SLUAAL2 Application note

Equation 59.

G_{cv} (s) = |\frac{V_{f b} (s)}{V_{o} (s)}| = \frac{R_{f b} C T R}{R_{L E D}} (\frac{1}{(C_{1} + C_{2}) \cdot R_{1}} \frac{1 + R_{3} C_{1} s}{(1 + \frac{s R_{3} C_{1} C_{2}}{C_{1} + C_{2}}) s})

Equation 60.

\begin{array}{l} Assuming C_{2} < < C_{1}, G_{cv} (s) further simplifies to \\ G_{cv} (s) = \frac{R_{f b} C T R}{R_{L E D}} (\frac{1}{C_{1} \cdot R_{1}} \frac{1 + R_{3} C_{1} s}{(1 + s R_{3} C_{2}) s}) \end{array}

Equation 61.

This can be written as G_{cv} (s) = G_{o} (\frac{\frac{ω_{L}}{s} + 1}{1 + \frac{s}{ω_{p 1}}})

Equation 62.

where G_{o} = \frac{R_{f b} C T R}{R_{L E D}} (\frac{R_{3}}{R_{1}}) ω_{L} = \frac{1}{R_{3} \cdot C_{1}} ω_{p 1} = \frac{1}{R_{3} \cdot C_{2}}

Here $ω_{L}$ is low frequency inverted zero and $ω_{p 1}$ is a high frequency pole.