LM1247 National Semiconductor, LM1247 Datasheet - Page 9

• Manufacturer Part Number: LM1247
• Description: 150 MHz I2C Compatible RGB Preamplifier with Internal 512 Character OSD ROM, 512 Character RAM and 4 DACs
• Manufacturer: National Semiconductor

Typical Performance Characteristics
Pin Descriptions and Application Information
Pin
No.
1
2
3
4
5
6
7
PLL=1
PLL=2
PLL=3
Green Video In
Blue Video In
V
Red Video In
Analog Input
Pin Name
REF
V Flyback
Ground
V
REF
Bypass
25 - 61
PPL=0
NR
NR
25 - 53
PPL=1
NR
NR
TABLE 3. OSD Register recommendations
25 - 48
48 - 98
PPL=2
Schematic
NR
88 - 110
25 - 43
43 - 88
PPL=3
V
CC
9
= 5V, T
81 - 110
25 - 40
40 - 81
PPL=4
A
= 25˚C unless otherwise specified (Continued)
Required for OSD synchronization and is also
used for vertical blanking of the video outputs.
The actual switching threshold is about 35% of
V
but for flyback inputs, an AC coupled
differentiator is recommended, where R
enough to prevent the voltage at pin 1 from
exceeding V
be small enough to flatten the vertical rate ramp
at pin 1. C
Provides filtering for the internal voltage which
sets the internal bias current in conjunction with
R
proper filtering. This capacitor should be placed
as close to pin 2 and the pin 4 ground return as
possible.
External resistor, 10k 1%, sets the internal bias
current level for optimum performance of the
LM1247. This resistor should be placed as close
to pin 3 and the pin 4 ground return as possible.
This is the ground for the input analog portions
of the LM1247 internal circuitry.
These video inputs must be AC coupled with a
.0047 µF cap. Internal DC restoration is done at
these inputs. A series resistor of about 33Ω and
external ESD protection diodes should also be
used for protection from ESD damage.
CC
EXT
. For logic level inputs C
. A minimum of 0.1 µF is recommended for
74 - 110
25 - 36
36 - 74
PPL=5
24
CC
may be needed to reduce noise.
or going below GND. C
Description
69 - 110
25 - 34
34 - 69
PPL=6
4
can be a jumper,
64 - 110
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25 - 31
31 - 64
4
PPL=7
V
should
is large