Isolation forum - Recent Threads

ISO1641: ISO1641 pull-up resistor time constant check for 1 MHz SWD signals

David Kim2 — Tue, 06 Oct 2026 05:37:18 GMT

Part Number: ISO1641

Hello,

We are using ISO1641BDR to isolate an SWD program download interface (SWDIO and SWCLK), as shown in the attached schematic.

Signal line speed (SWDIO/SWCLK): 1 MHz
ISO1641 maximum I2C operating frequency: 1.7 MHz (as we understand from the datasheet)
Side 1 (VCC1 = 5 V): 1 kohm pull-ups on SDA1 and SCL1
Side 2 (VCC2 = 3.3 V): 1.5 kohm pull-ups on SDA2 and SCL2

Question:
With these pull-up resistor values and the resulting RC time constants, is there any problem operating at a 1 MHz signal rate?

Thank you.

RE: ISO7740: SPI with Digital Isolator

Aaditya V. — Tue, 06 Oct 2026 05:25:57 GMT

Hi Ahmed,

Please give me additional time to review and respond.

Regards,
Aaditya

ISO7740: SPI with Digital Isolator

Ahmed Mostafa — Mon, 05 Oct 2026 11:33:30 GMT

Part Number: ISO7740

Dear,

I hope you're fine.

I'm using two digital isolators to isolate SPI which have 4 Dout, 1 Din, 1 CLK, 1 CS. I put 4 Dout in one isolator, and [Din, CLK, CS] in another isolator.

is there any issue for synchronizing clock of SPI with 4 Dout pins that are in another Isolator?

Best Regards,
Ahmed Mostafa

ISO1412: ISO1412 RS422 Full duplex Schematic

Wonho Park — Mon, 05 Oct 2026 14:22:31 GMT

Part Number: ISO1412

Hello.

I'm Daniel Park.

I have some question about ISO1412 for RS422 communication.

I want to design isolated RS422 interface circuit for full duplex(baudrate 115200).

For reference, sending and receiving will proceed simultaneously.

As attached image, I draw a schematic.

Q1. For RS422 full duplex Interface, I enable both RE pin and DE pin simulataneously. Is there any probelm to work properly?

Q2. Are the transmitter and receiver independent at the IC? Does one have any effect on the other?

If possible, I would appreciate it if you could provide a reference circuit diagram for RS422 full duplex.

RE: ISO1412: ISO1412 RS422 Full duplex Schematic

Eric Hackett — Mon, 05 Oct 2026 20:45:07 GMT

Daniel,

Q1. No, there will not be any problem with this, this is how full duplex communication works on this device. Both the receiver and the transmitter need to be enabled.

Q2. They are independent in the sense that they are enabled separately, and that whatever happens on one during communication won't affect the other due to any connection internal to the IC.

Please reference the ISO1412DWEVM user's guide and schematic for help with full duplex design.

Regards,

Eric Hackett

ISOUSB211: ISOUSB211: USB2.0 Compliance Failure Sync Bit

Michael Hans Andres — Mon, 05 Oct 2026 09:03:10 GMT

Part Number: ISOUSB211

Hello

While running a USB 2.0 compliance signal integrity test, we observed that several sync bits appear to be missing after the ISOUSB211.

The setup is shown in the diagram below. The USB host is operating in Test Packet mode and sends the downstream signal through a PCB interconnect to the ISOUSB211. The USB signal on the host side is measured directly at the ISOUSB211 pins using a differential probe (green).
On the isolated side, the USB signal leaves the PCB through a USB-C connector and is routed through a short cable to a USB 2.0 test fixture. The single-ended signals from the test fixture are routed via SMA connectors to the oscilloscope (yellow = P, blue = N).

For better visualization, the non-isolated USB signal has been time-shifted (skewed) to overlap with the isolated-side signal. Additionally, the differential signal is reconstructed from the two single-ended signals (purple).

As shown in the USB 2.0 compliance signal integrity test, and clearly visible in the waveform, approximately 5 bits of the sync pattern appear to be missing after passing through the ISOUSB211. .

Question: Why does the ISOUSB211 appear to shorten or remove approximately 5 sync bits from the USB packet?

ISO1228: Follow-up to whether or not nINT pin of ISO1228 is open drain or not

Targo Dove — Tue, 29 Sep 2026 09:36:41 GMT

Part Number: ISO1228

I am busy designing a board with the ISO1228 IC. When the IC is in SPI/Serial mode I would like to know if the nINT pin is open-drain or push-pull. The discussion here (https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/1645787/iso1228-nint-pin-and-wirebreak-bits) seems to indicate that it is open-drain however this wasn't confirmed.

RE: ISO1228: Follow-up to whether or not nINT pin of ISO1228 is open drain or not

Pavel Efremov — Sun, 04 Oct 2026 23:42:56 GMT

Hi Eric,

Just to confirm, this does also mean that multiple nINT pins from several ISO1228 parts can be tied together into a wired-OR configuration without causing conflict, correct?

Thanks.

RE: ISO1228: Follow-up to whether or not nINT pin of ISO1228 is open drain or not

Eric Hackett — Fri, 02 Oct 2026 20:38:13 GMT

Targo,

Correct, the nINT pin behaves like an open-drain during serial/SPI mode. And since this is an output pin, it doesn't particularly matter what it is pulled up to since it won't be driven high, and the pin it is feeding into is set to 1.8V logic as well.

Please let us know if you have any other questions.

Regards,

Eric Hackett

RE: ISO1432: RS422-RS232

Eric Hackett — Fri, 02 Oct 2026 19:52:51 GMT

Aidan,

This device is purely a Isolated RS485/RS422 transceiver. You are correct that it goes from single-ended to differential and vice versa, but that is how RS485 and RS422 work. RS232 has a different physical layer than either, and thus it would not work correctly. To my knowledge, there isn't a device that directly translates RS232-RS422, isolated or not.

Can you explain more about your application? I may be able to find some sort of solution that will work.

Regards,

Eric Hackett

ISO1432: RS422-RS232

Aidan Hamm — Fri, 02 Oct 2026 18:32:41 GMT

Part Number: ISO1432

This module appears to be able to work between RS232-RS422. Is this correct? Since one side is a differential (RS422) and the other is not (RS232). Can someone please confirm, or point to where a part like this is available?

RE: ISO1228: Follow-up to whether or not nINT pin of ISO1228 is open drain or not

Targo Dove — Fri, 02 Oct 2026 05:14:50 GMT

Hi Varun,

Thank you for your answer.

What do you mean by "not exactly an open-drain"? Does the OUT5/nINT pin behave like a open-drain pin when in serial mode? In my use case, I have an IC running at 1.8V that is interfacing with the ISO1228 which is running at 3.3V. I would like to connect the nINT and nFAULT pins and pull-up both with a single 4.7kOhm resistor to 1.8V. Would this be possible or would I require some level translation specifically for the nINT pin?

Kind Regards,

Targo

ISO7340-Q1: ISO7340-Q1 unused inputs

Elizabeth Gallegos — Tue, 29 Sep 2026 20:07:52 GMT

Part Number: ISO7340-Q1

I couldn't find anything information in the datasheet about what to do with unused inputs. Do I tie them low or high? Pull them low or high?

RE: ISO7340-Q1: ISO7340-Q1 unused inputs

Aaditya V. — Wed, 30 Sep 2026 18:23:21 GMT

Hi Elizabeth,

As mentioned in the FAQ, parts with F suffix have a default LOW state, therefore, the input should be tied to LOW with a 4.7kohm pull down resistor.

Regards,
Aaditya

RE: ISO7340-Q1: ISO7340-Q1 unused inputs

Elizabeth Gallegos — Wed, 30 Sep 2026 17:45:25 GMT

The full part number is ISO7340FCQDWQ1, since it has an F suffix it defaults to the low state. Should I tie the unused inputs directly to ground or pull them to ground with a 4.7k resistor?

RE: ISO1452: Power Rail And Current Consumption value

Eric Hackett — Wed, 30 Sep 2026 17:33:12 GMT

Bhavanish,

Thanks for bringing this question to E2E. Please see Figures 6-3 through 6-6 on page 15 in the datasheet. They are supply current vs. data rate graphs, and along with these plots there are also power dissipation numbers in the electrical characteristics section on page 6.

Please let us know if you have any other questions.

Regards,

Eric Hackett

ISO1452: Power Rail And Current Consumption value

BHAVANISH P — Wed, 30 Sep 2026 11:36:17 GMT

Part Number: ISO1452

I need power rails and current consumption value for each power rails

RE: ISO7340-Q1: ISO7340-Q1 unused inputs

Aaditya V. — Wed, 30 Sep 2026 17:25:36 GMT

Hi Elizabeth,

This FAQ uses the ISO6441 as an example but the same recommendation is true for all TI digital isolators. Additionally, all FAQ threads are kept to date (ISO6441 is our latest generation of digital isolator). Although the post was originally created 8 years ago, all FAQ threads are updated constantly to make sure all viewers get the most up to date recommendations. Considering this, we recommend tying unused input pins to the default state of the device (for ISO7340-Q1, please tie it to HIGH state). Unused output pins can be left open.

I would like to point out that the ISO73xx device family is an older generation of digital isolator. Please feel free to check out our latest generation of digital isolator, the ISO6440 which supports a higher data rate and uses our latest isolation technology.

Regards,
Aaditya

ISOW1050: ISOW1050 & ISOW3086 Availability

Mario Castro — Wed, 30 Sep 2026 10:10:11 GMT

Part Number: ISOW1050

Hello every one!

I am designing a front-end PCB where size and isolation are critical. To meet footprint and EMC requirements, ISOW3086 and ISOW1050 are just perfect, the only issue is that we don´t know when they reach mass-pruduction status. Could you share this information?

PD: if this information cannot be shared publicly, please reach out through email.

Thank you very much,

Mario

RE: ISOW1050: ISOW1050 & ISOW3086 Availability

Varun Kumar — Wed, 30 Sep 2026 12:20:19 GMT

Hi Mario,

Thanks for reaching out.

We'll reach out to you via registered email.

Regards
Varun

RE: TPS25981: Schematic Verification of TPS259813ARPWR

Irfan Shaikh — Wed, 30 Sep 2026 05:54:39 GMT

Hi Mani,

Could you please tell me why I have to select No load if there is a load in my board?

Regards,
Irfan

TPS25981: Schematic Verification of TPS259813ARPWR

Irfan Shaikh — Thu, 23 Jul 2026 04:40:25 GMT

Part Number: TPS25981

Hi Team,

I have used TPS259813ARPWR for eFuse in my design, where input is 12V, 8A and i have attached the schematics for verification.
Kindly verify it let me know if any changes is required to be done?

DESIGN8.pdf

Regards,
Irfan

RE: ISO7340-Q1: ISO7340-Q1 unused inputs

Elizabeth Gallegos — Wed, 30 Sep 2026 05:45:41 GMT

I'd like information about my specific part not a different part number and a thread that is 8 years old.

RE: ISO7420: MTBF Data

Aaditya V. — Wed, 30 Sep 2026 05:29:03 GMT

Hello,

Please use the data reflected for small reel orderable, the ISO7420DR: MTBF and FIT Rate Estimator

Regards,
Aaditya

ISO7420: MTBF Data

Jithesh Shetty — Wed, 30 Sep 2026 04:57:24 GMT

Part Number: ISO7420

Please Provide the MTBF Details of this Part Number.