Isolation forum - Recent Threads

ISOW1432: GPIO Pins

Venkata Rami Reddy Vempati — Sat, 16 May 2026 18:41:07 GMT

Part Number: ISOW1432

Hi Team,
part Number: ISOW1432DFMR

Regarding GPIO pins, what is the purpose of IN and OUT pins, and what are their key features?

ISO1212EVM: DC 12V to pin 16 of IC1212?

nakahama hisanori — Fri, 15 May 2026 04:20:03 GMT

Part Number: ISO1212EVM

What happens if you directly apply DC 12V to pin 16 of IC1212?

RE: ISO1212EVM: DC 12V to pin 16 of IC1212?

Varun Kumar — Fri, 15 May 2026 10:02:06 GMT

Hello Nakahama,

[quote userid="699670" url="~/support/isolation-group/isolation/f/isolation-forum/1646151/iso1212evm-dc-12v-to-pin-16-of-ic1212/6346522"]

Thank you for your reply.

I applied 12V DC directly to SENSE1 without a 560Ω resistor to IN1, but will it be damaged?

[/quote]

Please note RSENSE of 560ohm is absolutely needed for device functionality by limiting the INx current - although it will not get damaged as the pins can take up to 60V.

Regards
Varun

ISO1228: nINT pin and wirebreak bits

jose gaa — Thu, 14 May 2026 08:06:01 GMT

Part Number: ISO1228

Dear Sirs,

I'm trying to use the nINT pin as an interrupt, connected to a pin on my microcontroller (MCU), 
to read the input state only when there's a change. However, the nINT pin is always low. 
Does this pin need a pull-up resistor? Once the nINT pin goes low after detecting a change, 
how do I bring it back high? Should it automatically go high after a read?

Regarding the wire break register, I have wire break bits enabled even when the corresponding 
pin is at a level of 24V and the pin status read register is correct and set to 1. What am I 
doing wrong? In my PCB I followed the design of the development board.

RE: ISO1228: nINT pin and wirebreak bits

Varun Kumar — Fri, 15 May 2026 09:50:41 GMT

Hi Jose,

Thanks for the schematics.

There's no obvious red flag that I could see in the schematic connection.

While probing the waveforms it is best to set both F0 and F1 as low so that there are glitches being filtered

Regards
Varun

RE: ISO1212EVM: DC 12V to pin 16 of IC1212?

nakahama hisanori — Fri, 15 May 2026 06:34:54 GMT

返信ありがとうございます。

IN1に560Ω抵抗なしで、直接SENSE1にDC12Vを印加したのですが、破損しませんか。

RE: ISO1212EVM: DC 12V to pin 16 of IC1212?

Varun Kumar — Fri, 15 May 2026 06:25:57 GMT

Hi Nakahama,

Thanks for reaching out.

As you can see from the pin diagram that Pin16 is SENSE1.

Connecting without RTHR (direct short to 12V) is acceptable as 12V is >VIH and the device should still be functional.

Regards
Varun

RE: ISOM8110-EP: Bond wire material for XISOM8110DFGTEP

Varun Kumar — Fri, 15 May 2026 05:07:47 GMT

Hi Neil,

Thanks for reaching out.

We cannot share such TI confidential information on public forum.

Will reach out to you via email.

Regards
Varun

ISOM8110-EP: Bond wire material for XISOM8110DFGTEP

Neil Gagne — Thu, 14 May 2026 18:28:30 GMT

Part Number: ISOM8110-EP

What is the bond wire material for the XISOM8110DFGTEP opto isolator? Does this part have gold wire bonds?

SN6507: SN6507 huge current

Arvid de Witte — Wed, 13 May 2026 12:05:51 GMT

Part Number: SN6507

Hello Team,

I'm an intern, trying to use the SN6507 to stabilize a variable input (between 18-30V with 24V nominal) to 24V. The only problem is that my setup is pulling a lot of amps (2A+). I have found this problem in both real life and simulations. Am I missing something?

I have a similar setup for 24 to 3V3 that works perfectly. If I replace the 750319697 transformer with the 750320325 transformer, my output will be a stable 3V3.

Are you able to find the problem with my setup? I've added my simulation files, in case it helps

Best regards,

Arvid

SN6507_24V_test.zip

RE: SN6507: SN6507 huge current

Jose Rojo — Thu, 14 May 2026 17:17:19 GMT

Hello Arvid,

Apologies for the delay! One of our team members will reach back to you shortly.

Thanks,

Jose R.

UC1843A: Request for Schematic Review and Failure Analysis Support

Oussama Dallali — Wed, 13 May 2026 15:53:41 GMT

Part Number: UC1843A

Hello Texas Instruments Support Team,

We are currently testing our power supply design and we have observed a failure on the schematic during operation.

The main issue is abnormal heating on the following components:

IRF640S MOSFET
R6
R7

We are using the Würth Elektronik transformer 750311625 in this design.

Could you please assist us with reviewing the schematic and helping us identify the possible root cause of the failure and overheating? We would appreciate your support in checking whether the component values, MOSFET drive, transformer connection, snubber network, and overall power stage configuration are correct.

We can send you the schematic.

Thank you in advance for your support.

Best regards,
Oussama Dallali

POWER SUPPLY 600.pdf

RE: UC1843A: Request for Schematic Review and Failure Analysis Support

John Gomez — Thu, 14 May 2026 17:14:19 GMT

Hi Oussama,

Please provide specifications for the following:

-Input Voltage

-Target Output Voltage

-Target Output Current

-Turns ratio of transformer

A couple of questions and observations:

-Do you observe any voltage on the output? Your transformer dot polarity as shown in the schematic is incorrect for a flyback converter. You should have the diode coming off the non-dotted terminal of the secondary winding of the transformer.

-The R6 and R7 resistance in the RC snubber is quite small, which will result in high clamping of the switch node waveform at turn-off, but will also generate more losses. You can try increasing this resistance to about 10k each.

RE: ISO1228: nINT pin and wirebreak bits

jose gaa — Thu, 14 May 2026 14:58:55 GMT

e2e.ti.com/.../msio_2D00_pcb_2D00_16x-DIGITAL-INPUTS.pdf

RE: ISO1228: nINT pin and wirebreak bits

jose gaa — Thu, 14 May 2026 14:58:30 GMT

Hi Varun,

attached my circuit.I send you waveform tomorrow.

Thanks.

RE: ISO1228: nINT pin and wirebreak bits

Varun Kumar — Thu, 14 May 2026 12:33:45 GMT

Hi Jose,

Thanks for reaching out.

In order to comment on what is causing this issue for you, we need see your full schematic connection showing all the pin connections rather than just IN1 and LED1.

Also, it will really help if you have any waveform illustrations to share on how you're seeing the wire-break enabled and nINT getting pulled low along with data on INx.

Regards
Varun

RE: ISOUSB111: ISOUSB111 manage disconnections DFP side

Giacomo Gasparini — Wed, 13 May 2026 13:11:37 GMT

Thank you,

Giacomo

ISOUSB111: ISOUSB111 manage disconnections DFP side

Giacomo Gasparini — Wed, 06 May 2026 14:51:10 GMT

Part Number: ISOUSB111

Hi,

we are designing a isolated USB 2.0 FS industrial peripheral with USB C connector.

The MCU USB internal USB module is configured as Peripheral.

The DD side of the isolator is supplied by the internal MCU supply.
The DU side of the isolator is supplied by the VBUS from the USB cable.
For the isolation the ISOUSB111 is planned to be used.

In our use case the USB Host is not easily reachable from our USB peripheral and we want to avoid the need to reconnect the USB cable in any situation.

But I see from datasheet that:

"Whichever side sees a connect first (D+ or D- pulled up to 3.3 V) becomes the downstream facing side."

"When there is no peripheral device connected to the downstream side of ISOUSB111, internal 15 kohm pulldown resistors on DD+ and DD- pins pull the bus lines to zero, creating an SE0 state. [...] After connect is detected, the ISOUSB111 device waits for a reset to be asserted by the host/hub on the upstream side"

I want to dig deeper about the role detection mechanism of the ISOUSB111:

1) if the DD side of ISOUSB is power cycled (unpowered and then powered), while the VBUS is still present, are the roles swapped and does our Peripheral get configured as a Host? In this case a connector reconnect is needed? (we wouldn't want to, as said before)

2) if the DD side of ISOUSB MCU is reset (so the USB bus at MCU side is temporary undriven), while the VBUS is still present, are the roles swapped and does our Peripheral get configured as a Host? In this case a connector reconnect is needed? (we wouldn't want to, as said before)(we wouldn't want to, as said before)

Thank you for clarification,

Giacomo

RE: ISOUSB111: ISOUSB111 manage disconnections DFP side

Varun Kumar — Wed, 13 May 2026 12:09:53 GMT

Hi Giacomo,

Thanks for the details. One thing that I quickly want to mention below is that:

[quote userid="328703" url="~/support/isolation-group/isolation/f/isolation-forum/1643122/isousb111-isousb111-manage-disconnections-dfp-side/6341770"]The isolator DD+ is the pin connected to MCU but it includes a configurable 1,5kohm pull up to 3.3V.[/quote]

This is not at all required for ISOUSB111 operation. The ISOUSB has internal pull ups integrated.

[quote userid="328703" url="~/support/isolation-group/isolation/f/isolation-forum/1643122/isousb111-isousb111-manage-disconnections-dfp-side/6341770"]In both aforementioned scenarios could you confirm that, as the Host remains connected, the USB roles are mantained (i.e. host at DU side, peripheral at DD side) without cable reconnection?[/quote]

In the both the scenarios, the DD MCU will get disconnected momentarily but once the power comes back it will initiate a connect pull-up which will again configure it as a peripheral - and hence no cable reconnection will be required.

[quote userid="328703" url="~/support/isolation-group/isolation/f/isolation-forum/1643122/isousb111-isousb111-manage-disconnections-dfp-side/6341770"]As a bonus: is there a state diagram for the ISOUSB111? It's not included in the datasheet.[/quote]

This is TI's confidential IP and cannot be shared.

Regards
Varun

RE: SN6507: Need R clock resistor value to give 170 Kc clock for SN6507

Prateek Verma — Wed, 13 May 2026 11:29:28 GMT

Hi Bruce,

Thanks for reaching out E2E support, Let me know if you have further questions.

Thanks,

Prateek

SN6507: Need R clock resistor value to give 170 Kc clock for SN6507

Bruce BUSHEY — Wed, 06 May 2026 19:44:20 GMT

Part Number: SN6507

I am interested in the SN6507 because it has a variable clock freq. and has spread sprectum to reduce EMI. There is a figure to derive clock frequency by a resistor value. Figure 8-6 is hard to read accuractly between a frequency of 1000 to 2000 KHz, because it is logrithmic.

Can you give the formula to obtain a resistor value that will produce a given frequency ?

Bruce

RE: SN6507: Need R clock resistor value to give 170 Kc clock for SN6507

Bruce BUSHEY — Tue, 12 May 2026 15:53:29 GMT

Thank you so much. I got my R value of 5.41 K, whic I can get with some resistor in series. So, great!

RE: ISOUSB111: ISOUSB111 manage disconnections DFP side

Giacomo Gasparini — Tue, 12 May 2026 13:11:05 GMT

Thank you Varun.

The isolator DU side is connected to USB cable towards the host.

The isolator DD+ is the pin connected to MCU but it includes a configurable 1,5kohm pull up to 3.3V.

If I power down the 3,3V MCU side or the MCU is reset (as mentioned in my scenarios) the pull up won't work.

But as I read in the doc:

" When in Full-speed (FS) and Low-speed (LS) modes, disconnection of a peripheral is indicated when the host/hub is not driving any signal on the upstream side, and when the downstream bus is in the SE0 state (Both DD+ and DD- are below the VIL threshold) for a time period higher than TDDIS"

In both aforementioned scenarios could you confirm that, as the Host remains connected, the USB roles are mantained (i.e. host at DU side, peripheral at DD side) without cable reconnection?

As a bonus: is there a state diagram for the ISOUSB111? It's not included in the datasheet.

Thank you again,

Giacomo

RE: SN6507DGQEVM: Tech question on Transformer Design

Prateek Verma — Tue, 12 May 2026 12:18:35 GMT

Hi Brian,

I'll look into your query and get back to you by thursday.

Thanks,

Prateek

SN6507DGQEVM: Tech question on Transformer Design

Brian Wang0928 — Fri, 08 May 2026 12:49:50 GMT

Part Number: SN6507DGQEVM

Hi Team,

Customer currently working with the SN6507 and have the following technical questions:

Transformer Inductance Calculation – The datasheet provides the turn ratio formula, but does not explain how to calculate the transformer inductance. Could you please clarify the methodology? You may refer to the SN6507EVM, its transformer inductance is about 500uH made by Bourns show below .

Inductance vs. Switching Frequency Relationship – What is the relationship between the transformer inductance and the switching frequency setting? Alternatively, how should the switching frequency be designed based on a given inductance value?
Output Power vs. Frequency & Inductance – What is the relationship between output power, switching frequency, and transformer inductance? How do these parameters interact in the design?

Any guidance or reference material would be greatly appreciated. Customer need exactly calculation. Please offer the calculation example. thanks.

Regards

Brian