TXS0108E: level shift for SPI and UART

Howard Zou

Part Number: TXS0108E
Other Parts Discussed in Thread: SN74LVC8T245, SN74LVC2T45, SN74AHCT125, SN74AHCT1G125, SN74AHCT541, SN74LVC2G34

Hi,

my customer need level shift for SPI and UART. And they may need 1 SPI master(3.3V) and several SPI slaves(5V) connected together. So the more channel, the better.

The question is:

1. Is TXS0108E best suitable for this case?

2. Any risk connecting several SPI slaves together with TXS0108E?

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 243850 points

How many channels are actually required? Two for UART, three for SPI, plus one chip select for each slave? How many slaves?

0 Howard Zou over 3 years ago in reply to Clemens Ladisch

TI__Genius 12365 points

In fact, there are up to 8 SPI slaves, but we don't need one level shift to do that, we could use several pieces.

0 Clemens Ladisch over 3 years ago in reply to Howard Zou

Guru 243850 points

So you need to shift ten channels up, and two channels down?

Translating from 3.3 V to 5 V could be done with shifters like the SN74LVC8T245 and SN74LVC2T45, but these particular voltages can also be handled by plain buffers with TTL-compatible inputs, such as the SN74AHCT541, SN74AHCT125, or SN74AHCT1G125. One CMOS output can drive many slaves.

Translating from 5 V to 3.3 V could be done with a shifter like the SN74LVC2T45, but can also be handled by plain buffers with overvoltage-tolerant inputs, such as the SN74LVC2G34.

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TXS0108E: level shift for SPI and UART