LM2698 datasheet(12/17 Pages) NSC

tên linh kiện	LM2698

Giải thích chi tiết về linh kiện	SIMPLE SWITCHER 1.35A Boost Regulator

PDF	17 Pages

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nhà sản xuất	NSC [National Semiconductor (TI)]

Trang chủ	http://www.national.com

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12 / 17 page

Operation (Continued)

If the output capacitor is of high ESR (0.1

Ω or higher), it may

be necessary to use C

C2.

A rule of thumb is that if

1/(2

πC

OUTESR) (Hz) is lower than fS/2 (Hz), CC2 should be

used. Choose C

C2 such that:

C +ROUT)(COUTESR) / (RCROUT) (F)

where R

OUT = output impedance of the error amp (875 kΩ).

Improving Transient Response Time

The above compensator design provides a loop gain with

high phase margin for a large stability margin. The transient

response time of this loop is limited by the lower

mid-frequency gain necessary to achieve a high phase mar-

gin. If it is desired to increase the transient response time,

C1 may be decreased. Decreasing CC1 by 2x, 4x, and 6x

will yield increasingly shorter transient response times, how-

ever the loop phase margin will become progressively lower

as C

C1 is decreased. When optimizing the loop gain for

transient response time, it is recommended to keep the

phase margin above 40˚.

LM2698 bảng dữ liệu(PDF) 12 Page - National Semiconductor (TI)