 |
Motore di ricerca datesheet componenti elettronici |
|
|
Motore di ricerca datesheet componenti elettronici |
|
TDA4857 Scheda tecnica(PDF) 9 Page - NXP Semiconductors |
|
||||||||||||||||||||||||||||||
TDA4857 Scheda tecnica(HTML) 9 Page - NXP Semiconductors |
|
|
9 / 56 page  2000 Jan 31 9 Philips Semiconductors Product specification I2C-bus autosync deflection controller for PC monitors TDA4857PS X-ray protection The X-ray protection input XRAY (pin 2) provides a voltage detector with a precise threshold. If the input voltage at XRAY exceeds this threshold level for a certain time then control bit SOFTST is reset, which switches the IC into protection mode. In this mode several pins are forced into defined states: HUNLOCK (pin 17) is floating The capacitor connected to HPLL2 (pin 30) is discharged Horizontal output stage (HDRV) is floating B+ control driver stage (BDRV) is floating Vertical output stages (VOUT1 and VOUT2) are floating CLBL provides a continuous blanking signal. There are two different methods of restarting the IC: 1. XSEL (pin 9) is open-circuit or connected to ground. The control bit SOFTST must be set to logic 1 via the I2C-bus. The IC then returns to normal operation via soft start. 2. XSEL (pin 9) is connected to VCC via an external resistor. The supply voltage of the IC must be switched off for a certain period of time before the IC can be restarted again using the standard power-on procedure. Vertical oscillator and amplitude control This stage is designed for fast stabilization of vertical size after changes in sync frequency conditions. The free-running frequency ffr(V) is determined by the resistor RVREF connected to pin 23 and the capacitor CVCAP connected to pin 24. The value of RVREF is not only optimized for noise and linearity performance in the whole vertical and EW section, but also influences several internal references. Therefore the value of RVREF must not be changed. Capacitor CVCAP should be used to select the free-running frequency of the vertical oscillator in accordance with the following formula: To achieve a stabilized amplitude the free-running frequency ffr(V), without adjustment, should be at least 10% lower than the minimum trigger frequency. The contributions shown in Table 2 can be assumed. Table 2 Calculation of ffr(V) total spread Result for 50 to 160 Hz application: The AGC of the vertical oscillator can be disabled by setting control bit AGCDIS via the I2C-bus. A precise external current has to be injected into VCAP (pin 24) to obtain the correct vertical size. This special application mode can be used when the vertical sync pulses are serrated (shifted); this condition is found in some display modes, e.g. when using a 100 Hz upconverter for video signals. Application hint: VAGC (pin 22) has a high input impedance during scan. Therefore, the pin must not be loaded externally otherwise non-linearities in the vertical output currents may occur due to the changing charge current during scan. Adjustment of vertical size, VGA overscan and EHT compensation The amplitude of the differential output currents at VOUT1 and VOUT2 can be adjusted via register VSIZE. Register VOVSCN can activate a +17% step in vertical size for the VGA350 mode. VSMOD (pin 21) can be used for a DC controlled EHT compensation of vertical size by correcting the differential output currents at VOUT1 and VOUT2. The EW waveforms, vertical focus, pin unbalance and parallelogram corrections are not affected by VSMOD. The adjustments for vertical size and vertical position also affect the waveforms of the horizontal pincushion, vertical linearity (S-correction), vertical linearity balance, focus parabola, pin unbalance and parallelogram correction. The result of this interaction is that no re-adjustment of these parameters is necessary after an adjustment of vertical picture size or position. f fr V () 1 10.8 R VREF × C VCAP × ----------------------------------------------------------- = Contributing elements Minimum frequency offset between ffr(V) and lowest trigger frequency 10% Spread of IC ±3% Spread of RVREF ±1% Spread of CVCAP ±5% Total 19% f fr V () 50 Hz 1.19 --------------- 42 Hz == |
Codice articolo simile - TDA4857 |
|
Descrizione simile - TDA4857 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEETIT.COM |
| Lei ha avuto il aiuto da alldatasheet? [ DONATE ] |
Di alldatasheet | Richest di pubblicita | contatti | Privacy Policy | scambio Link | Ricerca produttore 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 |
Italian ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
