The reason of the mysterious I2C probe problem

HI

I have found the reason of the I2C probe failure.

The main reason is the setting up time!

This I2C chip needs a 50us to 150us setup time.

But the typical setting time of VER_SP3 is 500us.

We double checked this time by oscilloscope(1).

 

There are three solutions for this issue.

One:

The typical setting time of VER_WIFI is 100us(2).

This VREG_WIFI could match the requirement of the chip.

But VREG _WIFI could not be shut down during none sleep time.

 

Two:

We can use an extra MOS and a GPIO to control the VDD(3).

But need add one more component and use one more gpio.

 

Three:

Find one useless VREG for the chip.

(1)

(2)

(3)