Image signal processor addresses video monitoring applications

January 11, 2013 // By Julien Happich
ON Semiconductor has released two highly integrated image signal processor ICs designed for use in applications such as vehicle reversing cameras, in-vehicle navigation systems and various consumer video monitoring security systems where small LCD screens are utilised.

The LC749000PT for automotive applications and the LC749000AT for consumer products, support important end application energy savings and utilise advanced signal technology to improve the picture quality of digitally compressed images. Capable of supporting installations with screen resolutions up to Wide Video Graphics Array (WVGA), the LC749000PT and LC749000AT integrate an analog to digital converter which receives direct analog picture signal inputs from a camera. The built-in picture decoding circuit is able to decode analog picture signals in both NTSC and PAL formats. The size of the decoded picture signal is then adjusted according to the resolution of the connected LCD panel by a de-interlacer / scaler to enhance the picture quality. The 24bit RGB output or 18bit RGB output with dithering function is then transferred to the application LCD panel by a built-in programmable timing controller.

ON Semiconductor's new image signal processor ICs incorporate features designed to optimise the displayed image.

Both new devices feature a built-in onscreen display (OSD) function which allows text characters to be superimposed on the picture data. These devices also have a built-in OSD switch that achieves more advanced graphical overlays by employing an additional graphics IC. Meanwhile, pulse width modulation (PWM) supports adaptive LED backlight control functionality that can help yield valuable application power savings of approximately 35 percent. The LC749000PT and LC749000AT are controlled by an external microcontroller via an I2C or serial peripheral interface (SPI). Hardware-driven picture processing minimises the burden on the software of the microcontroller and in vehicle camera applications. External fast EEPROM booting ensures that the LCD panel is operational immediately after the vehicle engine is switched on – an important feature for rear back-up cameras and many other non-automotive applications.

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