WM8952ECSSLASHRV datasheet(45/72 Pages) WOLFSON

45 / 72 page

Pre Production

WM8952

PP, Rev 3.1, June 2011

The PLL frequency ratio R = f2/f1 (see Table 33) can be set using the register bits PLLK and PLLN:

N = int R

K = int (224 (R - N))

N controls the ratio of the division, and K the fractional part.

The PLL output then passes through a fixed divide by 4, and can also be further divided by

MCLKDIV[3:0] (see Figure 24). The divided clock (SYSCLK) can be used to clock the WM8952

DSP core.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R36

PLL N value

PLL_POWERDOWN

PLL POWER

0=ON

1=OFF

FRACEN

Fractional Divide within the PLL

0=Disabled (Lower Power)

1=Enabled

5:4

PLLPRESCALE

00 = MCLK input multiplied by 2

(default)

01 = MCLK input not divided

10 = Divide MCLK by 2 before input to

PLL

11 = Divide MCLK by 4 before input to

PLL

3:0

PLLN

1000

Integer (N) part of PLL input/output

frequency ratio. Use values greater

than 5 and less than 13.

R37

PLL K value 1

5:0

PLLK [23:18]

0Ch

Fractional (K) part of PLL1

input/output frequency ratio (treat as

one 24-digit binary number).

R38

PLL K Value 2

8:0

PLLK [17:9]

093h

R39

PLL K Value 3

8:0

PLLK [8:0]

0E9h

Table 33 PLL Frequency Ratio Control

INTEGER N DIVISION

The integer division ratio (N) is determined by N[3:0] and must be in the range 5 to 12 .

If the PLL frequency is an exact integer (5,6,7,8,9,10,11,12) then FRAC_EN can be set to 0 for low

power operation.

INPUT CLOCK

(F1)

DESIRED PLL

OUTPUT (F2)

DIVISION

REQUIRED (R)

FRACTIONAL

DIVISION (K)

INTEGER

DIVISION (N)

SDM

11.2896MHz

90.3168MHz

12.2880MHz

98.3040MHz

Table 34 PLL Modes of Operation (Integer N mode)

FRACTIONAL K MODE

The Fractional K bits provides K[23:0] provide finer divide resolution for the PLL frequency ratio (up

to 1/224). If these are used then FRAC_EN must be set. The relationship between the required

division X, the fractional division K[23:0] and the integer division N[3:0] is:

K = 224 ( R – N)

where 0 < (R – N) < 1 and K is rounded to the nearest whole number.

WM8952ECS/RV Datenblatt(PDF) 45 Page - Wolfson Microelectronics plc

WM8952ECS/RV Datenblatt(HTML) 45 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72

Datenblatt Download

Link URL