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TPS562212: Question about TPS562212

Jimmy Huang
Genius 3535 points
Part Number: TPS562212
Other Parts Discussed in Thread: TPS562211,

Tool/software:

Hello：

The customer originally used TPS562211 to convert 5V into various voltages (1.0V, 1.8V, 1.5V). Now the customer reported that after switching from TPS562211 to TPS562212, the ripple of 1.5V output was too large, mainly because the output ripple of the two pins VCC_1V5 and VDD_DDR was too large, causing the PG signal to become a square wave, which caused problems when enabling the subsequent 3.3 V circuit. After switching to TPS562212, the 1.0V and 1.8V circuits had no problems.

       

The customer suspected that the abnormal FB feedback bandwidth caused ripples in the startup phase. A 150uf capacitor was connected in parallel to the R289 resistor to increase the feedback bandwidth. After multiple tests, there was no problem for the time being.

   

The customer wanted to confirm whether there was a difference between the TPS562211 and TPS562212 in the application circuit. The only difference was in the Typical Application FB, 2211 is DNP, 2212 is 0 ohm R6, 10pf C7. The only difference was suspected to be related to the feedback bandwidth.

  

It is necessary to confirm the feedback bandwidth of TPS562212. What is the built-in feedback bandwidth, and what is the bandwidth range after adding 10pf.？Thanks！！！

  • 0
    Genius 4015 points

    The actual test on the client side was conducted when the chip was not completely powered off and the device was restarted.  Sometimes, it couldn't boot up normally, imitating this actual application scenario.





    1) We have communicated on-site at the client.  The current solution is to set the C7 capacitor in the reference design to 150PF for loop compensation.  However, the capacitance value of this capacitor is much larger than that in the reference design.  Could you please help confirm if this is feasible?  What is the actual value range of this capacitor?

    2) Apart from the switching frequency, what other differences are there between TPS562211 and TPS562211?

    3) Are there any other suggestions regarding the current situation



    The issue is important and urgent.  Currently, there are at least 2K boards accumulated on the client's side waiting to be handled.  Thank you!

  • 0 in reply to Tonyx.wu
    TI__Expert 5660 points

    Hi Tony,

    Below is the formula to calculate Cff

    Where Fco is the unity gain crossover frequency of the control loop without the external feedforward capacitor installed and R1 and R2 are the high-side and low-side feedback resistors.

    I see apart from Switching Frequency i don't see a major difference.

    Regards,

    Haseen.

  • 0 in reply to Haseen Reddy Siripi Reddy
    Genius 4015 points

    1）So, a value of 150PF for Cff is acceptable, right? And as long as it meets the calculation of the formula, doesn't it have a specific range of values? I remember that under normal circumstances, this Cff has a fixed value range. Please confirm it again. This matter is very important.

    2) Are there any other suggestions? The client is still checking if there are any other issues and other solutions

  • 0 in reply to Tonyx.wu
    TI__Expert 5660 points

    Hi Tonyx,

    Please go through this app note and calculate the required values.

    https://www.ti.com/lit/an/slva466a/slva466a.pdf?ts=1750826490222&ref_url=https%253A%252F%252Fwww.google.com%252F

    Reagrds,

    Haseen.