L64777 LSI Logic Corporation, L64777 Datasheet - Page 113

• Manufacturer Part Number: L64777
• Description: DVB Qam Modulator
• Manufacturer: LSI Logic Corporation

B.3 Connecting the L64777 to the LSI Logic L64724
The L64777 can be connected to the satellite receiver device L64724.
The L64724 uses an interpolation-based digital receiver. Thus, it outputs
a transport-rate byte clock with the granularity of the L64724 internal
processing clock, PCLK. See the LSI Logic L64724 Satellite Receiver
Technical Manual (April 2000).
A digital NCO generates this byte clock, which consists of clock cycles
having a length of k or k + 1 PCLK cycles. Usually, the rate of the byte
clock is exactly that of the received transport stream rate.
To ease interfacing, the L64724 supports two modes of byte-clock
generation. Mode 2 of the synchronous parallel interface (SPI) is best
suited for interconnection with L64777. In this mode, the L64724 outputs
204-byte clock cycles, together with an indication for the 188 valid data
bytes. Connect the byte clock to the ICLK input of the L64777, as a
reference for generating the output sampling rate (OCLK); and connect
the PCLK output of the L64724 to the PCLK input of L64777.
To keep the loop bandwidth as low as possible, L64777 provides a digital
interpolation scheme and an NCO to lock to the byte clock in PLL mode 2.
Figure B.2 provides a simplified illustration of the signals between the
L64724 and the L64777.
Figure B.2
Connecting the L64777 to the LSI Logic L64724
L64724
DVALIDOUT
BCLKOUT
CO(7:0)
PCLK
Signals between the L64724 and L64777
PCLK
ICLK
DVALIDIN
DIN(7:0)
L64777
B-3