Product category: Analogue and Mixed Signal ICs
News Release from: Maxim Integrated Products | Subject: MAX7456
Edited by the Electronicstalk Editorial Team on 01 November 2007
On-screen display generator adds
flexibility
Device integrates all the functions needed to generate and insert user-defined OSD onto a video signal, and is compatible with composite NTSC and Pal video standards.
The MAX7456 is a single-channel, monochrome on-screen-display (OSD) generator with integrated nonvolatile memory (EEPROM) The device integrates all the functions needed to generate and insert user-defined OSD onto a video signal, and is compatible with composite NTSC and Pal video standards
This article was originally published on Electronicstalk on 27 Aug 2002 at 8.00am (UK)
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CCTV security applications typically consist of many cameras, routed through a video switch matrix, viewed, and then recorded on a small number of monitors and recorders.
Each of the various pieces of equipment in the application can contain an OSD function to display information such as date, time, camera ID, system setup and control.
Traditionally, designers had to choose between inflexible fixed-character OSDs or expensive graphics controllers to generate and insert the OSD.
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Fixed-character OSDs offer only a limited selection of characters that can be displayed.
Graphics controllers, moreover, are very expensive and involve complex system implementation.
"With the MAX7456 single-channel OSD generator, designers can now display information like company logo, custom graphics, time and date with increased flexibility and simpler implementation", says Jeremy Tole, Maxim's Director of Business Management for Advanced Video Products.
Using the device's EEPROM, designers can insert 256 user-defined characters and graphics - a customer request that was not possible with fixed-character OSDs.
"This implementation is quite simple, and costs significantly less than a full-featured graphic controller", adds Tole.
The MAX7456 integrates all the functions and EEPROM needed to generate and insert user-defined OSD onto a composite video signal.
The device includes an input clamp, sync separator, video timing generator, OSD insertion MUX, nonvolatile (EEPROM) character memory, display memory, OSD generator, crystal oscillator, an SPI-compatible interface to read/write the OSD data, and a video driver.
With this high level of integration, MAX7456 simplifies the design, saves board space, and reduces system cost.
In addition, the MAX7456 provides special character attributes such as blinking, inverse grey scale, and background control.
The MAX7456 accepts standard NTSC or Pal CVBS signals, which are the most commonly used video standards in the security industry.
The device thus serves all US and international markets.
The MAX7456's EEPROM, which stores characters or graphic images, comes preloaded with 256 default characters and graphics.
The EEPROM is user-programmable and provides the flexibility to load user-defined characters or graphics.
A display memory stores character addresses and points to the characters stored in the EEPROM that are to be displayed.
Access to all MAX7456 operations, including display memory and EEPROM, are through the SPI registers.
The MAX7456 provides vertical sync, horizontal sync, and loss-of-sync outputs for system synchronisation.
A clock-output signal reduces system cost by allowing daisychaining of multiple devices using a single crystal.
An internal sync generator enables the display of the OSD data even when the input video signal is absent.
The device's video-driver output has a gain of 2V/V with a 6MHz large-signal bandwidth and is capable of driving two 150ohm video loads.
Moreover, the MAX7456 has internal sag compensation that eliminates the need for large coupling capacitors while achieving acceptable line-time distortion.
The MAX7456 saves significant board space and design time, while providing increased performance at lower cost.
It operates over the -40 to +85C industrial temperature range, and is offered in a 28-pin TSSOP package.
Prices start at US $9.00 (1000-up).
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