Connecting LDOI pins in C5505

What does the C5505 data sheet say about LDOI?

SelvaKumaran R said:

Hi,

One of my customer followed the EZDSP schematics for their design. They do not need the USB section for their design. Hence they grounded USB_LDOI (pin F13). ANA_LDOI (pin B12), DSP_LDO_IN(pin F14) are connected to +3.3V power rails...

After assembling the processor on PCB, they are finding short between VCC and GND even before powering the board. Do the above pins connected to each other internally in the proceesor. Please help.

Do we have any workaround for this issue. If we remove the F13 ball and leave it open, will DSP function normally?

Best Regards,

Selva Kumaran R

Hi,

I think you'll find the LDOI needs to always have power applied to it. According to the documentation :

The LDOI pins (B12, F13, F14) provide power to the internal Analog LDO, DSP LDO, USB LDO, the bandgap reference generator, and some I/O input pins, and can range from 1.8 V to 3.6 V. The bandgap provides accurate voltage and current references to the POR, LDOs, PLL, and SAR; therefore, for proper device operation, power

 

must always be applied to the LDOI pins even if the LDO outputs are NOT used.

Hi SelvaKumaran,

LDOI pins has to be powered even if all of the LDOs are not used at all. I am sorry that there is no work around.

Best Regards,

Peter Chung