Logic forum - Recent Threads

SN74LVC1T45: SN74LVC1T45 behaviour when one VCC is set close to GND

Tobias Fischer — Thu, 21 May 2026 19:35:38 GMT

Part Number: SN74LVC1T45

Dear TI team,

within one of our applications, we use the SN74LVC1T45 to do level shifting of an SPI-MISO signal from 5.5V (Slave) to 1.8V (Master). To prevent driving the bus either high or low when the CS of the peripheral, we switch the Vcca of the level shifter with the help of an inverter, that is fed by the low-active Chip Select signal, according to the picture below:

We verified that during the sampling and Piloting phase with a couple of hundred devices without any issues. When CHip Select was High, the output of D8 went low. Vcca went to GND and the output A of D7 wnet High Impedance.

However, it now seems this behaviour changed with later batches and the output of D7 is indeed driving pulling or pushing the SPI_MISO, even when Chip Select is inactive (High).

Could this be related to the fact, that the ouput of D8 is just close to GND, maybe related to the Ioff of the Vcca input from D8? Is this approach suitable in general or do you not recommend to use the SN74LVC1T45 in this way, with its Vcca fed by another logic IC?

Thank you for your support on this.

BR, Tobias

SN74AC08: SN74AC08 Slew Rate

Katherine Rosas — Thu, 21 May 2026 16:24:38 GMT

Part Number: SN74AC08

Hello,

What is the slew rate of SN74AC08? Is there a difference between SN74AC08-EP and SN74AC08-Q1 slew rate or are they the same?

Thank you!

LSF0204: LSF0204YZPR YZP‑Package Indicator Dot Orientation Mismatch vs Datasheet Specification

Yokesh J — Thu, 21 May 2026 15:46:32 GMT

Part Number: LSF0204

We are using the LSF0204YZPR part in our design. As per the datasheet, the location of YZP-package indicator dot corresponds to the A3 position. However, the components that we received and assembled on the board show a different orientation.

As observed in Image A, the package indicator dot is positioned at location D1. This interpretation is based on the assumption that the pin‑1 reference marking, which is present on the backside of the IC, corresponds to coordinate A1 in the package grid. Using this backside marking as the reference origin (A1), the visible indicator dot on the top side of the package appears straight opposite, aligning with D1 rather than A3 as specified in the datasheet. Based on this understanding, the part has been mounted on the board as shown in Image B.

Is there any change in the YZP‑package indicator dot location that has not been documented in the datasheet revision history?

Since there is a mismatch between the datasheet‑defined orientation and the physical marking on the received component. Kindly confirm the correct orientation and advise on the proper method for mounting the IC.

SN54HC273: Junction-to-ambient thermal resistance

Bart Odjas — Thu, 21 May 2026 15:06:56 GMT

Part Number: SN54HC273

Hi,

What is the Junction-to-ambient thermal resistance for SN54HC273 LCCC and CDIP packages?

Thanks,

Bart

LSF0108: Logic Level from 1.8V to 3.3V switching is not working from VREF_A 1.8V to VREF_B 3.3V

Siddaiah H — Thu, 21 May 2026 13:39:19 GMT

Part Number: LSF0108

Dear Team,

We are currently bringing up the initial power supplies and testing the LSF0108RKSR bidirectional buffer used in our design to convert logic levels from 1.8V to 3.3V. During testing, we are facing an issue where the logic switching from 1.8V to 3.3V is not happening as expected.

We have attached our schematics for your reference. Could you please review them and share your valuable suggestions to help us resolve the logic switching issue?

Thank you for your support.

Regards

Siddaiah Hiremath

TXS0104E: Voltage glitch/spike observed on rising edge during communication

Yuxi Liu(Tony) — Thu, 21 May 2026 09:39:09 GMT

Part Number: TXS0104E

Hi Team,

I am supporting a customer who is using the TXS0104EPWR. Both VCCA and VCCB are connected to the same 3.3V power supply.

They are experiencing an issue where a voltage spike/glitch occurs on the rising edge of the signal. This glitch appears every time during active communication, not just at power-up.

Here are the details and the troubleshooting steps we have already tried:

The spike is observed on both the input and output sides.
There is already a 33-ohm series resistor on the signal line. The amplitude of the spike is larger on the side closer to the TXS0104E chip.
We suspected the internal one-shot rise-time accelerators (OSAs) might be causing this due to high transient current.
To address this, the customer tried reducing the external pull-up resistor values to provide more strength, but it did not help.
They also replaced the oscilloscope and probes to rule out measurement/probing artifacts, but the glitch remains.

Could you please help check if this behavior is expected for the TXS0104E due to the one-shot architecture? Are there any other recommendations or solutions to mitigate this rising edge spike?

Best regards,
Tony Liu

SN74LVC32A: Regarding the overshoot tolerance of the SN74LVC series logic ICs.

takaya suzuki — Thu, 21 May 2026 02:19:10 GMT

Part Number: SN74LVC32A

I have a question regarding the input voltage of the SN74LVC series ICs. The datasheet specifies an absolute rating of -0.5 to +6.5V, but is there any tolerance for overshoot, where the voltage may drop below -0.5V for about 1 to 5 ns?

TPS50601A-SP: Regarding the pin configuration of TPS50601A-SP

tomohisa urano — Thu, 21 May 2026 01:37:15 GMT

Part Number: TPS50601A-SP

I have a question regarding the pin configuration of the TPS50601A-SP.

The "Pin Configuration and Functions" section on page 3 of the datasheet shows a "Bottom View," but this doesn't seem to match the "Pin Configuration" on page 34 of the "PACKAGE OUTLINE."

Shouldn't the "Pin Configuration" on page 3 be a "Top View"?

Please provide your answer.

Thank you.

tps50601a-sp.pdf

TXB0106-Q1: Use of TXB0106-Q1 as level shifter

kyle oliveira — Wed, 20 May 2026 18:29:24 GMT

Part Number: TXB0106-Q1

Hello,

I am writing to make sure that my planned use of the TXB0106-Q1 as a 5.0V->3.3V level shifter will work. I intend to drive an attenuator that requires 6 3.3V control signals with our hardware driver that uses 5.0V logic, basic diagram attached:

My concern is that since the 5V signal is the driver (rather than the 3.3V) there will be issues.

No requirements for switching speed, but the application requires low spurs and 6 logic signals, which is why I chose this part. The device does not send any signals back to the control source.

Thanks,

Kyle Oliveira

System Engineer

Keysight Technology

SN74LV165A: Allowable Negative Voltage on Vi Beyond Absolute Maximum Rating with Current Limitation

Hori Shota — Wed, 20 May 2026 15:54:55 GMT

Part Number: SN74LV165A

Hi team,

Purpose
I would like to understand the allowable negative voltage range on Vi beyond the absolute maximum rating under certain current-limited conditions.

Background / Setup

The datasheet states that the absolute maximum rating for Vi is -0.5 V to 7 V.
There is an additional note indicating that negative voltage on input/output pins may be tolerated beyond this limit if the specified input/output current is within limits.

Issue

The datasheet does not clearly specify how much negative voltage can be tolerated when the current is limited within the recommended values.

Questions

To what extent (voltage level) can negative voltage on Vi be tolerated if the input/output current stays within the specified limits?
Is there any guaranteed or recommended negative voltage range under such conditions?
Can this tolerance be extended or relaxed by applying timing constraints (for example, limiting the duration of the negative voltage)?
If there are any application notes or guidelines for safely handling negative voltage conditions, could you please share them?

Best Regards,
Shota

LSF0204: LSF0204YZPR- Pin 1 Marking

SATHYA SHREE S — Wed, 20 May 2026 06:34:55 GMT

Part Number: LSF0204

Hi,

We are using LSF0204YZPR in our design.

Pin1 marking in datasheet is located near A3 pin as per pinout image.

While mounting the component, pin 1 marking mismatch will be seen with respect to layout pin 1 marking.

Can we consider pin 1 marking as A1 for our assembly purpose. kindly guide us.

SN74AUP2G240: JunctionTemperature details at >70deg ambient temperature

Ra Krishna — Wed, 20 May 2026 05:38:22 GMT

Part Number: SN74AUP2G240

Hi team,

Please confirm the Junction temperature for the PN: SN74AUP2G240DQER when the ambient temperatures are >70 degC,

If possible please provide the graph of junction temperature vs ambient temperature ( ranging from 50 degC to 100degC).

Regards,

Rama Krishna.

SN74AXC4T774: SN74AXC4T774 & SN74AVC4T774

switch — Wed, 20 May 2026 00:35:12 GMT

Part Number: SN74AXC4T774
Other Parts Discussed in Thread: SN74AVC4T774,

Hi ti team,

Is the software compatible between SN74AXC4T774 and SN74AVC4T774?Thanks！

TXU0101: Regarding -S suffix in part number TXU0101DTQR-S

Syed Hossain — Tue, 19 May 2026 17:21:49 GMT

Part Number: TXU0101

What does the suffix -S mean in TI part number TXU0101DTQR-S

We ordered TXU0101DTQR-S from TI but TI shipped TXU0101DTQR . What is the difference between them ?

SN74AVC2T244: Looking for similar item as SN74AVC2T244DQMR, but for 4-Bits

Ido Sasson — Tue, 19 May 2026 12:50:26 GMT

Part Number: SN74AVC2T244
Other Parts Discussed in Thread: SN74AVC4T245,

Hello,

We arwe using today SN74AVC2T244DQMR, which is 2-bit item.

Please propose the most recommedned options of same functional item, but for 4-bits.

Please advise if all these options are recommended for new designs.

Thank you,

Ido

MSPM0G5187: Request for Detailed Guidance on MSPM0G5117 DFU Flashing via TinyUSB

Ramanathan S — Tue, 19 May 2026 06:48:25 GMT

Part Number: MSPM0G5187
Other Parts Discussed in Thread: MSPM0G5117,

Hi,

We need to flash the firmware via TinyUSB on the MSPM0G5117 MCU, which belongs to the same family as the MSPM0G5187.

As suggested by the local TI team, we added the Config NVM settings and modified the BSL Invoke Pin configuration accordingly (reference image attached). Additionally, under:

Project → Properties → Debug

the checkboxes for both Main and Non-Main memory erase were enabled before flashing the code.

After flashing, we are following the below BSL entry sequence:

Hold the BSL button
Hold the Reset button
Release Reset after 1 second
Release BSL after 2 seconds

However, the COM port is not becoming visible, and the system is not entering DFU mode as expected.

As per the README available under:

SDK → TinyUSB → BSL → Readme.html

I have already completed the mentioned setup steps, including installation of Zadig and dfu-util.

In our case, Config NVM modification is mandatory because, by default, BSL mode is triggered using a HIGH signal. However, based on our hardware design, the trigger must work in LOW condition, which is why the Config NVM changes are required.

At this stage, both the .out and .bin files have been successfully generated, and we would like to proceed with direct DFU flashing to the MSPM0 device.

Currently, we are facing two major issues:

Entering into BSL / DFU Mode
- The device is not reliably entering DFU mode after the configured button sequence.
- COM port is not getting detected after the BSL invoke sequence.
Flashing the Firmware Without XDS110 Debugger
- Our requirement is to flash the firmware directly through TinyUSB/DFU without using the XDS110 debug interface.
- We need confirmation on the correct process and supported method for standalone USB flashing.

Additionally, we request guidance on the following points:

Correct DFU commands required for flashing
Exact execution order / flashing sequence
Recommended tool or simplified method for direct TinyUSB flashing
Validation whether the current Config NVM settings are correct for DFU operation

Since the device is expected to already be in DFU mode, it would be very helpful if you could share a detailed step-by-step flashing procedure, along with any reference scripts or tools available for this process.

Looking forward to your guidance and support in resolving this issue.

Before Inoke sequence

After BSL Invoke Sequence

MSPM0G3519-Q1: DRV8363 DVDD Voltage Dropping to 0V in Custom PCB with 12V Supply

P RAO — Tue, 19 May 2026 06:23:54 GMT

Part Number: MSPM0G3519-Q1
Other Parts Discussed in Thread: DRV8363

Hi Team,

I am using the DRV8363 in my custom PCB with a 12V architecture for BLDC/BDC application. We have observed that DRV8363 is not working at all.

The following are the observations during debugging:

VDRAIN output = 11.42V
GVDD output = 11.4 V
DVDD initially rises to around 9.3V and then gradually drops to 0V.
I captured the waveform on PicoScope for the DVDD.

I have also captured the waveform on Picoscope for the GVDD.

Could you please suggest why DVDD is collapsing to 0V even though GVDD remains stable at 11.42V?

Could you please suggest:

What conditions can cause DVDD collapse in DRV8363?
Whether this behavior indicates protection mode or internal regulator shutdown?

Thank you

Puneeth

SN74LVC1G126: IBIS model issue

Shweta chendake — Tue, 19 May 2026 04:53:00 GMT

Part Number: SN74LVC1G126

i am shweta from Knorr bremse technology center india, we are using
SN74LVC1G126DCK this part in one of our project while checking its IBIS model i found the power and Ground clamp diode are not working, i checked this by driving this pin with high volatge so ideally it should clamp at thereshold but it is not showing like this, could you please help me with this

Thanks

SN74LVC2G14: IBIS model issue

Shweta chendake — Tue, 19 May 2026 04:51:38 GMT

Part Number: SN74LVC2G14

Hello team,

i am shweta from Knorr bremse technology center india, we are using
SN74LVC2G14DCKT this part in one of our project while checking its IBIS model i found the power and Ground clamp diode are not working, i checked this by driving this pin with high volatge so ideally it should clamp at thereshold but it is not showing like this, could you please help me with this

Thanks

SN74ACT08: Higher current support by tying output pins

Yuto Kitamura — Tue, 19 May 2026 04:12:55 GMT

Part Number: SN74ACT08

Dear team,

Are we able to tying the output pins of SN74ACT08DR to support higher output current?

FYI, Toshiba has the applicatio note about it?
https://toshiba.semicon-storage.com/jp/semiconductor/knowledge/faq/logic_common/logic_common_12.html

If we have another solution, please let us know.

Best regards,
Yuto Kitamura

SN74AHCT04: SN74AHCT04PWR Part Marking Verification

Darrell Mayfield — Mon, 18 May 2026 17:10:20 GMT

Part Number: SN74AHCT04

Hello,

I need to determine if the part marking on some TI chips we have are authentic. What I consider "authentic" TI chips have always had the "TI and Texas logo".

We are currently testing an assembly through flying probe, and we have a part failing that has a completely different top side marking and has "TI" in text.

Images attached:

IMG_1344 - passing test

IMG_1347 - failing test

Are both of those chips authentic TI components?

TXS0104E-Q1: TXS0104EQRUTRQ1.A vs. TXS0104EQRUTRQ1

Matthias Teichmann — Mon, 18 May 2026 14:13:04 GMT

Part Number: TXS0104E-Q1

Dear support team,

what are the differences between your ordering code "TXS0104EQRUTRQ1.A" and "TXS0104EQRUTRQ1" (without the A at the end) in detail?

Many thanks in advance.

Best regards
Matthias Teichmann

CD74HC08: request: reason for NRND and active replacement MPN

Tapendra Yadav — Mon, 18 May 2026 09:59:17 GMT

Part Number: CD74HC08

Hello Team,

As per website status, the status of MPNs
CD74HC08E
SN74HCT02N
SN74HC148N
CD74ACT04E
SN74HC4060DBR
SN74ACT240DBR
are NRND. Could you please share the reason for NRND and active replacement MPN (if available)?

SN74LVC1G08-Q1: Need SN74LVC1G08QDCKRQ1 top marking picture

Roy Chan — Mon, 18 May 2026 01:59:29 GMT

Part Number: SN74LVC1G08-Q1

Hello Expert:

can you please help provide SN74LVC1G08QDCKRQ1 top marking picture for our reference ?

or is there any top marking information can share for us due to we need check the part in factory ?

thank you

Roy

CD74HC4515: Decode or demultiplexer

Girish Rao — Sat, 16 May 2026 19:31:44 GMT

Part Number: CD74HC4515
Other Parts Discussed in Thread: CD74HC4514, DRV8220, SN74HC259, CD74HC154

I looked at CD74HC4514 & 4515 with lathces for input.

This can work but this IC is expensive $1.8 for 1k pcs.

74HC154 is a much cheaper part and can be used as a 1 to 16 demltiplexer.

The data sheet of 74HC154 says "The device can be used as a 1-to-16 demultiplexer by using one of the enable input as the multiplexed data input. When the other enable input is LOW the addressed output will follow the state of the applied data.

My application is send Switch ON or OFF commands to the ON or OFF coil of 16 bi-stable relays.

Usinet 74HC154 seem to be a good solution for this application.

I can set the address by address inputs to Ao, A1, A2, A3 and command input HIGH or LOW to one of the enable input Pins, say E0. To send the command to one of 16 relays coils, I can set the data input to HIGH to SW ON the relay or LOW to SW OFF the relay.

However, I cannot understand the truth table in data sheet of 74HC154.

If either of E0 or E1 is set HIGH, the output at all 16 output lines is HIGH.

I need the 16 outputs to mutually exclusive.

Please help me to use 74HC154 for this application.

Thanks

GGRUK