PM6680ATR datasheet(38/48 Pages) STMICROELECTRONICS

部件名	PM6680ATR

功能描述	Dual synchronous step-down controller with adjustable output voltages plus LDO

PDF	48 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

标志

38 / 48 page

Design guidelines

PM6680A

38/48

Equation 30

where RTOT is the sum of the ESR of the output capacitor Rout and the equivalent ESR given

by the virtual ESR network RESR.

Moreover CINT must meet the following condition:

Equation 31

Where k is a free design parameter greater than 3 and determines the minimum integrator

capacitor value CINT:

Equation 32

C must be selected as shown:

Equation 33

R must be chosen in order to have enough ripple voltage on integrator input:

Equation 34

R1 can be selected as follows:

Equation 35

Example:

OUT1=1.5 V, fSW = 290 kHz, L = 2.5 µH, Cout = 330 µF with Rout < 12 mΩ.

We design RESR = 12 mΩ. We choose CINT = 1 nF by equations 30, 33 and Cfilt = 47 pF,

RINT = 1 kΩ by eq.27, 28. C = 5.6 nF by Eq.34. Then R = 36 kΩ (eq.34) and R1 = 3 kΩ

(eq.35).

TOT

out

TOT

out

OUT

INT

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

INT

ESR ×

−

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

PM6680ATR 数据表(PDF) 38 Page - STMicroelectronics

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