TA1204AF Datasheet, PDF (16/25 Pages) Toshiba Semiconductor – γ CORRECTION IC FOR LCD TV

TA1204AF
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Signal frequency characteristics, inter-axis deviation
• Test condition 5 (CP mode, fixed polarity)
• Input : X In1
Test signal 2 (sweep)
Input test signal 2 to X In1, raise its frequency from 500kHz to 20MHz, and observe the amplitudes
of the frequency components. Measure the frequency for a 3dB fall in output amplitude. Take the
same measurements as for positive polarity by changing SW7B from a to b.
Output dynamic range
• Test condition 4 (CP mode)
• Input : X In1
Test signal 3
• VR23 : →Max / Min
Input a signal (0.7Vp-p) including black and white levels to input A (X In1). Change SW23 from a to b,
raise and lower the voltage applied to pin 23 by turning VR23 clockwise and anticlockwise, measure
the maximum and minimum black waveform levels for an output pin (pin 21 when X = B, pin 19
when X = G, and pin 14 when X = R), and thus obtain the voltage difference.
Signal output through-rate
• Test condition 4 (CP mode)
• Input : X In1
Test signal 5
Input to input A (X In1) a test signal whose 10 to 90% rise / fall times are less than 50ns in a
rectangular waveform that repeats black and white levels. Measure the 10 to 90% rise / fall times in
the waveform of the output pin (pin 21 when X = B, pin 19 when X = G, and pin 14 when X = R), and
convert this to a through-rate.
Signal output S / N
• Test condition 5 (CP mode, fixed polarity)
• Input : no signal
Noise measurement band DC to 6MHz
Change SW27 from a to b, and adjust VR27 while looking at the waveform of an output pin (pin 21,
pin 19, pin 14) so that the difference between the γ0 and black levels becomes 0. Measure the noise
voltage (measurement band: ~6MHz) of the output pins in this state. Repeat this measurement for
each output pin. Calculate the ratio of the No. 9 typical output amplitude to the measured noise
voltage, and express it in dB units.
For a positive polarity measurement, repeat the above measurement by changing SW7B from a to b.
Reversed polarity center voltage, typical value, inter-axis deviation
• Test condition 4 (CP mode)
• Input : no signal
Measure the γ0 levels of the positive and negative polarities of the output waveform at an output pin
(pin 21 when X = B, pin 19 when X = G, and pin 14 when X = R), and measure the mean value of the
two levels.
Repeat this measurement replacing B, G, and R as the X-axis.
Reversed polarity center voltage, maximum and minimum variable ranges, inter-axis deviation
• Test condition 4 (CP mode)
• Input : no signal
• VR23 : →Max / →Min
Change SW25 from a to b, adjust VR26 and set the voltage applied to pin 25 at 5V, thereby
minimizing the cut-off. Change SW23 from a to b, raise and lower the voltage applied to pin 23 by
turning VR23 clockwise and anticlockwise. Obtain the center voltage of the positive and negative γ0
levels when the waveform of an output pin (pin 21 when X = B, pin 19 when X = G and pin 14 when
X = R) approaches VDD and stops rising, and set this as the maximum value. Obtain the center
voltage of positive and negative γ0 levels when the waveform of the output pin approaches GND and
these levels stop decreasing, and make this voltage the minimum value.
Repeat this measurement replacing B, G, and R as the X-axis.
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