PCA9548A: PCA9548A connect to level shifter

Woon Nee Tan

Prodigy 70 points

Part Number: PCA9548A
Other Parts Discussed in Thread: TCA9548A

Tool/software:

I would like to ask can I connect PCA9548A to multiple level shifter ? before connect to end device ?

5 months ago

0 Clemens Ladisch 5 months ago

Guru 316690 points

The PCA9548A already is a level shifter; just ensure that its supply is the lowest voltage.

Other level shifters might or might not work, depending on their architecture.

0 Woon Nee Tan 5 months ago

Prodigy 70 points

Hi ,

May I know what is the range of I2C level that supported by PCA9548A ?

as the datasheet information and block diagram is in different range.

For the supply to PCA9548A, if I am level shift it 3.3V to 1.8V, then I have to ensure the supply is 1.8V ?

0 Nir Gilgur 5 months ago in reply to Woon Nee Tan

TI__Mastermind 18075 points

Hello Woon,

The range for the I/Os is up to 5.5V.

The supply can't be below 2.3V.

You need to implement external pull-up resistors to pull the bus up to the desired voltage.

Thanks,

Nir

0 Woon Nee Tan 5 months ago in reply to Nir Gilgur

Prodigy 70 points

Hi ,

If I use TCA9548A, the supply can range from 1.65V to 5.5V. Correct ?

What is the difference between PCA9548A and TCA9548A ?

0 Clemens Ladisch 5 months ago in reply to Woon Nee Tan

Guru 316690 points

Yes. The TCA is a modernized version; the only practical difference is the supply voltage range.

With the TCA9548A's V_CC at 1.8 V, you can level shift between 1.8 V and any higher voltage.

0 Woon Nee Tan 5 months ago

Prodigy 70 points

If using TCA9548A, the supply used should be 1.8V or 3.3V ?

0 Woon Nee Tan 5 months ago in reply to Woon Nee Tan

Prodigy 70 points

If I have some I2C rails pull up to 3.3V and some pull up to 1.8V.

0 Woon Nee Tan 5 months ago in reply to Woon Nee Tan

Prodigy 70 points

Main I2C master is 3.3V, downstream I2C are 3.3V and 1.8V. The supply to TCA9548A should be 1.8V or 3.3V ?

0 Clemens Ladisch 5 months ago in reply to Woon Nee Tan

Guru 316690 points

The TCA9548A's V_CC should not be larger than the lowest signal voltage. So use 1.8 V.

0 Woon Nee Tan 5 months ago in reply to Clemens Ladisch

Prodigy 70 points

If the pull up rails of 1.8V are powered-on on different sequence, I should use 1.8V which powered-on on the early stage ?

0 Clemens Ladisch 5 months ago in reply to Woon Nee Tan

Guru 316690 points

It does not matter.

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PCA9548A: PCA9548A connect to level shifter