treez
Advanced Member level 5
Hello,
Please assist with the expression for the transfer function of the modulator and error amplifier of this TL431 based feedback loop for a TOPswitch Flyback from Power integrations.
It looks like they are mixing in decibel numbers and “normal” numbers in the same expression?
The modulator and error amplifier circuit is shown as attached on page 466. Page 467 (Equn 8.35) shows the transfer function. However, Equn 8.35 on page 467 shows the parameter “G0”.
“G0” is shown in Equn 8.36 on page 467.
“G0” comprises the “Gpwm” parameter which is shown on page 455 (also attached)
The question is, “Gpwm” is a decibel number…… Why are they putting a decibel number into equation 8.35 on pg 467?
…..Equn 8.35 (pg 467) is an expression that needs to be calculated, (working through the complex numbers), and then that should have a log taken of its magnitude to express it in decibels…..so why is “Gpwm” in there as a decibel number already?
(by the way the pages are from a single SMPS book)
Please assist with the expression for the transfer function of the modulator and error amplifier of this TL431 based feedback loop for a TOPswitch Flyback from Power integrations.
It looks like they are mixing in decibel numbers and “normal” numbers in the same expression?
The modulator and error amplifier circuit is shown as attached on page 466. Page 467 (Equn 8.35) shows the transfer function. However, Equn 8.35 on page 467 shows the parameter “G0”.
“G0” is shown in Equn 8.36 on page 467.
“G0” comprises the “Gpwm” parameter which is shown on page 455 (also attached)
The question is, “Gpwm” is a decibel number…… Why are they putting a decibel number into equation 8.35 on pg 467?
…..Equn 8.35 (pg 467) is an expression that needs to be calculated, (working through the complex numbers), and then that should have a log taken of its magnitude to express it in decibels…..so why is “Gpwm” in there as a decibel number already?
(by the way the pages are from a single SMPS book)
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