LM1229YA National Semiconductor, LM1229YA Datasheet - Page 14

• Manufacturer Part Number: LM1229YA
• Description: I2C Compatible CMOS TV RGB and Deflection Processor
• Manufacturer: National Semiconductor

www.national.com
Pin
No.
41
42
43
41
42
43
44
45
46
47
50
Application Information
Green Video In
(Analog Mode)
(Digital Mode)
Blue Video In
Red Video In
OSD Enable
Green OSD
Green OSD
Pin Name
Blue OSD
Blue OSD
Red OSD
Red OSD
Clamp
(Continued)
Schematic
14
These inputs can be used for either analog or
digital inputs. In the digital mode these inputs
accept either TTL or CMOS input levels. Each
color is either fully on (logic high) or fully off
(logic low). Unused pins should be connected to
ground with a 47k resistor. National
Semiconductor does not recommend mixing
analog and digital inputs in the same application.
In the analog OSD mode, the inputs should be
AC coupled through a 1000 pF capacitor, and
the gain is about 3.5, so that a peak to peak
input of 0.7V results in a 2.45V peak to peak
signal at the RGB outputs when the OSD
contrast is maximum. Signal input amplitudes
larger than 0.7V are not recommended. The
external ESD diodes are recommended if the
input OSD video is generated some distance
away from the LM1229. The 75Ω termination
may not be needed if the signal amplitude is
already 0.7V.
This input accepts either TTL or CMOS input
levels. When this input is a “0”, only video is
displayed. When it is a “1”, the OSD from pins 1,
2 and 3 is displayed. If bit 3 of the OSD register
(0x0B) is a “1” then the background of the OSD
(when the Enable is a “1” and the OSD inputs
are “0”) will be video attenuated by the
OSD_TRANS register (0x0A). If this input is
unused, connect it to ground through a 47k
resistor.
These video inputs must be AC coupled with a
1000 pF cap. Internal DC restoration is done at
these inputs. A series resistor of at least 33Ω
and external ESD protection diodes should also
be used for protection from ESD damage.
This pin accepts either TTL or CMOS logic
levels. The internal switching threshold is about
one-half of V
between 1k and 3.9k is recommended to
attenuate the peak to peak signal at pin 50. The
resistor must be large enough to prevent the
voltage at pin 50 from going higher than V
below GND. The capacitor C
eliminate noise on the clamp pulse which could
cause false triggering during video.
CC
. An external series resistor R
Description
F
should be used to
CC
S
or