L64704 LSI Logic Corporation, L64704 Datasheet - Page 131

• Manufacturer Part Number: L64704
• Description: Satellite Decoder Technical Manual 5/97
• Manufacturer: LSI Logic Corporation

Equation 5.15
5.9.2
External
Controls
5.9.3
Hi-Z Mode on
Functional
Outputs
V
5.9.1.2 Carrier Tracking Phase
In the tracking phase, the mean value of the phase error should be zero.
The mean value is internally computed and subtracted from the phase
error before Sigma-Delta conversion. This estimation and subtraction
system is only enabled in tracking mode, that is, when CAR_SW = 0.
The maximum offset voltage that can be compensated for by this mech-
anism is shown in
Note the following examples:
Five external control bits are available on the L64704. Four of these bits
are output signals, and one is an input signal. These controls can be
used to set up or to read parameters from other components on the
board (like the RF front end and the tuner) using only the microcontroller
interface of the L64704.
The four output controls use pins XCTR_OUT.0, XCTR_OUT.1,
XCTR_OUT.2, XCTR_OUT.3. They are programmed by setting their
respective bits in the XCTR[3:0] register (Group 4, APR 36). The XCTR[i]
register drives the XCTR_OUT.i pin; that is, programming the XCTR[i]
register to 0 sets a 0 volt level on pin XCTR_OUT.i, and programming
the XCTR[i] register to 1 sets a 3.3 volt level on pin XCTR_OUT.i.
The input control is sensed on the XCTR_IN pin. The logic level applied
to this pin is read using the XCTR_IN bit (Group 3, APR 6).
When F_OUT_HiZ is set to 1, all the functional outputs of the L64704
are set to the high-impedance mode. These outputs include
CLK_VCON/P, CAR_VCOxN/P and PWRP.
Other Functions
offmax
for CAR_KP = 255, V
for CAR_KP = 30, V
=
CAR OFFSET
------------------------------------------ -
32
Equation
offmax
offmax
------------------------- -
CAR KP
5.15.
3.3 V
= 436 mV (resolution 3.4 mV)
= 51 mV (resolution 0.4 mV)
5-27