Texas Instruments ADS8028EVM-PDK User manual

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ADS8028EVM-PDK
ADCPro is a trademark of Texas Instruments.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
SPI is a trademark of Motorola.
All other trademarks are the property of their respective owners.
User's Guide
SBAU198A–April 2012–Revised February 2016
ADS8028EVM-PDK
Figure 1. ADS8028EVM-PDK
This user's guide describes the characteristics, operation, and use of the ADS8028EVM-PDK. This
evaluation module and performance development kit (EVM-PDK) is an evaluation system for the
ADS8028, a 12-bit, 1-MSPS, 8-channel, successive approximation register (SAR) analog-to-digital
converter (ADC). The EVM-PDK allows evaluation of all aspects of the ADS8028 device.
This document includes an EVM QuickStart section, hardware and software details, bill of materials, and
schematic.
The following related documents are available through the Texas Instruments web site at
http://www.ti.com.
Table 1. EVM-Compatible Device Data Sheets
Device Literature Number
ADS8028 SBAS549
OPA836 SLOS712
REF5025 SBOS410

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ADS8028EVM-PDK
Contents
1 EVM Overview ............................................................................................................... 3
2 EVM Setup.................................................................................................................... 4
3 ADS8028EVM Hardware Details .......................................................................................... 6
4 Using the ADS8028EVM-PDK with ADCPro ........................................................................... 11
5 Schematics and Bill of Materials ......................................................................................... 13
List of Figures
1 ADS8028EVM-PDK ......................................................................................................... 1
2 Jumper Locations and Default Settings................................................................................... 4
3 Headers and Pin Numbers ................................................................................................. 6
4 Analog Input Header Schematic........................................................................................... 7
5 Digital Interface Header Schematic ....................................................................................... 8
6 Power Header Schematic .................................................................................................. 9
7 EVM Voltage Reference Schematic ..................................................................................... 10
8 ADCPro: ADS8028EVM Panel ........................................................................................... 11
9 ADCPro: Channel Selection Tab......................................................................................... 12
10 ADCPro: Controls Tab..................................................................................................... 12
List of Tables
1 EVM-Compatible Device Data Sheets .................................................................................... 1
2 Related Documents.......................................................................................................... 3
3 Default Jumper Configurations............................................................................................. 4
4 Critical Connections ......................................................................................................... 6
5 ADS8028EVM Bill of Materials .......................................................................................... 14

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ADS8028EVM-PDK
1 EVM Overview
The ADS8028EVM-PDK is designed to evaluate the ADS8028. The ADS8028 is a 12-bit, 8-channel,
multiplexed, SAR ADC, with a maximum throughput rate of 1 MSPS. The ADS8028 also offers an internal
2.5-V voltage reference and internal temperature sensor with 0.25°C resolution. The ADS8028EVM allows
access to every pin of the converter and makes it easy to connect the ADS8028 SPI™-compatible serial
interface to any host microprocessor or TI DSP based system with 1.8-V, 3.3-V, or 5-V logic capability.
The ADS8028EVM-PDK combines the ADS8028EVM daughtercard with the digital sensor processor
(DSP)-based MMB0 motherboard and ADCPro™ evaluation software for complete evaluation of the
ADS8028.
1.1 Features
ADS8028EVM Features
• Easy-to-use ADCPro evaluation software for Microsoft®Windows®operating systems
• Built-in analysis tools for ADCPro, including scope, FFT, and histogram displays
• Simple device operation with full control of single 16-bit control register
• Data collection to text files
• 1.8-V, 3.3-V, or 5-V logic compatible with 16-bit, 20-MHz SPI Interface
• Contains all support circuitry needed for the ADS8028:
– Voltage reference options: ADS8028 (2.5 V) internal reference, on-board REF5025 (2.5 V)
reference, or external reference
– Two on-board OPA836 (205-MHz unity-gain bandwidth / 1-mA quiescent current) ADC input drivers
– Power supplied by MMB0 motherboard
• Compatible with the TI modular EVM system
ADS8028EVM-PDK Features
The ADS8028EVM-PDK includes the ADS8028EVM board with the DSP-based MMB0 motherboard, that
can be used with ADCPro to quickly evaluate the device.
This manual covers the operation of the ADS8028EVM-PDK. Throughout this document, the abbreviation
EVM and the term evaluation module are synonymous with the ADS8028EVM.
Related Documentation from Texas Instruments
The related documents listed in Table 2 are available for download through the Texas Instruments web
site at www.ti.com.
Table 2. Related Documents
Device Literature Number
ADS8028 SBAS549

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2 EVM Setup
This section is a quick guide to begin evaluating the ADS8028EVM with ADCPro.
2.1 Default Jumper Configuration
Figure 2 shows the location of jumpers on the EVM and their respective factory default settings.
Figure 2. Jumper Locations and Default Settings
Table 3 lists the jumpers on the ADS8028EVM and their factory default settings.
Table 3. Default Jumper Configurations
Jumper Default Position Description
J-1 Open 1.8-V logic not selected
J-3 Short 3.3-V logic selected (BVDD = 3.3 V)
J-5 Open 5-V logic not selected
J-CS Pins 1-2 (Down) MMB0 FSX pin connected to CS
J-REF Pins 2-3 (Right) Allows for external voltage reference input or internal voltage reference output
CAUTION
Only one of the digital interface jumpers (J-1, J-3, or J-5) should be shorted at a
time to prevent large reverse currents that could potentially damage voltage
regulators on the MMB0 motherboard.

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2.2 ADS8028EVM-PDK Kit Operation
To prepare to evaluate the ADS8028 with the ADS8028EVM-PDK, complete the following steps:
1. Verify the ADS8028EVM jumper settings from the factory as shown in Figure 2 and also listed in
Table 3.
2. Install ADCPro and the ADS8028EVM plug-in software. Complete hardware connections and driver
installation as per the ADCPro HW/SW Installation Manual. Use the following jumper settings on the
MMB0 to configure power with the external supply.
• MMB0 J12 →Short (power supplied to the MMB0 through MMB0 J2 jack)
• MMB0 J13A →Open (+VA supply is not used on the ADS8028EVM)
• MMB0 J13B →Short (power supplied to the ADS8028EVM through the MMB0 J5 header)
• No additional power connections are required
3. Plug the ADS8028EVM onto the MMB0 motherboard. The female portion of J-ANALOG, J-DIGITAL,
and J-POWER on the bottom of the EVM align with male connectors J7, J4, and J5 (respectively) on
the MMB0.
4. Connect the included USB cable to J1 on the MMB0 and to an unused USB port on the computer with
ADCPro installed.
5. Connect an external supply (using the included CA-2186 cable) to the MMB0.

Pin 1 2
3 4
6
8
5
7
9 10
12
14
11
13
15 16
18
20
17
19
Pin 1 2
3 4
6
8
5
7
9 10
12
14
11
13
15 16
18
20
17
19
Pin 1
2 4 6 8 10
3 5 7 9
J-ANALOG.1 J-DIGITAL.1
J-POWER.1
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3 ADS8028EVM Hardware Details
Figure 3 shows the location of headers J-ANALOG, J-DIGITAL, and J-POWER and their assigned pin
numbers. The notation J-NAME.<#> is used in this user's guide for identifying header pins. For example,
J-ANALOG.1 refers to pin 1 on the J-ANALOG header.
Figure 3. Headers and Pin Numbers
Table 4 provides a quick summary of the connections required for operation of the ADS8028. The purpose
of the MMB0 motherboard is to provide power and SPI communication to the ADS8028EVM. Analog
inputs of interest must be applied to the ADS8028EVM by the user. For a complete list of connections and
pins, refer to the ADS8028EVM schematic in Section 5.2.
(1) Only one digital supply connection (BVDD) is required when evaluating the ADS8028EVM as a stand-alone board. Check that
the corresponding jumper (J-1, J-3, or J-5) is correctly selected to power the ADS8028 digital interface.
(2) AGND and DGND are shorted on the ADS8028EVM.
(3) All ADS8028 analog inputs are single-ended and connect between the even and odd pins on the J-ANALOG header. All odd
pins on J-ANALOG are connected to AGND.
Table 4. Critical Connections
Function Header and Pin Pin Name Description
SPI
CS J-DIGITAL.7 FSX Chip select; active low logic input
SCLK J-DIGITAL.3 CLKX SCLK
DIN J-DIGITAL.11 DX Data In
DOUT J-DIGITAL.13 DR Data Out
TM_BUSY J-DIGITAL.15 INT Busy output; high during temperature conversion
Power
1.8V J-POWER.7 +1.8VD Digital interface supply (BVDD)(1)
3.3V J-POWER.9 +3.3VD Digital interface supply (BVDD)(1)
5.0V J-POWER.10 +5VD Digital interface supply (BVDD)(1)
5.0V (AVDD) J-POWER.3 +5VA Analog operation supply (AVDD)
GND J-POWER.5 and
J-POWER.6 DGND and AGND Digital and Analog supply grounds(2)
Analog inputs Channels 0 and 1 J-ANALOG.1-4 — Analog Inputs (Buffered)(3)
Channels 2 to 7 J-ANALOG.5-16 — Analog Inputs(3)

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3.1 Analog Inputs
The ADS8028 provides eight single-ended input channels plus an internal temperature sensor. The eight
analog input channels to the ADS8028 (AIN0 to AIN7) are connected to J-ANALOG on the ADS8028EVM.
Channels 0 and 1 are buffered converter inputs. The OPA836 is configured as a unity-gain buffer on these
channels. Channels 2 to 7 connect directly to the converter with an option to add an RC filter before the
converter input. Figure 4 shows the EVM schematic portion of the analog inputs. All discrete resistors and
capacitors shown in Figure 4 are size 0603 and can be modified to adjust circuit gain and filtering. Note
that not all components shown in Figure 4 are installed and have values "NI" (not installed).
Optionally, the user can add an SMA connector at J-SMA and use an SMA input for channels 0 and 1 if
an SMA connection is more convenient. RS0 and RS1 resistors select the SMA input channel. If the SMA
input has a 50-Ωsource impedance, R10 and other input resistors can be modified for impedance
matching, otherwise they can provide signal attenuation and input current limiting.
Figure 4. Analog Input Header Schematic
NOTE: All odd pins on J-ANALOG connect to GND. Therefore, all analog input connections can be
easily made across even and odd pin numbers (The channel 0 input connects to J-
ANALOG.1-2, channel 1 input connects to J-ANALOG.3-4, etc.).

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3.2 Digital Control
The SPI digital control signals are applied directly to the J-DIGITAL header on the ADS8028EVM. When
using the ADS8028EVM-PDK (the combination of the ADS8028EVM, MMB0 motherboard, and ADCPro
software), these signals are supplied by the MMB0 motherboard through J4. If the ADS8028EVM is
instead evaluated as a stand-alone board, these signals must be supplied by another microcontroller or
processor according to the timing characteristics in the ADS8028 data sheet.
Figure 5 shows the schematic connections to the J-DIGITAL header. The CS signal can be routed to J-
DIGITAL.1 or J-DIGITAL.7 (default) through the J-CS jumper. Ensure that the J-CS jumper is positioned to
route CS to J-DIGITAL.7 (short pins J-CS.1-2) for proper SPI communication when using the
ADS8028EVM-PDK. Additionally, the S1 push-button switch allows the user to manually reset and power-
down the ADS8028 and OPA836 op amps on the ADS8028EVM while the button is held. When the button
is released, the ADS8028 powers up with default conditions.
Figure 5. Digital Interface Header Schematic
NOTE: By default, the J-CS jumper on the ADS8028EVM is shorted between pins J-CS.1-2. This
setting is required for proper SPI communication between the MMB0 motherboard and the
ADS8028.

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3.3 Power Supply
The ADS8028EVM requires two power-supply rails: one 5-V analog supply (AVDD) and a configurable
digital interface (BVDD). Three selectable voltages are available for the digital interface to make the EVM
compatible with different logic levels. Jumpers J-1, J-3, and J-5 on the ADS8028EVM select 1.8-V, 3.3-V,
or 5-V BVDD digital interface voltages, respectively. Refer to Table 3 for the ADS8028EVM jumper
functions and default settings. The default jumper settings of J-1 (open), J-3 (short), and J-5 (open) are
recommended when using the ADS8028EVM with the MMB0 3.3-V logic.
Power rails are supplied to the ADS8028EVM through the J-POWER header. If the ADS8028EVM is being
evaluated as a stand-alone board, the user must supply power to the J-POWER header by direct
connections to a power supply. Otherwise, the MMB0 motherboard supplies the ADS8028EVM with power
through J-5 when the ADS8028EVM daughtercard is mounted on the MMB0. Check the MMB0 jumper
settings listed in the ADS8028EVM-PDK Kit Operation section if the ADS8028EVM is not receiving power
when connected to the MMB0 motherboard. Figure 6 shows a schematic of J-POWER header
connections on the ADS8028EVM.
Figure 6. Power Header Schematic
CAUTION
Do not apply voltages that the exceed the absolute maximum ratings of the
installed components. The absolute maximum supply voltage of the OPA836
limits the maximum analog supply voltage of the ADS8028EVM to 5.5 V. The
digital supply voltage should not exceed the analog supply voltage.

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3.4 Voltage Reference
The ADS8028EVM allows the user flexibility to select different voltage reference sources for the ADS8028.
Options include the:
• ADS8028 internal 2.5-V voltage reference,
• Onboard REF5025 2.5-V reference, or
• External reference source
When the ADS8028 powers up, the internal 2.5-V reference is selected as the reference source by
default. To use an external reference source, the internal voltage reference must be disabled by
performing a serial interface write to the ADS8028 control register to update bit 2. When using an external
source, shorting pins J-REF.1-2 uses the REF5025 external 2.5-V reference. If a reference voltage other
than 2.5 V is needed, the REF5025 can be replaced with any other reference in the REF50xx family.
Shorting pins J-REF.2-3 connects J-ANALOG.20 to the ADS8028 reference input. This short allows the
user to output the internal ADS8028 voltage reference to another circuit or allows a external reference
voltage to be applied to the ADS8028 reference input when the internal reference is disabled. The
allowable voltage range for an external voltage reference is 1 V to AVDD (5 V when the ADS8028EVM is
used with the MMB0).
Figure 7. EVM Voltage Reference Schematic
CAUTION
The user should avoid connecting any external voltage reference to the
ADS8028 before a serial write to the ADS8028 control register disables the
internal reference source. Providing an external source prior to this
communication draws additional current from the external source. The
ADS8028 internal protection circuitry limits this current to 20 mA.