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TXS0104E: Can I use the TXS0104E as a replacement for the TXS0102 for I2C applications?

WooJin Lee

Prodigy 10 points

Part Number: TXS0104E
Other Parts Discussed in Thread: TXS0102, TXB0104, , TCA9800, TCA9803

Tool/software:

Hello,

I have some questions regarding your voltage translators.

According to the information displayed beneath the featured voltage translators image, it appears that only the TXS0102 is recommended for I2C, while the TXS0104 is indicated for I2S.

In this context, I'd like to inquire whether it's permissible to use the TXS0104 for I2C applications. Additionally, if I2C compatibility is confirmed, I'd like to know if there are any issues associated with exclusively using the TXS0104 for I2C communication.

I have an additional question regarding your voltage translators.

The image does not indicate GPIO functionality for the TXB0104 and TXS0102. I would like to inquire whether it's permissible to use these devices for GPIO purposes.

Regarding the TXB010X Series and TXS010X Series, I'd like to inquire whether the difference in the last digit primarily indicates the number of bits or if it signifies a difference in purpose.

Additionally, I'm experiencing signal degradation when using TXS0104 and TXS0102 consecutively on the board, as shown in the circuit diagram below. I'm inquiring about possible solutions to ensure signal integrity.

Thank you.

url : translators & level shifters | TI.com

0 Clemens Ladisch 5 months ago

Guru 280160 points

1. The TXS0102 and TXS0104E are the same on the electrical level. The only reason that the TXS0104E is not recommended for I²C is that it does not have two channels.

2. All translators can be used for GPIO signals, if their electrical characteristics match what you're doing with the GPIOs.

3. The last digit indeed shows the number of channels.

4. TXS translators are passive switches. Note that all pull-up resistors act in parallel, so the resulting pull-up current is probably way too much for your devices. The TXS's internal pull-up resistors usually are enough. If you want to isolate I²C bus segments from each other, use a buffer like the TCA9800/1/2/3.

0 Jack Guan 5 months ago

TI__Mastermind 26061 points

Hey Woojin,

I agree with Clemens' inputs here. On the schematic, you may remove the external pullups as they will contend with the internal 10kohm pullups inside the TXS device and result in a higher VOL.

Please let us know if you have any further questions.

Regards,

Jack

0 WooJin Lee 5 months ago in reply to Clemens Ladisch

Prodigy 10 points

Is it acceptable to use the TXS0104E for two I2C buses as shown in this circuit?
If there is no issue with question 1, can the TXS0106 be used for three I2C buses without any problems?
Can the TXB Series be used for I2C applications?

4. Is it acceptable to use TXS0104E and TXS0102 consecutively for I2C applications?

0 Clemens Ladisch 5 months ago in reply to WooJin Lee

Guru 280160 points

1. Yes. But note that the TXS already has internal pull-up resistors.

2. Yes.

3. No.

4. Yes. But it cannot help you when the bus is so long that its total capacitance is too high.

0 WooJin Lee 5 months ago in reply to Clemens Ladisch

Prodigy 10 points

Thank you, Clemens Ladlsch

In general, I2C waveforms can degrade at low or high temperatures. Are the I2C waveforms stable within the operating temperature range of the TXS series? Additionally, what is the tolerance of the internal pull-up resistors?

0 Clemens Ladisch 5 months ago in reply to WooJin Lee

Guru 280160 points

The TXS is guaranteed to handle 2 Mbps over temperature (with a low-enough capacitive load). I²C is much slower than that.

For the resistor tolerances, see [FAQ] What is the TXS device internal resistor variation/ tolerance. But note that rising edges are handled by the edge accelerators.

But TXS translators can have another problem: When the total bus capacitance is so high that the edge accelerators time out before the voltage has reached V_CC. In that case, the remaining rising edge becomes much slower because the line is pulled up only by the two 10 kΩ resistors. (See section 4 of A Guide to Voltage Translation With TXS-Type Translators, Effects of External Pullup and Pulldown Resistors on TXS and TXB Devices, and section 3.4. of Leveraging Edge Rate Accelerators with Auto-Sensing Level Shifters.) For high-capacitance buses, (i.e., long traces, cables, or connectors), it might be a better idea to use not a passive switch like the TXS, but an I²C buffer like the TCA9803.