Digital audio delay chip eases 'lip sync'

Texas Instruments Inc. (TI) has introduced the TPA5050 digital audio delay with IIC control designed for high-definition and flat-panel TV applications. According to the company, the TPA5050 digital audio delay provides cost-effective synchronization of audio and video in a single integrated package that conserves board space and simplifies channel configuration.

Audio/video (A/V) synchronization issues arise because video processing is more intensive than audio processing. As a result, audio is ready for playback before the video. Without synchronization, what viewers hear will not match what they see on the screen—where the timing of lips moving is off from the words being heard, for example—significantly impacting the overall viewing experience. Also known as "lip sync," A/V synchronization is maintained by delaying playback of the audio stream, until the video stream has finished processing. The actual delay required for synchronization depends upon the type of A/V signals and the current video mode.

Synchronization also plays a role in wireless multi-channel speaker applications. Given the inherent processing delays of wireless transmission, it takes more time for transmitted channels than non-transmitted channels to output audio. The non-transmitted channels, therefore, must have additional delay to synchronize them with the transmitted channels.

"As TV applications are getting more sophisticated and more wireless components are being adopted, there is a real need in the market for lip sync devices that can be easily implemented and meet the needs of manufacturers," says Kevin Belnap, marketing manager for Home Audio, Texas Instruments. "The TPA5050 digital audio delay is practically a drop-in device that provides lip sync delay in the most cost-effective and compact manner."

TI said the new digital audio delay device offers developers a cost-effective way to implement lip sync delay in a single chip that is easily configured and reduces system complexity, which will ultimately provide consumers an even better end product when purchasing newer TV technologies, including DLP HDTVs. Additionally, given the tight physical constraints of A/V applications such as LCD TVs, minimizing the size of components on the PCB is an important design consideration.

Because the new chip can provide up to 170ms of delay per channel—and with resolution down to a single sample—the device can synchronize the most demanding TV applications and make the audio and video delay imperceptible, said TI. Its integrated architecture and 4-by-4mm QFN package minimizes board footprint.

In addition to minimizing cost, board space and configuration complexity, TI said the device will automatically clear the delay memory during a delay time change, eliminating undesirable pops and clicks. The device supports 16- to 24bit data, sample rates from 32- to 192kHz, and all standard audio configuration interfaces, including I²S, Left- and Right-Justified. All internal clocking on the device is generated from the bit clock so no crystal or oscillator is needed. The inputs are 5V tolerant so interfacing with a host of microcontrollers and audio processors is not an issue. Developers requiring longer delays for professional or specialized applications can cascade multiple TPA5050 chips.

TPA5050 complements other TI digital and analog products that support audio applications, such as Class D amplifiers, audio converters, processors and switch mode power management.

Available in production volumes, the TPA5050 digital audio delay costs $3.20 each in 1,000-unit quantities. Two other members of the TPA505x family are currently sampling. TPA5051 offers support for four channels with up to 85ms lip sync delay per channel. TPA5052 is controlled through five mode pins, providing 32 programmable delay settings ranging from zero to 170ms and is otherwise pin-for-pin compatible with TPA5050. The mode pins eliminate the need to manually configure delay length at power on, said TI.