accuracy of the ADuM3190 and perform other tests. The
EVAL-ADuM3190EBZ is a 4-layer PC board, complete with
ground and power layers as shown in the Evaluation Board
Schematics and Artwork section.
EVAL-ADUM3190EBZ SCHEMATIC
Figure 2 shows the ADuM3190 schematic of the EVAL-
ADuM3190EBZ evaluation board. U1 is the ADuM3190 in
the center of the board and Pin 1 is the top-left pad with respect
to the notch in the silkscreen’s package outline. C1, C2, C3, and
C4 are ceramic 0603 1 µF bypass capacitors provided for proper
bypassing of the ADuM3190 internal 3 V regulators on both
sides of part. Also added to the board are 10 µF 0805 ceramic
capacitors to the VDD1 and VDD2 connections to provide
additional bypassing in case long wires are used from power
supplies to the evaluation board.
Test point connectors are provided for most of the important
connections to pins of the ADuM3190. The following sections
describe connections to make to power the EVAL-ADuM3190EBZ
and make performance tests.
LEFT-SIDE POWER CONNECTIONS
Connect the left-side external power supply (3 V to 20 V) to
P1 (labeled VDD1) and return it to P2 (labeled GND1).
RIGHT-SIDE POWER CONNECTIONS
Connect the right-side external power supply (3 V to 20 V) to
P9 (labeled VDD2) and return it to P10 (labeled GND2).
UG-534
ACCURACY TEST CONNECTIONS
In the EVAL-ADuM3190EBZ schematic (see Figure 2), a
blue line outlines the EAOUT accuracy circuit. Capacitor C7
(2.2 nF) together with R8 (680 Ω) and R7 (0 Ω) resistors form
an integrator circuit to close the loop from the −IN input to the
EAOUT output. A ±1% accurate internal reference voltage of
1.225 V at REFOUT is connected to the noninverting op amp
input +IN through a 0 Ω resistor, R9, providing the reference
for the accuracy test circuit. See Figure 3, ADuM3190 Test
Circuit 1, or the ADuM3190 data sheet for more information
about the operation of the ADuM3190.
For accuracy tests, add a wire between GND1 and GND2
for EAOUT and EAOUT2 (see Figure 3). This connection is needed
because the accuracy tests connect a 680 Ω resistor across the
isolation barrier and creates a current path between the two
isolated areas, so a ground return is needed for the accuracy
tests. The accuracy of the EAOUT output will be within ±1%
of the reference voltage specified value of 1.225 V. Next, the
EAOUT2 accuracy in Figure 4 (Test Circuit 2) can be performed
by removing the R7 (0 Ω) resistor and placing a 0 Ω resistor at
R5, completing the EAOUT2 circuit. Because the EAOUT2 circuit
has a high gain and uses the same internal reference voltage
to connect to the −IN input of the op amp, the accuracy of
the EAOUT2 output is also within ±1% of the reference voltage
specified value of 1.225 V.
For tests other than the accuracy tests, open the 680 Ω resistor
connections by removing R5 and R7 (0 Ω), the C7 integrating
capacitor, and the external wire connection made between
GND1 and GND2. Once completed, other components may
be added to the evaluation board per the schematic in Figure 2
to make circuits for other tests such as ADuM3190 data sheet
specifications for the op amp, reference, UVLO, output
characteristics, or power supply.
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