LM1229YA datasheet(10/27 Pages) NSC

10 / 27 page

Application Information

PIN CONNECTIONS

No.

Pin Name

Schematic

Description

ALC

OSC

ALC is the feedback loop filter which maintains

constant vertical ramp amplitude according to the

value set in the vertical height register.

OSC is the capacitor which determines the

slope of the vertical ramp.

VDRIVE

OUT

VDRIVE

REF

These two outputs provide the inputs to a

vertical output amplifier which drives the vertical

yoke winding. Since the VDRIVE

OUT amplitude is

from 1.5V to 2.5V peak to peak, the gain of the

output amplifier must be set with external

resistors to match the vertical yoke being used.

The VDRIVE

OUT slope is positive (increasing

voltage with time).

REF Caps

Provides filtering for the internal voltages which

set the internal bias currents in conjunction with

EXT. For proper filtering, pins 5, 6 and 7 should

be 10 µF, pin 23 should be 54 µF and pin 54

should be .01 µF. These capacitors should be

placed as close to their pins as possible.

VEHT1

This input pin is used to control the height of the

vertical ramp based on changes in the high

voltage. A 1V negative change at pin 8 causes a

maximum of 5% reduction in the ramp amplitude

when the VEHT[3:0] is set to 0xF. If this pin is

not used, bit 3 of the SYNCPOL register should

be set to 1. The values shown give a 350 mV

change at pin 8 from a 2.5V change at the ABL

pin.

VEHT2

This input pin is used to control the level of the

E-W parabola based on changes in the high

voltage. A 1V negative change at pin 9 causes a

maximum of 300 mV increase in the ramp DC

level when the VEHT[7:4] is set to 0xF. If this pin

is unused, bit 4 of the SYNCPOL register should

be set to 1. The values shown give a 350 mV

change at pin 9 from a 2.5V change at the ABL

pin.

LM1229YA Datasheet(PDF) 10 Page - National Semiconductor (TI)

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