AD EVAL-AD7719-EB Evaluation board for the ad7719, 16&24-bit, dual sigma delta adc Datasheet

a
Evaluation Board for the AD7719,
16&24-Bit, Dual Sigma Delta ADC
EVAL-AD7719-EB
FEATURES
Full-Featured Evaluation Board for the AD7719
On-Board Reference and Digital Buffers
Various Linking Options
PC Software for Control of AD7719
INTRODUCTION
This Technical Note describes the evaluation board
for the AD7719, Low Voltage, Low Power, 16&24Bit, Dual Sigma Delta ADC. The AD7719 is a
complete analog front end for low frequency measurement applications. The AD7719 is factory calibrated
and therefore does not require field calibration. The
device can accept low level input signals directly from
a transducer and produce a serial digital output. It
employs a sigma-delta conversion technique to realize
up to 24 bits (Main ADC) or 16 bits (Auxiliary ADC)
of no missing codes performance. The selected input
signal is applied to a proprietary programmable gain
(Main ADC only) front end based around an analog
modulator. The modulator output is processed by an
on-chip digital filter. The first notch of this digital
filter can be programmed via an on-chip control
register allowing adjustment of the filter cutoff and
output update rate. Full data on the AD7719 is
available in the AD7719 datasheet available from
Analog Devices and should be consulted in conjunction with this Technical Note when using the evaluation board.
ation board which allows the user to easily program the
AD7719.
Other components on the AD7719 Evaluation Board
include two AD780s (precision 2.5V references), a
32.7680 kHz crystal and digital buffers to buffer
signals to and from the PC.
OPERATING THE AD7719 EVAL BOARD
Power Supplies
This evaluation board has two analog power supply
inputs: AVDD and AGND. An external +5V must be
applied between these inputs which is used to provide
the VDD for the AD7719 and the reference. Digital
Power connections are also required through DGND
& DVDD. The DVDD is used to provide the DVDD for
the digital circuitry. DGND and AGND are connected together at the AD7719 GND pin. Therefore,
it is recommended not to connect AGND and DGND
elsewhere in the system.
All power supplies are decoupled to their respective
grounds. DVDD is decoupled using a 10µF tantalum
capacitor and 0.1µF ceramic capacitor at the input to
the evaluation board. It is again decoupled using
0.1µF capacitors as close as possible to each logic
device. AVDD is decoupled using a 10µF tantalum
capacitor and 0.1µF ceramic capacitor as close as
possible to the AD7719 and also at the reference.
The evaluation board interfaces to the parallel port of an
IBM compatible PC. Software is available with the evalu-
Fig. 1. Evaluation Board
Set-up
REV.
B
Information furnished by Analog Devices is believed to be accurate
and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights
of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of
Analog Devices.
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106,
U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
EVAL-AD7719-EB
LINK AND SWITCH OPTIONS
There are fourteen link options which must be set for the required operating setup before using the evaluation
board. The functions of these link options are outlined below.
Link No.
Function
LK1-LK6 These links are in series with the AIN1 through AIN6 analog inputs respectively.
With these links in place, the analog inputs on the relevant SKT input is connected directly to the
respective AIN input on the part. For example, with LK1 in place, the analog input applied to SKT1
is connected directly to AIN1 of the AD7719.
LK7&8
This option selects the master clock source for the AD7719. The master clock is generated by the
on-board crystal or from an external source via SKT7. This is a double link and both links must
be moved together for the correct operation of the evaluation board.
With both links in position "A", the external clock option is selected and an external clock applied
to SKT7 is routed to the XTAL1 pin of the AD7719.
With both links in position "B", the on-board crystal is selected to provide the master clock to the
AD7719.
LK9
This link is used to select the reference source for the REFIN(-) input of the AD7719.
With this link in position "A", REFIN1(-) is connected directly to AGND.
With this link in position "B", the voltage generated across R10 (IOUT1*R10) is selected as the onboard reference for REFIN(+). LK10 should also be connected for this set-up to connect R10 and
REFIN(-) to AGND. LK11 & LK12 should also be connected for this set-up to connect IOUT1 to
R10.
With this link in position "C", the REFIN(-) pin is connected to SKT14. An external voltage applied
to SKT14 can now be used as the REFIN(-) for the AD7719.
LK10
This link is used to select the reference source for the REFIN(+) input of the AD7719.
With this link in position "A", REFIN1(+) is connected to the output of the on-board reference
(AD780 - U6).
With this link in position "B", the REFIN1(+) pin is connected to SKT15. An external voltage
applied to SKT15 can now be used as the REFIN(+) for the AD7719.
With this link in position "C", the REFIN(+) pin is connected to AVDD.
This link should be disconnected if using the voltage generated across R10, due to IOUT1.
LK11
This link is used for selecting IOUT1*R10 as a reference voltage.
LK12
This link is used for selecting IOUT1*R10 as a reference voltage.
LK13
This link is used for selecting IOUT1*R10 as a reference voltage.
LK14
This link selects the reference source for the REFIN2 input of the AD7719.
With this link in positon "A", REFIN2 is connected to the output of the on-board reference (AD780
- U2).
With this link in position "B", the REFIN2 pin is connected to SKT16. An external voltage applied
to SKT16 can now be used as the REFIN2 for the AD7719.
SET-UP
CONDITIONS
Care should be taken before applying power and signals to the evaluation board to ensure that all link positions
are as per the required operating mode. Table 1 shows the position in which all the links are set when the
evaluation board is sent out.
Table 1: Initial Link and Switch Positions
Link No.
Position
Function
LK1-LK6
AD7719.
IN
Connects analog inputs from SKT1-SKT6 to the input pins AIN1-AIN6 of the
LK7&LK8 B+B
AD7719.
Both links in position B to select the on-board crystal as the master clock for the
LK9
This connects the REFIN1(-) input of the AD7719 to AGND.
A
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Rev. B
EVAL-AD7719-EB
LK10
A
The on-board reference (U6) provides the reference voltage for the REFIN1(+) input
of the AD7719.
LK11
OUT
IOUT1*R10 not used as REFIN1 voltage reference.
LK12
OUT
IOUT1*R10 not used as REFIN1 voltage reference.
LK13
OUT
IOUT1*R10 not used as REFIN1 voltage reference.
LK14
A
The on-board reference (U2) provides the reference voltage for the REFIN2 input of the
AD7719.
EVALUATION BOARD INTERFACING
Interfacing to the evaluation board is via either a 9-way d-type connector, J4 or a 36-way centronics connector, J1. The
pin-out for the J4 connector is shown in Fig. 2 and its pin designations are given in Table 2. The pin-out for the J1
connector is shown in Fig. 3 and its pin designations are given in Table 3.
J1 is used to connect the evaluation board to the parallel (printer) port of a PC. Connection is via a standard printer cable.
J4 is used to connect the evaluation to any other system. The evaluation board should be powered up before a cable
is connected to either of these connectors.
1
2
6
3
7
4
8
5
9
Fig. 2: Pin Configuration for the 9-Way D-Type Connector, J4.
J4 Pin Description 1
Table 2.:
1 SCLK
Serial Clock. The signal on this pin is buffered before being applied to the SCLK pin of the
AD7719.
2 RDY
Logic output. This is a buffered version of the signal on the AD7719 RDY pin
3 CS
Chip Select. The signal on this pin is buffered before being applied to the CS pin on the AD7719.
4 RESET Reset Input. Data applied to this pin is buffered before being applied to the AD7719 RESET pin.
5 DIN
Serial Data Input. Data applied to this pin is buffered before being applied to the AD7719 DIN pin.
6 DGND
Ground reference point for the digital circuitry. Connects to the DGND plane on the Evaluation board.
7 DOUT
Serial Data Output. This is a buffered version of the signal on the AD7719 DOUT pin.
8 DVDD
Digital Supply Voltage. If no voltage is applied to the board's DVDD input terminal then the voltage applied
to this pin will supply the DVDD for the digital buffers.
9 NC
Not Connected.
Note
1
An explanation of the AD7719 functions mentioned here is given in Table 3 below as part of the J1 pin descriptions.
Table 3: 36-Way Connector Pin Description
1
NC
No Connect. This pin is not connected on the evaluation board.
2
DIN
Serial Data Input. Data applied to this pin is buffered before being applied to the
AD7719 DIN pin. Serial Data Input with serial data being written to the input shift
register on the part. Data from this input shift register is transferred to the calibration
or control registers, depending on the register selection bits of the Communications
Register.
3
RESET
Reset Input. The signal on this pin is buffered before being applied to the RESET pin of the
AD7719. RESET is an active low input which resets the control logic, interface logic,
calibration coefficients, digital filter and analog modulator of the part to power-on status.
-3-
Rev. B
EVAL-AD7719-EB
18
1
36
19
Fig. 3:
36-way Centronics (SKT2) Pin Configuration
4
CS
Chip Select. The signal on this pin is buffered before being applied to the CS pin of the
AD7719. CS is an active low Logic Input used to select the AD7719. With this input hardwired low, the AD7719 can operate in its three-wire interface mode with SCLK, DIN and DOUT
used to interface to the device. CS can be used to select the device in systems with more than
one device on the serial bus or as a frame synchronization signal in communicating with the
AD7719.
5
SCLK
Serial Clock. The signal on this pin is buffered before being applied to the SCLK pin of the
AD7719. An external serial clock is applied to this input to read/write serial data from/to the
AD7719. This serial clock can be continuous with all data transmitted in a continuous train
of pulses. Alternatively, it can be non-continuous with the information being transmitted to
the AD7719 in smaller batches of data.
6
SYNC
Logic Input. The signal on this pin is buffered before being applied to the SYNC pin of the
AD7719. The SYNC input allows for synchronisation of the digital filters and modulators
across a number of AD7719s. While SYNC is low, the nodes of the digital filter, the filter
control logic and the calibration control logic are held in a reset state.
7-8
NC
No Connect. These pins are not connected on the evaluation board.
9
DV DD
Digital Supply Voltage. This provides the supply voltage for the buffer chips, U3-U5,
which buffer the signals between the AD7719 and J1/J4.
10
RDY
Logic output. This is a buffered version of the signal on the AD7719 RDY pin. A logic low
on this output indicates that either the Main ADC or Auxiliary ADC has valid data in their
data register. The RDY pin will return high upon completion of a read operation of a full output
word. If data is not read RDY will return high prior to the next update indicating to the user
that a read operation should not be initiated. The RDY pin also returns low after the
completion of a calibration cycle. The RDY pin is effectively the NOR of the RDY0 and RDY1
bits in the Status register. If one of the ADCs is disabled the RDY pin reflects the active ADC.
RDY does not return high aftera calibration until the mode bits are written to enabling a new
conversion or calibration.
11-12
NC
No Connect. These pins are not connected on the evaluation board.
13
DOUT
Serial Data Output. This is a buffered version of the signal on the AD7719 DOUT pin. Serial
Data Output with serial data obtained from the output shift register on the AD7719. The output
shift register can contain information from of the on-chip registers depending on the register
selection bits of the Communications Register.
14-18
NC
No Connect. These pins are not connected on the evaluation board.
19-30
DGND
Ground reference point for digital circuitry. Connects to the DGND plane on the evaluation
board.
31-36
NC
No Connect. These pins are not connected on the evaluation board.
SOCKETS
There are eighteen sockets relevant to the operation of the AD7719 on this evaluation board. The functions of
these sockets are outlined in Table 4.
Table 4. Socket Functions
Socket
Function
J4
9-way D-Type connector used to interface to other systems.
-4-
Rev. B
EVAL-AD7719-EB
J1
SKT1
36-way centronics connector used to interface
to PC via parallel printer port.
SKT13
Sub-Miniature BNC (SMB) Connector. The
analog input signal for the AIN1 input of the
AD7719 is applied to this socket.
Sub-Miniature BNC (SMB) Connector. The
AD7719 current source pin IOUT2 is connected
to this socket.
SKT14
Sub-Miniature BNC (SMB) Connector. The
reference voltage for the REFIN1(-) input of
the AD7719 is applied to this socket when the
board is configured for an externally applied
reference voltage.
SKT15
Sub-Miniature BNC (SMB) Connector. The
reference voltage for the REFIN1(+) input of
the AD7719 is applied to this socket when the
board is configured for an externally applied
reference voltage.
SKT16
Sub-Miniature BNC (SMB) Connector. The
reference voltage for the REFIN2 input of the
AD7719 is applied to this socket when the
board is configured for an externally applied
reference voltage.
SKT2
Sub-Miniature BNC (SMB) Connector. The
analog input signal for the AIN2 input of the
AD7719 is applied to this socket.
SKT3
Sub-Miniature BNC (SMB) Connector. The
analog input signal for the AIN3 input of the
AD7719 is applied to this socket.
SKT4
Sub-Miniature BNC (SMB) Connector. The
analog input signal for the AIN4 input of the
AD7719 is applied to this socket.
SKT5
Sub-Miniature BNC (SMB) Connector. The
analog input signal for the AIN5 input of the
AD7719 is applied to this socket.
SKT6
Sub-Miniature BNC (SMB) Connector. The
analog input signal for the AIN6 input of the
AD7719 is applied to this socket.
SKT7
Sub-Miniature BNC (SMB) Connector. The
master clock signal for the XTAL1 input of the
AD7719 is applied to this socket when the
board is configured for an externally applied
master clock.The AD7719 can be operated
with internal clock frequencies in the range
32.768 kHz +/-10%.
CONNECTORS
There are two connectors on the AD7719 evaluation
board as outlined in Table 5.
Table 5. Connector Functions
Connector
Functions
J3
PCB Mounting Terminal Block. The
Digital Power Supply to the Evaluation Board is provided via this Connector if it is not being supplied via
SKT1 or SKT2.
PCB Mounting Terminal Block. The
Analog Power Supply to the Evaluation Board must be provided via this
Connector.
SKT8
Sub-Miniature BNC (SMB) Connector. The
output value from AD7719 output pin P1/SW1
is available from this socket.
SKT9
Sub-Miniature BNC (SMB) Connector. The
output value from AD7719 output pin P2/SW2
is available from this socket.
J2
Sub-Miniature BNC (SMB) Connector. The
output value from the AD7719 I/O pin P3 is
available from this socket when P3 is
configured as an output. The input signal for
AD7719 I/O pin P3 is applied to this input
when P3 is configured as an input.
SWITCHES
SKT10
SKT11
Sub-Miniature BNC (SMB) Connector. The
output value from the AD7719 I/O pin P4 is
available from this socket when P4 is
configured as an output. The input signal for
AD7719 I/O pin P4 is applied to this input
when P4 is configured as an input.
SKT12
Sub-Miniature BNC (SMB) Connector. The
AD7719 current source pin IOUT1 is connected
to this socket.
There is one switch on the AD7719 Evaluation board. SW1
is a push-button reset switch. Pushing this switch activates the active low RESET input on the AD7719 which
resets the control logic, interface logic, calibration coefficients, digital filter and analog modulator of the part to
power-on status.
-5-
Rev. B
EVAL-AD7719-EB
AD7719 SOFTWARE DESCRIPTION
The AD7719 evaluation board is shipped with a CD-ROM containing software that can be installed onto a standard PC
to control the AD7719.
The software uses the printer port of the PC to communicate with the AD7719, so a Centronics printer cable is used to
connect the PC to the evaluation board.
Software Requirements and Installation
The software runs under Windows ME 2000 NT™ and typically requires 8Mb of RAM.
To install the software the user should start Windows and insert the CD-ROM disc. The installation software should
launch automatically. If not, use Windows Explorer to locate the file 'setup.exe' on the CD-ROM. Double clicking on
this file will start the installation procedure. The user is prompted for a destination directory which is "C:\Program
Files\ANALOG DEVICES\AD7719" by default. Once the directory has been selected the installation procedure will copy
the files into the relevant directories on the hard drive. The installation program will create a Program Group called
"Analog Devices" with sub-group 'AD7719' in the "Start" taskbar. Once the installation procedure is complete the user
can double click on the AD7719 icon to start the program.
Features of the Software
1. The software will allow the user to write to and read from all the registers of the AD7719.
2. Data can be read from the AD7719 and displayed or stored for later analysis.
3. The data that has been read can be exported to other packages such as Mathcad or Excel for further analysis.
-6-
Rev. B
EVAL-AD7719-EB
What follows is a description of the various windows that appear while the software is being used. Fig. 4. shows the
main screen that appears once the program has started. The printer port that will be used by the software is determined
automatically. There are three possible printer ports that can be handled by the software, LPT1 (standard), LPT2 and
PRN. The user can change to another printer port by clicking on the "Printer Port" dropdown menu. A brief description
of each of the buttons on the main screen follows:
Program AD7719
Allows the user to program or read the on-chip registers of the AD7719.
ReadData from Main ADC
Allows the user to read a number of samples from the AD7719 Main ADC.
These samples can be stored for further analysis or just displayed for reference.
Read Data from Aux ADC
Allows the user to read a number of samples from the AD7719 Aux ADC. These
samples can be stored for further analysis or just displayed for reference.
Main ADC Noise Analysis
Allows the user to perform noise analysis on the data that has been read in from the
Main ADC.
Aux ADC Noise Analysis
Allows the user to perform noise analysis on the data that has been read in from the
Aux ADC.
ResetAD7719
Allows the user to perform a software or hardware reset on the AD7719.
Read From File
Allows the user to read in previously stored data for display or analysis - user needs
to specify Aux or Main ADC data.
Write To File
Allows the user to write the current set of data to a file for later use - user needs to
specify Aux or Main ADC data.
About
Provides information about the version of software being used.
Read Dual ADC
Allows the user to display samples from the Main and Aux ADCs
simultaneously. These samples can be stored for further analysis or just displayed
for reference.
Quit
Ends the program
Fig. 4. The Main Screen
-7-
Rev. B
EVAL-AD7719-EB
The Program AD7719 Screen
Fig. 5. shows the screen that appears when the Program AD7719 button is selected. This screen allows the user to select
which register is to be programmed.
Fig. 5. The Program AD7719 Screen
-8-
Rev. B
EVAL-AD7719-EB
Fig.
6.
The
Filter
Register
Screen
The Filter Register Screen
Fig. 6. shows the Filter Register screen. When the screen is loaded the software will read the current contents from the
Filter Register of the AD7719 and change the display accordingly. The Filter register is used to change the update rate
of the AD7719, the allowable range for the word written to the Filter Register is 13(dec) to 255(dec) or 0D(Hex) to FF(Hex).
The user can enter the filter word in Hex values in the text box provided. The user should consult the datasheets for
more information on the use of the Filter Register.
-9-
Rev. B
EVAL-AD7719-EB
The Main ADC Calibration Registers Screen
Fig. 7. shows the Main ADC Calibration Registers screen. When this screen is displayed the values of the Gain and
Offset Registers are read from the Main ADC of the AD7719 and displayed. The user has the ability to change the values
of either register if required. the default value for the Fullscale Main Cal Register is 535xx5 hex and the default value for
the Zero Scale Main Cal Register is 800000 hex. The Aux ADC Calibration Registers screen has the same function with
the default values being 555X hex for the Full Scale Aux Cal Register and 8000 hex for the Zero Scale Aux Cal Register.
Fig. 7. The Calibration Registers Screen
- 10 -
Rev. B
EVAL-AD7719-EB
The Main ADC Control Register Screen
Fig. 8. shows the Main ADC Control Register Screen. This register controls the Word-length, Bipolar/Unipolar
operation, Channel selection and Range selection for the Main ADC. When the screen is loaded the software reads
the current contents from the Main ADC Control Register of the AD7719 and sets the buttons accordingly. Note
if the Channel Configure bit is set in the Mode Register the channels the Main and Aux ADCs can use is changed - see
AD7719 datasheets for more information. Everytime a change is made, the software writes the new conditions to the
AD7719 and then reads back from the Main ADC Control Register for conformation. The Aux ADC Control Register
Screen performs a similar operation for the Aux ADC Control Register - see AD7719 datasheets for more information.
Fig. 8. The Main ADC Control Register Screen
- 11 -
Rev. B
EVAL-AD7719-EB
Fig.
9.
The
I/O
and
Current
Source
Control
RegisterScreen
The I/O and Current Source Control Register Screen
Fig.9. shows the I/O and Current Source Control Register Screen. This screen allows the user to control the on-chip
200uA current sources and also the two I/O ports P3 & P4 and the output ports P1 & P2. When the screen is loaded,
the software reads the current contents of the I/O and Current Source Control Register of the AD7719 and sets the
buttons accordingly. The current sources IEXC1 & IEXC2 can be enabled and directed to the two AD7719 output pins
IOUT1 & IOUT2 by the user. The on-chip burnout current can be turned on/off by the user.
The two I/0 ports P3 & P4 can be selected as inputs or outputs, the user can set the outputs as required - note 'high'
represents a 5V output on the pin, 'low' represents AGND. The user can also read in the value at the inputs P3 & P4 if
configured as inputs. Note pressing Update Display button will read the current contents of the I/O and Current Source
Control Register and update the screen.
The two outputs P1 & P2 can be configured as a standard Output pin or as a Power Switch to PWRGND. When selected
as an Output pin P1 or P2 can be enabled as a regular digital output or as a tri-state output. Everytime a change is made,
the software writes the new conditions to the AD7719 and then reads back from the I/O and Current Source Control
Register for conformation - ignoring databits P1DAT - P4DAT. Refer to AD7719 datasheets for more information.
The Mode Register Screen
The Mode Register Screen is shown in Fig. 10. When the screen is loaded the software reads the current contents from
the Mode Register of the AD7719 and sets the buttons accordingly. This screen allows the user to change the operating
mode of the AD7719, change the channel configuration and power down the crystal oscillator. When the user selects
a calibration the software will start a calibration by writing to the AD7719 (prompt user for input if system calibration)
and then monitor the RDY pin. A falling edge of the RDY pin will indicate that the calibration has been completed. After
a calibration the AD7719 is placed in the idle mode and the screen is updated to indicate this. Everytime a change is
made, the software writes the new conditions to the AD7719 and then reads back from the Mode Register for
conformation. The AD7719 should be powered-down or placed in Idle Mode before writing to Filter, ADC Control or
Calibration registers. The default status for the Mode register is 0 hex - refer to AD7719 datasheets for more information.
- 12 -
Rev. B
EVAL-AD7719-EB
Fig. 10. The Mode Register Screen
The Status Register Screen
Fig. 11. shows the Status Register Screen. When the screen is loaded the software reads the current contents from
the Status Register of the AD7719 and sets the buttons accordingly. This is a read-only register and flags the
operating conditions of the AD7719 such as data ready or Main ADC Error. Refer to AD7719 datasheets for more
information.
Fig.
11.
The
Status
- 13 -
Register
Screen
Rev. B
EVAL-AD7719-EB
Fig. 12. The Read Data from Main ADC Screen
The Read Data from Main ADC Screen
Fig. 12. shows the Main ADC Read Data screen. This is where the user can read a number of samples from the AD7719
Main ADC. The user has the option of either reading data for analysis or display.
When the Read For Analysis button is selected the software will read the required number of samples from the AD7719
Main ADC and store them in an array so that they can be graphed or analysed later. It is possible to read and graph
up to 5000 samples at any one time. The read can be interrupted with a user key press.
When the Read for Display button is selected the software will read one sample from the AD7719 and display its value
in the Current Code text box. The software will continue to read and display the samples until a key has been pressed.
It is possible to add a delay to the read cycle by entering the required number of milliseconds between reading samples.
It should be noted however that the accuracy of the time delay can be affected by other programs running under
Windows, therefore this method is not suitable where equidistant sampling is required. Note the Read Data from Aux
ADC Screen has a similar function to the Read Data from Main ADC Screen, only reading from the Aux ADC and storing
in a seperate array.
- 14 -
Rev. B
EVAL-AD7719-EB
Fig. 13. The Read Data from Dual ADC Screen
The Read Data from Dual ADC Screen
Fig. 13 shows the Read Data from Dual ADC display. This is where the user can read a number of samples from both
ADCs simultaneously. The results are stored in two arrays so that the results can be graphed or analysed later by
selecting the Aux or Main ADC Noise Analysis Buttons on the Main Menu Screen. It is possible to read and graph up
to 5000 samples at any one time. The read can be interrupted with a user key press. Note both ADCs must be enabled
for this screen to operate. The user is informed if both ADCs aren't enabled. This will also overwrite results from single
Main or Aux ADC analysis unless the data has been saved.
When the Read for Display button is selected the software will read one sample from the AD7719 and display its value
in the Current Code text box. The software will continue to read and display the samples until a key has been pressed.
It is possible to add a delay to the read cycle by entering the required number of milliseconds between reading samples.
It should be noted however that the accuracy of the time delay can be affected by other programs running under
Windows, therefore this method is not suitable where equidistant sampling is required.
- 15 -
Rev. B
EVAL-AD7719-EB
Fig. 14. The Main ADC Noise Analysis Screen
The Main ADC Noise Analysis Screen
Once data has been read from the AD7719 Main ADC, it is possible to perform some analysis on it. Fig. 14 shows the
Main ADC Noise Analysis Screen. This screen displays the maximum and minimum codes read from the AD7719 Main
ADC (in decimal and hexadecimal), as well as the average code, the average value and the RMS and Peak-Peak noise
values. From this screen it is possible to display the data on a graph or as a histogram of codes. Figures 15 & 16 show
the Graph and Histogram screens. The Aux ADC Noise Analysis Screen performs the same function on data from the
Aux ADC.
The Main ADC Graph Screen
Fig. 15 shows the Main ADC Graph Screen. This screen displays the data in a graph format. A grid can be placed
on the graph by pressing the Grid on/off button. The graph screen also has zoom and scroll functions using the
two white handles at either end of the x-axis.
Fig. 15. The Main ADC Graph Screen
- 16 -
Rev. B
EVAL-AD7719-EB
Fig. 16. The Main ADC Histogram Screen
- 17 -
Rev. B
EVAL-AD7719-EB
Fig.
17.
The
Evaluation
- 18 -
Board
Schematic
Rev. B
EVAL-AD7719-EB
Table 6. Component Listing and Manufacturers
INTEGRATED CIRCUITS
Component
Location
Vendor
AD7719
U1
Analog Devices
AD780AN
U2/U6
Analog Devices
74HC4050N
U3
Philips
74C08SMD
U4
Texas Instruments
74ACT244
U5
Fairchild Semiconductor
SD103C
D1/D2
ITT
CAPACITORS
Component
Location
Vendor
10µF ± 20% Tantalum (16 V)
C12 C13 C17 C19 C20 C22 C23 C24
AVX-Kyocera
Mftrs No. TAG106MO16
0.1µF Ceramic (0805 SMD)
C1-C6 C8 C15 C18 C21
FEC No. 499-768
0.1uF Ceramic (X7R ±20%)
C7 C9 C10 C11 C14 C16
Philips
Mftrs No. CW20C104M
Component
Location
Vendor
Short Circuits
R1-R6
Bourns
10kΩ±5% 0.25W Carbon Film
R7-R9
Bourns
12kΩ±5% 0.25W Carbon Film
R10
Bourns
3kΩ±5% 0.25W Carbon Film
R12
Bourns
Component
Location
Vendor
Pin Headers
Lk1-Lk6 Lk11-Lk13 (1x2 way)
Lk7 Lk8 (2x2 way)
Lk9 Lk10 Lk14 (3x2 way)
Harwin
Mftrs No. M20-9983606
Shorting Plugs
Pin Headers
(14 required)
Harwin
Mftrs No. M7571-05
RESISTORS
LINK OPTIONS
SWITCH
Component
Location
Vendor
Sealed Push Button Switch
SW1
Omron Mftrs No. B3W1000
Component
Location
Vendor
Miniature BNC Connectors
SKT1-SKT16
M/A - Com Greenpar
Mftrs No. B65N07G999X99
9-Way D-Type Connector
J4
McMurdo Mftrs No. SDE9PNTD
SOCKETS
- 19 -
Rev. B
EVAL-AD7719-EB
36 Way Centronics Connector
J1
Fujitsu Mftrs No. FCN785J036G0
2 Way Terminal Block
J1 J2
Bulgin RIA
Low profile socket
U2,U3,U6
Harwin (32 pins needed)
Farnell No. 519-959
CRYSTAL
OSCILLATOR
Component
Location
Vendor
32.768 kHz Oscillator
Xtal 1
IQD
FEC No. 221-533
Fig. 18. The Evaluation Board Component Layout Diagram
- 20 -
Rev. B
EVAL-AD7719-EB
Fig. 19. The Evaluation Board Component Side Artwork
Fig. 20. The Evaluation Board Solder Side Artwork
- 21 -
Rev. B