bt865a Conexant Systems, Inc., bt865a Datasheet - Page 36

• Manufacturer Part Number: bt865a
• Description: Ycrcb To Ntsc/pal Digital Video Encoder
• Manufacturer: Conexant Systems, Inc.

Circuit Description
Figure 1-19. Teletext Timing for Tb864A/Bt865A Encoder
Table 1-5.
1-26
GENERAL NOTE:
1. TXE is enabled and video line is a valid teletext line. See "teletext" on page 1-26.
FOOTNOTE:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Clock (CLK)
Max. Value
Max. Value
Min. Value
Min. Value
Counter
Horizontal
TTXREQ
TTXDAT
CVBS
Placement of rising edge of TTXREQ is definable using register TXHS[10:0].
Placement of falling edge of TTXREQ is definable using register TXHE[10:0].
TTXREQ is generated by the encoder using programmable registers TXHS and TXHE. This allows the user to adjust for
the propagation delay (t
TTXDAT is supplied to the encoder at the proper time to be interpolated by the encoder (t
the video output signals. The Teletext data must follow the correct protocol. See "Teletext" on page 1-26.
t
Luma Delay is set to zero.
t
If the falling edge of TTXREQ does not occur by the end of a video line, the beginning of a new line will automatically
reset TTXREQ.
2 clock (CLK) counts = 1 pixel clock count.
CVBS/G
Y/CVBS
TTXOWS
TTXIWS
Internal
Internal
Reset
(6)
(9)
Legal Values to TXHS and TXHE
is the start of the teletext input window and is fixed internally.
is the start of the teletext output window and is fixed internally by the encoder at 10.2 usec.
2
3 4 5 . . .
14.75 MHz
14.75 MHz
Pixel rate
13.5 MHz
13.5 MHz
PD
) in CLK cycles of the teletext data source.
t
TTXOWS
t
TTXIWS
(1)
(7)
(5)
t
PD
Conexant
0x6BE
TXHS
0x75E
(3)
2
2
t
TTXINT
(4)
TTXINT
TXHS + 2
TXHS + 2
TXHE
0x7FF
0x7FF
) and inserted into
(2)
Bt864A/Bt865A Data Sheet
(8)
2 3 4 5 . . .
100138C
02/17/03
100138_020