describe
The WT8043 is a silicon monolithic circuit designed for simultaneous signal processing of multiple simultaneous displays, capable of handling a wide variety of PCs and workstations. It can be applied to monitors that support standard IBM VGA, VESA Super VGA and IBM 8514 /A video modes. It can also be used on other high-end monitors that support non-standard video modes with user-defined horizontal/vertical frequency ranges.
The WT8043 integrates many functional circuits, horizontal/vertical frequency discrimination, display mode selection and sync pulse polarity detection into one chip. Therefore, by using the WT8043, display manufacturers can reduce the size of the PC board, reduce the cost of materials with fewer components, and also reduce labor costs.
Features • Accepts independent H&V sync signals of any polarity • Supports VESA VGA (640x480, 640x400, 640x350), VESA SVGA (800x600), European SVGA (800x600), VESA New SVGA (800x600), XGA (1024x768) and 1280x1024. • Also includes NEC (24K) mode, 3 new VESA 75Hz timing modes and Apple Mac II (35K) mode. • Capable of handling horizontal frequencies from 25 kHz to 80 kHz • Capable of handling vertical frequencies from 50 Hz to 120 Hz • Standard IBM video mode control output (1024x768, 640x480, 640x400, 640x350) • Six non-standard horizontal frequencies with predetermined frequency ranges Control output. (Users can define their own horizontal frequency range) • Fixed polarity horizontal and vertical sync signal output • Power supply voltage: 5V, but mode selection control output and frequency discrimination control output, these open collector outputs can be combined with pull-up resistors to pull up to 12V.

The evaluation description generally describes a simplified WT8043 functional block diagram. It includes tracking functional blocks: sync pulse polarity detector; horizontal and vertical frequency discriminator, mode selector.
The sync pulse polarity detector receives H and V sync signals separated from any polarity. It determines their extremes and provides extreme information to the video mode selection mode. In its input polarographic spinel, it generates H and V signals.
H and V frequency discrimination determines the frequency range of the H and V sync signals. Depending on the frequency range and extremes of the H and V sync signals, the mode selection should determine the video operating mode. Operating video modes include standard IBM VGA (640x350, 640x400, 640x480), SuperVGA (800x600) and IBM8514/A (INerlaced, non-interlaced), VESA VGA&SVGA Mode, VESA New SVGA Mode, XGA (1024x768), and 1280x1024 Mode, also including NEC 24khz and 3 Vesa New 75Hz Timing Modes.
The mode selector also includes an output signal representing the frequency range of the H. sync signal. For WT8043 and WT804N20, the H sync signal is divided into 6 frequency ranges (3 frequency ranges). However, it also provides the flexibility to provide user-defined points of differentiation for non-standard video modes.
The digital noise filter is used to suppress noise on the incoming horizontal and vertical sync signals. Input Section uses two techniques to improve noise recovery. Therefore, low-level noise and short-term large noise rotations will be rejected. The horizontal sync pulse width is 0.56 microseconds and the vertical sync pulse width is 0.56 microseconds.

Typical frequency ranges for H/V crossover and video mode display H and V sync signals. The operating video mode is determined by the H and V frequencies and occasionally by their polarity. Typical video modes for monitors include NEC 24K mode, IBM VGA, VESA VGA, European VGA/Super VGA, Apple Mac II, VESA Super VGA, IBM 8514/A, 3 VESA New 75Hz modes, XGA and 1280x1024.
WT8043 can determine 18 standard video modes according to H, V frequency and polarity

These standard video modes include ibm vga, vesa vga, vesa super vga and ibm 8514/a. This provides users with the ability to resize the screen according to different modes.
The WT8043 pre-sets the identification points on the H and V frequencies. The identification points for H sync are 33kHz, 36.2kHz, 45kHz, 52kHz, 62kHz and 72kHz. These recognition points will be capable of recognizing various video modes, and the WT8043 also provides the user with the flexibility to define these recognition points through a masking option.
The tolerance of synchronous frequency discrimination is 0.05kHz. For example, a 33kHz identification point would be able to distinguish between "less than or Euqal to" 32.95kHz or "greater than or equal to" an H sync frequency of 33.05kHz. There is an area of blur between 32.95kHz and 33.05kHz.
The WT8043 has three identification points, 64Hz, 73.5Hz and 78Hz, with a tolerance of 0.01Hz. The mode selection is performed using the identification result of the V sync frequency.
Based on software package considerations, IBM VGA mode and VESA VGA mode (both have the same resolution: 640x480, 640x400, 640x350) output pins on the same drain structure (e.g. N20p1 pin package pin 14 to pin 14). Decode on pin 16). If decoding of all 6 modes is required, the horizontal discriminator pin F33K or F36K must be considered. The horizontal frequency of ibm vga mode is 31.4KHz, and the horizontal frequency of vesa ibm vga mode is 37.5KHz. These two standard modes are clearly identified using the F33K or F36K pins