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TPS3421EGEVM-156: Using TPS3421 Evaluation Board to Evaluate TPS3420

Katelyn Jobes
Prodigy 10 points
Part Number: TPS3421EGEVM-156
Other Parts Discussed in Thread: TPS3420, TPS3421, TPS3422

Per the TPS3421EGEVM-156 Evaluation Module manual, the evaluation module can be modified to evaluate the TPS3420 by removing R1 and R2, and shorting TS to GND. Based on Figure 6, RST should stay low until PB1 is released and goes high. 

After making the modifications, I am seeing that RST is not staying low for the duration of the pushbutton hold, but is instead going high after 400ms, which is the intended behavior of the TPS3421, not the TPS3420.

Is this the intended behavior of the evaluation module in TPS3420 mode?

  • 0
    TI__Genius 12890 points

    Hi Katelyn,

    Yes, the 400ms Reset pulse width is only applicable on the TPS3421 and TPS3422. The TPS3420 de-asserts the Reset when PB1 and/or PB2 is release after being held for 7.5s first. The Reset de-assertion happens without delay after condition is met. Just to be safe, could you please double check that you are using a TPS3420, also could you please probe TP1 and TP2 just to make sure the button does not release unexpectedly. I will also test the TPS3420 on my EVM as well to check on my side.

    Jesse  

  • 0 in reply to Jesse Villanueva
    Prodigy 10 points

    Hi Jesse, 

    I am using the TPS3421EGEVM-156 evaluation module, which is populated with a TPS3421. According to the EVM product description and user guide, it can be modified to evaluate the TPS3420. Due to the current stock situation, I have not been able to obtain a TPS3420 for evaluation, which is why I am using the TPS3421 EVM to evaluate the TPS3420

    I am measuring the reset pin, and the reset is consistently 400ms. The automatic reset de-assertion is a problem for what I am trying to test. 

    Katelyn

  • +1
    TI__Genius 12890 points

    Hi Katelyn,

    Unfortunately, the steps outline in section 7 of the user manual only provides the steps if you replace the TPS3421 in the TPS3421EGEVM-156 with a TPS3420. The removal of the R1 and R2 is necessary because the PB1 and PB2 of the TPS3420 has a different architecture than the PB1 and PB2 of the TPS3421. 

    Jesse