sta003t STMicroelectronics, sta003t Datasheet - Page 7

• Manufacturer Part Number: sta003t
• Description: Mpeg 2.5 Layer Iii Audio Decoder
• Manufacturer: STMicroelectronics

Figure 6. PLL and Clocks Generation System
This signal is used as interrupt signal inside
STA003T.
Within a WorldSpace Broadcast Frame, there are
a fixed number of PCM samples, depending on
the nominal audio sampling rate (Fig. 7).
Using this information, with the SRC_INT signal
Figure 7. WorldSpace BC Framing
SRC_INT
XTI
BC Frame Time Lenght:
MPEG Frames into 1 BC Frame:
PCM Samples into 1 BC Frame:
PLLCTL_N reg
PLLFRAC reg
PLLFRAC
N
t
INT
Switching
Circuit
PLLCTL_M reg
M
t
LOW
PFD
432 ms
18 for 48 & 24 KHz
12 for 32 & 16 KHz
20736 for 48 KHz
10368 for 24 KHz
13824 for 32 KHz
6912 for 16 KHz
5184 for 12 KHz
3456 for 8 KHz
9 for 12 KHz
6 for 8 KHz
as external timer source, STA003T performs the
compensation of the audio sampling rate.
The sampling rate control is done by the
STA003T core, by setting PLLFRAC internal reg-
ister. The PLLFRAC value is updated, in steps of
few ppms, by Update PLLFRAC signal.
VCO
Disable PLL
CP
XTI2OCLK
XTI2DSPCLK
MFSDF(X) reg
X
S
C
OCLK
DCLK
R
C
STA003T
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