8RDA+ Vdd mod: Vout calculation

[KS1]

Vdd out = 1.6 + 176/R ..... (a)
where R is the value of the resistor you want to use.

Alternatively, you can also derive R from V that you want:
R = 176/(V-1.6) .................(b)

Source: (a) and (b) is derived from page 5 of IRU3037 datasheet:
Vout = Vref x (1 + R6/R5) .......(c)
where Vref = 0.8V
R6 and R5 = 220 ohms (resistors installed on 8RDA+)

I hope this helps esp. for those who want to use a fixed value resistor.

[eliteone]

You lost me dood O_o. If I get 1.6V by default...what would I get by using a 540ohm resistor? I'm sitting at 1.85 now with a 680ohm.

[k1114]

Great info, added it to my FAQ! (Of course you were given full credit in the "credits" section :D )

[dykz34]

By my calculations (since I have a 1.568 right now), if I wanted to get 1.8 I would need a 758ohm (give or take) resistor? 176/(1.8-1.568)=~758

[KS1]

Eliteone,

If you use a 540 ohm resistor, you should get about 1.92V.
Do you get 1.85V reading from USDM/BIOS or DMM?
If you read from USDM or BIOS, try using a DMM at Voutput.

Anyway, the calculation and the actual reading might not be exactly the same due to standard error of each component e.g. resistors, volt regulator etc. But I am sure that the result is very close to what you would get.