Data converters forum - Recent Threads

ADS131E08: Status word [GPIO byte] format?

Bruce McKenney — Mon, 18 May 2026 21:36:38 GMT

Part Number: ADS131E08

Per Data Sheet (SBAS561C) Fig 37, the third byte of the status word contains GPIO[7:4] (presumably referring to the GPIO register (20)). This uses 4 bits to define an 8-bit byte, so I want to make sure what it means.

Observed behavior is that GPIO[7:4] appears as bits [3:0] (low nybble) in that status word byte. The high-order nybble seems to always read as 0xF0 (but maybe I'm not watching closely enough).

My notion is to put a "well known" bit pattern into the GPIO register and use the status word to detect whether the ADC has been Reset. I'll be using a fairly heavy hammer if that happens (presumed rare), so I want to get it right.

Is it correct that GPIO[7:4] appears as bits [3:0] in the third status word byte? Is there any useful information in bits [7:4] of the third status word byte?

ADS7953: ADS7953 Delay times measurement voltage

Joao Barbosa — Mon, 18 May 2026 20:18:18 GMT

Part Number: ADS7953

Hello,

Regarding the delay times td1 and td2 specified in the ADS7953 datasheet (for a 5 V supply), could you please clarify whether these values include the output pin rise/fall time when driving the specified load (50 pF)?

If so, at which voltage threshold is the delay measured (e.g., VIH, VCC/2, or another reference level)?

Additionally, is there any available information on how temperature and/or supply voltage variations affect the effective delay times?

Thank you for your support.

ADS1278-SP: ADS1278-SP SEU test data

Frédéric Chastellain — Wed, 13 May 2026 12:36:26 GMT

Part Number: ADS1278-SP

Hi,

it has been mentioned in a previous thread which has now been locked that there's SEU test data available at TI for the ADS1278-SP. Could you please share it with me?

Also, what is the status with the ADS1278QML-SP? Is the aforementioned SEU test data still valid? If not, do you have SEU test data / an SEE test report for the ADS1278QML-SP?

Thanks and best regards

Fred

RE: ADS1278-SP: ADS1278-SP SEU test data

Taiwo Arojojoye — Mon, 18 May 2026 18:56:50 GMT

Hello Fred,

Can I get permission to email you directly?

Regards, Taiwo.

ADS8558: using problem

Allen Chu — Mon, 18 May 2026 11:35:46 GMT

Part Number: ADS8558

Hello,

Do I need to change the hardware circuit diagram, software register configuration, and software timing to replace ADI's AD7658 with ADS8558 P2P?

Hi Allen,

Thanks for your post. The devices are P2P. The main difference is: The power-up sequence from partial power-down to normal operation is different between AD7656 and ADS8556. For the ADS8556 another reset pulse has to be applied to wake up the device again, for the AD7658 a CONVST pulse is required.

Best regards,

Samiha

New question:

In our existing design, MCU the give ADC7658 reset signal to the pin 28 only one time during the drive initialisation.

But from the ads8558 datasheet, we can see the reset signal works during the signal transferring.

Is that what you mean "wake up the device again"?

RE: ADS8558: using problem

Yolanda Gonzalez — Mon, 18 May 2026 18:28:20 GMT

Hello Allen,

What Samiha was referring to was the devices going from a partial power-down mode back to normal operation. Both devices have a functionality where any channel can be placed in partial power-down mode by setting the CONVSTx signal low before the falling edge of BUSY. To exit the partial power down mode, the AD7658 requires a CONVST pulse before it goes back into normal operation, while the ADS8556 requires a RESET pulse instead.

Doing a reset during initialization is a good practice, and in this aspect the initialization sequence does not need to change between both devices.

Best regards,

Yolanda

ADS8688W: use ADS8688WDBTR to replace ADS8678IDBT

Jayden Li — Mon, 18 May 2026 07:48:16 GMT

Part Number: ADS8688W

Hi team,

Currently, my customer is using ADS8678IDBT to realize Single-ended input, including voltage and current input (voltage or current input determined by Optocoupler Relay)

Now, customer is going to use ADS8688WDBTR to replace ADS8678IDBT, and customer is going to remove R73 to realize both differential voltage input and single end voltage input, is it fine w/ this design?

Besides, they found it difficult to realize the current input if R73 was removed, how can customer allow the current ipput as well?

Thanks!

Jayden Li

RE: ADS8688W: use ADS8688WDBTR to replace ADS8678IDBT

Yolanda Gonzalez — Mon, 18 May 2026 17:50:19 GMT

Hello Jayden,

The ADS8678 and ADS8688W are pin-to-pin compatible and should have no issues when making a direct replacement.

Like noted, the the ADS8688W does have differential as well as single-ended capability, so measuring both differential and single-ended voltage input should be fine with the design.

For the current measurement, is the option to connect or set the AINN to SGND possible? either via an additional relay or externally setting the AINN to the same level as SGND, the latter being a single-ended measurement.

If possible to include an INA, would be another option.

Best regards,

Yolanda

RE: ADS9327EVM: Unable to get sensical output from eval board

Yolanda Gonzalez — Mon, 18 May 2026 17:25:57 GMT

Hello Jake,

Thank you for sharing all the images, they are all very helpful. From the images shared, I will also confirm that the hw configurations are great and there should be no issue reading from the device from that stand point. I believe this is a software issue.

We have found and fixed a couple of issues we have seen on the GUI since the initial release. Apologies for the confusion, we are in the process of updating the user's guide accordingly as well.

Could you please use our latest GUI (V3.2.0): https://www.ti.com/tool/download/ADS9327EVM-GUI

The most recent version of the GUI should not have the issue you are currently seeing. Please let me know if the issue is still seen with the latest GUI as well.

Best regards,

Yolanda

ADS9327EVM: Unable to get sensical output from eval board

Jake Zimmer — Sat, 16 May 2026 05:09:34 GMT

Part Number: ADS9327EVM

Hello,

After purchasing a brand new eval board, we have been unable to get any sensical output from the device. Normally, it looks like full scale noise but after much trial, we've been able to get something at almost resembles a wave with similar features to our input sine wave. Is there something that we've missed? Do you see anything wrong with our test setup?

I can confirm that the all we've done is plug in the device and follow the EVM guide. No configuration of parameters seems to make a difference. This is a device purchased two days ago from Digikey.

Thank you for any insights you might have,

Jake

ADS8681: How the damping resistors in the Evaluation Board was selected

ASLAM SHAIK — Fri, 15 May 2026 22:46:26 GMT

Part Number: ADS8681

The R25 resistor of 0.22ohm and R12 resistor of 0.47Ohms in the EVM schematic shown below. Is it required in the design to use these resistors. Please confirm. As the datasheet has not recommended any snubber design guidelines, I want to make sure whether TI recommends these 2 resistors if I am using internal reference. If I need to use the resistors, is there any design guidelines to determine the value of the resistors based on my design. Whether these resistor values depends on the sampling frequency?

RE: ADS8681: How the damping resistors in the Evaluation Board was selected

Yolanda Gonzalez — Mon, 18 May 2026 17:17:39 GMT

Hello Aslam,

The resistors in series with the capacitors on both REFIO and REFCAP are not required. For the REFIO they are added by recommendation of the voltage reference used as well as a good practice to ensure there is a low ESR on those pins.

When using the internal reference this is the recommended:

For the REFCAP we do suggest using a capacitor with an ESR less than 0.2Ω. In the schematic shared, the 0.22Ω was included as a precaution, but if the capacitors used already meet that specification there is no need to add any additional impedance. So long as Figure7-7 is met and the layout recommendations are met as close as possible then that should be sufficient.

Best regards,

Yolanda

AFE20408EVM: DAC output is not changed

Isao Takigasaki — Mon, 18 May 2026 16:52:19 GMT

Part Number: AFE20408EVM

Hi,

My customer is evaluating AFE20408 on the EVM with GUI.

When the customer change the DAC value on GUI, the DAC output is not changed at DACA0 to 3..
Could you give us any advise to solve it?

The attached pdf shows the GUI settings. Please refer it.
At the setting, DAC output voltage was -5V at DACA0 to 3. The customer changed the buffer value on the GUI, but DAC output voltage is not changed.
VSSA=-5V and VCCA=0V.
The customer refered user's guide to set the GUI. If you also give us any other documentation of usage of the GUI, it helps us.

ScreenShot.pdf

Best Regards, Taki

DAC80516EVM: 80516EVM - Altium Design Files

Callum Matthews — Mon, 18 May 2026 07:41:24 GMT

Part Number: DAC80516EVM

Hi,

I was wondering if it was possible to receive the design files for the 80516EVM board - preferably in Alitum compatible format to speed up design.

Reference on the page appears to only exist in pdf format.

Regards,

Callum

RE: DAC80516EVM: 80516EVM - Altium Design Files

Erin Bowrie — Mon, 18 May 2026 16:43:45 GMT

Hi Callum,

Please email me at e-bowrie@ti.com to get the files.

Thanks,
Erin

RE: ADS124S08: ADS124S08 – Incorrect Lead Resistance on First 3-Wire RTD During Multi-Channel Scan

Bryan Lizon86 — Mon, 18 May 2026 15:01:25 GMT

Hi Manikandan Velayudham,

If you switch the channel scanning order does the behavior change to the other channel? For example, I assume you are measuring RTD3 and then RTD4 in the schematic you sent me, so AIN1 / AIN2 and AIN2 / AIN11 followed by AIN4 / AIN8 and AIN8 / AIN6. If you switch so you are measuring RTD4 and then RTD3, do you still see the same behavior on RTD3, or does it switch to RTD4 since now RTD4 is the first measured channel?

You can try removing some of the caps and the TVS diode to see if you can narrow down where the problem is. Do this one or two at a time just in case there is a specific component that is causing the issue.

-Bryan

ADS124S08: ADS124S08 – Incorrect Lead Resistance on First 3-Wire RTD During Multi-Channel Scan

Manikandan Velayudham — Tue, 12 May 2026 05:05:02 GMT

Part Number: ADS124S08

Hi TI Team,

I am using the ADS124S08 with a TMS320F28P650DK6 MCU to measure two 3-wire RTDs. I am observing an issue only during continuous multi-channel scanning.

The first RTD in the scan sequence shows an incorrect lead resistance measurement, while the second RTD measures correctly.

Hardware Setup

Two 3-wire RTDs connected
RTD resistance ≈ 82ohms
IDAC current = 1 mA
External RC filters used on ADC inputs
PGA Gain = 8
2000 SPS, continuous conversion mode

ADC Configuration
ads_write_reg(0x03, 0x0B, CS); // PGA ON, Gain = 8 ads_write_reg(0x04, 0x1C, CS); // Continuous mode, low latency, 2000 SPS ads_write_reg(0x05, 0x3A, CS); // Internal 2.5V reference ON ads_write_reg(0x06, 0x07, CS); // IDAC = 1mA ads_write_reg(0x08, 0x00, CS); // VBIA OFF ads_write_reg(0x09, 0x10, CS); // Normal mode ads_send_command(0x08, CS); // START
Measurement Sequence
1. Measure RTD + Lead Resistance
ads_write_reg(0x07, IDACMUX, CS); // Route IDAC1 ads_write_reg(0x02, INPMUX1, CS); DELAY_US(1000); raw1 = ads124s08_read_data(CS);
1. Measure Lead Resistance Only
ads_write_reg(0x02, INPMUX2, CS); DELAY_US(1000); // or 10000 us raw2 = ads124s08_read_data(CS);
1. Calculate RTD Resistance
r_rtd = (V1 / IDAC) - (V2 / IDAC);

Observed Behavior

When measuring channels individually:

Both RTDs measure correctly (~82 ohms)

During continuous scanning:

RTD2 (First channel scanned):

RTD Voltage = 82.77 ohms

Lead Voltage = 59.16 ohms

Final RTD = 23.61 ohms

RTD3 (Second channel scanned):

RTD Voltage = 83.29 ohms

Lead Voltage = 0.47 ohms

Final RTD = 82.82 ohms

Key Observation

The issue occurs only on the FIRST RTD channel and only during the lead-resistance measurement.

Settling delay before reading lead voltage has major impact:

1 ms delay → Incorrect lead resistance (~59 ohms)

10 ms delay → Correct lead resistance (~0.5 ohms)

The second RTD works correctly even with 1 ms delay.

Questions

Why does only the first scanned RTD require a much longer settling time?

Is there a recommended method for scanning multiple 3-wire RTDs with ADS124S08?

External RC filter charging/discharging causing this issue?

Please help us to resolve this issue. Also I have shared the schematic snip for reference.

Thanks,

Manikandan V

ADS131A02: noise problem

Liteng Zeng — Sun, 17 May 2026 06:23:41 GMT

Part Number: ADS131A02

When designing a three-phase power monitoring system using multiple ADS131A02 devices in a daisy-chain configuration, what are the key SPI timing and synchronization constraints to ensure accurate simultaneous sampling across all channels, and how should the DONE signal be routed to avoid phase mismatch between devices?

RE: ADS131A02: noise problem

Bryan Lizon86 — Mon, 18 May 2026 14:42:28 GMT

Hi Liteng Zeng

You can likely review all of the ADS131A04 reference designs for answers to your questions: https://www.ti.com/product/ADS131A04#reference-designs

Specifically this ref design was created to show how to use 2x daisy-chained ADS131A04s to measure multi phase current and voltage signals

You can also consider using the ADS131M0x devices, which offer 2-ch, 3-ch, 4-ch, 6-ch, and 8-ch variants with an integrate gain stage. There are many reference designs available for these devices as well, on the product page

-Bryan

RE: DAC38J84EVM: Board files for DAC38J84EVM

Kang Hsia — Mon, 18 May 2026 14:29:20 GMT

Hi,

Could you please check the following design package? We have ODB++ file which may help you

https://www.ti.com/lit/zip/SLAC646

e2e.ti.com/.../odbjob_5F00_dac3xj8x_5F00_d.tgz

We currently do not have .asc file available

-Kang

DAC38J84EVM: Board files for DAC38J84EVM

David Cipolle — Mon, 18 May 2026 12:25:01 GMT

Part Number: DAC38J84EVM

Would it be possible to get the .ASC file for the design files? I do not have Allegro, but the .ASC file can be exported from Allegro to allow import into other PCB tools.

Thanks

ADS1203: No voltage output from ADS1203

otsuka.masahiro — Fri, 15 May 2026 10:26:33 GMT

Part Number: ADS1203

Dear TI Representative,

I am designing a circuit to output a 5V-0V square wave using the following circuit.

However, the output from the photocoupler remains at 0V.

What measures can I take to enable the output?

Thank you for your guidance.

RE: ADS1203: No voltage output from ADS1203

Bryan Lizon86 — Mon, 18 May 2026 14:27:36 GMT

Hi otsuka.masahiro,

I'd expect the clock duty cycle to be approximately 50:50, and should be consistent. Also, the duty cycle doesn't change with input signal - the modulator output should change, but the clock should be very consistent.

The MCLK pin is the modulator clock input or output - you can see this and the expected output frequency in the images below. In modes 0 and 1 you should be able to measure the clock output using an oscilloscope. Have you tried this?

Is it possible the device has been damaged?

-Bryan

RE: ADS124S06: Query Regarding ADS124S06 SPI Mode Compatibility with Shared SPI Bus Display Integration

Bryan Lizon86 — Mon, 18 May 2026 14:21:05 GMT

HI Manogna V

The correct SPI mode number doesn't really matter, instead you need to ensure two things: first, that SCLK idles low; and two, that you are capturing data from the ADC on the SCLK falling edge. Some MCUs call this mode different things, so that is why the number doesn't really matter. But as long as the communication follows those two rules you will be able to communicate with the ADC, assuming everything else is correct of course (e.g. power, ground, clock, etc.)

-Bryan

ADS124S06: Query Regarding ADS124S06 SPI Mode Compatibility with Shared SPI Bus Display Integration

Manogna V — Mon, 18 May 2026 06:20:18 GMT

Part Number: ADS124S06

Hi Team,

We observed the following behavior during SPI testing with ADC and display integration:

As per the ADC datasheet, the ADC is specified to support SPI Mode 1.
The display is working in SPI Modes 0, 1, and 3 when tested independently.
Since both ADC and display share the same SPI bus with different chip select lines, we tested both devices together in SPI Mode 1 (common mode for ADC and display). In this configuration, the display behavior was not stable and heavy flickering, reverse text, and unclear display output were observed.
During further testing, the ADC was also observed to work properly in SPI Mode 3.
Currently, both ADC and display are being tested together in SPI Mode 3, and the display behavior appears stable.

Query:

Since the ADC is functioning correctly in SPI Mode 3 during our tests, can SPI Mode 3 be considered reliable and recommended for continuous operation?
Or should we strictly follow SPI Mode 1 as specified in the ADC datasheet?
If SPI Mode 3 is used for the ADC, are there any known limitations, timing concerns, compatibility issues, or long-term behavioral concerns that need to be considered?

Please suggest the preferred SPI mode for stable operation when both ADC and display are used on the same SPI bus.

Thanks,
Manogna V

Data converters forum - Recent Threads

ADS131E08: Status word [GPIO byte] format?

ADS7953: ADS7953 Delay times measurement voltage

ADS1278-SP: ADS1278-SP SEU test data

RE: ADS1278-SP: ADS1278-SP SEU test data

ADS8558: using problem

RE: ADS8558: using problem

ADS8688W: use ADS8688WDBTR to replace ADS8678IDBT

RE: ADS8688W: use ADS8688WDBTR to replace ADS8678IDBT

RE: ADS9327EVM: Unable to get sensical output from eval board

ADS9327EVM: Unable to get sensical output from eval board

ADS8681: How the damping resistors in the Evaluation Board was selected

RE: ADS8681: How the damping resistors in the Evaluation Board was selected

AFE20408EVM: DAC output is not changed

DAC80516EVM: 80516EVM - Altium Design Files

RE: DAC80516EVM: 80516EVM - Altium Design Files

RE: ADS124S08: ADS124S08 – Incorrect Lead Resistance on First 3-Wire RTD During Multi-Channel Scan

ADS124S08: ADS124S08 – Incorrect Lead Resistance on First 3-Wire RTD During Multi-Channel Scan

Hardware Setup

ADC Configuration

Measurement Sequence

Observed Behavior

Key Observation

Questions

ADS131A02: noise problem

RE: ADS131A02: noise problem

RE: DAC38J84EVM: Board files for DAC38J84EVM

DAC38J84EVM: Board files for DAC38J84EVM

ADS1203: No voltage output from ADS1203

RE: ADS1203: No voltage output from ADS1203

RE: ADS124S06: Query Regarding ADS124S06 SPI Mode Compatibility with Shared SPI Bus Display Integration

ADS124S06: Query Regarding ADS124S06 SPI Mode Compatibility with Shared SPI Bus Display Integration