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LT1248 PFC controller has too little gain in current amplifier?

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treez

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Hello,

In the LT1248 PFC controller datasheet,
page 7 (bottom left of page) says that the current amplifier of the LT1248 PFC controller should be compensated to have a gain of >250 at twice the line frequency (100Hz).

However, the schematic on page 7 shows that the current amplifier stage there is compensated to have a gain of just 79 at 100Hz.

This is well under 250, so have they got this wrong?

LT1248 datasheet:
https://cds.linear.com/docs/en/datasheet/1248fd.pdf
 

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Which schematic? Page 11 application circuit has gain of 360 @ 100 Hz.
 
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    treez

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treez

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I did Z(FB)/z(IN)

z(fb) = complex number based on 20k and 1nF (R -J/wC)
Z(IN) = 4K

I did it in excel, then did "imabs" and it came out as 79.
 

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