saa7120 NXP Semiconductors, saa7120 Datasheet - Page 10

• Manufacturer Part Number: saa7120
• Description: Digital Video Encoder Condenc
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Analog output voltages
The analog output voltages are dependent on the
open-loop voltage of the operational amplifiers for
full-scale conversion (typical value 1.35 V), the internal
series resistor (typical value 2 ), the external series
resistor and the external load impedance.
The digital output signals in front of the DACs under
nominal conditions occupy different conversion ranges, as
indicated in Table 1 for a
Values for the external series resistors result in a 75
load.
Input levels and formats
The ConDENC expects digital Y, Cb, Cr data with levels
(digital codes) in accordance with “CCIR 601” (see
Tables 2 and 3).
For C and CVBS outputs, deviating amplitudes of the
colour difference signals can be compensated by
independent gain control setting, while gain for luminance
is set to predefined values, distinguishable for 7.5 IRE
set-up or without set-up.
Reference levels are measured with a colour bar,
100% white, 100% amplitude and 100% saturation.
1997 Jan 06
handbook, full pagewidth
Digital Video Encoder (ConDENC)
CVBS/Y
TTX
TTXRQ
textbit #:
t PD
t TTX
100
100
1
colour bar signal.
2
t FD
3
4
5
6
Fig.7 Teletext timing.
7
8
9 10 11 12 13 14
10
Table 1 Digital output signals conversion range
Table 2 “CCIR 601” signal component levels
White
Yellow
Cyan
Green
Magenta
Red
Blue
Black
TIP-TO-PEAK CARRIER
COLOUR
CONVERSION RANGE (peak-to-peak) (digits)
CVBS, SYNC
t TTXWin
1016
15
16 17 18 19 20 21 22 23
235
210
170
145
106
81
41
16
SAA7120; SAA7121
Y
SIGNALS
Preliminary specification
Y (VBS) SYNC
TIP-TO-WHITE
128
166
202
240
128
Cb
16
54
90
MBH788
881
24
128
146
222
240
110
128
Cr
16
34