WM8352 datasheet(45/336 Pages) WOLFSON

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Production Data

WM8352

PD, February 2011, Rev 4.4

12 CLOCKING, TIMING AND SAMPLE RATES

12.1 GENERAL DESCRIPTION

The WM8352 includes clocking circuitry for the on-chip audio CODEC, the DC-DC converters and

the auxiliary ADC. It provides the following capabilities:

The WM8352 has two internal clock generators: a 2MHz RC oscillator and a 32kHz crystal oscillator.

Clocks are required for system start-up and also for the DC-DC converter clocks; these are derived

from the internal 2MHz RC oscillator. The 32kHz crystal oscillator (or external 32kHz source) is used

to drive the internal Real Time Clock (RTC), and may also be used as a reference source for the

CODEC clock generators.

The CODEC clocks may be derived either directly from MCLK, or else via an on-chip Frequency

Locked Loop (FLL) to generate the required clocking from a wide range of reference inputs. The FLL

can take as input the external MCLK, or ADCLRCLK / DACLRCLK (in Slave modes), or the 32kHz

crystal oscillator (or external 32kHz source), and generates (typically) a 12.288MHz clock for the

CODEC.

The flexible clocking arrangements are illustrated in Figure 33.

Figure 33 Clock Generation and Distribution Scheme

WM8352 Datasheet(PDF) 45 Page - Wolfson Microelectronics plc