MC44S803EP FREESCALE [Freescale Semiconductor, Inc], MC44S803EP Datasheet - Page 29

• Manufacturer Part Number: MC44S803EP
• Description: Low Power CMOS Broadband Tuner
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Freescale Semiconductor
crystal. The oscillator circuit is designed to accept a crystal in
the frequency range of 4.0 MHz to 28 MHz.
LO2. Additionally, it goes through a Divide-By-R3 stage.
Possible divider ratios are 1, 2, 4, 6, 8, or 10. For divide by 1,
the signal is routed around the divider. The signal passes
though a low pass filter to produce a sine wave. It is then
buffered internally and output at pins BufIOP and BufIOM so
that it can be used to drive other ICs such as an audio-video
modulator in a settop box. If no other ICs are driven from this
oscillator, nothing should be connected to BufIOP and
BufIOM. The IC can be programmed to shut down the
oscillator buffer if it is not used. It is enabled at power up and
on reset.
as shown in the following figures. This saves cost and
The integrated reference oscillator requires an external
The oscillator drives the reference dividers for LO1 and
In dual tuner applications, one crystal can drive two tuners,
Crystal Input
Oscillator
Oscillator
Silicon Tuner IC
Silicon Tuner IC
Crystal Input
SW1
SW1
Figure 33. Two Receivers Sharing One Crystal
Crystal
Crystal
Buffer
Buffer
REFERENCE OSCILLATOR
Tuner # 1
Tuner # 2
Reference
Reference
To PLLs
Dividers
To PLLs
Dividers
eliminates spur problems due to having multiple frequencies
that are very close to each other but not exactly the same. In
this case, the second tuner is connected up to the same
crystal but fed into the Buffer In/Out pins. Internal switches of
the second tuner are programmed to feed this signal to the
Crystal Buffer. The internal switches of the first tuner are
programmed to feed the output of the Sine Wave Buffer to a
modulator or other IC. The other switches shown are to allow
for a divide by 1 state.
Table 39. Switch States
Reset State
Tuner #1
Tuner #2
SW3
SW3
Buffer
Buffer
Wave
Wave
Sine
Sine
BufI/O bit
0
0
7
SW2
SW2
Closed
Closed
Open
SW1
Buffer In/Out
Buffer In/Out
Closed
Closed
Open
SW2
MC44S803
Closed
Open
Open
SW3
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