Device description

L6911E

20/34

Considering the previous relationships R2, R3, R8 and R9 may be determined in order to

obtain the desired droop effect as follow:

●

Choose a value for R2 in the range of hundreds of K

Ω to obtain realistic values for the

other components.

●

From the above equations, it results:

Equation 15

Equation 16

●

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

the output voltage deviation under load transient is minimum when the output impedance is

constant with frequency.

R8

∆V

+

R2

⋅

V

PROG

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

R

L

I

MAX

⋅

V

DROOP

∆

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

⋅

=

R9

R8

=

V

DROOP

∆

R

L

I

MAX

⋅

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

1

1

V

DROOP

∆

R

L

I

MAX

⋅

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

+

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

⋅⋅