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Original question:

ADS1194: About ADS1194

ADS1194: About ADS1194 (continual query)

user6064816
Prodigy 140 points
Part Number: ADS1194
Other Parts Discussed in Thread: ADS1294

Hello.

Thank you for answering.

(1)The figure in the ADS1294 datasheet is correct. I will make a note to have this changed. 

→I understood.

(2)There is no issue or change in characteristics when using DVDD = 3.3V as opposed to 1.8V. 

→I understood.

(3)With DVDD = 0V, I would expect no response from the device, regardless of what is on the inputs. Please see the "Data Format" section for additional information. 

→Sorry, DGND=0(V) instead of DVDD=0(V).Correct the question as follows.

(Q.)

[Power Supply AVDD: +1.5(V), AVSS: -1.5(V), DVDD: +3.3(V)]
[External References: VREFN = AVSS, VREFP - VREFN = +2.5(V)]

In the case of AINN=DGND=0(V), Gain=1, will VREF, input-signal VIN, Full-Scale-Range, VIN range, ADC-Code be as follows?
・VREF=VREFP-VREFN=+2.5(V)
・VIN=AINP-AINN=AINP
・Full-Scale-Range=5(V)
・VIN range: -2.5(V) ~ +2.5(V)
・ADC-Code
(VIN : ADC-Code)
> +2.5(V) : 7FFF
+2.5/32767(V) : 0001
0(V) : 0000
-2.5/32767(V) : FFFF
<-2.5/(32768/32767)(V) : 8000

  • 0
    TI__Mastermind 47595 points

    Hi,

    I'm glad you understood and happy to help! 

    In this configuration, the Full-Scale-Range and VIN range will be limited by the power supplies as opposed to the reference voltage. The VIN range will be +/-1.5V,or 3Vpp. Using the reference of 2.5V is still fine and the code range stays the same, but not all of it will be used. 

  • 0 in reply to Alexander Smith
    Prodigy 140 points

    Hello.

    >In this configuration, the Full-Scale-Range and VIN range will be limited by the power supplies as opposed to the reference voltage.The VIN range will be +/-1.5V,or 3Vpp.

    →I understood.

    >Using the reference of 2.5V is still fine and the code range stays the same, but not all of it will be used. 

    →Does that mean the following?

    VIN > + 1.5 V (approx.) ⇒ 4CCC

    VIN = 0V ⇒ 0000

    VIN < 1.5 V (approx.) ⇒ B334

    Will the VIN range be ± 2.5V if I do the following?

    AVDD: +1.5 (V) ⇒ + 2.5 (V)

    AVSS: -1.5 (V) ⇒-2.5 (V)

  • 0 in reply to user6064816
    TI__Mastermind 47595 points

    Hi,

    VIN > + 1.5 V (approx.) ⇒ 4CCC

    →Correct

    VIN = 0V ⇒ 0000

    →Correct

    VIN < 1.5 V (approx.) ⇒ B334

    →Correct

    Will the VIN range be ± 2.5V if I do the following?

    AVDD: +1.5 (V) ⇒ + 2.5 (V)

    AVSS: -1.5 (V) ⇒-2.5 (V)

    →Correct

    Please let me know if you have additional questions and have a good weekend. 

  • 0 in reply to Alexander Smith
    Prodigy 140 points

    Thank you very much.

    I made a mistake. It was the following correctly.

    VIN < 1.5 V (approx.) ⇒ B334 → VIN < - 1.5 V (approx.) ⇒ B334

    Is there no problem with the above?

    Finally, I have a question.

    (Q.)

    (Input Condition)

    ・Power Supply: AVDD = +1.5(V), AVSS = -1.5(V), DVDD = +3.3(V), DGND = 0(V)

    ・External References: VREFN = AVSS, VREF = VREFP - VREFN = +2.5(V)

    ・InputSignal: AINN=0(V), VIN = AINP, Gain = 3

    FSR(Full-Scale-Range), VIN range, ADC-Code be as follows?

    ・FSR = ±2.5(V)/Gain = 5(V)/3 ≒ 1.667(V)

    ・VIN range ≒ -0.833(V) ～ +0.833(V)

    ・ADC-Code

    (VIN : ADC-Code)

    VIN > + 0.833(V) (approx.) ⇒ 7FFF

    VIN = 0(V) ⇒ 0000

    VIN < - 0.833(V) (approx.) ⇒ 8000

  • 0 in reply to user6064816
    TI__Mastermind 47595 points

    Hi,

    Correct and correct.