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PCA9534A: No communication with expander

Gruffalo
Intellectual 310 points
Part Number: PCA9534A

Dear Sir or Madam,

 I am having problems getting communication with the PCA9534A. 

I see the CLK and SDA lines are pulling the commands on the i2c bus low in the correct way. the same circuit work when implemented on a different board. The only difference between the two is the power supply structure.

The expander circuit is similar to the one in the datasheet (Fig. 10-1). 

The only reason I can think of is the ramp-up speed of Vcc.

I am attaching it. Is this kind of Vcc ramp-up ok?