Is the use of Reset and Alert Pins mandatory on STUSB4500BJR?

[Martin Leibinnis]

We are planning to use the STUSB4500BJR (WLCSP-25 package).

Since we want to avoid using micro-vias, we will not be able to fanout the inner 9 balls of the package.

This would afffect the following signals:

Pin B4 - CC1DB (not used, can be connected to ground)

Pin C4 - CC2DB (not used, can be connected to ground)

Pin D3 - ADDR0, connected to ground

Pin D2 - ADDR1, connected to ground

Pin C2 - A_B_Side, not used

Pin B2 - Alert

Pin D4 - Reset (would be hardwired to ground)

The above list only leaves the Reset and Alert pins unconnected.

Not connecting the Reset and Alert Pins would mean relying only on the I2C connection. So three question come to mind:

1. Is it safe to not use the RESET-Pin by directly connecting it to GND (with no pull-down resistor)?

2. Is it safe to not use the Alert Pin?

3. Is this a viable approach, or is there a circumstance where the RESET pin or the Alert-Pin is the only way to get the part working?

Thanks in advance,

Martin

[Gregory Go.]

Hello,

Be careful The CC1DB and CC2DB pins are mandatory:

 - CC1DB must be connected to CC1

 - CC2DB must be connected to CC2

1. Is it safe to not use the RESET-Pin by directly connecting it to GND (with no pull-down resistor)?

Yes, you can force the RESET pin to GND, to make the device always Active.

2. Is it safe to not use the Alert Pin?

Yes, Alert (IRQ) pin is optional. 

It is only useful if you want to connect the STUSB4500 to a microcontroller and having the STUSB4500 to interrupt the software.

3. Is this a viable approach, or is there a circumstance where the RESET pin or the Alert-Pin is the only way to get the part working?

No issues here, the STUSB4500 is a standalone product. So it can work without using the Reset pin or Alert pin.

[Martin Leibinnis]

Hi Gregory,

thanks for the confirmation.

 - CC1DB must be connected to CC1

 - CC2DB must be connected to CC2

Yep, I just wrote that wrong. They are already connected CC1/CC2.