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UCC25705. Small-signal PWM gain.

WIM
Prodigy 10 points
Other Parts Discussed in Thread: UCC25705

Hello!
I have a question about small-signal  PWM gain of the UCC25705.
For a buck converter transfer function of the power stage is K_PWR = Vin * K_LC, where Vin - input voltage, K_LC - transfer function of the output LC-filter.
From the block diagram of UCC25705 small-signal PWM gain = (20/50) / Vsaw, where Vsaw = Vff - amplitude of "saw" and 20/50 - input divider's ratio of the PWM comparator. In voltage feedforward mode Vff = 2 * I * Rff and I = Vin / Rdisch, hence
PWM_gain * K_PWR = 0.4 / (2 * Rff * Vin / Rdisch) * Vin * K_LC = 0.4 * Rdisch / (2 * Rff) * K_LC, ie is independent of the input voltage, as it should be for the voltage feedforward mode. If an expression for the product of the transfer function of the power stage and the PWM gain is correct?

Sorry for my english and thanks.

WIM