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OPA333: Auto-zeroing function and auto calibration function

Hirotaka Matsumoto
Guru 27545 points
Part Number: OPA333
Other Parts Discussed in Thread: OPA335

Hi all

Would you mind if we ask OPA333?

<Question1>
What is the difference auto-zeroing function(OPA335) and auto calibration function(OPA333)?
Is that the same?

<Question2>
In relation to <Question1>, in case of auto-zeroing = auto calibration, on the following document, about the figure Auto zero(OPA335), there are some SWs.
http://www.tij.co.jp/jp/lit/an/jaja017/jaja017.pdf
On OPA335's datasheet, there is the description "This  amplifier  is  zero-corrected  every  100µs  using  a proprietary technique."
So, it occurs switching operation every 100us, right?

<Question3>
If you have the detail content of auto-zeroing function(and auto calibration function), could you give us it?

<Question4>
Does Auto-zeroing function(or auto calibration function) have any temperature effect?
The customer will use the device with following temparature condtion.
Temparature range : -30C～60C
So, if you have some temperature characteristics for this function, could you give us it?

<Question5>
The customer are looking for zero drift amp without auto-zeroing function or auto calibration function.
If you have know these devices, could you let us know?
(We assume that it doesn't exist.)

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Expert 6275 points

    See attached article for a good discussion of auto-zero vs chopper topology.  If you can give us some more customer application details we can recommend best part and circuit for customer. Auto-zero or Chopper correct offset over temperature per the datasheet specs and curves.

    Final Application Requirements:

    Power Supply:

    1) Single or Dual?

    2) Voltages?

    3) Switching DC/DC or Linear LDO?

    Input Signal:

    1) Magnitude (peak or peak to peak?) & Voltage or Current?

    2) Frequency Range?

    3) Signal source impedance?

    4) If pulse input, rise/fall times and duty cycle, and amplitudes?

    Output Signal:

    1) Magnitude (peak or peak to peak?) & Voltage or Current?

    2) Frequency Range?

    3) If pulse Output, rise/fall times and duty cycle, and amplitudes?

    Output Load:

    1) Resistive, Capacitive, Inductive?

    2) Input to ADC?  ADC part number, sample rate?

    Other:

    1) Ambient operating temperature range?

    2) If input is sensor:

    a. Sensor voltage or current amplitude range?

    b. Sensor signal frequency range?

    c. Sensor type and datasheet

    slyt204.pdf

  • 0 in reply to Tim Green1
    Guru 27545 points

    Tim san and team member

    Thank you so much for your reply.

    We will confirm these things, and feed back you.
    We will send these infromation using private message on E2E because these infromation contain customer's confidential contents.

    And then, could you give us the reply about <Question1>, <Question2> and <Question4> previously?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Tim Green1
    Guru 27545 points

    Tim san

    We sent you detail contents.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Expert 6275 points
    I have replied on the private conversation.
    With regards to your questions:
    1> See slyt204.pdf
    2> Auto-zero frequency of correction is 10kHz
    4> Datasheets will show temperature Vos Drift, etc. In general auto -zero or chopper are very good for Vos and Vos drift since they are always correcting for this offset and they also have no 1/f noise, just flat broadband noise all the back to DC.