´

³

´

OUT

SW

X

V

ESR

20mV

f

L

V

VDDQSNS

V

REFIN

(1)

(2)

t

ON

t

OFF

Slope (2)

Jitter

20 mV

Slope (1)

Jitter

UDG-10139

V

REFIN

+Noise

TPS51916

SLUSAE1D – DECEMBER 2010 – REVISED JUNE 2012

www.ti.com

Jitter is another attribute caused by signal-to-noise ratio of the feedback signal. One of the major factors that

determine jitter performance in D-CAP™ mode is the down-slope angle of the VDDQSNS ripple voltage.

Figure 36 shows, in the same noise condition, that jitter is improved by making the slope angle larger.

Figure 36. Ripple Voltage Slope and Jitter Performance

For a good jitter performance, use the recommended down slope of approximately 20 mV per switching period as

shown in Figure 36 and Equation 2.

where

•

•

(2)

18

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