SC4808B-1 데이터 시트보기 (PDF) - Semtech Corporation

부품명

상세내역

제조사

SC4808B-1

High Performance Dual Ended PWM Controller

Semtech Corporation 

SC4808B-1

POWER MANAGEMENT

Application Information (Cont.)

Below the benefits from the slope compensation become apparent. The top wave form shows the stable operation

before the perturbation. The second wave form shows the perturbation and the instability caused from it if no slope

compensation is added to the current information. The last wave form shows the slope compensation and the effect of

it. The increase in the slope of the current information results in an early termination of the inductor current, hence a

reduction in the amount of error. As the cycle is repeated, the perturbation is reduced and finally eliminated.

iδ L

I∆ L

ISense

: Small Inductor current perturbation

: Inductor current

: Sensed Mosfet current

Stable current mode operation with Slope

Compensation

D>50%

ICS

: Summation of Isense and slope compensation, at the CS pin of the SC4808.

Stable operation

( no perturbation)

I∆ L

ISense

Error Signal from Error amplifier

Instable operation

( with perturbation)

I∆ L

ISense

iδ L

Note: After a few cycles the perturbation

becomes larger, and causes instability.

Error Signal from Error amplifier

Stable operation

(Slope Compensation Added)

Note: After a few cycles the perturbation

disappears and stable operation returns.

Error Signal from Error amplifier

I I i CS

∆L

δL

 2006 Semtech Corp.

17

www.semtech.com

Share Link: