CS4954-CQ Cirrus Logic Inc, CS4954-CQ Datasheet - Page 24

• 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

therefore allow the user to have full control over to
when sending teletext data to this device.
The time t
text input data and inserting it into the CVBS and
Y output signals, such that it appears between
t
edge of the horizontal synchronization pulse. t
changes with the TV standard and the selected
teletext standard. Please refer to ITU-R BT.653-2
for more detailed information.
The time t
by the source that is gated by TTXRQ in order to
deliver teletext data. This delay is programmable
through the register TTXHD. For every active
HIGH transition at output pin TTXRQ, a new tele-
text bit must be provided by the source. The time
between the beginning of the first TTXRQ pulse
and the leading edge of H-sync is programmable
through the TTXHS register.
Since the beginning of the pulses representing the
TTXRQ signal and the delay between the rising
edge of TTXRQ and valid teletext input data are
fully programmable, the TTXDAT data is always
inserted at the correct position after the leading
edge of the outgoing horizontal synchronization
pulse.
The time t
window for TTX data; it has a constant length
depending on the selected teletext standard which
allows insertion of 360 TTX bits (6.9375
Mbit/sec) (European teletext) or 296 TTX bits
24
TTX
TTXDAT
CVBS/Y
TTXRQ
= 9.8 s and t
Figure 12. Teletext Timing (Pulsation Mode)
FD
PD
TTXWin
is the time needed to interpolate tele-
is the pipeline delay time introduced
t
is the internally used insertion
TTX
textbit #: 1
TTX
t
PD
= 12 s after the leading
t
FD
2
3
4
t
TTXWin
5
FD
TTXDAT
CVBS/Y
TTXRQ
(5.6427875 Mbit/sec) (WST PAL) or 288 TTX bits
(5.727272 Mbit/sec) (NABTS) or 296 TTX bits
(5.727272 Mbit/sec) (WST NTSC) respectively.
Using the appropriate programming, all suitable
lines of the odd field (TTXOVS through TTX-
OVE) plus all suitable lines of the even field
(TTXEVS through TTXEVE) can be used for tele-
text insertion. In addition it is possible to selec-
tively disable the teletext insertion on single lines.
This can be programmed by setting the
TTX_LINE_DIS1,
TTX_LINE_DIS3 registers appropriately.
Note that the TTXDAT signal must be synchro-
nized with the 27 Mhz clock. The pulse width of
the TTXRQ signal varies between three and four
27 Mhz clock cycles. The variation is necessary in
order to maintain the strict timing requirements of
the teletext standard.
Table 5 shows how to program the TTXHS register
for teletext instantiation into the analog signals for
the various supported TV formats. TTXHS is the
time between the leading edge of the HSYNC sig-
nal and the rising edge of the first TTXRQ signal
and consists of multiples of 27 Mhz clock cycles
Note that with increasing values of TTXHS the
time t
for the internal pipeline delay due to processing,
synchronization and instantiation of the teletext
data. The time t
register.
Figure 13. Teletext Timing (Window Mode)
TTX
increases as well. The time t
t
TTX
PD
textbit #: 1
t
PD
is dependant on the TTXHD
TTX_LINE_DIS2
t
CS4954 CS4955
FD
2
3
4
FD
t
TTXWin
DS278PP4
accounts
5
and