ADAU1701 IOVDD, PVDD and AVDD Minimum operating voltage

Hello Nir,

The spec is somewhat hidden. +/- 10% is the range. 

If you look at the bottom of table 3 you will see a note there. 

IOVDD is not mentioned but it is also +/- 10%. 

I know that it should have been in the datasheet in the tables. If I had written this I would have done it that way.

Dave T

Hi Dave,

If you had written it the right way...then you had no job in product support :)

Anyway... I actually saw this note, just couldn't understand why it only refers to DVDD, AVDD and not to PVDD and IOVDD.

You wrote that IOVDD minimum operating voltage is also 3.3V +/-10%, but what about PVDD?

Assuming that PVDD can also be powered from 3.0V supply, I have another more complex question:

Lets say that all of the PCB components (DSP, MCU, EEPROM, POR etc...) can operate from 3.0V supply, I still have a problem connecting the USBi board, because obviously using 3.0V changes the logic levels from 3.3 down to 3.0V.

And yet, the USBi board runs on 3.3V I/O levels (taken from AN-1006):

Now, the way I see it, I have three options:

1- connect the USBi board as is, and assume the DSP and EEPROM can tolerate 3.3V logic levels, when powered from 3.0V (from damage perspective and logic levels recognition perspective)

2- Add a bidirectional level translator on all of the USBi relevant pins (SCL, SDA, RESET) 

3- Modify the USBi to operate at 3.0V, by replacing the LDO with a pin compatible one.

Option 3 is the most easy way, I only have to deal with one component...the big question, which I understand could be difficult to answer, is what will happen if I replace the LDO from 3.3V to a fixed 3.0V...

So, My questions are:

1- PVDD is ok with 3.0V?

2- Will the USBi board can operate at 3.0V?

Thanks again,

Nir 

Hi Dave,

If you had written it the right way...then you had no job in product support :)

Anyway... I actually saw this note, just couldn't understand why it only refers to DVDD, AVDD and not to PVDD and IOVDD.

You wrote that IOVDD minimum operating voltage is also 3.3V +/-10%, but what about PVDD?

Assuming that PVDD can also be powered from 3.0V supply, I have another more complex question:

Lets say that all of the PCB components (DSP, MCU, EEPROM, POR etc...) can operate from 3.0V supply, I still have a problem connecting the USBi board, because obviously using 3.0V changes the logic levels from 3.3 down to 3.0V.

And yet, the USBi board runs on 3.3V I/O levels (taken from AN-1006):

Now, the way I see it, I have three options:

1- connect the USBi board as is, and assume the DSP and EEPROM can tolerate 3.3V logic levels, when powered from 3.0V (from damage perspective and logic levels recognition perspective)

2- Add a bidirectional level translator on all of the USBi relevant pins (SCL, SDA, RESET) 

3- Modify the USBi to operate at 3.0V, by replacing the LDO with a pin compatible one.

Option 3 is the most easy way, I only have to deal with one component...the big question, which I understand could be difficult to answer, is what will happen if I replace the LDO from 3.3V to a fixed 3.0V...

So, My questions are:

1- PVDD is ok with 3.0V?

2- Will the USBi board can operate at 3.0V?

Thanks again,

Nir 

Hello Nir,

We test everything to +/- 10% so it should be fine at 3.0V. But it is close to -10% so make efforts to be sure the power supply will not be much lower than 3.0. 

I would expect the USBi to also work at 3.0V. We have not tried that but it works at 1.8V so I see no reason why it would not work at 3.0V.

Dave T

Hi Dave,

Great news! 

I will use an adjustable LDO so I can set it just slightly above 3.0V (maybe 3.05V) so it covers all tolerances (temperature, load/line regulation etc...)

I will try to modify both EVAL-ADAU1701MINIZ and USBi control interface board to work with 3.0V and try this for real.

Thanks again,

Nir