S5D2650 Samsung Semiconductor, Inc., S5D2650 Datasheet - Page 12

• Manufacturer Part Number: S5D2650
• Description: Multistandard Video Decoder/scaler
• Manufacturer: Samsung Semiconductor, Inc.

S5D2650 Data Sheet
1.2. VIDEO TRACKING AND TIMING GENERATION
When the S5D2650 is configured for analog video input, the chip tracks the video input and generates a sampling
clock that is line locked to the input video. The S5D2650 requires an external reference clock for video tracking.
This reference can be supplied via a crystal using the on chip crystal interface or any TTL compatible source.
These configurations are shown in Figure 5
1.2.1. Clock Input Timing Reference
The S5D2650 can use either a 24.576 MHz or a 26.8 MHz reference. However, it is recommended that the 24.576
MHz reference be used for CCIR 601 operation, and the 26.8 MHz reference be used for square pixel or dual mode
operation. Other specifications for the crystal are:
• Fundamental or third overtone
• Load capacitance of ~20 pF
• Series resistance of 40 Ω or less
• Frequency deviation of 50 ppm or less over operating temperature range
1.2.2. The Sampling Clock
The sampling clock is generated by multiplying the line rate by N. This ensures that samples are aligned
horizontally, vertically and in time. The required N factor for the S5D2650 is based upon the field rate (60 Hz or 50
Hz) and the desired sampling rates (CCIR 601 or square pixel). Field rate can be automatically detected and can
be monitored with the FFRDET bit in the STAT register. Manual control of the field rate can be controlled with the
MNFMT and IFMT bits. The PIXSEL bit in register CMDA selects CCIR 601 or square pixel. Table 3 shows the
constants for the various combinations of input formats and output pixel rates.
Optional for 3rd
harmonic crystal
ELECTRONICS
22 pF
22 pF
5.7 µH
391 pF
24.576 MHz
7
8
Using a Crystal
Figure 5.
XTALI
XTALO
S5D2650
Standard Clock Configurations
24.576 MHz
TTL Clock
Using a Clock
N. C.
7
87
MULTIMEDIA VIDEO
XTALI
XTALO
S5D2650
PAGE 12 OF 95
7/18/03