PCA9546A: PCA9546A issue

Perry Chuang

Prodigy 130 points

Part Number: PCA9546A

HI,

I would like to confirm whether the PCA9546A can be used in 1.8V for SMBus any individual SCn/SDn channel.

in spec, page 11

8.3 Feature Description

Depending on the application, voltage translation of the I2C bus can also be achieved using the
PCA9546A to allow 1.8-V, 2.5-V, or 3.3-V parts to communicate with 5-V parts.

B&R

perry

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 271300 points

The supply voltage must not be much larger than the lowest signal voltage (see V_pass in section 6.5, and figure 9-2). So V_CC should be below 3 V.

0 Perry Chuang over 2 years ago in reply to Clemens Ladisch

Prodigy 130 points

HI,

If the PCA9546A Vcc is 3.3V, these VDPU0 – VDPU3 can use 1.8V and what value is for Pull-up resistors?

Thanks

perry

+1 Clemens Ladisch over 2 years ago in reply to Perry Chuang

Guru 271300 points

With a 3.3 V supply, the pass-gate voltage will be about 2.1 V. The easiest solution would be to use the 1.8 V supply for the switch.

For the pull-up resistors, see figures 9-3 and 9-4.

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PCA9546A: PCA9546A issue