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AMC80 questions

Takumi Suzuki1
Mastermind 8610 points
Other Parts Discussed in Thread: AMC80, LM96080, LM80

Hi,

 

I would like to ask you some questions about AMC80 as below.

 

Q1) What is the difference between LM80, LM96080 and AMC80?

 

Q2) Data read out cycle time condition of AMC80

Is there a restriction time to access “Value RAM” to read ADC data?

For example, about LM80, there is a limitation to access that is “120mSec”. (LM80 Datasheet page 14)

 

Q3) The usage of Register 0Ah

I do not understand well about “ADC control register”(0Ah).

I suppose this register has a relation to “conversion rate” (07h register).

Could you tell me how to use it?

 

Best Regards,

 

  • 0
    TI__Expert 7220 points
    Hi Takumi,

    A1) The LM80 is the original hardware monitor IC. The LM96080 is an improved version of the LM80 with the same package and pinout. Differences include a wider VDD range, improved temperature sensor resolution, and an option to change the conversion rate. The AMC80 is based on the LM96080 and is almost identical besides a few extra registers that controls sampling rates and input modes.

    A2) The AMC80 has a conversion time of up to 810ms (max) to convert all the ADC channels, temperature, and tachometer readings. We recommend waiting at least 810ms between readings for the part to update the register contents.

    A3) I will get back to you on this.

    -Michael Wong
  • 0
    TI__Expert 7220 points
    A3) Register 0x0A bits [5:3] sets the input voltage range of the ADC. Bits [2:0] sets the conversion rate of the ADC.

    -Michael Wong
  • 0 in reply to Michael Wong
    Mastermind 8610 points

    Hi Michael-san,

     

    Thank you very much for your reply!

     

    Can I ask you some extra questions as below to understand well?

     

    EQ1) Cycle time

    I understood that we should wait at least 810mSec to get all right data.

    But in case of less time of 810mSec to access, what is happened?

    • The data we got is invalid?

    • The current AD conversion is terminated?

      If yes, do we have to re-start ADC?

       

      EQ2) Register 0x0Ah, Bits[2:0]

      We can change the ADC conversion time by these 3 bits, right?

      What is the difference by changing ADC conversion rate?

      For example, the ADC accuracy(Bit) is changed? (worse when the rate is faster?)

      Or nothing is changed by ADC speed? Just ADC speed is changed?

       

      EQ3) Register 0x07h/0x0Bh : Conversion Rate Register/Conversion Rate Count Register

      I think that we can change the “Total conversion time” (default setting (CR1=1, 0x07h) is 728mSec typ) by this register setting.

      If we need to readout all data every 10mSec, I suppose that we should set “0” to 0x0Bh and bit0 of 0x07h.

      That is to say, in this case, conversion rate is set to 8.52mSec (= 1.42*(8*0+6)).

      Is my idea correct?

       

      EQ4) seems to be typo, register 0x0Bh (Table14 description)

      I suppose the following description seems to be typo…

      0000000 = 0, 0000001 = 1, …….., 1111111 = 256

      Probably following is correct, I think.

      00000000 = 0, 00000001 = 1, ….. , 11111111 = 256

      Sorry to ask you slight question.

       

      Thank you for you support.

      Best Regards,

  • 0 in reply to Takumi Suzuki1
    TI__Mastermind 37370 points
    Hi Takumi-san,

    Let me review this, and get back to you.

    Aaron
  • 0 in reply to Aaron Heng
    Mastermind 8610 points

    Hi Aaron-san,

    Could I ask you about the situation??

    Sorry to ask you again.

    Regards,

  • 0 in reply to Takumi Suzuki1
    TI__Expert 7220 points
    Hi Takumi-san,

    EQ1) If a request to read the ADC comes before the 810ms conversion time then the previous conversion data will be read. The current conversion data will be updated to the register after the I2C communication is completed.

    EQ2) Yes these three bits change the conversion rate of the ADC. The conversion rate of the ADC depends on the signal being read. The customer will need to characterize the signal being read and select the best conversion rate for their system.

    EQ3) This is correct.

    EQ4) This is also correct.

    -Michael Wong
  • 0 in reply to Michael Wong
    Mastermind 8610 points
    Michael-san,

    Thank you so much!

    Regards,