LM1229VEC National Semiconductor, LM1229VEC Datasheet - Page 15

• Manufacturer Part Number: LM1229VEC
• Description: I2C Compatible CMOS TV RGB and Deflection Processor
• Manufacturer: National Semiconductor

Pin
No.
51
53
57
58
59
62
Application Information
Vertical Flyback
Green Output
Blue Output
Red Output
V
Pin Name
REF
ABL
R
EXT
(Continued)
Schematic
15
The Automatic Beam Limiter input is biased to
the desired beam current limit by R
and normally keeps D
forward biased. When the current resupplying
the CRT capacitance (averaged by C
exceeds this limit, then D
begin to turn off and the voltage at pin 51 begins
to drop. The LM1229 then lowers the gain of the
three video channels until the beam current
reaches an equilibrium value. The 1N4148 is
needed to prevent overcurrent in D
where the ABL limit is greater than 1 mA.
External current set resistor, 10k 1%, sets the
internal bias current level for optimum
performance of the LM1229. This resistor should
be placed as close to pin 53 and the pin 52
ground return as possible.
These are the three video output pins. They are
intended to drive the National family of cathode
drivers. Nominally, about 2.8V peak to peak will
produce 140V peak to peak of cathode drive with
the LM2426.
This input is used to start the VBLANK output
pulse which is used internally for vertical
blanking of the RGB outputs. It is also used for
the V Protect function which blanks the RGB
video outputs if the vertical deflection fails. The
values of C
eliminate the long vertical rate slope at pin 62
and also ensure that this pin is not forced above
V
about 25% of V
threshold is about 35% of V
CC
or below GND. The bias level at this pin is
V
and R
CC
Description
and the actual switching
V
should be chosen to
INT
INT
and the 1N4148
CC
and the 1N4148
.
INT
ABL
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ABL
in cases
and V
)
BB