L6910A L6910

10/21

Figure 7. Compensation Network

the highest 0dB crossing frequency to have fast response (but always lower than fsw/10) and the highest gain

in DC conditions to minimize the load regulation.

A stable control loop has a gain crossing with -20dB/decade slope and a phase margin greater than 45°. Include

worst-case component variations when determining phase margin.

To locate poles and zeroes of the compensation networks, the following suggestions may be used:

Modulator singularity frequencies:

Compensation network singularity frequency:

– Put the gain R5/R3 in order to obtain the desired converter bandwidth;

–Place

–Place

–Place

–Place

– Check the loop gain considering the error amplifier open loop gain.

Vin

L

ESR

Cout

R3

R5

C19

EAREF

Vcomp

PWM

Comparator

Vout

∆Vosc

R4

C18

C20

+

-

ω

LC

1

LC

OUT

⋅

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

ω

ESR

1

ESR C

OUT

⋅

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

==

ω

P1

1

R5

C18 C19

⋅

C18

C 19

+

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





⋅

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

ω

P2

1

R4 C 20

⋅

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

==

ω

Z1

1

R5 C19

⋅

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

ω

Z2

1

R3

R 4

+

() C20

⋅

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

==