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Could you tell me about TPS62240's output voltage accuracy?

Pokkun
Genius 4695 points
Other Parts Discussed in Thread: TPS62240, TPS62560, TPS62097

Hello.
My customer is currently in using TPS62240,now.

＜Question＞

1. The customer have requested that is fit to ±3.0% at output voltage accuracy(within including the Ripple),while maintaining a high efficiency(must PFM Mode).

   What percentage is the output voltage accuracy at the time of PFM Mode operation in the worst case?

By the way , that VFB accuracy will be fit to ± 3.0% is confirmed


< Customer specification conditions >
VIN: 5.0V ± 3.0%
VOUT: 3.1V ( less than ± 3.0%)
※ RFB1 / RFB2 using ± 0.5% resistance accuracy
IOUT: 0.1A@MAX
COUT = 10uF
Temp: -40 ~ 125 ℃

2. Also, I have that this(TPS62240 / TPS62560) was heard the same Chip.

     Does TPS62240 have a DVP (Dynamic Voltage Positioning)?

Could you help us?

Best Regards,

Pokkun

  • 0
    TI__Guru*** 147320 points
    Yes, the TPS62240 can work here. There is no DVP as shown by the 0% spec under the 1.5% accuracy line.

    The TPS62097 would be another device to look at. It is in the same size 2x2 package as well as having a tighter Vout accuracy (and a PFM spec).
  • 0 in reply to Chris Glaser
    Genius 4695 points
    Chris, Thank you for Immediate reply !


    Sorry , I want to question involved a little more just TPS62240.


    If The customer wants to use the TPS62240 in VOUT accuracy of fit to ±3.0%(at the PFM operation and Including Ripple voltage),
    is it available?
    ※However , with the following specifications range .

    ＜Customer specification conditions＞
    VIN: 5.0V±3.0%
    VOUT:3.1V(less than ±3.0%)
    ※ RFB1 and RFB2 using ±0.5% accuracy resistance
    IOUT: 0.1A@MAX
    COUT：10uF
    Temp:-40～125 ℃


    Please help me!
  • 0 in reply to Pokkun
    TI__Guru*** 147320 points
    I'm sorry, but your question is still not clear to me. Do you want to understand if a device will meet the above specification and how to show that?

    The first question is back to the customer: what does the +/-3% include? It seems like it does include temperature variations and ripple, but it is unclear if transients are also included or not.

    In any case, this app note shows how the accuracy of the FB resistors affects the overall accuracy: www.ti.com/.../slva423.pdf

    This is summed with the 1.5% output voltage tolerance in the D/S.

    Then, you have the ripple component which is usually very small but can average up the output voltage a little (compare figure 11 to figure 14).

    Lastly, you have line and load reg which are also very small as shown in the above figures.
  • 0 in reply to Chris Glaser
    Genius 4695 points
    Chris, Thank you for Immediate reply !

    I'm already considered for "Effect of Resistor Tolerances".　⇒　www.ti.com/.../slva423.pdf

    However , we have a concern that the fit to ±3.0% when considering the ripple during PFM.
  • 0 in reply to Chris Glaser
    Genius 4695 points
    I'm sorry ,Chris.
    I change the question .


    ★How long is it about the "on-time" ?
    ※See of Data Sheet - p8 - "8.4.2 Power Save Mode"
  • 0 in reply to Pokkun
    TI__Guru*** 147320 points
    The ripple in PFM is very low as you can see in Figures 19 and 20. It can be further reduced by increasing the output capacitance.

    There is no equation for estimating the ripple in PFM mode.
  • 0 in reply to Chris Glaser
    Genius 4695 points
    Thanks for the answer , Chris!

    The ripples calculation is difficult in the PFM operation .


    (Apr 12, 2016 4:10 AM)
    ↑ For this question also , please tell me ！


    Pokkun @ MRB
  • 0 in reply to Pokkun
    TI__Guru*** 147320 points
    The on time in PFM is not quite as long as twice the PWM mode on time. The PWM mode on time is, of course, D * the period.

    Again, I don't think it's possible or needed to compute a ripple magnitude. You meet your 3% need as is.