L6983 datasheet(18/63 Pages) STMICROELECTRONICS

部件名	L6983

功能描述	38 V, 3 A synchronous step-down converter with 17 μA quiescent current

PDF	63 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

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18 / 63 page

6.4.2

Low noise mode (LNM)

The low noise mode implements a forced PWM operation over the different loading conditions. The LNM features

a constant switching frequency to minimize the noise in the final application and a constant voltage ripple at fixed

VIN.

The regulator in steady loading condition operates in continuous conduction mode (CCM) over the different

loading conditions.

The triangular shape current ripple (with zero average value) flowing into the output capacitor gives the output

voltage ripple, that depends on the capacitor value and the equivalent resistive component (ESR). Consequently,

the output capacitor has to be selected in order to have a voltage ripple compliant with the application

requirements.

VOUT RIPPLE=ESR∙∆ILMAX+ ∆ILMAX

8∙COUT∙fSW

(3)

Usually the resistive component of the ripple can be neglected if the selected output capacitor is a multi-layer

ceramic capacitor (MLCC).

Figure 13. Low noise mode operation at zero load

L6983

Light-load operation

DS13116 - Rev 1

page 18/63

L6983 数据表(PDF) 18 Page - STMicroelectronics