audio/videoZONE Products for the week of February 3, 2003
Wolfson Microelectronics Says . . .
WM9712L: Audio + Touchscreen Codec Provides Power
Savings
High Performance Audio Sub-System And Touchscreen Controller
Drives
PDA, Smartphone and Handheld Consumer Devices
Wolfson Microelectronics today expanded its mobile device IC offering
with the introduction of an ultra low-power, single-chip design that combines
a streaming data touchscreen interface with the company's leading audio
sub-system codec capability. The highly integrated WM9712L IC builds upon
the existing features of previous generation products, cutting power consumption
by more than half. It also adds new features, including an on-chip speaker
driver, graphic equalizer, GPIO pins and 5-wire touchscreen support.
Running from supply voltages between 1.8V and 3.6V and core voltages down to 1.42V, the WM9712L reduces power consumption by up to 50% over previous generations. This has been achieved through the use of low power silicon technology and power efficient design of the analog circuit blocks.
"The increasing need for high-performance audio and touchscreen ergonomics in mobile applications is driving power requirements to new extremes and creating a new set of challenges for consumer device manufacturers," commented David Milne, managing director of Wolfson Microelectronics. "Wolfson has solved this problem by engineering a highly integrated codec that reduces power consumption, software overheads and component count, thus providing consumers a superior value for their mobile devices."
The WM9712L is compatible with the AC'97 standard, carrying audio, touchscreen and control data on a single serial interface. Variable-rate support is built into the WM9712L, making it easy to support all of the audio sample rates used in WinCE systems. This removes the need for power-hungry Phase Locked Loop (PLL) circuits or sample rate conversion algorithms that slow down the CPU. In contrast, the majority of audio + touchscreen interface ICs on the market today cannot simultaneously play and record audio at different sample rates.
The continuous-mode touchscreen interface has been designed to reduce CPU loading, as data can be written directly to a DMA buffer at a pre-programmed rate. This eliminates time-consuming polling routines to access touchscreen data, reducing CPU loading to as little as 5% of that used by polling techniques.
Wolfson's WM9712L is the first audio codec to provide all the audio functions
for a smartphone, mixing voice with other audio signals like MP3 music,
and connecting directly to stereo headphones, a phone receiver, and a separate
8 Ohm loudspeaker. It is also the first audio + touchscreen interface IC
to support 5-wire touchscreens, an important feature for large screen applications,
such as tablet PCs, where superior reliability and accuracy are critical.
analogZONE Says . . .
When Wolfson announced the predecessor to this part in May 2001 (the WM9705) it brought a mini-revolution to the PDA business and it maybe even was encouraged by or caused some major rethinks in the industry. The PDA market is not a place you particularly want to be emphasizing at the moment, but an explanation of why sales are totally in the dumps seems difficult to explain. Has everybody who would ever buy a PDA got one? Or is the device itself a faulty premise for today's market? I personally believe that the markets are once more coalescing into something new so that we are very close to seeing multi-functioning devices that are not exactly PDAs, not exactly handheld computers, not exactly tablets, and certainly not exactly phones. And if that's the case Wolfson is in the right place with products stretching over those boundary lines.
There are small architecture changes from the original product to the new WM9712L, the most noticeable ones being the provision of a speaker output in addition to the ear bud and headphone outputs, as well as 5-wire touchscreen support. Other small changes are the moving of the phone input and PC "beep" from insertion on the output side to their being included on a much cleaner input mux with PGAs. There is also provision for microphone bias which was implicit in the earlier version but not spelled out. The internal battery monitor potential divider has been taken out but there is still a spare auxiliary input available to the ADC used for the touch-screen controller and Wolfson has added "dead battery" and "low battery" comparators. It also looks like there are some changes to the digital processing but the data available cannot explain what those changes are.
The most important change, however, is the reduction of rail voltages. The WM9705 operated from 3 V to 5 V, whereas the WM9712L can now operate from 1.8 V to 3.6 V (with the digital sections down to 1.5 V) making the part dramatically more acceptable to the markets it is addressing.
The WM9712L is in production in a 7 x 7 mm QFN-48 and a TQFP-48, priced at $6.64 in 1000-piece lots. Device drivers are available.
At the time of publication the data sheet had not yet been posted on
Wolfson's web site.