L6911D

12/17

s

From the above equations, it results:

;

;

s

The component R3 must be chosen in order to obtain R3<<R8//R9 to permit these and successive

simplifications.

Therefore, with the droop function the output voltage decreases as the load current increases, so the DC output

sient is minimum when the output impedance is constant with frequency.

To choose the other components of the compensation network, the transfer function of the voltage loop is con-

sidered. To simplify the analysis is supposed that R3 << Rd, where Rd = (R8//R9).

Figure 8. Compensation network definition

The transfer function may be evaluated neglecting the connection of R8 to PHASE because, as will see later,

this connection is important only at low frequencies. So R4 is considered connected to VOUT. Under this as-

sumption, the voltage loop has the following transfer function:

R8

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---------------------------

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-------------------------------------

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