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REF4132: ADC128S052 Recommended Reference IIC

Shuji Ishiwata
Mastermind 8060 points
Part Number: REF4132
Other Parts Discussed in Thread: ADC128S052, LM4128, LM4132

Hi All,

I have a question about LM4128A and REF4132.

(1)The recommended reference IC when using the ADC128S052 is LM4128A as a result of checking with ADC-TO-VREF-SELECT.
If you search for LM4128A on the product page, you will find REF4132 as a new version.
Which is better, LM4128AMF or REF4132, when using ADC128S052?
Also, are there any precautions to take when changing from LM4128AMF to REF4132?

(2)The result of the load response of LM4128A (left) and REF4132 (right),
I think REF4132 is worse. Why is the result of REF4132 bad?
For example, the conditions are different.


(3)There is an overshoot in the red frame of Fig.13 of REF4132 datasheet.
Is this a characteristic of REF4132? Please tell me the reason for overshoot.


Best Regards,
Ishiwata

  • 0
    TI__Genius 11401 points

    Hi Ishiwata 

    • Load is switching  from -10 to +10mA in case of REF4132 whereas it is 0 t0 10mA in case of LM4128.Transient  behavior gets poorer when load switch from sourcing to sinking. But the transient settles much faster compare to LM4128. 
    • Overshoot is device property. You can include that in startup time. Once it settles, the device will function normally. 

    Can you please explain your system requirement. We will help you with it. 

    Regards

    Trailokya 

  • 0 in reply to Trailokya Rai
    Mastermind 8060 points

    Hi Trailokya,

    Thank you for your answer.

    Regarding load response, I understand that different load conditions give different results.
    I also found that REF4132 has better transients.
    I understand that overshoot is a product-specific property of REF4132.
    Please answer the question (1) again.

    I have additional questions.

    (4)The data sheet of LM4132 describes the result of the rise time when the output capacitor is changed.
    Is there any data that shows the rise time when the output capacity of LM4128A and REF4132 are different as well?

    (5)The REF4132 datasheet does not have a 3.3V characteristic diagram.
    Is there any document showing the characteristics of 3.3V?


    I am very grateful for your support.


    Best Regards,
    Ishiwata

  • 0 in reply to Shuji Ishiwata
    TI__Genius 11401 points

    Ishiwata 

    Below are the answers to your questions - 

    1> REF4132 has superior performance compare to LM4128. REF4132 will give better accuracy compare to LM4128. REF4132 can support max +10mA load whereas LM4128 can support +20mA and max Drop out of REF4132 is 100mV higher compare to LM4128.  

    4> REF4132 is shows startup plot  with 10uF capacitor. It will reduce as the capacitor decreases. Can you please tell me your load capacitor, I will tell you the rise time .

    5> REF4132 shows common table for all the variant. 3.3V will follow the data table characteristic. 

    Regards

    Trailokya   

  • 0 in reply to Trailokya Rai
    Mastermind 8060 points

    Trailokya,

    Thank you for your reply.

    (4)
    The capacitor capacity is undecided.
    The customer wants to see how much the rise time changes when the capacitor capacities of the LM4128A and REF4132 are changed.
    Please tell me the rise time as a guide. For example, in the case of 5uF or in the case of 1uF, etc.

    Thank you for your wonderful support.

    Best Regards,
    Ishiwata

  • 0 in reply to Shuji Ishiwata
    TI__Genius 11401 points

    Ishiwata 

    Let's discuss this over mail. 

    Regards

    Trailokya