Texas Instruments ADS7861 EVM User manual

 
October 2002 Data Acquisition Products
User’s Guide
SLAU094

IMPORTANT NOTICE
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enhancements, improvements, and other changes to its products and services at any time and to discontinue
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accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TIdoesnotwarrantorrepresentthatanylicense, eitherexpress orimplied, isgranted underanyTIpatentright,
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inwhichTIproductsorservicesareused.InformationpublishedbyTIregardingthird–partyproductsorservices
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Use of such information may require a license from a third party under the patents or other intellectual property
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Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated

EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
Thisevaluationkit being soldbyTI is intendedforuse 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.
ShouldthisevaluationkitnotmeetthespecificationsindicatedintheEVMUser’sGuide,thekitmaybereturned
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,ORSTATUTORY,INCLUDINGANYWARRANTY OF MERCHANTABILITY ORFITNESSFORANY
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
receivedmaynotberegulatorycompliant oragency certified (FCC,UL, CE,etc.). Dueto theopen construction
oftheproduct,itistheuser’sresponsibilitytotakeanyandallappropriateprecautionswithregardtoelectrostatic
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’sGuidepriortohandlingtheproduct.Thisnoticecontainsimportantsafetyinformationabouttemperatures
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
Copyright 2002, Texas Instruments Incorporated

EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of 3.3 Vdc to 5 Vdc and the
output voltage range of 0 Vdc to 5 Vdc.
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.
Applyingloadsoutsideofthespecifiedoutputrangemayresultinunintendedoperationand/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.
Duringnormaloperation,somecircuitcomponentsmayhavecasetemperaturesgreaterthan
30°C.TheEVM isdesignedto operateproperlywith certaincomponentsabove 85°C aslong
astheinputandoutput rangesare maintained.Thesecomponentsincludebut arenot limited
tolinearregulators,switchingtransistors,passtransistors,andcurrentsenseresistors.These
typesof devicescanbeidentifiedusingtheEVM schematiclocated intheEVMUser’sGuide.
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
Copyright 2002, Texas Instruments Incorporated

Related Documentation From Texas Instruments
iii
Preface
Read This First
About This Manual
This users guide describes the characteristics, operation, and use of the
ADS7861/8361EVM–12-/16-bitdual,500-KSPS,2+2channel,serialanalog-
to-digital converter evaluation module. A complete circuit description as well
as a schematic diagram and bill of materials are included.
How to Use This Manual
This document contains the following chapters:
-Chapter 1 –EVM Overview
-Chapter 2 –Analog Interface
-Chapter 3 –Digital Interface
-Chapter 4 –Power Supplies
-Chapter 5 –EVM Operation
-Chapter 6 –Bill of Materials and EVM Schematic
Related Documentation From Texas Instruments
To obtain a copy of any of the following TI documents, call the Texas
Instruments Literature Response Center at (800) 477–8924 or the Product
Information Center (PIC) at (972) 644–5580. When ordering, please identify
this booklet by its title and literature number. Updated documents can also be
obtained through our website at www.ti.com.
Data Sheets: Literature Number:
ADS7861 SBAS110
ADS8361 SBAS230
Op Amps for Everyone SLOD006

Trademarks
iv
FCC Warning
Thisequipmentisintendedforuseinalaboratorytestenvironmentonly.Itgen-
erates,uses,andcanradiateradiofrequencyenergyandhasnotbeentested
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 en-
vironmentsmaycauseinterferencewithradiocommunications,inwhichcase
the user at his own expense will be required to take whatever measures may
be required to correct this interference.
Trademarks
The TI Logo is a trademark of Texas Instruments Incorporated.

Contents
v
Contents
1 EVM Overview 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Analog Interface 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Digital Interface 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Additional Control Options 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Power Supplies 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Reference Voltage 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 EVM Operation 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 Bill of Materials and EVM Schematic 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tables
2–1 Header/Socket J1 Description 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 Header/Socket J2 Description 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–2 Header J5 Description 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–1 Bill of Materials 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
vi

1-1
EVM Overview
TheADS7861andADS8361arehigh-speed,low-power,12-bitand16-bitA/D
converters that operate from independent 5-V AVDD and 5-V DVDD (2.7-V to
3.6-V DVDD for ADS8361) supplies.
Thefourfullydifferentialanaloginputsaredividedintotwopairs(AandB).The
ADS7861andADS8361acceptananaloginputvoltageintherangeof–VREF
to+VREF(5 Vp–p),centeredontheinternal 2.5-Vreference.Thepartalsoac-
cepts bipolar input ranges when a level shift circuit is used in the analog front-
end circuitry. Refer to Section 12 of Op Amps for Everyone (literature number
SLOD006) for information on various circuit applications.
Topic Page
1.1 Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Features
1-2
1.1 Features
-Full-featured evaluation board for the ADS7861 and ADS8361, dual,
500-kSPS, 12-bit/16-bit, serial output, 2+2 analog input, simultaneous
sampling analog-to-digital converter
-Analog inputs can be configured as single-ended or differential
-Built-in reference
-High-speed serial interface

2-1
Analog Interface
Analog Interface
For maximum flexibility, the ADS7861/8361 EVM is designed for easy
interfacing to multiple analog sources. Samtec part numbers
SSW–110–22–F–D–VS–K and TSM–110–01–T–DV–P provide a convenient
ten-pin dual row header/socket combination at J1. This header/socket
provides access to the analog input pins of the ADC. Consult Samtec at
www.samtec.comorcall1–800–SAMTEC–9for a variety of mating connector
options.
Table 2–1.Header/Socket J1 Description
Pin Number Signal Description
J1.2 B1+ Noninverting input –channel B1
J1.4 B1–Inverting input –channel B1
J1.6 B0+ Noninverting input –channel B0
J1.8 B0–Inverting input –channel B0
J1.10 A1+ Noninverting input –channel A1
J1.12 A1–Inverting input –channel A1
J1.14 A0+ Noninverting input –channel A0
J1.16 A0–Inverting input –channel A0
J1.18 Unused Pins are unused and should be left open for use
with future amplifier and sensor input modules.
J1.20 REFIN External reference source input (2.5 V nom,
2.525 V max)
J1.1–J1.19
(odd) AGND Analog ground connections
Chapter 2

2-2

3-1
Digital Interface
Digital Interface
The ADS7861/8361 EVM is designed for easy interfacing to multiple control
platforms. Samtec part numbers SSW–110–22–F–D–VS–K and
TSM–110–01–T–DV–P provide a convenient ten-pin dual row header/socket
combination at J2. This header/socket provides access to the digital control
and serial data pins of the ADS7861/8361. Consult Samtec at www.sam-
tec.com or 1–800–SAMTEC–9 for a variety of mating connector options.
Table 3–1.Header/Socket J2 Description
Pin Number Signal Description
J2.1 CS Chip select—Active low signal, enables data transfer
and device configuration
J2.3 SCLK Serial clock
J2.5 SCLK(R) Serial clock return for DSP host
J2.7 FS Frame sync
J2.9 FS(R) Frame sync return for DSP host
J2.11 SDI Serial data input
J2.13 SDO Serial data output
J2.15 INT Interruptoutput—providesaninterruptsourcetothehost
processor
J2.17 CSTART Conversion start—provides an alternate method of
conversion initialization
J2.19 SPARE
Topic Page
3.1 Additional Control Options 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3

Additional Control Options
3-2
3.1 Additional Control Options
Thefollowingtableshowsthepin-outofheaderJ5. Thisdualrow,four-position
header provides additional control functionality to the ADS7861/8361 EVM.
Signals A0, M0, and M1 are configured with pull-up resistors by default. The
jumpershunts supplied with theEVMcanbe used to setthesesignalstologic
low. These signals can also be connected to control signals in the users
system.
Table 3–2.Header J5 Description
Pin Number Signal Description
J5.1 M0 Selects two-channel or four-channel mode
J5.3 M1 Selects between serial outputs A and B
J5.5 A0 Operates in conjunction with M0. See data sheet
for details.
J5.7 OUT B B channel secondary output
J5.2 –J5.8 (even) DGND Digital ground connections

4-1
Power Supplies
Power Supplies
The ADS7861 EVM board requires 5 V dc for both the analog and digital
sections of the ADC. While filters are provided for all power supply inputs,
optimal performance of the EVM requires a clean, well-regulated power
source.Positive5-VdcpowerisappliedtoJ3andJ4(pin1referencedtopin 2).
The ADS8361 requires 5 V dc for the analog supply located on J3, and 2.7 V
to 5.5 V dc for the digital supply located on J4.
An alternate power source can be applied via J6 located on the bottom side
of the printed-circuit board. If a variable digital supply voltage is desired,
completelyremovetheshuntjumper fromW3.Applya100-mAcurrentlimited
dc voltage of not more than 5.5 V to J4.
Note:
Theshuntjumperatlocation W3 should beplacedacrosspin2 and pin
3forproperoperationoftheADS7861. Thisisthefactorydefaultcondi-
tion for both the ADS7861 and ADS8361 EVMs.
Topic Page
4.1 Reference Voltage 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 4

Reference Voltage
4-2
4.1 Reference Voltage
TheADS7861/8361canbeconfiguredtouseitsinternalreference,orexternal
referencesourcethroughjumperW1(seeschematicfordetails).Ifanexternal
reference is desired, the shunt jumper on W1 should cover pins 2 and 3. The
external reference is supplied through header/socket J1 pin 20 (J1.20).

5-1
EVM Operation
Apply a current limited (150 mA max) 5-V dc source to J3 and J4 prior to
connecting the analog input signals and digital control signals.
The analog input source can be applied directly to header/socket J1 (top or
bottom side) or through optional amplifier and signal conditioning modules.
The analog input level should not exceed 5 Vp–p.The analog input range is
from –VREF to VREF (0 V to 5 Vdc) centered at 2.5 V.
The digital control signals can be applied directly to header/socket J2 (top or
bottom side). The ADS7861/8361 EVM can also be connected directly to a
DSP interface board. Consult the ADS7861 and ADS8361 product folders for
a complete list of DSP interface cards and optional analog interface modules.
JumperW2isprovidedtoallowseparation of the convertstart(CONVST)and
read(RD)signals.ThefactorydefaultconditionfortheEVMistoplaceashunt
jumper between pin 1 and pin 2 of W2. This combines signals RD and
CONVST,whichareappliedtotheADCviapinJ2.7.WhenW2ismovedtopin
2 and pin 3, the RD signal is applied via pin J2.7 while CONVST is applied to
pin J2.17.
Header J5 is a means to access the M0, M1, and A1 control lines as well as
the OUTB serial data. Shunt jumpers are placed on pins 1 and 2, 3 and 4, and
5and6ofJ5,which defaults M0,M1,andA0tologiclowlevels.Removing the
jumpers allows these lines to go to logic high levels through the associated
pullup resistors R12, R13, and R14. In the factory default conditions, theADC
isconvertingtheA0andB0inputs,placingAOUTserialdataonpinJ2.13,and
BOUT serial data on pin J5.7.
Chapter 5

5-2

6-1
Bill of Materials and EVM Schematic
Bill of Materials and EVM Schematic
ThefollowingtablecontainsacompletebillofmaterialsfortheADS7861/8361
EVM. The schematic diagram is also provided for reference.
Table 6–1.Bill of Materials
Designators Description Manufacturer Mfg. Part Number
C1 C2 C3 C4 C5 C6
C7 C8 100-pF, 0805, Ceramic capacitor, NPO, 50-V, 5% PhyComp 0805CG101J9B200
C13 C14 C15 C16 C21 0.1-µF, 0805, Ceramic capacitor, X7R, 50-V,
10% Panasonic ECJ–2YB1H104K
C17 C18 10-µF, 16-V, Aluminum capacitor, Size C Cornell Dubilier AVS106M16B12T
FB1 FB2 SMT, EMI beads, Z = 47 Ωat 100 MHz Fair-Rite 2743019447
J1 J2 (top side) 10 Pin, dual row, SMT header (20 Position) Samtec TSM–110–01–T–DV–P
J1B J2B (bottom side) 10 Pin, dual row, SMT socket (20 Position) Samtec SSW–110–22–F–D–VS–K
J3 J4 2 Terminal screw connector OST ED1514
J5 4 Pin, dual row, TH header (8 Position) Samtec TSW–104–07–L–D
J6 (bottom side) 4 Pin, dual row, TH header (8 Position) Samtec SSW–105–22–F–D–VS–K
R1 R2 R3 R4 R5 R6
R7 R8 49.9-Ω, 0805, 1%, 0.1-W resistor Yageo America 9C08052A49R9FKHFT
R9 R10 R11 33-Ω, 0805, 5%, 0.1-W resistor Yageo America 9C08052A33R0JLHFT
R12 R13 R14 10-kΩ, 0805, 0.1-W resistor Yageo America 9C08052A1002JLHFT
R15 0-Ω, 0805, 0.1-W resistor Yageo America 9C08052A0R00JLHFT
TP1 TP2 TP3 Red test point loop Keystone 5000
U1 ADS7861 or ADS8361 ADC Texas Instruments ADS7861E or ADS8361I
W1 3 Pin, 2-mm header Samtec TMM–103–01–G–S
W2, W3 3 Pin header Samtec TSW–103–07–L–S
Chapter 6

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Engineer:
TP1
C19
0.01uF
TP2
C14
0.1uF
AVdd
W1
B1+
2
DGND 1
A1+
6
A1-
7
AGND
12
REFout
11
A0 16
CONVST 17
/CS 19
RD 18
B1-
3
A0+
8
AVdd
13 DVdd 24
Data B 22
B0+
4
A0-
9M1 14
BUSY 21
B0-
5
REFin
10
M0 15
CLOCK 20
Data A 23
U1
ADS7861E or ADS8361E DVdd
C15
0.1uF
C20
0.01uF
W2
C13
0.1uF
+C17
10uF
C16
0.1uF
+C18
10uF
FB1
FB2
R1
49.9
R2
49.9
C1
100pF
C2
100pF
C9
1nF
R3
49.9
R4
49.9
C3
100pF
C4
100pF
C10
1nF
R5
49.9
R6
49.9
C5
100pF
C6
100pF
C11
1nF
R7
49.9
R8
49.9
C7
100pF
C8
100pF
C12
1nF
R9
33
AVdd
DVdd
1
2
J3
1
2
J4
1 2
3 4
5 6
7 8
910
11 12
13 14
15 16
17 18
19 20
J2
R10 33
R11 33
1 2
3 4
5 6
7 8
910
11 12
13 14
15 16
17 18
19 20
J1
1 2
3 4
5 6
7 8
J5
R12
10K R13 10K R14 10K
DVdd
C21
0.1uF
TP3
R15
0
1 2
3 4
5 6
7 8
910
J6
+5Vd
+5Va
+5Va
+Vd
+3.3Vd
W3
+Vd
ADS78/8361 EVM Schematic
A11 B
Tom Hendrick
Tom Hendrick
6443174_A.DDB