STA529Q datasheet(20/57 Pages) STMICROELECTRONICS

Part #	STA529Q

Description	FFX™ audio codec with analog and digital inputs and 2 x 1.2 W (or 2 x 100 mW HP) class-D amplifier

PDF	57 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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20 / 57 page

PLL

STA529

20/57

Doc ID 13095 Rev 3

PLL

Figure 5 shows the main components of the PLL.

Figure 5.

PLL block diagram

6.1

Functional description

Phase/frequency detector

The phase/frequency detector (PFD) compares the phase difference between the

corresponding rising edges of INFIN and FBCLK, (clock output from the loop frequency

divider) by generating voltage pulses with widths proportional to the input phase error.

Charge pump and loop filter

This block converts the voltage pulses from the phase/frequency detector to current pulses

which charge the loop filter and generate the control voltage for the voltage-controlled

oscillator. The loop filter is placed external to the PLL on pin FILT.

Voltage controlled oscillator

The voltage controlled oscillator (VCO) is the oscillator inside the PLL. It produces a

frequency (fVCO) proportional to the input control voltage.

Input frequency

Output

frequency

divider

Loop frequency divider

CLKIN

LOCKP

fVCO

IDF

Lock detect

INFIN

FBCLK

Phase

Buffer

Fractional controller

VCO

INFIN

FBCLK

DITHER_DISABLE

FRAC_INPUT

NDIV

PHI

INFOUT

divider

Charge

REFOUT

FILT

VCONT

pump and

loop filter

STRB

STRB_BYPASS

FRAC_CTRL

frequency

divider

(PFD)

STA529Q Datasheet(PDF) 20 Page - STMicroelectronics

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