Philips Semiconductors
Product specification
I2C-bus autosync deflection controller for
PC monitors
TDA4841PS
Adjustment of vertical position, vertical linearity and
vertical linearity balance
The pincushion (EW parabola) amplitude, corner and
trapezium correction track with vertical picture size
(VSIZE) and also with the adjustment for vertical picture
position (VPOS). The corner correction does not track with
horizontal pincushion (HPIN).
Register VOFFS provides a DC shift at the sawtooth
output VOUT1 and VOUT2 (pins 13 and 12) without
affecting any other output waveform. This adjustment is
meant for factory alignments.
Further the horizontal pincushion amplitude, corner and
trapezium correction track with the horizontal picture size,
which is adjusted via register HSIZE and the analog
modulation input HSMOD. If the DC component in the
Register VPOS provides a DC shift at the sawtooth output
VOUT1 and VOUT2 with correct tracking of all other
related waveforms (see Section “Tracking of vertical
adjustments”). This register should be used for user
adjustments. Due to the tracking the whole picture moves
vertically while maintaining the correct geometry.
EWDRV output signal is increased via HSIZE or IHSMOD
the pincushion, corner and trapezium component of the
EWDRV output will be reduced by a factor of
,
VHSIZE
V
HSIZE + VHEHT 1 –
----------------
Register VLIN is used to adjust the amount of vertical
S-correction in the output signal. This function can be
switched off by control bit VSC.
14.4 V
-------------------------------------------------------------------------
14.4 V
1 –
The value 14.4 V is a virtual voltage for calculation only.
The output pin can not reach this value, but the gain (and
DC bias) of the external application should be such that the
horizontal deflection is reduced to zero when EWDRV
would reach 14.4 V.
Register VLINBAL is used to correct the unbalance of
vertical S-correction in the output signal.
Tracking of vertical adjustments
The adjustments via registers VSIZE, VOVSCN and
VPOS also affect the waveforms of horizontal pincushion,
vertical linearity (S-correction), vertical linearity balance,
focus parabola, pin unbalance and parallelogram
correction. The result of this interaction is that no
readjustment of these parameters is necessary after an
user adjustment of vertical picture size and vertical picture
position.
HSMOD (pin 31) can be used for a DC controlled EHT
compensation by correcting horizontal size, horizontal
pincushion, corner and trapezium. The control range at
this pin tracks with the actual value of HSIZE. For an
increasing DC component VHSIZE in the EWDRV output
signal, the DC component VHEHT caused by IHSMOD will be
V HSIZE
reduced by a factor of 1 –
as shown in the equation
----------------
14.4 V
Adjustment of vertical moire cancellation
above.
To achieve a cancellation of vertical moire (also known as
‘scan moire’) the vertical picture position can be modulated
by half the vertical frequency. The amplitude of the
modulation is controlled by register VMOIRE and can be
switched off via control bit MOD.
The whole EWDRV voltage is calculated as follows:
V EWDRV,0 = 1.2 V + [VHSIZE + VHEHT f(HSIZE)
+ (VHPIN + VHCOR + VHTRAP) g(HSIZE,HSMOD)]
h(IHREF
)
IHSMOD
VHSIZE
with VHEHT
=
0.69 , f(HSIZE) = 1 –
-------------------
----------------
14.4 V
Horizontal pincushion (including horizontal size,
corner correction and trapezium correction)
120 µA
VHSIZE
V
HSIZE + VHEHT 1 –
----------------
14.4 V
EWDRV (pin 11) provides a complete EW drive waveform.
The components horizontal pincushion, horizontal size,
corner correction and trapezium correction are controlled
by the registers HPIN, HSIZE, HCORT, HCORB and
HTRAP.
g(HSIZE,HSMOD) = 1 –
-------------------------------------------------------------------------
14.4 V
IHREF
and h(IHREF) =
------------------------------------
IHREF
f = 70 kHz
The corner correction can be adjusted separately for the
top (HCORT) and bottom (HCORB) part of the picture.
1999 Oct 25
10
NXP [ NXP ]
