AMC7820EVM - Texas Instruments

AMC7820

Evaluation Module

User’s Guide

2001 Data Acquisition Products

SBAU074

IMPORTANT NOTICE

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any product or service without notice, and advise customers to obtain the latest version of relevant information

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subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those

pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in

accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent

TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily

performed, except those mandated by government requirements.

Customers are responsible for their applications using TI components.

In order to minimize risks associated with the customer’s applications, adequate design and operating

safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent

that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other

intellectual property right of TI covering or relating to any combination, machine, or process in which such

semiconductor products or services might be or are used. TI’s publication of information regarding any third

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Also see: Standard Terms and Conditions of Sale for Semiconductor Products. www.ti.com/sc/docs/stdterms.htm

Mailing Address:

Texas Instruments

Post Office Box 655303

Dallas, Texas 75265

EVM IMPORTANT NOTICE

Texas Instruments (TI) provides the enclosed product(s) under the following conditions:

This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION

PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided

may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective

considerations, including product safety measures typically found in the end product incorporating the goods.

As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic

compatibility and therefore may not meet the technical requirements of the directive.

Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned

within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE

WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,

IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY

PARTICULAR PURPOSE.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user

indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products

received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction

of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic

discharge.

EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE

TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not

exclusive.

TI assumes no liability for applications assistance, customer product design, software performance, or

infringement of patents or services described herein.

Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM

User’s Guide prior to handling the product. This notice contains important safety information about temperatures

and voltages. For further safety concerns, please contact the TI application engineer.

Persons handling the product must have electronics training and observe good laboratory practice standards.

No license is granted under any patent right or other intellectual property right of TI covering or relating to any

machine, process, or combination in which such TI products or services might be or are used.

Mailing Address:

Texas Instruments

Post Office Box 655303

Dallas, Texas 75265

EVM WARNINGS AND RESTRICTIONS

It is important to operate this EVM within the input voltage range of +5V and the output

voltage range of +5V.

Exceeding the specified input range may cause unexpected operation and/or irreversible

damage to the EVM. If there are questions concerning the input range, please contact a TI

field representative prior to connecting the input power.

Applying loads outside of the specified output range may result in unintended operation and/or

possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to

connecting any load to the EVM output. If there is uncertainty as to the load specification,

please contact a TI field representative.

During normal operation, some circuit components may have case temperatures greater than

60°C. The EVM is designed to operate properly with certain components above 60°C as

long as the input and output ranges are maintained. These components include but are not

limited to linear regulators, switching transistors, pass transistors, and current sense

resistors. These types of devices can be identified using the EVM schematic located in the

EVM User’s Guide. When placing measurement probes near these devices during operation,

please be aware that these devices may be very warm to the touch.

Mailing Address:

Texas Instruments

Post Office Box 655303

Dallas, Texas 75265

CAUTION

Read This First

Preface

About This Manual

How to Use This Manual

Information About Cautions and Warnings

This user’s guide describes the function and operation of the AMC7820 Analog Monitoring

and Control circuit evaluation module. This manual will help you quickly set up the

evaluation board and its accompanying software so that you may rapidly test and evaluate

the AMC7820. A complete circuit description, as well as a schematic diagram and bill of

materials, is included.

This manual begins with an introductory chapter that describes the EVM and what it can

do. If you’re anxious to set things up and start testing, we suggest you read at least the

first two chapters. These two chapters introduce you to the board and how to set it up to

start working with it. Later chapters go into more detail on the board’s design and how to

access its many features.

This book may contain cautions.

This is an example of a caution statement.

A caution statement describes a situation that could potentially damage your

software or equipment.

The information in a caution is provided for your protection. Please read each caution

carefully.

Related Documentation From Texas Instruments

Data Sheets Literature Number

AMC7820 SBAS231

SN74AHC244 SCLS226

REG711EA SBVS027

Related Documentation From Texas Instruments

If You Need Assistance

FCC Warning

Trademarks

If you have questions about this or other Texas Instruments data converter evaluation

modules, feel free to e-mail the data converter application team at dataconvapps@list.ti.com.

Include the product name in the subject heading.

This equipment is intended for use in a laboratory test environment only. It generates,

uses, and can radiate radio frequency energy and has not been tested for compliance with

the limits of computing devices pursuant to subpart J of part 15 of FCC rules, which are

designed to provide reasonable protection against radio frequency interference. Operation

of this equipment in other environments may cause interference with radio communica-

tions, in which case the user at his own expense will be required to take whatever

measures may be required to correct this interference.

Windows is a trademark of Microsoft Corporation.

SPI is a registered trademark of Motorola.

iii

Contents

Read This First......................................................................................................................... ii

About This Manual ........................................................................................................................................... ii

How To Use This Manual ................................................................................................................................ ii

Information About Cautions and Warnings ..................................................................................................... ii

Related Documentation From Texas Instruments.......................................................................................... iii

If You Need Assistance .................................................................................................................................. iii

FCC Warning .................................................................................................................................................. iii

Trademarks ..................................................................................................................................................... iii

Contents................................................................................................................................... iv

Figures ...................................................................................................................................... v

Tables........................................................................................................................................ v

Introduction ........................................................................................................................... 1-1

1.1 Device Characteristics ........................................................................................................................... 1-2

1.2 EVM Block Diagram .............................................................................................................................. 1-2

1.3 Analog Inputs/Outputs ........................................................................................................................... 1-3

1.4 Prototyping Area .................................................................................................................................... 1-3

1.5 Power Requirements ............................................................................................................................. 1-4

1.6 Computer Requirements........................................................................................................................ 1-4

Getting Started...................................................................................................................... 2-1

2.1 Unpacking the EVM............................................................................................................................... 2-2

2.2 Default Configuration ............................................................................................................................. 2-2

2.3 Quick Start ............................................................................................................................................. 2-2

Operation ............................................................................................................................... 3-1

3.1 Jumpers ................................................................................................................................................. 3-2

3.1.1 DC/DC Converter .......................................................................................................................................... 3-2

3.2 I/O Connectors and Signals .................................................................................................................. 3-2

3.2.1 Parallel Port Connector ................................................................................................................................. 3-2

3.2.2 External SPI Connector................................................................................................................................. 3-3

3.2.3 Power Connectors ......................................................................................................................................... 3-3

3.2.4 External Reference Connector...................................................................................................................... 3-3

3.2.5 Thermistor Input Connector .......................................................................................................................... 3-3

3.3 Circuit Description.................................................................................................................................. 3-4

3.3.1 SPI Interface.................................................................................................................................................. 3-4

3.3.2 DC/DC Converter .......................................................................................................................................... 3-4

3.4 Program Description .............................................................................................................................. 3-4

3.4.1 Configuration and Control ............................................................................................................................. 3-4

3.4.2 D/A Converters .............................................................................................................................................. 3-6

3.4.3 A/D Converters .............................................................................................................................................. 3-7

Physical Description ............................................................................................................. 4-1

4.1 Schematic ................................................................................................................................................................. 4-2

4.2 Component Locations ............................................................................................................................................... 4-3

4.3 Bill of Materials ......................................................................................................................................................... 4-4

Figures

Figure 1. AMC7820-EVM Block Diagram .................................................................. 1-2

Figure 2. Main Screen with Configuration/Status Display Selected ..................... 2-3

Figure 3. Configuration and Control Screen ........................................................... 3-5

Figure 4. D/A Converter Screen ................................................................................ 3-6

Figure 5. A/D Converter Scope Mode....................................................................... 3-7

Figure 6. A/D Converter Data Mode.......................................................................... 3-7

Tables

Table 1. Default Configuration Settings .................................................................. 2-2

Table 2. Configuration/Status Register Startup Values ........................................ 2-3

Table 3. Jumper/Function Reference ...................................................................... 3-2

Table 4. Parallel Port Connector .............................................................................. 3-2

Table 5. External SPI Connector .............................................................................. 3-3

Table 6. Power Connectors ...................................................................................... 3-3

Table 7. External Reference Connector .................................................................. 3-3

Table 8. Thermistor Input Connector ...................................................................... 3-3

Introduction

Chapter 1

The AMC7820 is a complete analog monitoring and control unit, which includes an

8-channel, 12-bit Analog-to-Digital (A/D) converter, three 12-bit Digital-to-Analog (D/A)

converters, nine operational amplifiers, an internal 2.5V reference, and an SPI™ serial

interface. The evaluation board for this multifunction device, the AMC7820-EVM, is

designed to ease the digital interface to the AMC7820 by connecting to a personal

computer running easy-to-use software which allows total access to the AMC7820’s

various control functions. A large prototype area on the board provides space to connect

circuitry to the AMC7820 and connections to configure the internal components.

Topic Page

Device Characteristics ........................................................................................................... 1-2

EVM Block Diagram................................................................................................................ 1-2

Analog Inputs/Outputs ........................................................................................................... 1-3

Prototyping Area..................................................................................................................... 1-3

Power Requirements .............................................................................................................. 1-4

Computer Requirements........................................................................................................ 1-4

1-1

1.1 Device Characteristics

The AMC7820-EVM supports the AMC7820, which is soldered onto the EVM. The

AMC7820’s 8-channel A/D converter, three D/A converters, voltage reference, and nine

operational amplifiers are all available for connection to the sizeable prototyping area

on the board. Connectors are provided for the three power supplies needed by the

AMC7820, as well as for a thermistor input and external reference input. An onboard

3V to 5V DC/DC converter can create the 5V analog supply needed by the AMC7820

if an external 5V supply is not available.

Introduction

1.2 EVM Block Diagram

Figure 1 shows a block diagram of the AMC7820-EVM.

Figure 1. AMC7820-EVM Block Diagram.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

41 38 39 37 40 20 42 36 48 47

SCLK

MISO

MOSI

RESET

ISET

Thermistor

Input

Ext Ref

SW2_OUT

T_SENSOR_VOLTAGE

OPA6_IN–

OPA6_OUT

OPA6_IN+

DAC0_OUT

DAC0_OUT_SET

OPA2_IN–

OPA2_OUT

OPA2_IN+

OPA5_IN+

OPA5_OUT

OPA5_IN+

OPA4_IN–

OPA4_OUT

OPA4_IN+

DAC2_OUT

DAC2_OUT_SET

DAC1_OUT_SET

DAC1_OUT

OPA3_IN–

OPA3_OUT

OPA3_IN+

REF_OUT_2.5V

SW1_OUT

OPA1_IN+

OPA1_OUT

OPA1_IN–

CH5

CH4

CH3

CH2

OPA7_IN–

OPA7_OUT

OPA7_IN+

J1 PC Parallel Port Interface

Buffer

AMC7820

J2 External SPI J5 AV

J3 DV

J4 BV

Breadboard

1-2

The digital control interface is either through the PC parallel port, or an external SPI bus.

The PC parallel port can be disabled, allowing the external SPI bus to control the

AMC7820. When using the PC parallel port, the digital interface voltage is 5V; when the

external SPI bus is used, the digital interface voltage may be 5V or 3V.

Power supplies are to be provided to the AMC7820-EVM through external connectors from

an external, user-supplied laboratory power supply. AVDD and DVDD must be supplied at

+5V, while BVDD can range from +2.7V to +5V.

A thermistor can be connected to the AMC7820 through a terminal block. The thermistor

is driven by a current source on the AMC7820, which is derived from the reference and

set by the ISET resistor. The ISET resistor (see Figure 1) is identified as R2 on the

AMC7820-EVM, and is socketed on the EVM so that the user can change its value.

All the remaining pins of the AMC7820 (i.e., all the analog inputs and outputs) are brought

out to a large prototype area on the AMC7820-EVM, so that external connections and

circuitry can be made in any manner the user wishes.

Introduction

1.3 Analog Inputs/Outputs

The analog inputs and outputs of the AMC7820 are available on the prototyping area and

are identified on the silkscreen. These include the op amps, A/D converter inputs, and

D/A converter outputs. Note that the direct inputs to the A/D converter (CH2-CH5) are not

buffered inside the AMC7820, and so should connect only to extremely-low impedance

sources, or should be buffered externally.

An external reference may be provided to the AMC7820 through J6. This reference

voltage must remain within the specifications of the AMC7820. Consult the AMC7820 data

sheet (SBAS231) at www.ti.com for these and other device specifications.

The AMC7820 connects to a thermistor through J7. The nominal value of this thermistor

is typically 10kΩ.

Since the AMC7820’s A/D converter runs at 100kHz, and must scan through eight

channels, each channel’s effective conversion time is 80µs. This means that each

channel’s effective sampling rate is 12.5kHz. Input signals above 6.25kHz, therefore,

would result in aliasing, unless external anti-aliasing filters are provided.

The voltage range of all the analog inputs and outputs of the AMC7820 are from 0V to 5V.

Note that the D/A converters’ outputs may be configured to range from 0V to VREF or from

0V to 2VREF. See the AMC7820 data sheet for details on the operating ranges of the

analog inputs and outputs.

1.4 Prototyping Area

The large prototype area of the AMC7820 provides plenty of room for external circuitry to

be connected to the AMC7820. Every analog signal from the AMC7820 (except for the

reference and thermistor connections, which are available on J6 and J7) is brought out to

the edge of the prototype area. Five holes at each signal point are connected together to

allow several connection points for external circuitry.

Six large areas of copper are available for use as heatsinks for power devices. These

copper areas are isolated from all other signals.

1-3

Introduction

1.5 Power Requirements

The AMC7820 requires an analog supply voltage (AVDD) of 5V, a digital supply voltage

(DVDD) of 5V, and an interface supply voltage (BVDD) that can range from 2.7V to 5.5V.

The user should provide power-supply voltages from a lab-quality power supply. DVDD

is provided on J3, AVDD is provided on J5, and BVDD is provided on J4. If a single 3.3V

supply is used (connected to BVDD) to simulate the user’s system supply, the onboard

DC/DC converter can generate AVDD and DVDD if JMP1 is removed and JMP2 and

JMP3 are installed.

1.6 Computer Requirements

The AMC7820-EVM software is designed to run on a PC running any Windows® platform

(Windows 95, 98, NT, 2000, etc).

Minimum System Requirements:

•IBM-Compatible 486 PC or Higher

•Windows 95, 98, 2000, or NT4.0

•32MB RAM Minimum

•20MB Available Hard Disk Space

•CD-ROM Drive

•Available Parallel Port

1-4

Getting Started

Chapter 2

This chapter will guide you through unpacking the EVM and setting it up so you can begin

working with it immediately.

Topic Page

Unpacking the EVM ................................................................................................................ 2-2

Default Configuration ............................................................................................................. 2-2

Quick Start............................................................................................................................... 2-2

2-1

Getting Started

2.1 Unpacking the EVM

After unpacking the AMC7820-EVM, check to make sure you received all the material that

should be in the box. The EVM kit should include the following:

•AMC7820-EVM Board, PWB 6432813

•CD-ROM, 6437057

•IEEE1284 25-Pin Parallel Cable

If any of these components are missing, contact Texas Instruments at

dataconvapps@list.ti.com for a replacement.

2.2 Default Configuration

The AMC7820-EVM is a simple board and the only configuration details needed are the

settings of the three jumpers and the value of R2, the resistor that sets the thermistor

current.

The default settings for these items are shown in Table 1. When you unpack your

AMC7820-EVM, make sure that your board is initially configured as shown here.

Table 1. Default Configuration Settings.

Board Identifier Description Default Setting

JMP1 DC/DC Converter Disable Installed

JMP2 AVDD = Onboard 5V Not Installed

JMP3 DVDD = Onboard 5V Not Installed

R2 Thermistor Current Set 100kΩ

2.3 Quick Start Once the AMC7820-EVM has been unpacked from its shipping container, and you have

verified that the board is configured as shown in Table 1, it can be connected to power

supplies.

Connect wires from the terminal blocks J3, J4, and J5 to a +5V laboratory power supply.

Make sure to observe correct polarity; the polarity for each terminal block is marked on

the printed circuit board. Do not turn on the power supply at this time.

If a thermistor is available, connect it to terminal block J7.

Connect the IEEE-1284 cable to your PC, but do not connect it to the AMC7820-EVM

board yet.

Place the CD-ROM into your PC’s CD-ROM drive. Locate the Setup program on the disk,

and run it. The Setup program will install the AMC7820-EVM software on your PC. Note

that if you are running a Windows platform that is NT-based, you will need administrator

privileges to install the software. Follow the installer’s instructions.

When the installation is complete, turn on the power supply, and then connect the parallel

port cable to the AMC7820-EVM. Once these connections have been made, launch the

AMC7820-EVM software on your PC.

The software should automatically determine the parallel port where the AMC7820-EVM

is connected. If the board is found, the screen shown in Figure 2 will appear.

2-2

Getting Started

On this screen the Configuration/Status register bits are displayed. These bits should be

as shown in Table 2.

Figure 2. Main Screen with Configuration/Status Display Selected.

Table 2. Configuration/Status Register Startup Values.

RST POL1 POL2 TSC1 TSC2

10101

If these bits are not as shown in Table 2, you will have an error message before Figure 2

is displayed. Generally, if this happens, a communication problem exists. Check the cables

and connections and make sure they are sound. Make sure that your power is on. Correct

any problems and restart the program.

2-3

Operation

Chapter 3

This chapter describes each function of the AMC7820-EVM and how to use the

accompanying software to control and use the AMC7820.

Topic Page

Jumpers ................................................................................................................................... 3-2

I/O Connectors and Signals .................................................................................................. 3-2

Circuit Descriptions................................................................................................................ 3-4

Program Description .............................................................................................................. 3-4

3-1

Operation

3.1 Jumpers Table 3 shows the function of each jumper on the EVM:

3.1.1 DC/DC Converter

The AMC7820-EVM has an onboard DC/DC converter designed to take 3.3V supplied

through the BVDD terminal block, J4, and step it up to 5V to supply the analog and digital

supply voltages. This feature is provided to illustrate how to use the AMC7820 in a system

that only has a 3.3V power supply available. To enable the DC/DC converter, JMP1 should

be removed and JMP2 and JMP3 installed. If the DC/DC converter is not used, JMP1

should be installed to disable the charge pump and minimize system noise.

Table 3. Jumper/Function Reference.

Reference

Designator Setting Function Subsection

JMP1 Installed DC/DC Converter Disabled 3.1.1

Open DC/DC Converter Enabled 3.1.1

JMP2 Installed AVDD Supplied by DC/DC Converter 3.1.1

Open AVDD Supplied Through J5 3.1.1

JMP3 Installed DVDD Supplied by DC/DC Converter 3.1.1

Open DVDD Supplied Through J3 3.1.1

3.2 I/O Connectors and Signals

The various connectors on the AMC7820-EVM are described in this section.

3.2.1 Parallel Port Connector

The connector for use with the PC parallel port is described in Table 4. This connector

provides a means of communicating with the PC through an IEEE-1284 cable.

Table 4. Parallel Port Connector.

Reference Pin

Designator Description Number Signal Name Function

J1 1 EVM_ENABLE Enables the SPI bus con-

trol from the PC.

2 SS Slave Select for SPI bus.

3 SCLK Serial Clock for SPI bus.

4 MOSI Master Out, Slave In data

line for SPI bus. Data trav-

els to the AMC7820 over

this line.

5 NC Not Connected

6 NC Not Connected

7 RESET

Reset line for the AMC7820.

8-14 NC Not Connected

15 MISO Master In, Slave Out data

line for SPI bus. Data trav-

els from the AMC7820 over

this line.

16-17 NC Not Connected

18-25 GND Ground

Digital communication

port between the

AMC7820-EVM and a

host PC.

3-2

Operation

3.2.2 External SPI Connector

If the SPI bus is not controlled from the PC, it may be controlled through J2. The user might

connect an external microprocessor or DSP to the AMC7820-EVM through this connector.

Table 5. External SPI Connector.

Reference Pin

Designator Description Number Signal Name Function

J2 1 RESET

Reset line for the AMC7820.

3 SS Slave Select for SPI bus.

5 SCLK Serial Clock for SPI bus.

7 MOSI Master Out, Slave In data

line for SPI bus. Data trav-

els to the AMC7820 over

this line.

9 MISO Master In, Slave Out data

line for SPI bus. Data trav-

els from the AMC7820 over

this line.

2, 4, 6, 8, 10 GND Ground

Digital communication

port between the

AMC7820-EVM and

an external processor.

3.2.3 Power Connectors Table 6. Power Connectors.

3.2.4 External Reference Connector Table 7. External Reference Connector.

3.2.5 Thermistor Input Connector Table 8. Thermistor Input Connector.

3-3

Reference

Designator Name Description

J3 DVDD IN Digital (+5V) supply for the AMC7820.

J4 BVDD IN Digital I/O supply (3.3V-5V) for the AMC7820.

J5 AVDD IN Analog (+5V) supply for the AMC7820.

Reference

Designator Name Description

J6 EXT REF IN External reference input.

Reference

Designator Name Description

J7 THERMISTOR INPUT Connection for the thermistor input to the AMC7820.

Operation

3.3.1 SPI Interface

The SPI interface to the AMC7820 can be controlled from two sources: the external SPI

header, J2, or from the PC parallel port, J1. The PC parallel port connection is buffered

through U1. U1’s outputs are enabled only when pin 1 of U1 is LOW. This pin is pulled

HIGH by R1, so that if no parallel port is connected, U1’s outputs are tri-stated, allowing

the external SPI bus to drive the AMC7820. When the PC parallel port is connected, the

PC software will pull pin 1 of the parallel port (which is connected to pin1 of U1) LOW in

order to enable the PC to control the SPI bus.

CAUTION

Do not drive the external SPI bus when the PC parallel port is connected.

Disconnect the PC parallel port cable from the AMC7820-EVM if you want to use

the external SPI bus.

3.3.2 DC/DC Converter

In order to supply the AVDD and DVDD supplies from a 3.3V input on BVDD, the DC/DC

converter circuit around U3 will boost the 3.3V input to 5V. U3 is enabled when ENABLE

pin 2, is HIGH. R3 pulls this pin HIGH when JMP1 is not installed. When JMP1 is installed,

the ENABLE pin is held LOW and the DC/DC converter will not operate. This helps reduce

noise on the board when this feature is not needed.

With JMP1 removed, 5V will appear on the output of U3 (pin 8). JMP2 and JMP3 should

be installed to connect this 5V to AVDD and DVDD.

3.4 Program Description

After having installed the software for the AMC7820-EVM as described in section 2.3, you

may begin using it to evaluate and develop with the AMC7820.

3.4.1 Configuration and Control

The program’s interface is a simple, three-tab interface. Clicking on a tab will take you to

the functions associated with that tab. The default tab that the program begins on is the

Configuration and Control tab (see Figure 3).

3-4

3.3 Circuit Description

The AMC7820-EVM consists of two circuits: the SPI interface and the DC/DC converter.

The board consists primarily of breadboard area around the AMC7820.

This screen gives you access to the Configuration/Status register and the Shutdown

Figure 3. Configuration and Control Screen.

Operation

3.4.1.1 Reset

The Reset section, in the lower left hand corner of this screen, allows you to reset the

AMC7820 by writing the correct code to the AMC7820’s Reset register. Pressing the Write

to Reset Register button will cause the AMC7820’s registers to be returned to their default

states.

3.4.1.2 Shutdown

The Shutdown section of this screen lets you determine if SW1 and SW2 are disabled.

This is done by writing the AMC7820’s Shutdown register. If the checkbox is checked, the

corresponding switch inside the AMC7820 is placed in its disabled state. Refer to the

AMC7820 data sheet for more information on these switches and their function.

3.4.1.3 Configuration/Status

This part of the screen allows you to see the bits in the AMC7820’s Configuration/Status

To read the register at any time, simply press the Read button and the program will read

the current data out of the AMC7820.

To change the bit settings, you may either use the radio buttons below the bit display to

set specific modes of operation, or you may simply type the bit values into the fields

displayed. Anytime a change is made, the change is NOT written to the AMC7820 device

until the Write button is pressed. This allows you to see the effects of changes in the bit

patterns without actually changing the configuration of the part until you are certain you

have what you want.

3-5

Operation

3.4.2 D/A Converters

This screen allows you to control the D/A converters in the AMC7820. You may read and

write the D/A register values and specify or display these values in either hexadecimal

format or in volts, as shown in Figure 4.

Figure 4. D/A Converter Screen.

3.4.2.1 DAC0, DAC1, DAC2

These controls enable you to write a value to the D/A converters and read that value back.

To set a D/A converter’s output level, type the value into the box in the units you have

chosen in the Display Units—either Hex or Volts. The value is not written to the D/A

converter until you push the Write button.

Pressing the Read button will cause the program to read the D/A converter register and

display its value.

The checkbox in this section tells the program how you have configured the hardware—

is the DACx_OUT_SET pin grounded? If so, then the D/A converter’s output range is from

0V to 2VREF, whereas if it is not grounded, the range is 0V to VREF. These are the two

typical cases; if you have external circuitry that changes these nominal gains, the program

cannot take that into account for you directly.

3.4.2.2 VREF

This section of the D/A converter screen allows you to specify the reference voltage you

are using. Typically, this will be 2.5V from the internal reference of the AMC7820.

However, if you supply an external reference, your voltage may be different and you may

enter it here so that voltage calculations shown on this screen are correct.

3.4.2.3 Display Units

You may select whether to display the D/A converter values as hexadecimal numbers

(Hex) or voltage (Volts). If voltage is chosen, the voltage shown will be determined by the

value of the reference voltage specified in the VREF section, and the value of the

DACx_OUT_SET checkbox associated with each D/A converter. See the D/A converter

section for more information.

3-6

Operation

3.4.3 A/D Converter

This screen, shown in Figure 5, displays the readings from the onboard 8-channel A/D

converter.

Figure 5. A/D Converter Scope Mode.

This screen gives you the option of viewing the converted data either in a Scope mode,

as shown in Figure 5, or in Data mode. In Scope mode, all 8 channels of the A/D converter

are displayed in a graphical format.

Data mode displays a listing of the most recent samples, as shown in Figure 6.

Figure 6. A/D Converter Data Mode.

The data values are shown in volts, hexadecimal, and binary units.

3-7

Physical Description

Chapter 4

Topic Page

Schematic ................................................................................................................................ 4-2

Component Locations............................................................................................................ 4-3

Bill of Materials ....................................................................................................................... 4-4

4-1

Physical Description

4.1 Schematic

SW2_OUT

T_SENSOR_VOLTAGE

OPA6_IN–

OPA6_OUT

OPA6_IN+

DAC0_OUT

DAC0_OUT_SET

OPA2_IN–

OPA2_OUT

OPA2_IN+

OPA5_IN–

OPA5_OUT

RESET

CH2

CH3

CH4

CH5

OPA1_IN–

OPA1_OUT

OPA1_IN+

SW1_OUT

EXT_REF_IN

REF_OUT_2.5V

OPA3_IN+

SCLK

MOSI

MISO

DGND

THERM_I_OUT

ISET_RESISTOR

OPA7_IN–

OPA7_OUT

OPA7_IN+

OPA3_OUT

OPA3_IN–

DAC1_OUT

DAC1_OUT_SET

DAC2_OUT_SET

AGND

DAC2_OUT

OPA4_IN+

OPA4_OUT

OPA4_IN–

OPA5_IN+

C4 1µF

C1 1µFC2 1µF

IN J4

IN J5

IN J6

EXT_REF IN

21 21 21 21

1µF

EXTERNAL SPI

A4 GND

PC PARALLEL PORT

THERMISTOR INPUT R2

RES_SKT

Analog and Digital ground should be connected together as a ground plane on layout.

Connections to the ground pins of voltage connectors should be made directly from

the connectors to the pins, so that the “mecca” of the grounds is at the part.

BREADBOARD AREA

2.7kΩ

JMP3JMP3 228

VIN

ENABLE

CPUMP+

CPUMP–

PGND GND REG711EA-5

JMP1

VOUT

2.2µFC7

10µF

0.22µF

NOTE: C5, C6, and C7 must be ceramic X7R capacitors.

Connect this ground point directly to pin 43 of U2.

4-2

Physical Description

4.2 Component Locations

EXTSPI

J4 BVDD

J3 DVDD

DGND

JMP1

C7 JMP2

JMP3

THERM IN

AGND

EXT REF IN

AVDD

J7 J6 J5

U1 C2

CH2

CH3

CH4

CH5

OPA1–

OPA1 OUT

OPA1+

SW1 OUT

EXT REF IN

REF OUT

OPA3+

OPA3 OUT

OPA3–

DAC1 OUT

OUT SET1

OUT SET2

DAC2 OUT

OPA4+

OPA4 OUT

OPA4–

OPA5+

OPA5 OUT

OPA5–

OPA2+

OPA2 OUT

OPA2–

DAC0 SET

DAC0 OUT

OPA6+

OPA6 OUT

OPA5–

SEN5 V

SW2 OUT

OPA7+

OPA7 OUT

OPA7–

AGND

AVDD

AGND

BVDD

DGND

DVDD

DGND

AMC7820EVM

Texas Instruments

643213 PWB

4-3

Physical Description

4.3 Bill of Materials

REFERENCE MFG’S

ITEM NO. VALUE DESIGNATORS QTY MFG PART NUMBER DESCRIPTION

1 0.22µF C5 1 Panasonic ECJ-3VB1E224K Cap 0.22µF 25V 10% Ceramic Chip 1206 X7R

or Alternate

21µF C1-C4 4 Panasonic ECJ-2VF1C105Z Cap 1µF 16V 20% Ceramic Chip 0805

or Alternate

32.2µF C6 1 Panasonic ECJ-3YB1C225K Cap 2.2µF 16V 10% Ceramic Chip 1206 X7R

or Alternate

410µF C7 1 Panasonic ECJ-4YB1C106K Cap 10µF 16V 10% Ceramic Chip 1210 X5R

or Alternate

5 J1 1 AMP Incorporated 747842-4 DB25 Right-Angle Female Conn w/Board Locks

6 J3-J7 5 On Shore Technology ED120/2DS 2 Contact Screw Terminal Blocks

7 J2 1 Samtec TSW-105-07-L-D 10-Pin Dual-Row Header (5x2)

8 JMP1-JMP3 3 Samtec TSW-102-07-L-S 2-Pin Single-Row Header (2x1)

9 2.7kΩR3 1 Panasonic ERJ8GEYJ272V Resistor, 2.7kΩ 1/8W 5% 1206 SMD

or Alternate

10 4.7kΩR1 1 Panasonic ERJ8GEYJ472V Resistor, 4.7kΩ 1/8W 5% 1206 SMD

or Alternate

11 R2 2 AMP Incorporated 50863-5 Miniature Spring Socket

12 U1 1 Texas Instruments SN74AHC244PWR Octal Buffers/Drivers with 3-State Outputs

13 U2 1 Texas Instruments AMC7820 Analog Interface

14 U3 1 Texas Instruments REG711EA-5 50mA Switched-Cap DC/DC Converter

15 NA 3 Samtec SNT-100-BK-TH Shorting Jumper

or Alternate

16 NA 4 Keystone Electronics 1808 1/4” x 0.625 Hex 4-40 Threaded Standoff

or Alternate

17 NA 4 Building Fasteners PMS 440 0050 PH Pan Head Machine Screws 4-40 x 1/2” Phillips

or Alternate

4-4

Document Control Number 6432611

Revision A