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LM5166: Output voltage accuracy

Hirotaka Matsumoto
Guru 27525 points
Part Number: LM5166

Hi all

Would you mind if we ask LM5166?

<Question1>
In case of LM5166Y(3.3V fixed), the datasheet shows REGULATION COMPARATOR is Min=3.23V and Max=3.37V.
Does it mean that output voltage accuracy is Min=3.23V and Max=3.37V?
So, does it contain COT and PFM mode?

<Question2>
Our customer uses LM5166(adj type).
And then, output voltage is 3.1V, Iout=75mA.
According to changing input voltage, output voltage changes.
-Input 12V :  3.190V
-Input 8V :  3.170V
-Input 14V : 3.220V
Our customer doesn't have wave form, however Ton depends on Vin, so Vout changes. 
Is our recognition correct?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Prodigy 700 points
    Hi Hirotaka-san,

    The regulation comparator Min/Max data are taken at 12Vin with internal set point 3.3V and reflect the "accuracy" of the IC internal comparator.
    If you ask for the application DC/DC output voltage regulation / accuracy we can look at the line and load regulation plots in the application section of the datasheet or in the EVM user guide www.ti.com/.../snvu544.pdf.

    In the LM5166 datasheet you will find in the application section 8.1 two designs.
    The plots for your customer 3.3V output voltage design you will find under 8.2.2.2.8 Application Curves in Figure 65. Converter Regulation.
    The plots for 5V output voltage design you will find under 8.2.1.2.9 Application Curves in Figure 54. Converter Regulation.

    Hope this answers your questions.

    Best Regards,
    Robert Loke
  • 0 in reply to Robert Loke
    Guru 27525 points

    Robert san

    Thank you for your reply.

    We have additional question.

    The datasheet P5 shows FB LINE-REG=0.005%/V.
    Is this condtion PFM or COT mode?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 49317 points
    Hi Hirotaka-san,

    This is a typ spec and a measure of lower FB threshold accuracy over the input voltage operating range. My understanding is that it applies to both COT and PFM modes.

    Regards,
    Tim