Maxim introduces the MAX7461, a single-channel loss-of-sync (LOS) alarm that provides composite-video sync detection in NTSC, PAL, and SECAM standard-definition television (SDTV) systems. This stand-alone LOS alarm operates from a single +5V supply while consuming 1.7mA. The circuitry make the MAX7461 usefull for security video systems, consumer electronics, and automotive rear-seat entertainment (RSE) systems. The MAX7461 accepts an AC-coupled composite (CVBS), luma (Y), or sync-on-green (SoG) video signal. When the MAX7461's input pin no longer detects a video sync signal, the device generates an alarm by pulling the open-drain output /LOS\ low. This approach eliminates the need for a microcontroller, unlike the typical competitive solution that needs the microcontroller to monitor the signal. Capable of detecting sync signals as small as 0.13Vp-p, the MAX7461 enhances sync detection with an internal filter that prevents false sync detection by reducing color burst, chroma, and system noise. The device is offered in a 3mm x 3mm 5-pin SOT23 package. The part operates over the extended temperature range (-40°C to +85°C) and prices start at $0.99 (1000-up, FOB USA).

The device simplifies loss-of-sync (LOS) detection. Common solutions often use a sync separator that first extracts and then outputs the sync signal from video input. The sync signal then must be monitored by a microcontroller, functioning like a watchdog timeout circuit. The MAX7461 simplifies the LOS alarm process by pulling its /LOS\ signal low only when the input pin no longer detects a video sync signal.