CS4954-CQ Cirrus Logic Inc, CS4954-CQ Datasheet - Page 11

• Manufacturer Part Number: CS4954-CQ
• Description: Digital Video Encoder IC
• Manufacturer: Cirrus Logic Inc

Specifications of CS4954-CQ

• No. Of Pins: 48
• Peak Reflow Compatible (260 C): No
• Ic Function: Digital Video Encoder IC
• Leaded Process Compatible: No
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The CS4954/5 is designed to function as a video
timing master or video timing slave. In both Master
and Slave Modes, all timing is sampled and assert-
ed with the rising edge of the CLK pin.
In most cases, the CS4954/5 will serve as the video
timing master. HSYNC, VSYNC, and FIELD are
configured as outputs in Master Mode. HSYNC or
FIELD can also be defined as a composite blanking
output signal in Master Mode. In Master Mode, the
timing of HSYNC, VSYNC, FIELD and Compos-
ite Blank (CB) signals is programmable. Exact hor-
izontal and vertical display timing is addressed in
the Operational Description section.
In Slave Mode, HSYNC and VSYNC are typically
configured as input pins and are used to initialize
independent vertical and horizontal timing genera-
tors upon their respective falling edges. HSYNC
and VSYNC timing must conform to the ITU-
R BT.601 specifications.
The CS4954/5 also provides a ITU R.BT656 Slave
Mode in which the video input stream contains
EAV and SAV codes. In this case, proper HSYNC
and VSYNC timing are extracted automatically
without any inputs other than the V [7:0]. ITU
R.BT656 input data is sampled with the leading
edge of CLK.
In addition, it is also possible to output HSYNC
and VSYNC signals during CCIR-656 Slave
Mode.
4.2.
The Video Input Formatter translates YCbCr input
data into YUV information, when necessary, and
splits the luma and chroma information for filter-
ing, scaling, and modulation.
4.3.
The subcarrier synthesizer is a digital frequency
synthesizer that produces the appropriate subcarri-
er frequency for NTSC or PAL. The CS4954/5
generates the color burst frequency based on the
DS278PP4
Video Input Formatter
Color Subcarrier Synthesizer
CLK input (27 MHz). Color burst accuracy and
stability are limited by the accuracy of the 27 MHz
input. If the frequency varies, then the color burst
frequency will also vary accordingly.
For environments in which the CLK input varies or
jitters unacceptably, a local crystal frequency refer-
ence can be used on the XTAL_IN and
XTAL_OUT pins. In this instance, the input CLK is
continuously compared with the external crystal ref-
erence input and the internal timing of the CS4954/5
is automatically adjusted so that the color burst fre-
quency remains within tolerance.
Controls are provided for phase adjustment of the
burst to permit color adjustment and phase com-
pensation. Chroma hue control is provided by the
CS4954/5 via a 10-bit Hue Control Register
(HUE_LSB and H_MSB). Burst amplitude control
is also made available to the host via the 8-bit burst
amplitude register (SC_AMP).
4.4.
The Video Input Formatter delivers 4:2:2 YUV
outputs into separate chroma and luma data paths.
The chroma path will be discussed here.
The chroma output of the Video Input Formatter is
directed to a chroma low-pass 19-tap FIR filter.
The filter bandwidth is selected (or the filter can be
bypassed) via the CONTROL_1 Register. The
passband of the filter is either 650 KHz or 1.3 MHz
and the passband ripple is less than or equal to
0.05 dB. The stopband for the 1.3 MHz selection
begins at 3 MHz with an attenuation of greater than
35 dB. The stopband for the 650 KHz selection be-
gins around 1.1 MHz with an attenuation of greater
than 20 dB.
The output of the chroma low-pass filter is connect-
ed to the chroma interpolation filter in which up-
sampling from 4:2:2 to 4:4:4 is accomplished.
Following the interpolation filter, the U and V
chroma signals pass through two independent vari-
able gain amplifiers in which the chroma amplitude
Chroma Path
CS4954 CS4955
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