It is microprocessor integrated circuit (IC) chip.
LCD controller, camera interface, serial interfaces, memory interface,USB controller, bluetooth and wifi controller,and more. are controlled by an the application processor.
Here's an example of an application processor block diagram below, on how this kind of IC works on mobile phones circuit. This kind of an application is commonly used on Nokia latest designed of mobile handsets. The description of this application processor below will help us understand how does this certain IC work.
The OMAP2420 processor is a single-chip applications processor that supports all cellular standards, and complements any modem or chipset and any air interface. It is intended for high-volume wireless handset manufacturers and is not available through distributors. The OMAP2420 includes the benefits of the OMAP 2 architecture’s parallel processing, giving users the ability to instantly run applications and operate multiple functions simultaneously without quality of service compromises. The OMAP2420 includes an integrated ARM1136 processor (330 MHz), a TI TMS320C55x™DSP (220 MHz), 2D/3D graphics accelerator, imaging and video accelerator, high-performance system interconnects and industry-standard peripherals.
The OMAP2420 processor embeds Imagination Technologies' POWERVR MBX™ graphics core, making it the first applications processor to support OpenGL ES® 1.1 and OpenVG™, providing superior graphics performance and advanced user interface capabilities. TI is enabling sophisticated and dynamic images with "smart pixel" technology offered via OpenGL ES 1.1. This unique technology allows each pixel in an image to be programmed individually, giving developers the power to create rich effects with cinematic realism. Users will now experience "life-like" facial features, advanced reflection effects and multi-textured backgrounds in the mobile environment.
Multimedia enhancements made in the OMAP2420 include an added imaging and video accelerator for higher-resolution still capture applications, multi-megapixel cameras and full-motion video encode and decode with VGA resolution of 30 frames per second. An added TV video output supports connections to television displays for displaying images and video captured from the handset. 5-Mb internal SRAM also boost streaming media performance. Access to the OMAP Developer Network also provides an extensive range of programs and media components that manufacturers can use for differentiating and delivering products to market fast.
- Dedicated 2D/3D graphics accelerator at 2 million polygons per second
- Added imaging and video accelerator enables high-resolution still image capture, larger screen sizes and higher video frame rates
- Supports high-end features including 4+ megapixel cameras, VGA-quality video, high-end interactive gaming functionality and analog/digital TV video output
- 5-Mb internal SRAM boosts streaming media performance
- Software compatibility with previous OMAP processors
- Parallel processing ensures no interruptions or degradation of service with simultaneously running applications
- Optimized power management companion chip, TWL92230 12 mm x 12 mm, 325-ball MicroStar BGA™, 0.5-mm pitch