Texas Instruments ADS125H02 User manual

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ADS125H02 Evaluation Module
User's Guide
SBAU318A–October 2018–Revised April 2019
ADS125H02 Evaluation Module
ADS125H02 Evaluation Module
The ADS125H02 is a 2-channel, 24-bit, 40-kSPS, delta-sigma (ΔΣ) analog-to-digital converter (ADC) with
an integrated ±18-V programmable gain amplifier (PGA) with a 1-GΩinput impedance. The device also
includes a voltage reference and features to enhance data reliability such as cyclic redundancy check
(CRC) and signal monitors.
The ADS125H02EVM is an evaluation module kit providing hardware and software support for evaluation
of the ADS125H0x, delta-sigma analog-to-digital converter (ADC). The kit uses the Texas Instruments
TM4C1294NCPDT processor to communicate with the ADC via SPI and provide communication with a PC
over the USB interface. The software application is downloaded from the Texas Instruments website and
runs on the Windows operating system allowing for register manipulation and data collection from the
ADC. The ADS125H02EVM kit includes the ADS125H02 device along with a USB micro cable.
This document includes a detailed description of the hardware (HW), software, bill of materials, and
schematic for the EVM.
Throughout this document, the term EVM is synonymous with the ADS125H02EVM, demonstration kit,
and evaluation module. The term GUI is synonymous with Delta-Sigma ADC EvaluaTIon Software, core
application, and EVM software. The use of Tiva™ is synonymous with the TM4C1294NCPDT
microcontroller.
Table 1. Related Documentation
Device Literature Number
ADS125H02 SBAS790
Delta-Sigma ADC EvaluatTIon
Software User Manual SBAU260

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Contents
1 EVM Overview ............................................................................................................... 3
2 Quick Start.................................................................................................................... 4
3 Hardware Reference ........................................................................................................ 6
4 Software Details............................................................................................................ 12
5 EVM Bill of Materials, PCB Layouts, and Schematics................................................................. 18
List of Figures
1 Default Configurations for ADS125H02 EVM............................................................................ 4
2 Input Terminal Blocks ....................................................................................................... 7
3 High-Voltage Supply Terminal Block...................................................................................... 9
4 Delta-Sigma Evaluation Engine Installation Instructions.............................................................. 12
5 Device Package Installation Instructions................................................................................ 13
6 GUI View Before Connecting............................................................................................. 14
7 GUI View After Connecting EVM......................................................................................... 14
8 Empty Register Map for an Unrecognized Device..................................................................... 15
9 Console Tab View of an Unrecognized Device ........................................................................ 15
10 Register Map for the ADS125H02 ....................................................................................... 15
11 Data Analysis Window..................................................................................................... 16
12 Top Silkscreen.............................................................................................................. 23
13 Top Layer (Positive) ....................................................................................................... 23
14 Ground Layer (Negative).................................................................................................. 24
15 Power Layer (Negative) ................................................................................................... 24
16 Bottom Layer (Positive).................................................................................................... 25
17 Bottom Silkscreen.......................................................................................................... 25
18 ADS125H02EVM Block Diagram Schematic........................................................................... 26
19 ADS125H02EVM Analog Inputs Header Schematic .................................................................. 27
20 ADS125H02EVM ADC Main Schematic ................................................................................ 28
21 ADS125H02EVM Digital Header Schematic ........................................................................... 29
22 ADS125H02EVM USB and Peripherals Schematic ................................................................... 30
23 ADS125H02EVM Processor Main Schematic.......................................................................... 31
24 ADS125H02EVM USB Power Schematic............................................................................... 32
25 ADS125H02EVM External Power Schematic .......................................................................... 33
List of Tables
1 Related Documentation..................................................................................................... 1
2 Default Settings.............................................................................................................. 4
3 Jumper and Switch Options................................................................................................ 6
4 Analog Input Terminal Blocks, J1–J3 ..................................................................................... 8
5 High-Voltage Supply Terminal Block, J4 ................................................................................. 9
6 Digital Interface, J5 ........................................................................................................ 10
7 Test Points .................................................................................................................. 10
8 ADS125H02 EVM Software Commands................................................................................ 17
9 EVM Bill of Materials....................................................................................................... 18
Trademarks
Tiva is a trademark of Texas Instruments, Incorporated.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
All other trademarks are the property of their respective owners.

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1 EVM Overview
1.1 Description
This user's guide describes the operation and use of the ADS125H02 evaluation module. The EVM
platform is intended for evaluating the ADS125H02 performance and functionality.
1.2 Requirements
1.2.1 Software Requirements
PC with Microsoft®Windows®7 or higher operating system.
1.2.2 Hardware Requirements
PC with available USB 2.0 or greater connection.
1.2.2.1 Power Supply
The ADS125H02EVM is USB powered and has an onboard ±15-V supply that is boosted from the USB
power. An external ±15-V supply may also be used for operation of the EVM. A header for an external
±15-V supply is provided at J4 through the left position of switch S1.
1.3 Software Reference
For the core software documentation, see the Delta-Sigma ADC EvaluaTIon Software User Manual or
navigate to the File -> About option from within the GUI, then click on the Software user guide icon.
1.4 Supported Functionality
1.4.1 Hardware Functionality
The EVM features the following hardware capabilities:
• Onboard 5-V AVDD supply operation
• Onboard 3.3-V DVDD supply
• Onboard or external high voltage power supply, either bipolar supplies or unipolar supply
• Digital header for external processor or controller configuration
• Analog header and configurable input circuitry for direct sensor connections
• Place holder for optional REF62xx external reference source
• Onboard (not installed) high-voltage multiplexer for analog inputs
• Fault LED for STATUS or CRC error notification
1.4.2 Software Functionality
The EVM features the following software functions:
• Device conversion control
• Device software reset
• Device power down
• Register read and write
• Conversion result readback
• Offset and system input calibration
• Readback of STATUS and CRC data bytes (for error detection)
• CRC of SPI communication between the ADC and the host (for error prevention or detection of data
transmission)

RIGHT OPEN
OPEN OPEN
JUMPER
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2 Quick Start
This section provides a guide to quickly begin using the EVM.
2.1 Default Jumper and Switch Configuration
The EVM is configured with the settings listed in Table 2 and shown in Figure 1.
Table 2. Default Settings
Jumper Position Function
JP1 (Not Installed) Use onboard processor
JP2 (Not Installed) USB-derived supplies ON
JP3 (Not Installed) DVDD from USB power (1-2 connection via R84)
JP4 (Not Installed) AVDD from USB power (1-2 connection via R85)
JP5 (Not Installed) External +5-V power down
JP6 Installed +5-V supply selection, jumper installed left
JP7 (Not Installed) Onboard HV supply disable, jumper not installed
JP8 Installed HV transformer driver clock input, jumper installed to select internal clock
Switch Position Function
S1 Left Bipolar high-voltage analog supply selection (±15 V)
Figure 1. Default Configurations for ADS125H02 EVM
2.2 Powering the EVM
The EVM is powered through the USB interface with the PC. This power includes a +5-V and an HV
supply generated onboard the EVM from the USB. Additionally, the HV supplies the ADS125H02 (±18 V
to ±5 V), which can be powered from an external source from header connections on J4 through switch
S1. Follow the installation and connection procedure in Section 2.3 before connecting the EVM to the PC.
Section 2.2.1 and Section 2.2.2 provide additional details about the analog and digital power supply
configurations of the ADC. Section 2.2.3 provides additional details about the high voltage supply.

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2.2.1 Analog Supply Configuration of the ADC
The ADS125H02 low-voltage analog supply requires a 5-V source for the AVDD. The EVM provides
onboard 5-V supply for the AVDD low-voltage analog supply.
Use R30 to measure the AVDD supply current, either by measuring the voltage drop across this resistor or
by removing the resistor and connecting a dc current meter between the A+ and A– test points.
2.2.2 Digital Supply Configuration of the ADC
The ADS125H02 digital supply requires a 2.7-V to 5.25-V source connected between DVDD and DGND.
The EVM provides a 3.3-V onboard digital supply for the digital supply of the ADC.
R31 can be use to measure the DVDD supply current, either by measuring the voltage drop across this
resistor or by removing the resistor and connecting a dc current meter between the D+ and D– test points.
2.2.3 High-Voltage Analog Supply Configuration of the ADC
The ADS125H02 high-voltage supply requires a high-voltage power supply ranging from ±18 V to ±5 V for
bipolar operation, or ranging from +36 V to +10 V for unipolar operation (when HV_AVSS = GND). An
onboard HV supply generator supplies ±15 V from the USB connection.
The EVM also provides terminal block J4 to connect an external ±15 V for the high-voltage analog supply
of the ADC when setting S1 to the left position. When switching S1, TI recommends disconnecting the
USB cable from the EVM, toggling the switch, and then reconnecting the USB cable.
R32 can be use to measure the high-voltage supply current, either by measuring the voltage drop across
this resistor or by removing the resistor and connecting a dc current meter between the HV_A+ and
HV_A– test points.
2.3 Software Installation and Hardware Connection Procedure
Use the following steps at startup:
1. Download all required software from www.ti.com/tool/ads125H02evm.
2. Install the GUI software on the PC.
3. Install the ADS125H02 device package software on the PC.
4. Ensure all jumpers and switches are configured in the default configuration per Table 2 and Figure 1.
5. Connect the EVM to the PC using a USB cable to power the board.
6. Attach the high-voltage supply to J4 and ensure that S1 is set to the left. Alternately, use the onboard
high-voltage supply (not installed) and set S1 to the right.
7. If prompted, install any required drivers.
8. Start the GUI application on your PC. The GUI automatically detects the connected EVM.
NOTE: After powering the EVM, the green D2 and +5V LEDs light up.

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3 Hardware Reference
3.1 Jumper and Switch Configuration Reference
Table 3 provides all jumper and switch configuration settings for the EVM.
(1) Switch is DPDT. Pin 1 is identified with a dot on the PCB silkscreen.
Table 3. Jumper and Switch Options
Jumper Position Description
JP1 Operation of EVM with external digital signals
Installed (ON) Hold the Tiva processor (U13) in reset and disable level shifters to allow external digital
signals
Uninstalled (OFF) Normal operation with onboard Tiva processor (default)
JP2 Power down USB power supplies
Installed (ON) USB-derived power supplies disabled and powered down
Uninstalled (OFF) USB-derived power supplies enabled and ON (default)
JP3 Digital supply source
1–2 shorted Digital supply (U18) powered from USB power (default using R94 as the short)
2–3 shorted Digital supply (U18) powered from external supply source
Open No digital system power provided
JP4 5-V supply source
Installed (ON) 5-V supply powered from USB (default using R85 as the short)
Uninstalled (OFF) No analog supply powering AVDD
JP5 EXT_5V supply power down
Installed (ON) External supply regulator (U18-not installed) disabled
Uninstalled (OFF) External supply regulator (U18-not installed) enabled (default)
JP6 Onboard 5-V source for the HV analog supply source
Right 5-V supply sourced from EXT_5V
Left 5-V supply sourced from USB power (default)
JP7 Disable for the onboard HV analog supply
Installed (ON) Holds enable low to disable onboard HV analog supply
Uninstalled (OFF) Onboard HV analog supply enabled (default)
JP8 External clock for transformer driver for the onboard HV analog supply
Installed (ON) Transformer driver (U22) uses onboard oscillator for onboard HV analog supply
(default)
Uninstalled (OFF) Connection to transformer driver (U22) external clock
Switch Position Description
S1(1) High-voltage analog supply selection switch
Right (pin connections:
5–6, 2–3) High-voltage supply sourced from onboard ±15-V supply (not installed)
Left (pin connections: 5–4,
2–1) High-voltage supply sourced from external supplies through J4 (default)
S2 Reset FAULT button
Closed (depressed) Clears FAULT indicator and writes 0x00 to the STATUS register of the ADC
Open (normally) Normal operation
S3 BSL button for Device Firmware Update (DFU) mode
Closed (depressed) Total Tiva FLASH erasure (on reset Tiva enumerates as a DFU device)
Open (normally) Normal operation
S4 Spare button (not installed)
Closed (depressed)
Open (normally)

IDAC2
IDAC1
AIN0
AIN1
REFN1
REFP1
REFN0
REFP0
GND
AINCOM
REFOUT
GND
J1
J2
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Table 3. Jumper and Switch Options (continued)
Jumper Position Description
S5 Tiva reset (U13 RST) button
Closed (depressed on
RESET) Tiva held in RESET, level shifters (U5, U6, and U7) tri-stated
Open (normally) Normal operation
3.2 Header, Connector, and Test Point Reference
This section provides the connection information and details for the connectors and test points utilized on
the EVM.
3.2.1 Analog Input Terminal Blocks
Connect the analog input to the EVM at the terminal blocks located on the left side of the board (as shown
in Figure 2) to evaluate the performance of the ADS125H02. The functions for these terminal blocks are
listed in Table 4. At no time apply a voltage to the inputs of the ADS125H02 that exceeds the absolute
maximum ratings for the device.
Figure 2. Input Terminal Blocks

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(1) Analog inputs are pinned out to terminal blocks through RC filters. See Figure 19 for additional connection details.
Table 4. Analog Input Terminal Blocks, J1–J3
Pin Function Test Point ADS125H02 Input
Pin
J1
1 IDAC current output IDAC2 IDAC2
2 IDAC current output IDAC1 IDAC1
3 Analog input(1) A0 AIN0
4 Analog input(1) A1 AIN1
5 External reference input 1 / GPIO 1 RP1 REFP1/GPIO0
6 External reference input 1 / GPIO 0 RN1 REFN1/GPIO1
7 External reference input 0 RP0 REFP0
8 External reference input 0 RN0 REFN0
9 GND – GND
J2
1 Analog input(1) ACOM AINCOM
2 Reference output – REFOUT
3 GND – GND
J3 (not installed)
1 Multiplexer analog input S1A –
2 Multiplexer analog input S2A –
3 Multiplexer analog input S3A –
4 Multiplexer analog input S4A –
5 Multiplexer analog input S1B –
6 Multiplexer analog input S2B –
7 Multiplexer analog input S3B –
8 Multiplexer analog input S4B –
9 GND – GND

+15V_EXT
J4
í15V_EXT GND
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3.2.2 High-Voltage Supply Terminal
The EVM has an optional external high-voltage supply connection (nominally ±15 V) that is connected to
the J4 terminal block located on the top center side of the board, as shown in Figure 3. This connection
provides a high voltage bipolar supply to the EVM for evaluation purposes. The functions for these
terminal blocks are listed in Table 5. Never apply a supply voltage that exceeds the absolute maximum
ratings for the power supply of the ADS125H02.
Figure 3. High-Voltage Supply Terminal Block
Table 5. High-Voltage Supply Terminal Block, J4
Pin Function Test Point ADS125H02 Input Pin
J4
1 –15-V supply input -15V_EXT HV_AVSS
2 GND GND GND
3 +15-V supply input +15V_EXT HV_AVDD
3.2.3 External Clock
By default, a clock is supplied by the internal oscillator of the ADC when the CLKIN pin is low. However,
the EVM also provides the capability to connect an external clock directly to the ADC using the J5
connector; see Figure 21. When connecting to J5, a direct connection can be made between pins 42
(CLKIN) and 40 (GND). A typical clock source of 7.3728 MHz (10.24 MHz only for 40000 SPS operation)
tracks with all timing described in the ADS125H02 data sheet.
NOTE: The CLKIN pin connects to the Tiva microcontroller. The microcontroller holds the CLKIN pin
low in order to enable the internal oscillator of the ADC. Before applying an external clock,
be sure to disable the GPIO output on this pin by sending the HOLDCLOCK 0 command, as
described in Table 8.

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3.2.4 Digital Interface Header
Table 6 lists the functions and pin numbers for all signals used on the digital interface.
(1) Even-numbered pins not included in this list are connected to GND.
(2) Odd-numbered pins not included are connected to the Tiva microcontroller (via level shifters) but the functionality is not used for
this EVM. For connection details, see Figure 21.
(3) Signals connected to the Tiva microcontroller are named according to their respective processor pin connections. For connection
details, see Figure 21.
Table 6. Digital Interface, J5
Function ADC Side Processor Side
Signal Name Pin Number(1) Pin Number(2) Signal Name , Tiva
Connection(3)
External voltage input GND 56 55 EXT_5V
Bank3 level-shifter voltage DVDD 54 53 LVDD1
GPIO for the ADC FAULT_LED 52 51 PD7
EXT_CLK 42 41 PD3 (Unused)
Bank2 level-shifter voltage DVDD 36 35 LVDD2
SPI0 ADC_nCS2 34 33 PA0
ADC_nDRDY 32 31 PA1
ADC_SCLK 30 29 PA2 (SSI0CLK)
ADC_nCS1 28 27 PA3
ADC_MOSI (DIN) 26 25 PA4 (SSI0XDAT0)
ADC_MISO (DOUT) 24 23 PA5 (SSI0XDAT1)
ADC GPIOs ADC_START 22 21 PA6
ADC_nRESET 20 19 PA7
Bank1 level-shifter voltage DVDD 18 17 LVDD3 (Unused)
3.2.5 Test Points
The test points listed in Table 7 may be used to probe onboard voltage supplies and signals.
Table 7. Test Points
Function Signal Name Restrictions
ADC side
Excitation current source (IDAC2) IDAC2 Probe only
Excitation current source (IDAC1) IDAC1 Probe only
Analog input (AIN0) A0 Probe only
Analog input (AIN1) A1 Probe only
Reference input (REFN1 / GPIO1) RN1 Probe only
Reference input (REFP1 / GPIO0) RP1 Probe only
Reference input (REFN0) RN0 Probe only
Reference input (REFP0) RP0 Probe only
Analog input (AINCOM) ACOM Probe only
Internal reference (REFOUT) REFOUT Probe only
External Reference Supply Source REF SUPPLY Probe only
Analog supply (AVDD supply side of sense resistor) A+ Probe only
Analog supply (AVDD device side of sense resistor) A– Probe only
Digital supply (DVDD supply side of sense resistor) D+ Probe only
Digital supply (DVDD device side of sense resistor) D– Probe only
HV analog supply (HV_AVDD supply side of sense resistor) HV_A+ Probe only
HV analog supply (HV_AVDD device side of sense resistor) HV_A– Probe only