ST18-AU1 STMICROELECTRONICS [STMicroelectronics], ST18-AU1 Datasheet - Page 51

• Manufacturer Part Number: ST18-AU1
• Description: SIX-CHANNEL DOLBY AC3/MPEG2 AUDIO DECODER
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

13 CLOCKS AND TIMERS UNIT
The clocks and timers unit provides all the necessary clocks and timer controls for DSP
processing, and all input/output operations. In addition, a 90 kHz System Time Clock (STC) is
provided to assist audio/video synchronization in systems which include a video decoder.
13.1 Operation
13.1.1 Audio clock prescaler
The programmable prescaler and clock dividers of Data Input and PCM Output interfaces are
used for the generation of data bit clocks.
The prescaler divide range is 1 to 510. It is defined by the content of the PSCTR register. Its
output SCLKINT is a 50% duty cycle signal.
inputs
outputs
input/output
AUDIOCLK: output of Audio Master clock PLL
MCLK_MODE: select internal or external Audio System Clock: (If bit CLK_sel1 of
register PSCTR=’0’)
0 = internal
1 = external
MCLK_PCM to PCM Output interface
MCLK_DIN to Data Input interface
SCLK
ST18-AU1
51/87