PCA9515A: Clarification on MCU Driving Multiple I2C Buffers

SIVAPOORANI M

Part Number: PCA9515A
Other Parts Discussed in Thread: TCA9517A

Tool/software:

I am working on the I2C interface where the MCU (MIMRT1024CAG4B) drives the two I2C buffer (PAC9515A) that are placed on the same board. One Buffer output drives the on-board devices, while the other I2C buffer is routed through a ribbon cable to the devices on a second board. I need clarification on whether this setup will work reliably and Considerations regarding the Pull-up resistor, bus loading and signal integrity.

The attached image shows the MCU interfacing two buffers through I2C interface.

2 days ago

0 Tyler Townsend 2 days ago

TI__Mastermind 46888 points

Hi Sivapoorani,

Just to confirm, side 0 is shared amongst both PCA9515A devices correct? The schematic net name is a little difficult for me to read.

Regards,

Tyler

0 SIVAPOORANI M 2 days ago in reply to Tyler Townsend

Prodigy 10 points

Hi Tyler,

Yes, Both PCA9515A has shared I2C3 SCL & SDA signals. U89 (Placed Below MCU) Buffer output is driving on-board I2C devices whereas U161 Buffer output is driving daughter board through Ribbon cable.

Regards,

Sivapoorani

0 Tyler Townsend 2 days ago in reply to SIVAPOORANI M

TI__Mastermind 46888 points

Hi Sivapoorani,

Let me get back to you by end of today.

Regards,

Tyler

0 Tyler Townsend 2 days ago in reply to SIVAPOORANI M

TI__Mastermind 46888 points

Hi Sivapoorani,

PCA9515A cannot be connected in parallel due to VILC spec. The output of one PCA9515A cannot be recognized by the other buffer in parallel as a logic LOW.

VILC = 0.4V

VOL = 0.52 V typical.

For TCA9517A, A-A, A-B, B-A connections are allowed, but never B-B connections.

See this application note for more information.

https://www.ti.com/lit/an/scpa054/scpa054.pdf?ts=1719932118796&ref_url=https%253A%252F%252Fwww.google.com%252F

Regards,

Tyler

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PCA9515A: Clarification on MCU Driving Multiple I2C Buffers