Voltage translators product selection

Qi Liu

Other Parts Discussed in Thread: TXU0304, SN74LVC3G17, TXB0106-Q1, TXB0104-Q1, TXS0104E-Q1

Hi Support Team,

1. My customer needs a Voltage translator to convert 5V to 3.3V.
5V is from MCU SPI.

My customer seached voltage translator in the above link, my customer would like to know the following questions:
①There are two input types: transmission gate and CMOS. What is the difference?
②What is the difference between applications and technology family?
Can be used for SPI, why can't it be used for I2C?

Thanks so much.

Best regards,
Yuki

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 286390 points

For the difference between these two types of auto-bidirectional translators, see these application notes:

Voltage-Level Translation With the LSF Family
A Guide to Voltage Translation With TXB-Type Translators

For open-drain signals like I²C, you need transmission gates. For SPI, both types can be suitable.

Please note that all SPI signals are unidirectional, so you do not need an auto-bidirectional translator but could use a more robust unidirectional or direction-controlled translator. If you have CS/CLK/MOSI/MISO, use the TXU0304. If there is no MISO (so that you need only downtranslation), you can use a buffer with overvoltage-tolerant inputs like the SN74LVC3G17.

0 Qi Liu over 3 years ago in reply to Clemens Ladisch

TI__Expert 3370 points

Thank you for your kindly reply!

My customer has some follow-up questions:

1. Why can't I²C signals use COMS? What happens if I use COMS?

2. Could you help me choose the product with automotive regulation?

I've seen three of the automotive regulation. Do you think it's ok? TLXS0104E-Q1,TXB0106-Q1,TXB0104-Q1

3. TXS0104E-Q1's Application is SPIO.
What is SPIO? What is the different between SPI and SPIO?

0 Dylan Hubbard over 3 years ago in reply to Qi Liu

TI__Mastermind 44895 points

Hi Qi,

1) Im not sure what COMS is, please explain.

2) All of those devices are Automotive Qualified.

3) I believe this is a typo and should say SDIO.

0 Clemens Ladisch over 3 years ago in reply to Qi Liu

Guru 286390 points

1. The input type actually is irrelevant, but these devices with standard inputs also have push/pull outputs. That would not work for a protocol with open-drain signals like I²C.

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Voltage translators product selection