Texas Instruments ADS9224REVM-PDK User manual

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ADS9224REVM-PDK
User's Guide
SBAU315A–July 2018–Revised June 2019
ADS9224REVM-PDK
This user's guide describes the characteristics, operation, and use of the ADS9224R evaluation module
(EVM) performance demonstration kit (PDK). The EVM-PDK eases the evaluation of the ADS9224R
device with hardware, software, and computer connectivity through a universal serial bus (USB) interface.
Throughout this document, the terms evaluation board, evaluation module, and EVM are synonymous with
the ADS9224REVM-PDK. This user's guide includes complete circuit descriptions, schematic diagrams,
and a bill of materials.
The following related documents are available through the Texas Instruments web site at www.ti.com.
Related Documentation
Device Literature Number
ADS9224R SBAS876
THS4551 SBOS778
REF5025 SBOS410
TPS7A4700 SBVS204

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Contents
1 Overview...................................................................................................................... 4
1.1 ADS9224REVM-PDK Features................................................................................... 4
1.2 ADS9224REVM Features ......................................................................................... 4
2 Analog Interface.............................................................................................................. 5
2.1 Connectors for Signal Source..................................................................................... 5
2.2 ADC Differential Input Signal Driver.............................................................................. 5
2.3 ADS9224R Internal Reference ................................................................................... 7
3 Digital Interfaces ............................................................................................................. 7
3.1 multiSPI™ for ADC Digital IO ..................................................................................... 7
4 Power Supplies .............................................................................................................. 8
5 Setup .......................................................................................................................... 9
5.1 Default Jumper Settings ........................................................................................... 9
5.2 EVM Graphical User Interface (GUI) Software Installation .................................................. 10
6 Operation.................................................................................................................... 13
6.1 EVM GUI Global Settings for ADC Control .................................................................... 14
6.2 Register Map Configuration Tool................................................................................ 15
6.3 Time Domain Display Tool....................................................................................... 16
6.4 Spectral Analysis Tool............................................................................................ 17
6.5 Histogram Tool .................................................................................................... 18
7 ADS9224REVM Bill of Materials, PCB Layout, and Schematics .................................................... 19
7.1 Bill of Materials .................................................................................................... 19
7.2 PCB Layout ........................................................................................................ 23
7.3 Schematics......................................................................................................... 26
List of Figures
1 THS4551 Differential Input Driving Path ................................................................................. 6
2 THS4551 Fully-Differential Amplifier Driver ............................................................................. 6
3 ADS9224REVM-PDK Jumper Locations ................................................................................. 9
4 ADS9224R Software Installation Prompts .............................................................................. 10
5 Device Driver Installation Wizard Prompts.............................................................................. 10
6 LabVIEW Run-Time Engine Installation................................................................................. 11
7 ADS9224REVM-PDK Folder Post-Installation.......................................................................... 12
8 EVM-PDK Hardware Setup and LED Indicators ....................................................................... 13
9 Launch the EVM GUI Software........................................................................................... 13
10 EVM GUI Global Input Parameters ...................................................................................... 14
11 Register Map Configuration............................................................................................... 15
12 Time Domain Display Tool Options...................................................................................... 16
13 Spectral Analysis Tool..................................................................................................... 17
14 Histogram Analysis Tool .................................................................................................. 18
15 ADS9224REVM PCB Top Overlay ...................................................................................... 23
16 ADS9224REVM PCB Layer 1: Top Layer .............................................................................. 23
17 ADS9224REVM PCB Layer 2: GND Plane............................................................................. 24
18 ADS9224REVM PCB Layer 3: Power Planes.......................................................................... 24
19 ADS9224REVM PCB Layer 4: Bottom Layer .......................................................................... 25
20 ADS9224REVM Schematic Diagram 1.................................................................................. 26
21 ADS9224REVM Schematic Diagram 2.................................................................................. 27
List of Tables
1 J2 to J5 SMA Analog Interface Connections............................................................................. 5
2 JP1 to JP4 Header Descriptions........................................................................................... 5

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3 SPI Test Points .............................................................................................................. 7
4 Power-Supply Test Points.................................................................................................. 8
5 Default Jumper Configurations............................................................................................. 9
6 External Source Requirements for Evaluation of the ADS9224R.................................................... 17
7 ADS9224REVM Bill of Materials ......................................................................................... 19
Trademarks
multiSPI is a trademark of Texas Instruments.
Windows is a registered trademark of Microsoft Corporation.
LabVIEW is a trademark of National Instruments.
All other trademarks are the property of their respective owners.

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1 Overview
The ADS9224REVM-PDK is an evaluation platform for the ADS9224R, a dual, simultaneous-sampling, 16-
bit, 3-MSPS, fully-differential input successive approximation register (SAR) analog-to-digital converter
(ADC). The ADS9224R features an enhanced serial multiSPI™ digital interface. The evaluation kit
includes the ADS9224REVM board and the Precision Host Interface (PHI) controller board that enables
the accompanying computer software to communicate with the ADC using a USB interface for data
capture and analysis.
The ADS9224REVM board includes the ADS9224R SAR ADC, all the peripheral analog circuits, and
components required to extract optimum performance from the ADC.
The PHI board primarily serves three functions:
• Provides a communication interface from the EVM to the computer through a USB port
• Provides the digital input and output signals necessary to communicate with the ADS9224R
• Supplies power to all active circuitry on the ADS9224REVM-PDK board
Along with the ADS9224REVM and PHI controller board, this evaluation kit includes an A-to-micro-B USB
cable to connect to a computer.
1.1 ADS9224REVM-PDK Features
The ADS9224REVM-PDK includes the following features:
• Hardware and software required for diagnostic testing as well as accurate performance evaluation of
the ADS9224R ADC
• USB powered—no external power supply is required
• A PHI controller that provides a convenient communication interface to the ADS9224R ADC over USB
2.0 (or higher) for power delivery as well as digital input and output
• Easy-to-use evaluation software for Windows®7, 8, and 10, 64-bit operating systems
• The software suite includes graphical tools for data capture, histogram analysis, spectral analysis,
linearity analysis, and reference settling analysis. This suite also has a provision for exporting data to a
text file for post-processing.
1.2 ADS9224REVM Features
The ADS9224REVM includes the following features:
• Onboard low-noise and low distortion ADC fully-differential amplifier input drivers optimized to meet
ADC performance
• Onboard ultra-low-noise, low-dropout (LDO) regulator for excellent, 5-V single-supply regulation of the
voltage reference and all the fully-differential amplifier input drivers

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2 Analog Interface
The ADS9224R is a dual-channel, simultaneous-sampling ADC that supports fully-differential inputs. Each
channel of the ADS9224R uses a THS4551 fully-differential amplifier (FDA) to drive the differential inputs
of the ADC. This section covers driver details and board connections for a differential signal source.
2.1 Connectors for Signal Source
The ADS9224REVM is designed for easy interfacing to multiple analog sources. SMA connectors allow
the EVM to have input signals connected through coaxial cables. In addition, header connectors JP1
through JP4 provide a convenient way to connect input signals. All analog inputs are buffered by the
THS4551 high-speed FDA in order to properly drive the ADS9224R ADC inputs.
Table 1. J2 to J5 SMA Analog Interface Connections
Pin Number Signal Description
J2 AIN-_A CHA negative differential input. This SMA connector can be grounded by installing a shunt on JP1 for single-ended signals.
1-kΩinput impedance
J3 AIN+_A CHA positive differential input or input for single-ended signals.
1-kΩinput impedance
J4 AIN+_B CHB positive differential input or input for single-ended signals.
1-kΩinput impedance
J5 AIN-_B CHB negative differential input. This SMA connector can be grounded by installing a shunt on JP4 for single-ended signals.
1-kΩinput impedance
Table 2. JP1 to JP4 Header Descriptions
Pin Number Signal Description
JP1.1 AIN-_A CHA negative differential input. This SMA connector can be grounded by installing a shunt on JP1 for single-ended signals.
1-kΩinput impedance.
JP2.1 AIN+_A CHA positive differential input or input for single-ended signals.
1-kΩinput impedance.
JP3.1 AIN+_B CHB positive differential input or input for single-ended signals.
1-kΩinput impedance.
JP4.1 AIN-_B CHB negative differential input. This SMA connector can be grounded by installing a shunt on JP4 for single-ended signals.
1-kΩinput impedance.
2.2 ADC Differential Input Signal Driver
The analog inputs of the ADS9224R SAR ADC are not high-impedance but rather present a dynamic load
as the sample-and-hold switches open and close. The current demand of the SAR ADC input increases as
a function of the sampling rate. Thus, the evaluation board provides the THS4551 FDA driver that
maintains ADC performance with maximum loading at the full device throughput of 3 MSPS.

AINP
AINN
3300 pF
4.32 
-
+
+
-
1 k
THS4551
VOCM = REF/2
2.048V
-1.828 V
+1.828 V 1 k
0 V
0.22 V
3.876 V
2.048 V
-3.876
V
+3.876 V
0 V
5V
A0(-)
FSR_ADC
±VREF =
±4.096V
1 k
1 k4.32 
10 
10 
100 pF
-1.828 V
+1.828 V
0 V
A0(+)
0.22 V
3.876 V
2.048 V
100 pF
ADS9224x
AINM_A (Pin 2)
AINP_A (Pin 1)
AINP_B (Pin 8)
AINM_B (Pin 7)
SMA J2 (IN-)
Header JP1.1
SMA J3 (IN+)
Header JP2.1
THS4551: Fully-Differential Amplifier
SMA J4 (IN+)
Header JP3.1
SMA J5 (IN-)
Header JP4.1
AIN-_A
AIN+_A
AIN+_B
AIN-_B -
++
-
5V
100 pF
100 pF
1 NŸ
1 NŸ
1 NŸ
1 NŸ
THS4551: Fully-Differential Amplifier
-
++
-
5V
100 pF
100 pF
1 NŸ
1 NŸ
1 NŸ
1 NŸ
4.32 Ÿ
4.32 Ÿ
4.32 Ÿ
4.32 Ÿ
3300pF
3300pF
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2.2.1 Input Signal Path
Figure 1 shows the signal path for the differential signal applied at the board inputs. The board input
impedance is 1 kΩ. The overall signal-path bandwidth is limited to 1.5-MHz by the 1-kΩresistor and 100-
pF capacitor at the FDA feedback. The two THS4551 FDAs drive the ADS9224R differential inputs
through an RC charge-kickback filter. These drivers provide a low dynamic impedance source at the ADC
inputs at the full throughput of 3 MSPS.
Figure 1. THS4551 Differential Input Driving Path
The ADS92x4REVM incorporates two THS4551 FDAs to drive the ADC inputs. The FDAs shift the signal
to the appropriate common-mode voltage level. Figure 2 shows the fully-differential amplifier circuit. A
differential input signal with a common-mode voltage of 0 V is applied to the inputs of the THS4551. The
FDA establishes a fixed common-mode voltage at the ADC inputs using the FDA VOCM input pin. The
ADS9224R incorporates a REF / 2 buffer output pin for setting the common-mode voltage. The
ADS9224R REF / 2 output is connected to each THS4551 VOCM input pin. The THS4551 shifts the signal
to the required common-mode voltage of REF / 2. Because of the THS4551 output swing specification to
GND, either the input signals must be limited to a differential voltage of ±3.876 V amplitude in order to
avoid saturating the amplifier output, or the negative supply must be driven below GND (in other words,
–200 mV) to extend the output range.
Figure 2. THS4551 Fully-Differential Amplifier Driver

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2.3 ADS9224R Internal Reference
The ADS9224R device incorporates an internal 2.5-V band-gap reference and independently matched
reference buffers for each ADC. The internal reference output pin (REFOUT) is decoupled with a 1-µF
capacitor and can be probed at test point TP8. The internally matched reference buffers provide a gain of
1.6384 V/V. These reference buffers generate a high-precision, 4.096-V reference voltage for each ADC
channel at pins REFP_A and REFP_B. These pins are decoupled with 10-µF decoupling capacitors.
Additionally, a mid-reference output (REFby2) is available at test point TP5. This internal REFby2 buffer
provides a common-mode voltage for input amplifiers driving the ADC inputs.
3 Digital Interfaces
As noted in Section 1, the EVM interfaces with the PHI that, in turn, communicates with the computer
using the USB interface. There are two devices on the EVM that communicate with the PHI: the
ADS9224R ADC (over SPI or multiSPI) and the EEPROM (over I2C). The EEPROM comes
preprogrammed with the information required to configure and initialize the ADS9224REVM-PDK platform.
After the hardware is initialized, the EEPROM is no longer used.
3.1 multiSPI™ for ADC Digital IO
The ADS9224REVM-PDK supports several interface modes, as detailed in the ADS9224R data sheet. In
addition to the standard SPI modes (single-, dual-, and quad-SDO lines), the multiSPI modes support
single- and dual-data output rates. The PHI is capable of operating at a 3.3-V logic level and is directly
connected to the digital I/O lines of the ADC. Table 3 lists the test points available for probing the SPI pins
in both SPI and parallel byte mode.
Table 3. SPI Test Points
Designator Signal Description
TP1 RST Asynchronous reset; active low.
TP2 READY/STR Indicates data-ready or strobe output for data capture.
TP3 SDO-0/0A SPI mode: data output 0 for channel A.
Parallel byte mode: least significant bit (LSB) from the data byte.
TP4 SDO-1/1A SPI mode: data output 1 for channel A.
Parallel byte mode: LSB+1 from the data byte.
TP6 SDO-2/2A SPI mode: data output 2 for channel A.
Parallel byte mode: LSB+2 from the data byte.
TP7 SDO-3/3A SPI mode: data output 3 for channel A.
Parallel byte mode: LSB+3 from the data byte.
TP9 SDO-4/0B SPI mode: data output 4 for channel A.
Parallel byte mode: LSB+4 from the data byte.
TP10 SDO-5/1B SPI mode: data output 5 for channel A.
Parallel byte mode: LSB+5 from the data byte.
TP11 SDO-6/2B SPI mode: data output 6 for channel A.
Parallel byte mode: LSB+6 from the data byte.
TP12 SDO-7/3B SPI mode: data output 7 for channel A.
Parallel byte mode: MSB from the data byte.
TP13 SCLK Clock input pin for the serial interface.
TP14 SDI Serial data input pin.
TP15 CS Chip-select input pin; active low.
TP16 CONVST Conversion start input pin.

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4 Power Supplies
The PHI controller provides multiple power-supply options for the EVM, derived from the USB supply of
the computer.
The EEPROM on the ADS9224REVM use a 3.3-V power supply generated directly by the PHI. The ADC
and analog input drive circuits are powered by the TPS7A4700 onboard the EVM. The TPS7A4700 is a
low-noise linear regulator that uses the 5.5-V supply out of a switching regulator on the PHI to generate a
much cleaner 5.0-V output. The 3.3-V supply to the digital section of the ADC is provided directly by an
LDO regulator on the PHI.
The power supply for each active component on the EVM is bypassed with a ceramic capacitor placed
close to that component. Additionally, the EVM layout uses thick traces or large copper fill areas, where
possible, between bypass capacitors and their loads in order to minimize inductance along the load
current path.
The LM7705 outputs a –230-mV option to drive the negative supply (VS–) of the fully-differential input
amplifiers. This option allows the amplifier outputs to swing all the way to ground and achieve a full-scale
differential signal at the ADC input. Configure JP8 in the [1-2] position to use the –230-mV supply for VS–.
If the entire full-scale range is not required, VS– can be connected to GND by configuring JP8 in the [2-3]
position. U8 can be disabled by uninstalling the jumper on JP7. Table 4 lists the relevant power supply
test points on the EVM.
Table 4. Power-Supply Test Points
Designator Signal Description
TP17 GND EVM ground
TP18 LDO_IN_5V5 5.5-V supply from PHI EVM controller
TP19 VA 5-V analog supply
TP20 DVDD 3.3-V digital supply
TP21 VS– Negative supply for fully-differential input amplifiers

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5 Setup
This section explains the initial hardware and software setup procedures that must be completed for the
proper operation of the ADS9224xEVM-PDK.
5.1 Default Jumper Settings
JP1-JP2 and JP3-JP4 are used to connect differential analog sources to channel A and channel B inputs,
respectively. In addition, shunts can be used on jumpers JP1 and JP4 to ground the negative inputs and
support single-ended signals, as described in Section 2.1.
.Figure 3 shows the default factory jumper locations and settings.
Figure 3. ADS9224REVM-PDK Jumper Locations
Table 5 explains the functionality of each of these jumpers and their default configurations.
Table 5. Default Jumper Configurations
Designator Default Configuration Description
JP1 Open CHA negative differential input. This pin can be grounded by shunting JP1 pin
1 and JP1 pin 2 for single-ended signals.
JP2 Open CHA positive differential input or input for single-ended signals.
JP3 Open CHB negative differential input. This pin can be grounded by shunting JP1 pin
1 and JP1 pin 2 for single-ended signals.
JP4 Open CHB positive differential input or input for single-ended signals.
JP5 Open EEPROM write protect function (EEPROM rewrite disabled).
JP6 Open External CONVST is disconnected.
JP7 Installed Shutdown pin on U8 LDO is disabled.
JP8 1-2 Negative supply for fully-differential input amplifiers is connected to –230 mV.

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5.2 EVM Graphical User Interface (GUI) Software Installation
Download the latest version of the EVM GUI installer from the Tools and Software folder of the
ADS9224R, and run the GUI installer to install the EVM GUI software on the user’s computer.
NOTE: Manually disable any antivirus software running on the computer before downloading the
EVM GUI installer onto the local hard disk. Otherwise, depending on the antivirus settings,
an error message may appear or the installer.exe file may be deleted.
Accept the license agreements and follow the onscreen instructions to complete the installation.
Figure 4. ADS9224R Software Installation Prompts
As a part of the ADS9224REVM GUI installation, a prompt with a Device Driver Installation will appear on
the screen. Click Next to proceed.
Figure 5. Device Driver Installation Wizard Prompts