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TDA4841 Scheda tecnica(PDF) 6 Page - NXP Semiconductors |
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TDA4841 Scheda tecnica(HTML) 6 Page - NXP Semiconductors |
6 / 60 page 1999 Oct 25 6 Philips Semiconductors Product specification I2C-bus autosync deflection controller for PC monitors TDA4841PS FUNCTIONAL DESCRIPTION Horizontal sync separator and polarity correction HSYNC (pin 15) is the input for horizontal synchronization signals, which can be DC-coupled TTL signals (horizontal or composite sync) and AC-coupled negative-going video sync signals. Video syncs are clamped to 1.28 V and sliced at 1.4 V. This results in a fixed absolute slicing level of 120 mV related to sync top. For DC-coupled TTL signals the input clamping current is limited. The slicing level for TTL signals is 1.4 V. The separated sync signal (either video or TTL) is integrated on an internal capacitor to detect and normalize the sync polarity. Normalized horizontal sync pulses are used as input signals for the vertical sync integrator, the PLL1 phase detector and the frequency-locked loop. Vertical sync integrator Normalized composite sync signals from HSYNC are integrated on an internal capacitor in order to extract vertical sync pulses. The integration time is dependent on the horizontal oscillator reference current at HREF (pin 28). The integrator output directly triggers the vertical oscillator. Vertical sync slicer and polarity correction Vertical sync signals (TTL) applied to VSYNC (pin 14) are sliced at 1.4 V. The output signal of the sync slicer is integrated on an internal capacitor to detect and normalize the sync polarity. The output signals of vertical sync integrator and sync normalizer are disjuncted before they are fed to the vertical oscillator. Video clamping/vertical blanking generator The video clamping/vertical blanking signal at CLBL (pin 16) is a two-level sandcastle pulse which is especially suitable for video ICs such as the TDA488x family, but also for direct applications in video output stages. The upper level is the video clamping pulse, which is triggered by the horizontal sync pulse. Via I2C-bus control, either the leading or trailing edge can be selected by setting control bit CLAMP. The width of the video clamping pulse is determined by an internal single-shot multivibrator. The lower level of the sandcastle pulse is the vertical blanking pulse, which is derived directly from the internal oscillator waveform. It is started by the vertical sync and stopped with the start of the vertical scan. This results in optimum vertical blanking. Via I2C-bus control, two different vertical blanking times are accessible by control bit VBLK. Blanking will be activated continuously, if one of the following conditions is true: Soft start of horizontal and B+ drive (voltage at HPLL2 (pin 30) pulled down externally or by the I2C-bus) PLL1 is unlocked while frequency-locked loop is in search mode No horizontal flyback pulses at HFLB (pin 1) X-ray protection is activated Supply voltage at VCC (pin 10) is low (see Fig.22). Via I2C-bus control, horizontal unlock blanking can be switched off by control bit BLKDIS while vertical blanking is maintained. handbook, halfpage TDA4841PS MHB604 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 HFLB XRAY BOP BSENS BIN BDRV PGND HDRV XSEL VCC EWDRV VOUT2 VOUT1 VSYNC FOCUS HSMOD HPLL2 HCAP HBUF HPLL1 HREF SGND VCAP VREF VAGC VSMOD ASCOR SDA HSYNC CLBL SCL HUNLOCK Fig.2 Pin configuration. |
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