PM6680 datasheet(40/49 Pages) STMICROELECTRONICS

Teilenummer	PM6680

Bauteilbeschribung	No Rsense dual step-down controller with adjustable voltages for notebook system power

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Hersteller	STMICROELECTRONICS [STMicroelectronics]

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Device description

PM6680

40/49

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 uH, Cout = 330 uF with Rout ≈ 12 mΩ.

We design RESR = 12mW. We choose CINT = 1nF 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.35) and R1 = 3 kΩ

(eq.36).

7.13.7

Other parts design

●

VIN filter

A VIN pin low pass filter is suggested to reduce switching noise. The low pass filter is

shown in the next figure:

Figure 38.

VIN pin filter

Typical components values are: R = 3.9

Ω and C = 4.7 uF.

●

VCC filter

A VCC low pass filter helps to reject switching commutations noise:

ESR ×

−

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

VIIN

Input

voltage

PM6680 Datenblatt(PDF) 40 Page - STMicroelectronics