CYW43907 internal LDO as VDDIO

[Yanyan]

Hi

I'm using the CYW43907 in a custom board. 

The MCU is powered from a buck that converts to 3.6V.

But for the VDDIO, I want voltage of 3.3V, because the MCU communicates with components with logic of 3.3V.

I don't want to add an external LDO, so I want to use the internal LDO (LDO3P3). My question is can I use LDO3P3 to power VDDIO, or do I have to use an external source.

Thanks

[Vivek_gunapati]

Hi ,

From the description we understand that you would like to use the CYW43907's internal LDO to source the VDDIO. From the datasheet  https://www.cypress.com/file/298236/download#page=33 we see the Pin 118 is an LDO out pin. 

Currently we are checking with the internal team if we could use the 118 Vout_3p3 to source the other VDDIO pins in LDO3P3 internal LDO mode. 

Regards

Vivek.

[Vivek_gunapati · Accepted solution]

Hi Yanyan,

Please find the feedback below

1. The design need to consider how much DC the VDDIO needs to supply. If the design connects too many I/O pins, then the internal vout_3p3 may not be enough to source DC current, it would make it be dropped too much.
2. It may introduce I/O noise from other I/O pins if the design connects vout_3p3 to supply other I/O pins.

Regards

Vivek.