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EVAL-AD7403FMCZ User Guide

UG-683

Rev. 0 | Page 7 of 20

EVALUATION BOARD HARDWARE

AD7403

DESCRIPTION

This user guide describes the evaluation board for the

AD7403

isolated ADC. The

AD7403

is a second-order, Σ-Δ modulator

that converts an analog input signal into a high speed, 1-bit data
stream with on-chip digital isolation based on Analog Devices,
Inc.,

Coupler technology. The

AD7403

operates from a

5 V (V

DD1

) power supply and accepts a differential input signal

of ±250 mV (±320 mV full scale). The differential input is
ideally suited to shunt voltage monitoring in high voltage
applications where galvanic isolation is required.
The analog input is continuously sampled by a high performance
analog modulator and converted to a ones density, digital
output stream with a data rate of up to 20 MHz. The original
information can be reconstructed with an appropriate digital
filter. The serial I/O can use a 5 V or a 3.3 V supply (V

DD2

The serial interface is digitally isolated. High speed CMOS,
combined with monolithic transformer technology, allows the on-
chip isolation to provide outstanding performance characteristics
that are superior to the performance of alternatives, such as
optocoupler devices. The

AD7403

device is offered in a 16-lead,

wide-body SOIC package and has an operating temperature range
of −40°C to +125°C.
Complete specifications for the

AD7403

device are provided in

the

AD7403

data sheet and should be consulted in conjunction

with this user guide when using the evaluation board. Full
details on the

EVAL-SDP-CH1Z

are available on the

SDP-H1

product page.

POWER SUPPLIES

Care should be taken before applying power and signals to
the evaluation board to ensure that all link positions are set
according to the required operating mode. See Table 2 for the
complete list of link options.
This evaluation board is designed to be supplied via the

EVAL-

SDP-CH1Z.

The

EVAL-SDP-CH1Z

generates 12 V and 3.3 V

supply rails. The 12 V supply is connected to the on-board 5 V
linear regulator that supplies the

ADuM6000

with power. The

ADuM6000

generates an isolated 5 V supply to power the V

DD1

rail of the

AD7403

. The 3.3 V supply rail from the

EVAL-SDP-

CH1Z

is used to supply the V

DD2

rail of the

AD7403

If the user wishes to supply V

DD1

externally, an external power

supply in the range of 24 V ± 5% can be connected to the
HIGH_V connector, J7. Alternatively, an external supply in the
range of 5 V ± 10% can be connected to the J5 connector.
The V

DD2

supply can also be supplied via an external power

supply in the range of 3 V to 5.5 V via the J6 connector.
There are two main ground planes: GND1 and GND2. These
planes are isolated with a creepage and clearance of 8 mm.

Caution

When the

EVAL-AD7403FMCZ

is connected to the

EVAL-

SDP-CH1Z

, care must be taken to ensure that if an external

voltage is supplied to the J6 input connector, the voltage does
not exceed 3.3 V. Exceeding this voltage may cause permanent
damage to the

EVAL-SDP-CH1Z

board.

INPUT SIGNALS

The analog input range to the

AD7403

is ±250 mV (±320 mV

full scale), which should not be exceeded. An input signal in the
range of 500 mV p-p should be connected to the evaluation
board via the analog input connector, J1.
The

EVAL-AD7403FMCZ

has analog and digital ground planes

that are physically isolated from one other. As such, power to
the analog supply rail is by default, supplied through the on-
board

ADuM6000

isolated

Coupler 5 kV, dc-to-dc converter.

DD1

can optionally be supplied from the J5 external connector

or from the J7 high voltage external connector. A 24 V supply
connected to J7 is stepped down to 5 V by means of the on-
board

ADP2441

step-down dc-to-dc regulator. See Table 2 for

more information about supplying V