Am121-2And Peripheral Circuits; General Description - NEC MultiSync LCD1920NX User And Service Manual

2.4 AM121-2and peripheral circuits

The AM121-2 is enhanced version of the AM100 chip. It is an IC designed for dual-interface SXGA TFT LCD
monitors. A dual-interface LCD monitor takes analog or digital RGB signals from a personal computer
graphics card. This feature makes a dual-interface LCD monitor.

2.4.1 General description

The analog input RGB signals are first sampled by six channels of the 8-bit A/D converter, and the 48-bit
RGB data is then fed into AM121-2. For digital interface, the input data is first received by a TMDS receiver,
and the 24/48 bit RGB output data of TMDS receiver is then fed into AM121-2. Without any manual
adjustment, AM101 is capable of performing automatic detection of the display resolution and timing of input
signals generated from various PC graphic cards. AM121-2 then automatically scales the input image to fill
the full screen of the LCD monitor. AM121-2 can interface with TFT LCD panels from various manufacturers
by generating either 24-bit or 48-bit RGB signal to the LCD panel based upon the timing parameters saved in
the EEPROM.
The AM121-2 implements four advanced display technologies:
Advanced mode detection and auto-calibration without any external CPU assist
Advanced programmable interpolation algorithm
Stand-alone mode support, and
Advanced true color support with both dithering and frame modulation
The AM121-2 also provides distinguished system features to the TFT LCD monitor solution. The first one is
"plug-and-play", and the second one is "cost-effective system solution". To be truly plug-and-display, the
AM121-2 performs automatic input mode detection and auto phase calibration, so the LCD monitor can
ensure that the A/D converters' sample clock is precisely synchronized with the input video data, and to
preserve the highest image bandwidth for the highest image quality. Furthermore, the AM121-2 can generate
output video even when the input signal is beyond the specifications or no input signal is fed.
For "cost-effective system solution", the AM121-2 implements many system support features such as OSM
mixer, error status indicators, 2-wire serial interface for both EEPROM and host CPU interface. Another
important contributing factor is that the AM121-2 does not require external frame buffer memory for the
automatic image
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