EVAL-ADUC7020MK,QS Datasheet by Analog Devices Inc.

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ANALOG DEVICES
AN-718
APPLICATION NOTE
One Technology Way P.O. Box 9106 Norwood, MA 02062-9106 • Tel: 781/329-4700 Fax: 781/326-8703 www.analog.com
TABLE OF CONTENTS
Evaluation Board Overview ............................................. 1
Evaluation Board Features ............................................... 1
DIP Switch Link Options ................................................... 2
External Connectors ......................................................... 3
Demonstration Circuit ...................................................... 4
Parts List ............................................................................ 5
OVERVIEW
The ADuC7020 evaluation board has the following
features:
2-layer PCB (4” 5” form factor)
9 V power supply regulated to 3.3 V on board
4-pin UART header to connect to RS232 interface
cable
20-pin standard JTAG connector to connect to ULINK
emulator
Demonstration circuit
32.768 kHz watch crystal to drive the PLL clock
ADR291 2.5 V external reference chip
Reset/Download/IRQ0 push-buttons
Power indicator/general-purpose LEDs
Access to all ADC inputs and DAC outputs from
external header. All device ports are brought out to
external header pins.
Surface-mount and through-hole general-purpose
prototype area
Notes
1. This document refers to the MicroConverter ADuC7020
Evaluation Board Rev. A.
2. All references in this document to physical orientation
of components on the board are made with respect to a
component side view of the board, with the prototype
area appearing in the bottom of the board.
3. The board is laid out to minimize coupling between
the analog and digital sections of the board. The ground
plane is split with the analog section on the left-hand
side and a digital plane on the right-hand side of the
board. The regulated 3.3 V power supply is routed
directly to the digital section, and is filtered before being
routed into the analog section of the board.
ADuC7020 Evaluation Board Reference Guide
MicroConverter® ADuC7020 Development System
by Aude Richard
FEATURES
Power Supply
The user should connect the 9 V power supply via the
2.1 mm input power socket (J5). The input connector is
configured as CENTER NEGATIVE, i.e., GND on the cen-
ter pin and 9 V on the outer shield.
This 9 V supply is regulated via a linear voltage regula-
tor (U5). The 3.3 V regulator output is used to directly
drive the digital side of the board. The 3.3 V supply is
also filtered, and is then used to supply the analog side
of the board.
When on, the red LED (D3) indicates that a valid 3.3 V
supply is being driven from the regulator circuit. All
active components are decoupled with 0.1 F at device
supply pins to ground.
RS232 Interface
The ADuC7020 (U1) P1.1 and P1.0 lines are connected
to the RS232 interface cable via connector (J1). The
interface cable generates the required level shifting to
allow direct connection to a PC serial port. Ensure that
the cable supplied is connected to the board correctly,
i.e., DVDD is connected to DVDD, and DGND is connected
to DGND.
Emulation Interface
Nonintrusive emulation and download are possible on
the ADuC7020 via JTAG by connecting the ULINK emula-
tor to the J4 connector.
Crystal Circuit
The board is fitted with a 32.768 kHz crystal from which
the on-chip PLL circuit can generate a 45 MHz clock.
External Reference (ADR291)
The external 2.5 V reference chip (U2) has two functions.
It is provided on the evaluation board to demonstrate the
external reference option of the ADuC7020, but its main
purpose is to generate the VOCM voltage of the differen-
tial amplifier, if required.
Reset/Download/IRQ0 Push-Buttons
A RESET push-button is provided to allow the user to
manually reset the part. When inserted, the RESET pin of
the ADuC7020 is pulled to DGND. Because the RESET pin
on the ADuC7020 is Schmitt-triggered internally, there is
no need to use an external Schmitt trigger on this pin.
When inserted, the IRQ0 push-button switch drives
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P0.4/IRQ0 high. This can be used to initiate an external
interrupt 0.
To enter serial download mode, the user must pull the
P0.0/BM pin low while reset is toggled. On the evalua-
tion board, serial download mode can be easily initiated
by holding down the serial download push-button (S2)
while inserting and releasing the reset button (S3), as
illustrated in Figure 1.
Power Indicator/General-Purpose LEDs
A red power LED (D3) is used to indicate that a sufficient
supply is available on the board. A general-purpose LED
(D2) is directly connected to P4.2 of the ADuC7020. When
P4.2 is cleared, the LED is turned on; when P4.2 is set,
the LED is turned off.
Analog I/O Connections
All analog I/O connections are brought out on header J3.
ADC0 and ADC1 are buffered using an AD8606 to
evaluate single-ended and pseudo differential mode.
A potentiometer can be connected to ADC0 buffered.
ADC3 and ADC4 can be buffered with a single-ended-
to-differential op amp on board, with the AD8132 used
to evaluate the ADC in fully differential mode.
ADC2 is not buffered. Be sure to follow the data sheet
recommendations when connecting signals to this in
put.
DAC1 can be used to control the brightness of the green
LED, D1, when connected via the S1 switch.
General-Purpose Prototype Area
A general-purpose prototype area is provided at the
bottom of the evaluation board for adding external
components as required in the user’s application. As can
be seen from the layout, AVDD, AGND, VDDIO, and DGND
tracks are provided in this prototype area.
DIP SWITCH LINK OPTIONS
S1-1 VREF
Function: Connects the output of the 2.5 V external
reference (ADR291) to the VREF pin (Pin 35)
of the ADuC7020.
Use: Slide S1-1 to the ON position to connect the
external reference to the ADuC7020.
Slide S1-1 to the OFF position to use the in-
ternal 2.5 V reference or a different external
reference on the VREF pin of the J3 header.
S1-2 VOCM
Function: Connects 1.67 V to the VOCM pin of the
AD8132. No extra dc voltage is required
on the board to use the ADC in differential
mode.
Use: Slide S1-2 to the ON position to connect
VOCM of the differential amplifier to 1.67 V,
divided output of the ADR291 reference.
Slide S1-2 to the OFF position to use a dif-
ferent voltage for VOCM by connecting a dc
voltage to the VOCM pin of the J3 header.
Note that VOCM value is dependent on refer-
ence value, as shown in Table I.
Table I. VOCM Range
VREF VOCM min VOCM max
2.5 V 1.25 V 2.05 V
2.048 V 1.024 V 2.276 V
1.25 V 0.75 V 2.55 V
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Figure 1. Entering Serial Download Mode on the Evaluation Board
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S1-3 POT
Function: Connects the potentiometer output to ADC0.
This input is buffered by an AD8606. This is
for demonstration purposes.
Use: Slide S1-3 to the ON position to connect
the potentiometer to the op amp of the
ADC0 input channel.
Slide S1-3 to the OFF position to use the
ADC0 input on the J3 header.
S1-4 ADC3
Function: Brings out ADC3 (Pin 1) on the J3 header.
Use: Slide S1-6 to the ON position to connect
ADC3 of the J3 header directly to the ADC3
pin (Pin 1) of the ADuC7020.
Slide S1-6 to the OFF Position to discon-
nect ADC3 of the J3 header from the ADC3
pin (Pin 1) of the ADuC7020.
S1-5 VIN–
Function: Connects –OUT of the single-ended-to-dif-
ferential op amp (AD8132) to ADC3. S1-5 and
S1-6 must be used together when VIN– is in
the ON position; VIN+ must also be in the ON
position to use the differential op amp on
channels ADC3 and ADC4.
Use: Slide S1-5 to the ON position to connect
–OUT of the AD8132 to ADC3.
Slide S1-5 to the OFF position to use ADC3
without the AD8132.
S1-6 VIN+
Function: Connects +OUT of the single-ended-to-dif-
ferential op amp (AD8132) to ADC4. When
VIN+ is in the ON position, VIN– must also
be in the ON position to use the differential
op amp on channels ADC3 and ADC4.
Use: Slide S1-6 to the ON position to connect
+OUT of AD8132 to ADC4.
Slide S1-6 to the OFF position to use ADC4
without the AD8132.
S1-7 ADC4
Use: Slide S1-6 to the ON position to connect
ADC4 of the J3 header directly to the ADC4
pin (Pin 2) of the ADuC7020.
Slide S1-6 to the OFF position to discon-
nect ADC4 of the J3 header from the ADC4
pin (Pin 2) of the ADuC7020.
S1-8 LED
Function: Connects the DAC1 output to the green LED
of the demo circuit, D1.
Use: Slide S1-7 to the ON position to connect
the DAC1 output to D1.
Slide S1-7 to the OFF position to use the
DAC1 output on the J3 header.
EXTERNAL CONNECTORS
J3 Analog I/O Connector
The analog I/O connector J3 provides external connections
for all ADC inputs, reference inputs, and DAC outputs. The
pinout of the connector is shown in Table II.
Table II. Pin Functions for Analog I/O Connector J3
Pin No. Pin Description
J3-1 AVDD
J3-2 AGND
J3-3 VREF
J3-4 ADC0
J3-5 ADC1
J3-6 ADC2
J3-7 ADC3
J3-8 ADC4
J3-9 VDIFF
J3-10 VOCM
J3-11 DAC0
J3-12 DAC1
J3-13 DAC2
J3-14 DAC3
J5 Power Supply Connection
J5 allows for the connection between the evalua -
tion board and the 9 V power supply provided in the
ADuC7020 development system.
J4 Emulation Connector
J4 provides a connection of the evaluation board to the
PC via a USB cable and ULINK provided in the ADuC7020
development system.
J1 Serial Interface Connector
J1 provides a simple connection of the evaluation board
to the PC via a PC serial port cable provided with the
ADuC7020 development system.
J6 I2C® Interface Connector
J6 provides a simple access to the two I2C interfaces of
the ADuC7020.
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J2 Digital I/O Connector
The digital I/O connector J2 provides external connec-
tions for all GPIOs. The pinout of the connector with pin
function descriptions is shown in Table III.
Table III. Pin Functions for Digital I/O Connector J2
Pin No. Pin Description
J2-1 DGND
J2-2 P4.2
PLAO[10]
J2-3 P1.0
SIN/SCL/PLAI[0]
J2- 4 P1.1
SOUT/SDA/PLAI[1]
J2-5 P1.2
RTS/PLAI[2]
J2-6 P1.3
CTS/PLAI[3]
J2-7 P1.4
RI/CLK/PLAI[4]
J2-8 P1.5
DCD/MISO/PLAI[5]
J2-9 P1.6
DSR/MOSI/PLAI[6]
J2-10 P1.7
DTR/CSL/PLAO[0]
J2-11 P0.7
ECLK/SIN/PLAO[4]
J2-12 P2.0
CONV/SOUT/PLAO[5]
J2-13 P0.5
IRQ1/ADCBUSY/PLAO[2]
J2-14 P0.4
IRQ0/ PLAO[1]
J2-15 P0.3
TRST/ADCBUSY
J2-16 P0.6
MRST/PLAO[3]
J2-17 P0.0
CMP/PLAI[7]
J2-18 DGND
POTENTIOMETER DEMONSTRATION CIRCUIT
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Figure 2. Circuit Diagram of the RTD Circuit
Using the sample code in \code\adc\pot.c, the variation
in the potentiometer resistance can be seen on the output
LED. Note that the internal reference and external refer-
ence are 2.5 V, which gives an ADC input range of 0 V to
2.5 V in single-ended mode. The potentiometer can give
a voltage between 0 V and AVDD = 3.3 V.
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ADuC7020 EVALUATION BOARD PARTS LIST
Component Qty. Part Description Order No. Order From
EVAL-ADuC7020QS 1 PCB-1 2-Sided Surface-Mount PCB
QuickStart™ PCB
PCB Stand-Off 4 Stand-Off Stick-On Mounting Feet 148-922 Farnell
U1 1 ADuC7020 MicroConverter (64-CSP) ADuC7020CP ADI
U2 1 ADR291 Band Gap Reference ADR291ER ADI
U3 1 AD8132 Differential Op Amp AD8132ARM ADI
U4 1 AD8606 Dual Op Amp, (8-Lead SOIC) AD8606AR ADI
U5 1 ADP3333 Fixed 3.3 V Linear Voltage Regulator ADP3333ARM3.3 ADI
Y1 1 32.768 kHz Watch Crystal 316-0312 Farnell
S1 1 SW\8-DIP 8-Way DIP Switch 566 -718 Farnell
S2, S3, S4 3 Push-Button Switch PCB-Mounted Push-Button Switch 177-807 Farnell
D1, D2, D3 3 LED 1.8 mm Miniature LED 515-620 Farnell
D4 1 PRLL4002 Diode BAV103DITR-ND Digi-Key
C1, C5, C13, C15, 7 10 F Surface-Mount Tantalum Cap, 197-130 Farnell
C18, C22, C23 Taj-B Case
C2C4, C6, C12, 8 0.1 F Surface-Mount Ceramic Cap, 0603 Case 317-287 Farnell
C14, C16, C17
C7, C8 2 22 pF Surface-Mount Ceramic Cap, 0603 Case 722-005 Farnell
C11, C19 2 470 nF Surface-Mount Ceramic Cap, 0603 Case 318-8851 Farnell
R1 1 10 k Potentiometer 0.25 W, 4 Series, 4 mm Square Sealed 307-1741 Farnell
R2 1 100 Surface-Mount Resistor, 0603 Case 911-732 Farnell
R3 1 200 Surface-Mount Resistor, 0603 Case 321-7978 Farnell
R4 1 49.9 Surface-Mount Resistor, 0805 Case 422-1825 Farnell
R5, R6, R8, R9 4 348 Surface-Mount Resistor, 0603 Case 422-2570 Farnell
R7 1 24.9 Surface-Mount Resistor, 0805 Case 422-1539 Farnell
R10, R11 2 60.4 Surface-Mount Resistor, 0805 Case 422-1904 Farnell
R12, R18, R20 2 270 Surface-Mount Resistor, 0603 Case 613-022 Farnell
R13, R14 2 0 Surface-Mount Resistor, 0603 Case 772-227 Farnell
R15R17 4 1 k Surface-Mount Resistor, 0603 Case 911-239 Farnell
R19 1 1.5 Surface-Mount Resistor, 0603 Case 758-267 Farnell
R21, R22, R24 3 100 k Surface-Mount Resistor, 0603 Case 911-471 Farnell
L1 1 Ferrite Bead Surface-Mount Inductor, 1206 Case 581-094 Farnell
J1 1 4-Pin Header 4-Pin 90 Single Row Header TSM-104-02-T-SH Samtec
J2 1 18-Pin Header 18-Pin Straight Single Row Header TSM-118-01-T-SV Samtec
J3 1 14-Pin Header 14-Pin Straight Single Row Header TSM-114-01-T-SV Samtec
J4 1 20-Pin Header 20-Pin Connector IMP-BV(SMT)-20 Imperial-
Connect
J5 1 PCB-Mounted Socket KLD-SMT2-0202-A Kycon
(2 mm Pin Diameter)
Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips
I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips.
REV. 0
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Figure 3. ADuC7020 Evaluation Board Schematic
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Figure 4. ADuC7020 Evaluation Board Silkscreen
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© 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.

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