TCA9517A: Can we connect 4 buffer in parallel with all enabled by default

ramesh murthy

Part Number: TCA9517A

Tool/software:

Can we connect this configuration. 4 buffers are connected in parallel with master. These 4 buffers are enabled by default and trying to establish the communication. All slaves have different slave address. Bus capacitance are within the limit. Im facing bus stuck error. Kindly support to resolve the issue.

7 months ago

0 Clemens Ladisch 7 months ago

Guru 316510 points

What are the A and B sides? This configuration is OK if the A sides are on the left.

The pull-ups are probably too strong (the I²C specification has a limit of 3 mA for most buses); use 2.2 kΩ or 4.7 kΩ.

Please show an oscilloscope trace of SCL/SDA on both sides of one of the buffers.

0 Jack Guan 7 months ago in reply to Clemens Ladisch

TI__Mastermind 39986 points

Hi Ramesh,

Similar to Clemens' comments, this is acceptable as long as the B-sides of the buffer are not connected at the same node. Also see figure 8-2 for more information for this configuration. Any waveforms showing the bus stuck error would be greatly helpful here.

Regards,

Jack

0 ramesh murthy 7 months ago in reply to Clemens Ladisch

Prodigy 50 points

Yes A sides on left and B sides on right. Find the bus stuck image. Blue is SDA and pink is SCL. SDA stuck at 1.2V during communication. totally 11 slave devices connected. 3+3+3+2 on b side of 4 buffer

0 Clemens Ladisch 7 months ago in reply to ramesh murthy

Guru 316510 points

Can you show the last I²C access before the bus gets stuck?

Can you determine which device pulls SDA low?

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TCA9517A: Can we connect 4 buffer in parallel with all enabled by default