Product category: Analogue and Mixed Signal ICs
News Release from: National Semiconductor | Subject: LM4934
Edited by the Electronicstalk Editorial Team on 14 December 2005
Handset audio chip has analogue and
digital paths
The LM4934 Boomer stereo audio subsystem is billed as the industry's first subsystem to incorporate both digital and analogue input paths for multimedia, smart and VoIP phones.
The LM4934 Boomer stereo audio subsystem is billed as the industry's first subsystem to incorporate both digital and analogue input paths for multimedia, smart and voice-over-Internet procotol (VoIP) phones National's Boomer audio power amplifiers provide high-quality output power with a minimal number of external components
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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"Cellphone manufacturers use a combination of digital and analogue sources in their designs", said Roland Dorn, Product Marketing Manager Audio at National Semiconductor in Europe.
"For example, the output of an MP3 decoder may be digital, while an FM radio module's output may be analogue".
"This flexibility, combined with the on-chip features, helps engineers save components, board space, cost and design time".
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The LM4934 audio subsystem integrates audio amplifiers, volume control, a mixer, power management control and National's 3D stereo sound-enhancement technology into a new, 3.3 x 3.9mm, 42-bump micro SMDxt package.
The 3D capability makes it easier for listeners to hear music more clearly through the phone by broadening the sound field of the closely placed speakers.
The LM4934 offers an I2S digital input and three analogue inputs, which eliminate the need for an external digital-to-analogue convertor (DAC) and a multiplexer integrated circuit.
Operating on a 3.3V supply, the single-chip LM4934 combines a stereo speaker amplifier delivering 500mW typical per channel into an 8ohm load and a stereo headphone amplifier delivering 30mW typical per channel into a 32ohm load.
The chip features a 25mW mono earpiece output and a separate line out to drive external audio devices.
The onboard phased-lock loop (PLL) simplifies the customer's selection of a clock frequency (from 8 to 24MHz) and saves cost by eliminating the need for an external crystal oscillator.
The entire chip is controlled through 25 separate I2C compatible registers for maximum flexibility of routing inputs and outputs through the two-wire interface.
In addition, the LM4934 routes and mixes the stereo and mono inputs into multiple, distinct output modes using a simple I2C compatible interface.
National's new micro SMDxt package provides high input/output analogue devices with the smallest possible footprint for any given pin count.
The micro SMDxt, which builds on the success of National's micro SMD package, uses a unique solder ball structure that enables high-reliability products with bump counts up to 100 bumps at a 0.5mm pitch.
With the new package, reliability requirements for typical portable applications such as thermal cycling, thermal shock, drop test and flex test can be met without the use of an underfill.
National produces billions of chips per year and packages them in more than 70 different package types.
The company has more than 290 patents in package technologies and receives approximately 30 new packaging patents each year.
National has introduced several packaging innovations to the industry, including both the micro SMD and LLP packaging technologies.
The LM4934, available now in a standard 42-bump micro SMDxt package, is priced at $3.80 in 1000-unit quantities.
A lead-free package will be available in early 2006.
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