Operation description - boost section

LED7706

20/31

Figure 12.

Main loop and current loop diagram

The SLOPE pin allows to properly set the amount of slope compensation connecting a

starts at 35 % (typ.) of each switching period and its slope is given by the following equation:

Equation 12

To avoi-d sub-harmonic instability, the compensating slope should be at least half the slope

of the inductor current during the off-phase for a duty-cycle greater than 50 % (i.e. at the

lowest input voltage). The value of

Equation 13

0.4V

PWM

Minimum voltage drop

selector

COMP

LX

ROWx

SGND

RILIM

g

m

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

−

=

SLOPE

BE

IN

OUT

SLOPE

E

R

V

V

V

K

S

)

V

V

(

)

V

V

V

(

L

K

2

R

IN

OUT

BE

IN

OUT

SLOPE

SLOPE

−

−

−

⋅

⋅

⋅

≤