Electronic Components Datasheet Search |
|
TDA9332H Datasheet(PDF) 7 Page - NXP Semiconductors |
|
TDA9332H Datasheet(HTML) 7 Page - NXP Semiconductors |
7 / 56 page 2002 Jun 04 7 Philips Semiconductors Preliminary specification I2C-bus controlled TV display processors TDA933xH series FUNCTIONAL DESCRIPTION RGB control circuit INPUT SIGNALS The RGB control circuit of the TDA933xH contains three sets of input signals: • YUV input signals, which are supplied by the input processor or the feature box. Bit GAI can be used to switch the luminance input signal sensitivity between 0.45 V (p-p) and 1.0 V (b-w). The nominal input signals for U and V are 1.33 V (p-p) and 1.05 V (p-p), respectively. These input signals are controlled on contrast, saturation and brightness. • The first RGB input is intended for external signals (SCART in 1fH and VGA in 2fH applications), which have an amplitude of 0.7 V (p-p) typical. This input is also controlled on contrast, saturation and brightness. • The second RGB input is intended for OSD and teletext signals. The required input signals have an amplitude of 0.7 V (p-p). The switching between the internal signal and the OSD signal can be realized via a blending function or via fast blanking. This input is only controlled on brightness. Switching between the various sources can be realized via the I2C-bus and by fast insertion switches. The fast insertion switches can be enabled via the I2C-bus. The circuit contains switchable matrix circuits for the colour difference signals so that the colour reproduction can be adapted for PAL/SECAM and NTSC. For NTSC, two different matrices can be chosen. In addition, a matrix for high-definition ATSC signals is available. OUTPUT AMPLIFIER The output signal has an amplitude of approximately 2 V (b-w) at nominal input signals and nominal settings of the controls. The required ‘white point setting’ of the picture tube can be realized by means of three separate gain settings for the RGB channels. To obtain an accurate biasing of the picture tube, a CCC circuit has been developed. This function is realized by a 2-point black level stabilization circuit. By inserting two test levels for each gun and comparing the resulting cathode currents with two different reference currents, the influence of the picture tube parameters such as the spread in cut-off voltage can be eliminated. This 2-point stabilization is based on the principle that the ratio between the cathode currents is coupled to the ratio between the drive voltages according to: The feedback loop makes the ratio between cathode currents Ik1 and Ik2 equal to the ratio between the reference currents (which are internally fixed) by changing the (black) level and the amplitude of the RGB output signals via two converging loops. The system operates in such a way that the black level of the drive signal is controlled to the cut-off point of the gun. In this way, a very good grey scale tracking is obtained. The accuracy of the adjustment of the black level is only dependent on the ratio of internal currents and these can be made very accurately in integrated circuits. An additional advantage of the 2-point measurement is that the control system makes the absolute value of Ik1 and Ik2 identical to the internal reference currents. Because this adjustment is obtained by adapting the gain of the RGB control stage, this control stabilizes the gain of the complete channel (RGB output stage and cathode characteristic). As a result, this 2-point loop compensates for variations in the gain figures during life. An important property of the 2-point stabilization is that the offset and the gain of the RGB path are adjusted by the feedback loop. Hence, the maximum drive voltage for the cathode is fixed by the relationship between the test pulses, the reference current and the relative gain setting of the three channels. Consequently, the drive level of the CRT cannot be adjusted by adapting the gain of the RGB output stage. Because different picture tubes may require different drive levels, the typical ‘cathode drive level’ amplitude can be adjusted by means of an I2C-bus setting. Depending on the selected cathode drive level, the typical gain of the RGB output stages can be fixed, taking into account the drive capability of the RGB outputs (pins 40 to 42). More details about the design are given in the application report (see also Chapter “Characteristics”; note 11). The measurement of the high and the low currents of the 2-point stabilization circuit is performed in two consecutive fields. The leakage current is measured in each field. The maximum allowable leakage current is 100 µA. For extra flexibility, it also possible to switch the CCC circuit to 1-point stabilization with the OPC bit. In this mode, only the black level at the RGB outputs is controlled by the loop. The cathode drive level setting has no influence on the gain in this mode. This level should be set to the nominal value to get the correct amplitude of the measuring pulses. I k1 I k2 ------- V dr1 V dr1 ----------- γ = |
Similar Part No. - TDA9332H |
|
Similar Description - TDA9332H |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |