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A/D simplifies digital audio conversion blocks

Austin, Texas — Cirrus Logic Inc. claims these are the smallest stereo analog-to-digital (A/D) converters available for consumer and automotive audio applications.

The 10-pin A/D converters (CS5343 and CS5344) give OEMs the industry's smallest (less than 15-square millimeters), stereo audio A/D converters, while still delivering superior sound quality, said Jason Rhode, vice president and general manager of Mixed-Signal Audio Division, Cirrus Logic.

Applications include set-top boxes, digital televisions, DVD recorders, audio/video receivers, in-car entertainment and concierge systems and musical instruments.

Based on an advanced multibit delta-sigma architecture, the CS5343 and CS5344 operate from a single 3.3-volt or 5 V power supply and utilize a proprietary automatic mode selection to eliminate external configuration. These parts also incorporate a unique input architecture, which provides a very high input impedance of 7.5 Megohms, Rhode said.

The CS5343 and CS5344 support audio sample rates up to 108 kHz and deliver 98 dB of dynamic range and -90 dB of total harmonic distortion plus noise (THD+N).

Consuming 50 milliwatts of power, the CS5343 and CS5344 differ only in the serial audio interface format they support, with the CS5343 supporting the I2S format and the CS5344 supporting left-justified serial data format.

The CS5343 and CS5344 are available in a 10-pin, lead-free TSSOP package and are each priced at $1.35 in 10,000-piece quantities.Click here for the CS5343 and CS5344 data sheets.

Cirrus Logic , 1-800-625-4084, www.Cirrus.com.

 
 
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The CS5343 and CS5344 are entry level A/D converters that are said to be simple to implement. Cirrus refers to them as “smart parts” because they require no configuration.

“The converter only needs a power supply and some clocks. Feed it some audio analog and the device will do the conversion and output digital audio in the form of I2S or left justified depending on the part,” said Carl Alberty, senior manager of Cirrus' Mixed-Signal Audio Division.

Cirrus has patented the technology that enables the converters to automatically detect the sample rate and configure the part internally with the appropriate filter and conditions. Cirrus' auto-mode selection technology is not new. The technology was used in a similar part (CS5340) that came out a few years ago. In master mode, speed modes are selected by pin-configuration — while in slave mode the speed mode configuration is automatic.

The older 16-pin CS5340 A/D converter required configuring two pins to set different modes of operation in master mode. The CS5343 and CS5344 converters have only 10 pins so there are no mode settings or configuration required.

The CS5343 and CS5344 are Cirrus' first A/D converters housed in the 10-pin TSSOP package. Historically, Cirrus' smallest package size for converters was a standard SLIC with 8 leads (8.1 x 5.35 mm). Including the package and leads, the new package size is 50 percent smaller (3 x 4.9 mm), according to Alberty.

The CS5340 A/D converter was considered an entry level device for low end consumer audio applications. However, the new 10-pin devices are smaller, feature 98 dB dynamic range, 24-bit resolution and a 96-kHz sample rate for cost-conscience, entry-level applications, Alberty said.

Cirrus' decade old CS5330A and CS5531A devices were also considered entry level 18-bit delta-sigma A/D converters with 94 dB noise performance. Cirrus believed there was a niche to fill between the CS5340 introduced a few years ago, and the decade old devices. “The CS5343 provides higher performance than the CS5330A/1A yet it is smaller and more cost effective compared to the CS5340/41,” Alberty said.

Cirrus optimized the latest A/D converters for very basic audio conversion sockets. The company reduced performance slightly, shrunk the package size, and reduced the number of external components required.

The CS5343 offers improved audio performance compared to the CS5330A/1A converters (24 bit compared to 18 bit in the CS5330A/1A; and a higher sample rate of 96 kHz). However, dynamic range dropped to 98 dB for the CS5343 down from 101 dB for the older CS5340, Alberty said.

The CS5340 included an active op amp circuit on the input, whereas the new pair requires no active off chip circuit. The CS5343 and CS4344 include a high impedance input architecture, which supports line-level audio inputs with passive input buffer circuitries. Furthermore, the CS5343 and CS4344 contain half of the external components needed compared to the CS5340.

 
 
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