Maxim introduces the MAX9597, a fully integrated, +3.3V SCART solution for set-top boxes and A/V receivers that have one SCART connector. Designed to enable greener consumer applications, this device utilizes power-saving technology to reduce power consumption. Maxim's DirectDrive technology enables the device to operate audio and video signals from +3.3V, thereby eliminating the need for a +5V supply and minimizing the use of a +12V supply. This low-voltage operation, combined with the MAX9597's miserly 53mW quiescent current consumption, makes it much easier to meet stringent energy-efficiency requirements for set-top boxes.
The MAX9597 eases the routing of audio and video signals between an MPEG encoder and an external SCART connector. It integrates standard-definition video filters on all video-encoder inputs, and all audio drivers deliver a full-scale (2.0VRMS, min) output. The audio section contains left and right audio paths with an independent operational amplifier at the inputs. The MAX9597 is controlled through an I²C-compatible interface. Traditionally, set-top box manufacturers have utilized low-cost discrete components to interface with the SCART connector. Although these designs can be inexpensive to implement, they do not maximize energy efficiency.
Typical discrete single-SCART implementations require +5V for video and +12V for audio signals. In contrast, the MAX9597 is a complete SCART solution designed to deliver the lowest possible power consumption. This fully integrated device operates audio and video circuitry from +3.3V, and only requires +12V for the slow-switching signal. Maxim's DirectDrive technology employs an internal charge pump to invert the +3.3V supply and generate a -3.3V supply, thereby providing sufficient voltage swing to support 2.0VRMS audio. To further reduce power consumption, the MAX9597 consumes a mere 53mW during quiescent operation, and 5µW in shutdown.
DirectDrive Audio Circuitry Suppresses Clicks and Pops
Conventional audio-line output drivers that operate from a single supply require series AC-coupling capacitors. During power-up, the DC bias on the AC-coupling capacitor moves from ground to a positive voltage. During power-down, the opposite occurs. The changing DC bias usually causes an audible transient, typically referred to as a "click" or "pop." In the MAX9597, DirectDrive audio circuitry suppresses this click-and-pop noise. With DirectDrive, the DC bias of the audio-line outputs is always at ground, regardless of whether the MAX9597 is being powered up or powered down. DirectDrive circuitry thus eliminates the need for AC-coupling capacitors on the audio outputs, thereby conserving board space, reducing system cost, and improving frequency response.
The MAX9597 operates from standard +3.3V and +12V power supplies. Available in a compact, 5mm x 5mm, 28-pin TQFN package, this device is fully specified over the 0°C to +70°C commercial temperature range. Prices start at $0.90 (1000-up, FOB USA).
