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Original question:

SM72445: How to use pin A0 to set the Max output voltage

SM72445: I2C Values for the ADC settings A0-A6

luminous
Intellectual 590 points
Part Number: SM72445

Good day

I note in the Datasheet reference is made to the ADC Config Worksheet when using the I2C to program the A0-A6 instead of using the external resistors. However, I cannot find the worksheet so cannot work out what values I can use for the various parameters.

Please can you advise.

Kind regards 

Nick

nick@heliskills.co.za

  • 0
    TI__Mastermind 46905 points

    Hi Nick,

    it is a complex device so i need more time to check your question. i would reply you by the end of this week.

  • 0 in reply to Jasper Li
    Intellectual 590 points

    Hi Jasper

    Thank you for your reply. I think I have figured out what is required.

    Where a Register value is say listed as 10'd1023 this means that in order to get the equivalent Voltage Value that is listed in the tables for say A2 or A6, one takes that listed Voltage of say:

    2.19 V 10V/1.2s Not applicable 0.006xVDDA 0.010xVDDA 1:1.2

    As listed in Table 2 for Pin A6, then

    2.19V = (RegisterValue / 1024) * 5 V since VDDA is 5 V.

    By simple rearranging one gets RegisterValue as 448 that must be Written into the associated location of the relevant Register. This will give the equivalent Voltage that would ordinarily have been created using the Resistor ladder onto A6, thereby giving greater control over the Voltages and accordingly the Setup of the SM72445.

    Unfortunately the Datasheet is just not sufficiently explicit for dummies like me - I managed to find the info in a thread on the Forum.

    The only other query I have is can I hold the 72445 in Reset until I have programmed these registers at power up, then release the Reset pin OR do I simply write all the required values and let the 72445 go through its start cycle before entering MPPT.

    Thanks again.

    Kind regards

    Nick

  • 0 in reply to luminous
    TI__Mastermind 46905 points

    Hi Nick,

    thanks for the sharing. 

    from my understanding, it should set the register firstly before releasing the Reset pin, otherwise the device will used the signal in external pins to determine the operation condition.