Production Data
WM8352
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
PD, February 2011, Rev 4.4
45
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
