Texas Instruments ADS1261EVM User manual

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ADS1261 and ADS1235 Evaluation Module
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User's Guide
SBAU293–March 2018
ADS1261 and ADS1235 Evaluation Module
ADS1261, ADS1235 Evaluation Module (ADS1261EVM Shown)
The ADS1261EVM and ADS1235EVM are evaluation module kits providing hardware and software
support for evaluation of the ADS1261, or ADS1235, delta-sigma analog-to-digital converter (ADC). The
kit utilizes the TM4C1294NCPDT processor to communicate with the ADC via SPI and provide
communication with a PC over USB interface. The kit also includes a software application that runs on a
PC allowing for register manipulation and data collection from the ADC. The ADS1261 and ADS1235 EVM
kit include the ADS12xx device along with a USB micro cable and downloadable supporting software
(SW).
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 ADS1261EVM and ADS1235EVM,
demonstration kit, and evaluation module. The term EVM applies to both the ADS1261EVM and
ADS1235EVM. 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
ADS1261 SBAS760
ADS1235 SBAS824

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Contents
1 EVM Overview ............................................................................................................... 3
1.1 Description........................................................................................................... 3
1.2 Requirements ....................................................................................................... 3
1.3 Software Reference ................................................................................................ 3
1.4 Supported Functionality............................................................................................ 3
2 Quick Start.................................................................................................................... 4
2.1 Default Jumper and Switch Configuration....................................................................... 4
2.2 Powering the EVM.................................................................................................. 4
2.3 Software Installation and Hardware Connection Procedure .................................................. 5
3 Hardware Reference ........................................................................................................ 6
3.1 Jumper and Switch Configuration Reference ................................................................... 6
3.2 Header, Connector, and Test Point Reference ................................................................. 7
4 Software Details............................................................................................................ 11
4.1 Installing the Software ............................................................................................ 11
4.2 Connecting to the EVM Hardware .............................................................................. 13
4.3 Using the Software With the EVM .............................................................................. 13
5 EVM Bill of Materials, PCB Layouts, and Schematics................................................................. 15
5.1 Bill of Materials .................................................................................................... 15
5.2 PCB Layouts....................................................................................................... 20
5.3 Schematic .......................................................................................................... 22
List of Figures
1 Default Configurations for ADS1261 and ADS1235 EVM.............................................................. 4
2 Input Terminal Blocks ....................................................................................................... 7
3 Delta-Sigma Evaluation Engine Installation Instructions.............................................................. 11
4 Device Package Installation Instructions................................................................................ 12
5 GUI View Before Connecting............................................................................................. 13
6 GUI View After Connecting EVM......................................................................................... 13
7 Top Silkscreen.............................................................................................................. 20
8 Top Layer (Positive) ....................................................................................................... 20
9 Ground Layer (Negative).................................................................................................. 20
10 Power Layer (Negative) ................................................................................................... 21
11 Bottom Layer (Positive).................................................................................................... 21
12 Bottom Silkscreen.......................................................................................................... 21
13 ADS1261EVM Block Diagram Schematic .............................................................................. 22
14 ADS1261EVM Analog Inputs Schematic................................................................................ 23
15 ADS1261EVM ADC Main Schematic.................................................................................... 24
16 ADS1261EVM Digital Header Schematic............................................................................... 25
17 ADS1261EVM USB and Peripherals Schematic....................................................................... 26
18 ADS1261EVM Processor Main Schematic ............................................................................. 27
19 ADS1261EVM USB Power Schematic.................................................................................. 28
20 ADS1261EVM External Power Schematic.............................................................................. 29
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 guide describes the operation and use of the ADS1261 and ADS1235 evaluation module. The
EVM platform is intended for evaluating the ADS1261 or ADS1235 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
USB powered.
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:
• 5-V unipolar or bipolar AVDD and AVSS supply operation
• Unipolar (5 V) and bipolar (±2.5 V) AVDD and AVSS supply operation
• 3.3-V DVDD
• Digital header for external processor or controller configuration
• Configurable for direct sensor inputs
• Onboard or external ADC clock operation
• Onboard (not installed) or external ADC voltage reference
• 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
• Self offset and system input calibration
• Error detection through device status information
• CRC of data and SPI communication (for error prevention or detection of data transmission)

OPEN
OPEN
OPEN
RIGHT
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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 illustrated 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 R94)
JP4 (Not Installed) AVDD from USB power (1-2 connection via R95)
JP5 (Not Installed) N/A
Jumper Position Function
S1 Right Unipolar analog supply (AVDD = 5 V, AVSS = 0 V)
Figure 1. Default Configurations for ADS1261 and ADS1235 EVM
2.2 Powering the EVM
The EVM is powered through the USB interface with the PC. Follow the installation and connection
procedure in Section 2.3 before connecting the EVM to the PC. Sections Section 2.2.1 and Section 2.2.2
provide additional details about the analog and digital power supply configurations of the ADC.
2.2.1 Analog Supply Configuration of the ADC'
The ADS1261 (or ADS1235) analog supply requires a 5-V source connected between the AVDD and
AVSS pins. The EVM provides onboard 5-V, 2.5-V and –2.5-V supply rails to allow for both unipolar and
bipolar supply polarities, respectively. The analog supply polarity can be selected by S1. When switching
S1, TI recommends disconnecting the USB cable from the EVM, toggling the switch, and then
reconnecting the USB cable.

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Use R33 to measure the AVDD supply current, 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 ADS1261 (or ADS1235) digital supply requires a 2.7- to 5.25-V source connected between DVDD
and DGND. The EVM provides a (typical) 3.3-V onboard digital supply for the digital supply of the ADC.
R38 can be use to measure the DVDD supply current, 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.
2.3 Software Installation and Hardware Connection Procedure
Use the following steps at startup:
1. Install the GUI software on the PC.
2. Install the device package software on the PC. (ADS1261 Device Package for the ADS1261EVM and
ADS1235 Device Package for the ADS1235EVM.)
3. Ensure all jumpers and switches are configured in the default configuration per Table 2 and Figure 1.
4. Connect the EVM to the PC using a USB cable to power the board.
5. If prompted, install any required drivers.
6. Start the GUI application on your PC. The GUI should automatically detect the connected EVM.
NOTE: After powering the EVM, the green D2, D3, and “+5V” LEDS will be lit.

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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 Tiva processor (U9) 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 (U19) powered from USB power (default using R94 as the short)
2–3 shorted Digital supply (U19) 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 R95 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)
Switch Position Description
S1(1) AVDD and AVSS supply polarity switch
Right (pin connections:
5–6, 2–3) Unipolar supply (AVDD = 5 V, AVSS = GND) (default)
Left (pin connections: 5–4,
2–1) Bipolar supply (AVDD = 2.55 V, AVSS = –2.5 V)
S2 Tiva reset (U1 RST) button
Closed (depressed) Tiva held in RESET, level shifters (U6, U7, and U8) tri-stated
Open (normally) Normal operation
S3 Reset FAULT button
Closed (depressed) Clears FAULT indicator and writes 0x00 to the STATUS register of the ADC
Open (normally) Normal operation
S4 BSL button for Device Firmware Update (DFU) mode
Closed (depressed on
RESET) Total Tiva FLASH erasure (on reset Tiva enumerates as a DFU device)
Open (normally) Normal operation

Pin 1
Pin 2
Pin 1
Pin 2
Pin 1
Pin 2
Pin 1
Pin 2
Pin 3
Pin 4
Pin 5
Pin 6
Pin 7
Pin 8
J1
J3
J4
J2
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3.2 Header, Connector, and Test Point Reference
This section provides the connection information and details for all of the connectors and test points
utilized on the EVM.
3.2.1 Analog Input Terminal Blocks
Analog input to the EVM can be connected at the terminal blocks located on the left side of the board (see
Figure 2) to provide external analog signal input to the EVM for evaluation purposes. The functions for
these terminal blocks are listed in Table 4. At no time should a voltage be applied that exceeds the
absolute maximum ratings for the input of the ADS1261 or ADS1235.
Figure 2. Input Terminal Blocks

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(1) J1 and J3 are not populated on the ADS1235EVM.
(2) Analog inputs are pinned out to terminal blocks through RC filters. Refer to Figure 14 for additional connection details.
Table 4. Analog Input Terminal Blocks, J1–J4
Pin Function Test Point ADS1261 Input Pin ADS1235 Input Pin
J1(1)
1 (ADS1261EVM) Analog input(2) A9 AIN9 –
2 (ADS1261EVM) Analog input(2) A8 AIN8 –
J2
1 Analog input(2) A7 AIN7 AIN5
2 Analog input(2) A6 AIN6 AIN4
3 Analog input(2) A5 AIN5 AIN3
4 Analog input(2) A4 AIN4 AIN2
5 Analog input(2) A3 AIN3 AIN1
6 Analog input(2) A2 AIN2 AIN0
7 Analog input(2) A1 AIN1 REFN0
8 Analog input(2) A0 AIN0 REFP0
J3(1)
1 (ADS1261EVM) Analog input(2) A10 AINCOM –
2 (ADS1261EVM) Reference output – REFOUT –
J4
1 GND – DGND DGND
2 AVSS – AVSS AVSS
3.2.2 External Clock
By default, a clock is supplied by the internal oscillator of the ADC when the CLKIN pin is pulled low.
However, the EVM also provides the capability to connect an external clock directly to the ADC using the
J6 connector (see Figure 16.) When connecting to J6, a direct connection can be made between pins 42
(CLKIN) and 40 (GND). A typical clock source of 7.3728 MHz (or 10.24 MHz for 40 kSPS mode, on the
ADS1261) will track with all timing shown in ADS126x Precision, 5-Channel and 10-Channel, 40-kSPS,
24-Bit, Delta-Sigma ADCs With PGA and Voltage Reference or ADS1235 High-Resolution, 24-Bit, 7200-
SPS, Delta-Sigma, Analog-to-Digital Converter With Programmable Gain Amplifier for Bridge Sensors.
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,
described in Table 7.

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3.2.3 Digital Interface Header
Table 5 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 (after passing through level shifters) but the
functionality is not used for this EVM. For connection details, see Figure 16.
(3) Signals connected to the Tiva microcontroller are named according to their respective processor pin connections. For connection
details, see Figure 16.
Table 5. Digital Interface, J6
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 ADC FAULT_LED 52 51 PD7
EXT_CLK 42 41 PD3 (Unused)
Bank2 level-shifter voltage DVDD 36 35 LVDD2
ADC GPIO ADC_nPWDN 34 33 PA0
SPI0 ADC_nDRDY 32 31 PA1
ADC_SCLK 30 29 PA2 (SSI0CLK)
ADC_nCS 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)
3.2.4 Test Points
The test points listed in Table 6 may be used to probe onboard voltage supplies and signals.
Table 6. Useful Test Points
Function Signal Name Restrictions
ADC side
Analog input (ADS1261EVM: AIN9) A9 Probe only
Analog input (ADS1261EVM: AIN8) A8 Probe only
Analog input (ADS1261EVM: AIN7, ADS1235EVM: AIN5) A7 Probe only
Analog input (ADS1261EVM: AIN6, ADS1235EVM: AIN4) A6 Probe only
Analog input (ADS1261EVM: AIN5, ADS1235EVM: AIN3) A5 Probe only
Analog input (ADS1261EVM: AIN4, ADS1235EVM: AIN2) A4 Probe only
Analog input (ADS1261EVM: AIN3, ADS1235EVM: AIN1) A3 Probe only
Analog input (ADS1261EVM: AIN2, ADS1235EVM: AIN0) A2 Probe only
Analog input (ADS1261EVM: AIN1, ADS1235EVM: REFN0) A1 Probe only
Analog input (ADS1261EVM: AIN0, ADS1235EVM, REFP0) A0 Probe only
Analog input (ADS1261EVM: AINCOM) A10 Probe only
External Bridge Supply (EXC+ positive supply) AVDD/EXC+ Remove R6 before connecting to an external
supply, consider the common mode voltage of
the ADC when selecting EXC+ voltage
External Bridge Supply (AVSS "ground" reference) AVDD For external supply ground reference only. Do
not apply a voltage to this testpoint.
External Bridge Supply (EXC– negative supply) AVSS/EXC– Remove R25 before connecting to external
supply, consider the common mode voltage of
the ADC when selecting EXC– voltage

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Table 6. Useful Test Points (continued)
Function Signal Name Restrictions
External reference source VIN U2–1 (VIN) Remove R27 before connecting to external
supply. Reference external supply source to
AVSS. Do not violate absolute maximum
ratings of U2.
Analog supply of the ADC (useful for current measurement) AVDD (A+) Probe only
Analog supply of the ADC (useful for current measurement) U3–4 (A–) Probe only
Digital supply of the ADC (useful for current measurement) DVDD (D+) Probe only
Digital supply of the ADC (useful for current measurement) U3–17 (D–) Probe only
5-V supply +5V Probe only
3.3-V supply +3.3V Probe only
2.5-V supply +2.5V Probe only
Ground GND Probe only
–2.5-V supply –2.5V Probe only
Processor Side
USB-sourced supply USB_VBUS
(VBUS+) Probe only
USB sourced supply USB_VBUSP
(VBUS–) Probe only
5.5-V output (U15) USB_BOOST
(+5.5V) Probe only
1.8-V output (U17) +1.8V Probe only
5.0-V output (U16) +5V Probe only
Ground GND Probe only
3.3-V output (U19) +3.3V Probe only
Step-up dc/dc converter output (U23 - not populated) HVBoost Probe only
High-voltage linear regulator output (U24 - not populated) +HVDD Probe only
Inverting dc/dc converter output (U25 - not populated) HVInvert Probe only
Negative high-voltage linear regulator (U26 - not populated) –HVSS Probe only

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4 Software Details
4.1 Installing the Software
4.1.1 Delta-Sigma ADC EvaluaTIon Software
Download the Delta-Sigma ADC EvaluaTIon Software installer from the DELTASIGMAEVAL-GUI page
and save to a known folder. Run the installer and follow the on-screen prompts. Note that future software
versions may show slightly different screens.
Figure 3. Delta-Sigma Evaluation Engine Installation Instructions

STEP 1 STEP 2
STEP 3 STEP 4
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4.1.2 ADS1261 and ADS1235 EVM Device Package
Download the ADS1261 Device Package installer from the ADS1261EVM tool page for the ADS1261EVM
(or the ADS1235 Device Package installer from the ADS1235EVM tool page for the ADS1235EVM) and
save it to a known folder. Run the appropriate device package installer and follow the on-screen prompts.
Note that future software versions may show slightly different screens.
Figure 4. Device Package Installation Instructions

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4.2 Connecting to the EVM Hardware
After the Delta-Sigma ADC EvaluaTIon Software and the ADS1261 Device Package (or ADS1235 Device
Package) are installed, connect the hardware with the provided USB micro cable, and start the Delta-
Sigma ADC EvaluaTIon Software. The GUI automatically detects the connected hardware and displays
the device register map under the Device tab as Figure 5 and Figure 6 show.
Figure 5. GUI View Before Connecting Figure 6. GUI View After Connecting EVM
4.3 Using the Software With the EVM
The Delta-Sigma ADC EvaluaTIon Software User Manual provides an overview of the GUI, an explanation
of how to modify device register settings, how to collect and analyze data, and control device operations
with scripts. For a list of commands that are supported on the ADS1261 and ADS1235 EVM, see
ADS1261 and ADS1235 EVM Commands.
4.3.1 ADS1261 and ADS1235 EVM Commands
The EVM commands are given in Table 7. These commands are available for use within the Scripts and
Console tabs of the Delta-Sigma ADC EvaluaTIon software. Many of these commands are SPI commands
that are defined in the device data sheet. All other command functions are provided by the EVM firmware.
In general, most device commands that communicate with the ADC via SPI will require the /PWDN pin to
be set high, prior to issuing the command. When the /PWDN pin is low, the device is in hardware power-
down mode and all device functions are disabled (only the internal LDO remains powered). Returning the
/PWDN pin resumes normal ADC operations and preserves the registers settings.
The ADC may also be placed into a software power-down mode by setting the PWDN bit high, in the
MODE3 register. In this mode the internal LDO, internal reference, and serial interface remain enabled.
SPI commands can be sent while the device is in software power-down mode; however, these actions
may or may not take effect in this mode.
Note that some of the commands shown in Table 7 may wake the ADC prior to taking effect, particularly
for EVM commands that are utilized by the GUI. Refer to the "Wakes Device?" column in Table 7 to
determine the intended behavior of the EVM firmware.

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(1) Returns device to previous state after completion.
(2) Resetting will wake the device from software-power down mode.
(3) Setting the /PDWN pin high exits hardware power-down mode; however, the previous software power-down mode will remain
unchanged.
Table 7. ADS1261 and ADS1235 EVM Software Commands 1
Command Command
Arguments Description Wakes Device?
ID Returns EVM ID string: "<DEVICE> <DATE> <TIME>", where "<DEVICE>" is either "ADS1261" or
"ADS1235", and "<DATE> <TIME>" indicates when the EVM firmware was complied. N
COMMANDLIST Returns a list of all commands supported by the EVM firmware. N
COLLECT <# Samples> Collects a number of ADC samples equal to "<# Samples>", where "<# Samples>" is an unsigned integer. During this operation, all other commands will be ignored and the BUSY LED will blink until all
samples have been collected. Y(1)
REGMAP This command is used by the GUI to read the values of all registers. Y(1)
NOP Issues the NOP device command to the ADC (via SPI). N
RESET Issues the RESET device command to the ADC (via SPI). N(2)
START Sets the START pin low and issues the START device command to the ADC (via SPI). N
STOP Sets the START pin low and issues the STOP device command to the ADC (via SPI). N
RDATA Starts a single conversion, waits for /DRDY to go low, and prints the conversion result to the console. N
SYOCAL Issues the system-offset calibration device command to the ADC (via SPI). N
SYGCAL Issues the system-gain calibration device command to the ADC (via SPI). N
SFOCAL Issues the self-offset calibration device command to the ADC (via SPI). N
RREG <ADDRESS> Issues a read register device command to the ADC (via SPI), where "<ADDRESS>" is the starting
register address in hexadecimal (without the "0x" prefix or "h" postfix). N
READSINGLE <ADDRESS> This command is used by the GUI. It provides the same function as RREG, but wakes the device from
power down and returns to previous power-down mode after completion. Y(1)
HOLDCLOCK <"0" or "1"> This command disables the Tiva GPIO output connected to "EXT CLK" to allow for external clocks to be
applied to J6. Refer to Section 3.2.2.N
WREG <ADDRESS>
<DATA>
Issues a write register device command to the ADC (via SPI), where "<ADDRESS>" is the starting
register address in hex, and "<DATA>" is the value to write to the register in hex (without the "0x" prefix
or "h" postfix). N
WRITESINGLE <ADDRESS>
<DATA> This command is used by the GUI. It provides the same function as WREG, but wakes the device from power down and returns to previous power-down mode after completion. Y(1)
LOCK Sends the lock register device command to the ADC (via SPI). While in this mode, all write register
commands will be ignored until the device is unlocked. N
UNLOCK Sends the unlock register device command to the ADC (via SPI). This command unlocks the device
register to allow write commands to take effect. N
HOLDPWDN <"0" or "1"> This command controls the state of the /PWDN GPIO pin. An argument of "1" sets the /PWDN pin high,
while a "0" argument sets the /PWDN pin low. ·(3)
HOLDSTART <"0" or "1"> This command controls the state of the START GPIO pin. An argument of "1" sets the START pin high,
while a "0" argument sets the START pin low. N
HWRESET This command toggles the /RESET GPIO pin. N(2)
CLEAR Clears the software fault flag, writes "0x00" to the STATS register (to clear the CRC_ERR and RESET bits), and turns off the FAULT LED. NOTE: Pressing S3 will perform the same action as the CLEAR
command. N
STATUS Reads the STATUS register (to check for any new fault conditions) and prints (to the console) a description of each fault type that has occurred since last clearing the software fault flag (with S3 or the
CLEAR command). N
CRC
<LENGTH>
<DATA1>
<DATA2>
<DATA3>
<DATA4>
Computes the CRC-n of the data bytes given in "<DATA1>" through "<DATA4>", where "<LENGTH>" is
the number of bytes to be used in the CRC-n calculation. If the number of data bytes provided is greater
than "<LENGTH>", the extra data bytes will be ignored. N
DONTCARE <VALUE> Sets the "Don't care" byte value that is used for all SPI commands that include a "Don't care" byte. Changing the value of this byte only has the effect of modifying the resulting CRC byte that is used with
CRC-mode. N
SPISEND <LENGTH> <BYTE1>
<BYTE2> ...
Sends a user-specified SPI command sequence to the ADC. /CS will remain low until all bytes have
been sent. After issuing this command the firmware will read the STATUS register to check for an CRC
errors. This command allows for testing of the CRC command validation of the ADC, for example, since
it allows the user to provide invalid CRC bytes with the various SPI commands.
N

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5 EVM Bill of Materials, PCB Layouts, and Schematics
The bill of materials and schematics are shown for the ADS1261EVM only. The main difference between the ADS1261EVM and the ADS1235EVM
is with respect to which device is populated, as well as additional components which are not installed on the ADS1235EVM. Components that are
not populated on the ADS1235EVM are noted in Table 8.
5.1 Bill of Materials
NOTE: All components should be compliant with the European Union Restriction on Use of Hazardous Substances (RoHS) directive. Some part
numbers may be either leaded or RoHS. Verify that purchased components are RoHS-compliant. (For more information about TI's
position on RoHS compliance, see http://www.ti.com.)
Table 8. EVM Bill of Materials
Designator Qty Value Description Package Reference Part Number Manufacturer
!PCB1 1 Printed Circuit Board PA044 Any
C1, C3, C4, C6, C7, C9, C10,
C12, C15, C17 10 1000pF CAP, CERM, 1000 pF, 50 V, ±10%, C0G/NP0, 0603 0603 06035A102KAT2A AVX
C2, C5, C8, C11, C16, C18 6 0.01uF CAP, CERM, 0.01 uF, 25 V, ±5%, C0G/NP0, 0603 0603 CL10C103JA8NNNC Samsung Electro-
Mechanics
C13, C35, C36 3 2.2uF CAP, CERM, 2.2 uF, 10 V, ±10%, X7R, 0603 0603 LMK107B7225KA-T Taiyo Yuden
C14 1 220pF CAP, CERM, 220 pF, 50 V, ±5%, C0G/NP0, 0603 0603 06035A221JAT2A AVX
C22, C24, C25, C27, C31, C37,
C38, C39, C40, C43, C44, C48,
C49, C50, C51, C52, C53, C54,
C59, C60, C61, C62, C63, C65,
C67, C72, C78
27 0.1uF CAP, CERM, 0.1 uF,50 V, ±5%, X7R, 0603 0603 C0603C104J5RACTU Kemet
C28 1 4700pF CAP, CERM, 4700 pF, 100 V, ±5%, C0G/NP0, 0603 0603 C0603C472J1GAC7867 Kemet
C29 1 10uF CAP, CERM, 10 uF, 10 V, ±10%, X7R, 0805 0805 CL21B106KPQNFNE Samsung Electro-
Mechanics
C32, C34 2 4.7uF CAP, CERM, 4.7 uF, 25 V, ±10%, X7R, 0805 0805 C2012X7R1E475K125AB TDK
C23, C26, C30, C33, C58, C74,
C75, C76, C79, C80 10 1uF CAP, CERM, 1 uF, 50 V, ±10%, X7R, 0603 0603 UMK107AB7105KA-T Taiyo Yuden
C45, C46 2 12pF CAP, CERM, 12 pF, 50 V, ±5%, C0G/NP0, 0603 0603 C0603C120J5GACTU Kemet
C47, C57 2 2.2uF CAP, CERM, 2.2 uF, 35 V, ±10%, X5R, 0603 0603 GRM188R6YA225KA12D Murata
C55, C56 2 6.8pF CAP, CERM, 6.8 pF, 50 V, ±4%, C0G/NP0, 0603 0603 06035A6R8CAT2A AVX
C68 1 4.7uF CAP, CERM, 4.7 uF, 50 V, ±10%, X7R, 1206 1206 UMK316AB7475KL-T Taiyo Yuden
C69 1 100pF CAP, CERM, 100 pF, 50 V, ±5%, C0G/NP0, 0603 0603 C0603C101J5GACTU Kemet
C70 1 22uF CAP, CERM, 22 uF, 16 V, ±10%, X7R, 1210 1210 GRM32ER71C226KE18L Murata
C71 1 10uF CAP, CERM, 10 uF, 35 V, ±10%, X7R, 1206 1206 GMK316AB7106KL Taiyo Yuden
C73 1 47uF CAP, CERM, 47 uF, 10 V, ±20%, X5R, 1206 1206 LMK316BJ476ML-T Taiyo Yuden
C77, C81 2 1000pF CAP, CERM, 1000 pF, 100 V, ±5%, X7R, 0603 0603 06031C102JAT2A AVX
D1 1 Orange LED, Orange, SMD LED_0603 LTST-C191KFKT Lite-On

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Table 8. EVM Bill of Materials (continued)
Designator Qty Value Description Package Reference Part Number Manufacturer
(1) Component is not populated on the ADS1235EVM.
D2, D3, D5 3 Green LED, Green, SMD LED_0603 LTST-C191TGKT Lite-On
D4 1 Red LED, Red, SMD LED_0603 LTST-C191KRKT Lite-On
H1, H2, H3, H4 4 Bumpon, Cylindrical, 0.312 X 0.200, Black Black Bumpon SJ61A1 3M
J1(1), J3(1), J4, J5 4 Terminal Block, 3.5mm Pitch, 2x1, TH 7.0x8.2x6.5mm ED555/2DS On-Shore Technology
J2 1 Terminal Block, 3.5mm, 8-Pos, TH Terminal Block, 3.5mm, 8-Pos,
TH ED555/8DS On-Shore Technology
J8 1 Connector, Receptacle, Micro-USB Type B, R/A, Bottom Mount
SMT 7.5x2.45x5mm 473460001 Molex
L1 1 1uH Inductor, Wirewound, Ferrite, 1 uH, 2.05 A, 0.054 ohm, SMD 1210 LQH32PH1R0NN0L Murata
R1, R2, R3, R4, R5, R7, R10,
R15, R18, R24, R26, R63, R72,
R74
14 100 RES, 100, 1%, 0.1 W, 0603 0603 RC0603FR-07100RL Yageo America
R6, R25 2 0 RES, 0, 5%, 0.25 W, 1206 1206 RC1206JR-070RL
R9, R12, R14, R17, R19, R23,
R49, R52, R65, R87, R90, R94,
R95
13 0 RES, 0, 5%, 0.1 W, 0603 0603 RC0603JR-070RL Yageo America
R21, R22, R34, R35, R36, R37,
R48, R57, R58, R84 10 100k RES, 100 k, 1%, 0.1 W, 0603 0603 RC0603FR-07100KL Yageo America
R33, R38, R82 3 0.1 RES, 0.1, 1%, 0.1 W, 0603 0603 ERJ-L03KF10CV Panasonic
R39, R40, R41, R42, R43, R44,
R45, R46, R47 9 47 RES, 47, 5%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060347R0JNEA Vishay-Dale
R50 1 1.69k RES, 1.69 k, 1%, 0.1 W, 0603 0603 RC0603FR-071K69L Yageo America
R53 1 604k RES, 604 k, 0.5%, 0.1 W, 0603 0603 RT0603DRE07604KL Yageo America
R54 1 549k RES, 549 k, 1%, 0.1 W, 0603 0603 RC0603FR-07549KL Yageo America
R55 1 511k RES, 511 k, 0.5%, 0.1 W, 0603 0603 RT0603DRE07511KL Yageo America
R56 1 536k RES, 536 k, 1%, 0.1 W, 0603 0603 RC0603FR-07536KL Yageo America
R60, R67, R70, R71, R73 5 10.0k RES, 10.0 k, 5%, 0.1 W, 0603 0603 RC0603JR-0710KL Yageo America
R61 1 1.0Meg RES, 1.0 M, 5%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06031M00JNEA Vishay-Dale
R62 1 51 RES, 51, 5%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060351R0JNEA Vishay-Dale
R64 1 2.00k RES, 2.00 k, 1%, 0.1 W, 0603 0603 RC0603FR-072KL Yageo America
R66 1 4.87k RES, 4.87 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06034K87FKEA Vishay-Dale
R68, R77, R93 3 1.00k RES, 1.00 k, 5%, 0.1 W, 0603 0603 RC0603JR-071KL Yageo America
R69 1 8.06k RES, 8.06 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06038K06FKEA Vishay-Dale
R78, R79 2 2.94k RES, 2.94 k, 1%, 0.1 W, 0603 0603 RC0603FR-072K94L Yageo America
R83 1 768k RES, 768 k, 1%, 0.1 W, 0603 0603 RC0603FR-07768KL Yageo America
R85 1 20.0k RES, 20.0 k, 1%, 0.1 W, 0603 0603 RC0603FR-0720KL Yageo America
R86 1 215k RES, 215 k, 1%, 0.1 W, 0603 0603 RC0603FR-07215KL Yageo America
S1 1 SLIDE SWITCH DPDT .1A, SMT SWITCH, 5.4x2.5x3.9mm CAS-220TA Copal Electronics

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ADS1261 and ADS1235 Evaluation Module
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Table 8. EVM Bill of Materials (continued)
Designator Qty Value Description Package Reference Part Number Manufacturer
(2) For the ADS1235EVM, U3 is replaced with the ADS1235IRHBR.
S2, S3, S4 3 Switch, Tactile, SPST-NO, 0.05A, 12V, SMT Switch, 4.4x2x2.9 mm TL1015AF160QG E-Switch
U1 1 Dual, 5A, High-Speed Low-Side Power MOSFET Driver, D0008A
(SOIC-8) D0008A UCC27524DR Texas Instruments
U3(2) 1 6- and 11-Channel, 40-kSPS, 24-Bit, Delta-Sigma ADC with PGA
and Voltage Reference, RHB0032E (VQFN-32) RHB0032E ADS1261IRHBR Texas Instruments
U4 1 DCK0005A SN74LVC1G06DCKT Texas Instruments
U5 1 Low-Noise Positive- and Negative-Output Charge Pump With
Integrated LDO, DSS0012B (WSON-12) DSS0012B LM27762DSSR Texas Instruments
U6, U7 2 8-Bit Bidirectional Voltage-Level Shifter For Open-Drain And
Push-Pull Application, RGY0020A (VQFN-20) RGY0020A TXS0108ERGYR Texas Instruments
U9 1 Tiva C Series Microcontroller, 1024 KB Flash, 256 KB SRAM, 12
Bit, 20 Channels, -40 to 85 degC, 128-Pin TQFP (PDT), Green
(RoHS & no Sb/Br), Tape and Reel
PDT0128A TM4C1294NCPDTI3R Texas Instruments
U10 1 Highly Integrated Full Featured Hi-Speed USB 2.0 ULPI
Transceiver, QFN-32 5x5 QFN-32 USB3320C-EZK Microchip
U11 1 High-Speed USB 2.0 (480 Mbps) 1:2 Multiplexer / Demultiplexer
Switch with Single Enable, 6 ohm RON, 2.5 to 3.3V, -40 to 85
degC, 10-Pin UQFN (RSE), Green (RoHS & no Sb/Br)
RSE0010A TS3USB221ERSER Texas Instruments
U12 1 USB ESD Solution with Power Clamp, 4 Channels, -40 to +85
degC, 6-pin SON (DRY), Green (RoHS & no Sb/Br) DRY0006A TPD4S012DRYR Texas Instruments
U13 1 Triple Inverter Buffer/Driver with Open-Drain Output, DCU0008A,
SMALL T&R DCU0008A SN74LVC3G06DCUT Texas Instruments
U15 1 3.5MHz, 1.5A, 92% Efficient Boost Converter with Adjustable
Input Current Limit, DSG0008A (WSON-8) DSG0008A TPS61252DSGR Texas Instruments
U16 1 36-V, 1-A, 4.17-uVRMS, RF LDO Voltage Regulator, RGW0020A
(VQFN-20) RGW0020A TPS7A4700RGWR Texas Instruments
U17 1 Single Output High PSRR LDO, 150 mA, Fixed 1.8 V Output, 2.5
to 6.5 V Input, with Low IQ, 5-pin SC70 (DCK), -40 to 85 degC,
Green (RoHS & no Sb/Br)
DCK0005A TPS71718DCKR Texas Instruments
U18 1 Voltage Supervisor with Active-Low, Open Drain Reset, 1 Supply
Monitored, -40 to 125 degC, 3-pin SOT-23 (DBZ), Green (RoHS
& no Sb/Br)
DBZ0003A TLV803MDBZR Texas Instruments
U19 1 Single Output LDO, 1A, Adj. (1.2 to 5.0V), Reverse Current
Protection, DRV0006A (WSON-6) DRV0006A TPS73733DRVR Texas Instruments
Y1 1 Crystal, 25 MHz, 18 pF, SMD ABM3 ABM3-25.000MHZ-D2Y-T Abracon Corporation
Y2 1 CRYSTAL, 32.768KHz, 7PF, SMD 1.5x1.4x6.7mm SSPT7F-7PF20-R Seiko Instruments
C19 0 22uF CAP, CERM, 22 uF, 10 V, ±10%, X7R, 1206 1206 LMK316AB7226KL-TR Taiyo Yuden
C20 0 2.2uF CAP, CERM, 2.2 uF, 10 V, ±10%, X7R, 0603 0603 GRM188R71A225KE15D Murata
C21 0 1uF CAP, CERM, 1 uF, 50 V, ±10%, X7R, 0603 0603 UMK107AB7105KA-T Taiyo Yuden
C41, C42, C64, C66, C83, C92,
C94, C102, C105 0 0.1uF CAP, CERM, 0.1 uF, 25 V, ±5%, X7R, 0603 0603 06033C104JAT2A AVX
C82, C84, C86, C89, C90, C91,
C96, C100, C101 0 10uF CAP, CERM, 10 uF, 35 V, ±10%, X7R, 1206 1206 GMK316AB7106KL Taiyo Yuden

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Table 8. EVM Bill of Materials (continued)
Designator Qty Value Description Package Reference Part Number Manufacturer
C85, C88, C93, C97, C103 0 0.01uF CAP, CERM, 0.01 uF, 25 V, ±10%, X7R, 0603 0603 GRM188R71E103KA01D Murata
C87 0 1uF CAP, CERM, 1 uF, 25 V, ±10%, X7R, 0603 0603 GRM188R71E105KA12D Murata
C98 0 4700pF CAP, CERM, 4700 pF, 100 V, ±10%, X7R, 0603 0603 06031C472KAT2A AVX
C99 0 10pF CAP, CERM, 10 pF, 50 V, ±5%, C0G/NP0, 0603 0603 06035A100JAT2A AVX
D6 0 12V Diode, TVS, Uni, 12 V, 19.9 Vc, SMB SMB SMBJ12A-13-F Diodes Inc.
D7 0 Green LED, Green, SMD LED_0603 LTST-C191TGKT Lite-On
D8 0 20V Diode, Schottky, 20 V, 1 A, SOD-123F SOD-123F PMEG2010AEH,115 Nexperia
D9 0 20V Diode, Schottky, 20 V, 1.1 A, DO-219AB DO-219AB SL02-GS08 Vishay-Semiconductor
F1 0 Fuse, 2 A, 125VAC/VDC, SMD SMD, 2-Leads, Body
9.73x5.03mm 0154002.DRT Littelfuse
FID1, FID2, FID3, FID4, FID5,
FID6 0 Fiducial mark. There is nothing to buy or mount. N/A N/A N/A
H5 0 CABLE USB-A TO MICRO USB-B 1M Used in PnP output and some
BOM reports 102-1092-BL-00100 CNC Tech
J6 0 Header, 2.54 mm, 28x2, Gold, TH Header, 2.54 mm, 28x2, TH TSW-128-07-S-D Samtec
J7 0 Header, 100mil, 7x1, Gold, TH 7x1 Header TSW-107-07-G-S Samtec
J9 0 Terminal Block, 3.5mm Pitch, 2x1, TH 7.0x8.2x6.5mm ED555/2DS On-Shore Technology
J10 0 Connector, DC Jack 2.1X5.5 mm, TH POWER JACK, 14.4x11x9mm PJ-102A CUI Inc.
JP1, JP2, JP5 0 Header, 100mil, 2x1, Gold, TH 2x1 Header TSW-102-07-G-S Samtec
JP3, JP4 0 Header, 100mil, 3x1, Gold, SMT Samtec_TSM-103-01-X-SV TSM-103-01-L-SV Samtec
L2 0 3.3uH Inductor, Shielded Drum Core, Ferrite, 3.3 uH, 1.5 A, 0.033 ohm,
SMD CDPH4D19F CDPH4D19FNP-3R3MC Sumida
L3 0 10uH Inductor, Shielded Drum Core, Ferrite, 10 uH, 1.2 A, 0.124 ohm,
SMD CDRH5D18 CDRH5D18NP-100NC Sumida
R8, R59 0 100k RES, 100 k, 1%, 0.1 W, 0603 0603 RC0603FR-07100KL Yageo America
R11, R16 0 0 RES, 0, 5%, 0.1 W, 0603 0603 ERJ-3GEY0R00V Panasonic
R13, R20, R76 0 100 RES, 100, 1%, 0.1 W, 0603 0603 RC0603FR-07100RL Yageo America
R27, R28, R29, R31, R32, R51 0 0 RES, 0, 5%, 0.1 W, 0603 0603 RC0603JR-070RL Yageo America
R30 0 0.005 RES, 0.005, 1%, 0.25 W, 1206 1206 WSL12065L000FEA Vishay-Dale
R75, R80, R81, R97, R109 0 10.0k RES, 10.0 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060310K0FKEA Vishay-Dale
R88, R89, R91, R92 0 0 RES, 0, 5%, 0.1 W, AEC-Q200 Grade 0, 0603 CRCW06030000Z0EA Vishay-Dale
R96 0 1.00k RES, 1.00 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06031K00FKEA Vishay-Dale
R98 0 9.31k RES, 9.31 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06039K31FKEA Vishay-Dale
R99 0 3.01k RES, 3.01 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06033K01FKEA Vishay-Dale
R100 0 158k RES, 158 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW0603158KFKEA Vishay-Dale
R101 0 453k RES, 453 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW0603453KFKEA Vishay-Dale
R102 0 15.0k RES, 15.0 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060315K0FKEA Vishay-Dale
R103 0 51.1k RES, 51.1 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060351K1FKEA Vishay-Dale

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Table 8. EVM Bill of Materials (continued)
Designator Qty Value Description Package Reference Part Number Manufacturer
R104 0 49.9k RES, 49.9 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060349K9FKEA Vishay-Dale
R105 0 1.30Meg RES, 1.30 M, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06031M30FKEA Vishay-Dale
R106 0 100k RES, 100 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW0603100KFKEA Vishay-Dale
R107 0 93.1k RES, 93.1 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060393K1FKEA Vishay-Dale
R108 0 121k RES, 121 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW0603121KFKEA Vishay-Dale
R110 0 10.0 RES, 10.0, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060310R0FKEA Vishay-Dale
S5 0 Switch, Tactile, SPST-NO, 0.05A, 12V, SMT Switch, 4.4x2x2.9 mm TL1015AF160QG E-Switch
TP7, TP10, TP12, TP15, TP32,
TP33, TP34 0 Terminal, Turret, TH, Double Keystone1573-2 1573-2 Keystone
U2 0 High-Precision Voltage Reference with Integrated High-
Bandwidth Buffer, DGK0008A (VSSOP-8) DGK0008A REF6225IDGKR Texas Instruments
U8 0 8-Bit Bidirectional Voltage-Level Shifter For Open-Drain And
Push-Pull Application, RGY0020A (VQFN-20) RGY0020A TXS0108ERGYR Texas Instruments
U14 0 256K I2C™ CMOS Serial EEPROM, TSSOP-8 TSSOP-8 24AA256-I/ST Microchip
U20 0 Single Output Fast Transient Response LDO, 1.5 A, Adjustable
1.21 to 20 V Output, 2.1 to 20 V Input, 6-pin SOT-223 (DCQ),
-40 to 125 degC, Green (RoHS & no Sb/Br)
DCQ0006A TL1963ADCQR Texas Instruments
U21 0 3-Pin Supply Voltage Supervisors for Automotive, DBV0003A
(SOT-23-3) DBV0003A TPS3809I50QDBVRQ1 Texas Instruments
U22 0 Single Inverter Buffer/Driver With Open-Drain Output,
DCK0005A, SMALL T&R DCK0005A SN74LVC1G06DCKT Texas Instruments
U23 0 Step-Up DC-DC Converter with Forced PWM Mode, 2.3 to 6 V,
-40 to 105 degC, 8-pin SOP (PW8), Green (RoHS & no Sb/Br) PW0008A TPS61085TPWR Texas Instruments
U24 0 Single Output High PSRR LDO, 150 mA, Adjustable 1.2 to 33 V
Output, 3 to 36 V Input, with Ultra-Low Noise, 8-pin MSOP
(DGN), -40 to 125 degC, Green (RoHS & no Sb/Br)
DGN0008D TPS7A4901DGNR Texas Instruments
U25 0 Inverting Buck-Boost Adjustable Converter with 2.7 to 5.5 V Input
and -15 to -2 V Output, -40 to 85 degC, 10-Pin SON (DRC),
Green (RoHS & no Sb/Br)
DRC0010J TPS63700DRCR Texas Instruments
U26 0 Single Output High PSRR LDO, 200 mA, Adjustable -1.18 to -33
V Output, -3 to -36 V Input, with Ultra-Low Noise, 8-pin MSOP
(DGN), -40 to 125 degC, Green (RoHS & no Sb/Br)
DGN0008D TPS7A3001DGNR Texas Instruments

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5.2 PCB Layouts
Figure 7 through Figure 12 illustrate the PCB layout. The same PCB is used for both the ADS1261EVM
and ADS1235EVM.
Figure 7. Top Silkscreen
Figure 8. Top Layer (Positive)
Figure 9. Ground Layer (Negative)