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REF3233: The output voltage question for REF3233

Mickey Zhang
Genius 12080 points
Part Number: REF3233
Other Parts Discussed in Thread: REF3433

Hi team,

The customer uses REF3233. The attach is his schematic. The output voltage of REF3233 is connected to ADC.

The input voltage is 3.8V. The ENABLE pin is controlled by the GPIO of MCU. The GPIO pin can send a 3.3V

level voltage to the ENABLE pin. 

When the output is no load, the output voltage is unstable. The output voltage can be 3.294V or 3.28V or 3.26V. 

Would you explain this?

Best Wishes,
Mickey Zhang
Asia Customer Support Center
Texas Instruments

  • 0
    Guru 140200 points
    Hi Mickey,

    this REF3233 is known for problems when the power-on rise time violates the datasheet recommendations. I would take another voltage reference...

    Kai
  • 0
    TI__Mastermind 19370 points
    Hi Mickey,

    I agree with Kai. The REF3233 has a sensitive power-on rise and can be difficult to debug. If the REF3233 can momentarily draw currents greater than the typical quiescent current on start-up which can have problems with slow ramp supplies. Does the customer have a slow ramp supply for Vin?

    My recommended solution would be the REF3433 which is drop in P2P, better specifications, lower cost device.

    -Marcoo Z
  • 0 in reply to Marcoo Z
    TI__Genius 12080 points
    Hi Marcoo,

    Thanks for your reply. What is P2P that you said?

    I note the Figure 20 of the datasheet, but there are no the recommend values of C1 and R1 for REF3233.

    Does you mean that the customer should add R1 and C1 which is in the figure 1 of the datasheet?
  • 0 in reply to Mickey Zhang
    Guru 140200 points
    Hi Mickey,

    I think Marcoo is saying that you should use the REF3433 instead of the REF3233.

    Kai
  • 0 in reply to Mickey Zhang
    TI__Mastermind 19370 points
    Hi Mickey,

    Table 1 on pg 9 of the REF3233 datasheet has recommended values for R1 and C1. The issue is that these values assume a fast rise time.
    The simplest solution would be to just replace the REF3233 with the REF3433. P2P stands for pin to pin compatible. This means that you can replace the REF3233 and use a REF3433 because they have the same pinout and foot print.

    -Marcoo Z