• Resolved

UCC28C45-Q1: Trimming of Flyback Controller UCC28c4x

Prodigy 30 points

Replies: 2

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Part Number: UCC28C45-Q1

I am using the Flyback Controller UCC28C45-Q1 and want to improve accuracy with additional external Control Components.

Datasheet mentiones that the reference Voltage is trimmed to +/-1% accuracy.

Is the 2.5V reference for the error amplifier trimmed itself or is the 5V output reference trimmed and the 2.5V is a fixed 50% from the trimmed 5V?

In case of that: how much is the 2.5V reference for the error amplifier deviating from 50% of the trimmed 5V reference? (initial, drift?)

In case the 2.5V reference is a fixed 50% from the trimmed 5V then my goal is to can make the design much more accurate than 1% because then I can use a external control loop with theoretical exact 50% match of the 5V reference output. Is that possible?

  • Hi Gregor,

    The error amplifier's noninverting input 2.5 V ±1%  is divided down internally from the reference voltage 5 V ±1%. I don't think it can get the more accuracy  if  the reference voltage of error amplifier is still exact 50% of 5 V ±1% reference voltage.  if you want to get a extreme accuracy, it is better to use an external reference afforded by the additional device.



  • In reply to Teng Feng:

    Hi Teng

    Thanks for the response.

    We will now add an external Error Amplifier on the secondary side of the Flyback with own Reference and let the UCC28C45 run with low gain only.

    This will eliminate the 1% and the drift down to the tolerance of our own reference and Errors of our Circuit on the secondary side.

    Thanks for your help.