EVAL-AD7405FMCZ Datasheet, PDF (7/20 Pages) Analog Devices – Full featured evaluation board

EVAL-AD7405FMCZ User Guide
UG-690
EVALUATION BOARD HARDWARE
DEVICE DESCRIPTION
This user guide describes the evaluation board for the AD7405
isolated ADC. The AD7405 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., iCoupler® technology. The AD7405 operates from a
5 V (VDD1) 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 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 (VDD2).
The serial interface is digitally isolated. High speed CMOS,
combined with monolithic transformer technology, allows
the on-chip isolation provide outstanding performance
characteristics, superior to alternatives such as optocoupler
devices. The AD7405 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 AD7405 device are provided in
the device data sheet, available from Analog Devices, Inc., which
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 EVAL-SDP-CH1Z product page.
HARDWARE LINK OPTIONS
The functions of the link options are described in Table 2.
The default setup is configured to operate the board with the
power supplied from the EVAL-SDP-CH1Z board and to supply
the analog supply rail (VDD1) via the on-board isoPower
ADuM6000.
POWER SUPPLIES
Take care 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 then generates an isolated 5 V supply to power the
VDD1 rail of the AD7405. The 3.3 V supply rail from the EVAL-
SDP-CH1Z is used to supply the VDD2 rail of the AD7405.
If the user wishes to supply VDD1 externally, an external power
supply in the range of 24 V ± 5% may be connected to the
HIGH_V connector, J4. Alternatively an external supply in the
range of 5 V ±10% may be connected to the J3 connector.
The VDD2 supply may also be supplied via an external power
supply in the range of 3 V to 5.5 V via the J5 connector.
There are two main ground planes, GND1 and GND2. These
are isolated planes with a creepage and clearance of 8 mm.
Caution
When the EVAL-AD7405FMCZ is connected to the EVAL-SDP-
CH1Z, take care to ensure that if an external voltage is supplied
to the J5 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 AD7405 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-AD7405FMCZ 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 iCoupler 5 kV, dc-to-dc converter.
VDD1 can optionally be supplied from the J3 external connector
or from the J4 high voltage external connector. A 24 V supply
connected to J4 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 VDD1 externally.
Table 1. External Power Supplies (Optional)
Power Supply
Connector
Voltage Range
VDD1
J3
4.5 V to 5.5 V
VDD2
J5
3 V to 5.5 V
3.3 V ± 5%
HIGH_V
J4
24 V ± 5%
(VDD1)
Purpose
Analog supply rail
Digital supply rail without EVAL-SDP-CH1Z connected
Digital supply rail with EVAL-SDP-CH1Z connected
Analog supply rail
(high voltage alternative to J5)
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