STUSB4500 not communicating on i2c or sinking power

[horatioPistachio]

I have a STUSB4500 chip which will be used to negotiate 9v out of a PD power supply (the same power supply is used to power a Pinecil which reports 9v). Unfortunately I have had several issues in getting it to work.  I am unable to communicate to the chip via i2c (unexpected nack when writing the address, the logic analyzer shows this and the ina219 on the same bus works as expected).

The chip also does not have any voltage on the 1V2 and 2V7 decoupling capacitors and does not activate (pull low) the vbus_en_snk pin. It does however read 4.6v on Vdd (5v input but voltage drop over the mosfet)

I initially believed that the chip was fried and replaced it with a spare. The spare I replaced it with turned out to be the lite version (STUSB4500L). (I purchased two batches and bought the wrong part in one of the batches). I was able to communicate via i2c with that chip(however could not negotiate 9v out of the power supply due to limitations of the lite version). Given how similar the two chips are, this makes me believe that the issue lies with the chip rather than the schematic. 

On discovering that I had put the lite version on by accident, I swapped it back to the spare STUSB4500 however the issues with the first STUSB4500 were still present. (I have 2x STUSB4500 and 2xSTUSB4500L).

The Schematic is a slightly modified version of what is suggested in the datasheet.  

Note that the schematic has 10k pullup resistors on the SDA and SCL lines however these are shown on the microcontroller sheet (esp32). When combined with the microcontrollers internal pullups, this measured around 7.2k.

Do you have any idea of what could be wrong?

Thanks for your help :)

[Didier HERROUIN · Accepted solution]

Hello,

The STUSB4500 seems correctly supplied, indeed you measure 4.5V on VDD (= VBUS - voltage drop due to the MOS internal diode). Nevertheless, you should measure 2.7V and 1.2V at regulators outputs.
It could mean that the chipset is not well soldered or in reset mode. Can you check the level of RESET signal (even if its level should be the same as STUSB4500L...) ?

Best regards,
Didier

[horatioPistachio]

Thanks Didier,

I reworked the chip by covering it in flux and reflowing with a hot air gun. It now works the treat. 

Thanks for your help :)

[Didier HERROUIN]

Good news and thank you for the feedback !