|
|
 |
Ultra-Small Digital Stereo Amplifier Chip that Delivers Superior Sound Quality for Mobile Phones and Portable Audio Devices
Supports filter-less output at maximum 2.5 watts per channel
Yamaha Digital Amplifier Chip YDA139
~Improves sound quality and reduces power consumption in mobile devices~ |
|
 |
Yamaha Digital Amplifier Chip YDA139
Sample price: ¥525 (including tax)
|
|
| YAMAHA CORPORATION (with its head office in 10-1, Nakazawa-cho, Hamamatsu-shi, Shizuoka; President: Shuji Ito) announces that it will start shipping samples of its YDA139 digital stereo amplifier chip on March 31, 2005 (Thursday). An ultra-small digital amplifier (Note 1) with maximum output of 2.5 watts per channel, the YDA139 is designed for application in mobile phones and portable audio devices. |
|
 |
 |
|
|
| Sample Price and Launch Date |
|
| Product name |
Product no. |
Sample price |
Shipment date
|
| YAMAHA digital stereo amplifier chip |
YDA139 |
¥525 (including tax) |
March 31, 2005 (Thursday)
|
Initial shipment volume (tentative): 500,000 per month
|
|
|
|
|
|
|
| Product Overview |
|
|
|
|
The YDA139 is the first ultra-small digital amplifier chip in its class to deliver 2.5-watt stereo amplification for both digital and analog input. Equipped with a speaker drive circuit, the ‘pure pulse direct speaker drive circuit’ (Figure 1), that supports high-efficiency filter-less output while retaining superior sound quality, the YDA139 achieves the lowest distortion and noise levels in its class.
Existing digital amplifier chips for portable devices consist of monaural amplifiers designed for audio amplification, making two chips necessary to play melody ring tones (Chaku-Melo), singing ring tones (Chaku-Uta), MP3 files, and other audio data in stereo format. Moreover, fluctuations in power supply voltage and the reacting voltage of the speaker’s voice coil often erode sound quality. The YDA139’s ‘pure pulse direct speaker drive circuit’ has a direct-drive function that reduces distortion and noise, achieving single-digit or better improvement in these areas compared with existing digital amplifier chips for portable audio equipment. Furthermore, because the drive is tailored to the specifications of small speakers used in portable devices, the YDA139 boosts power source efficiency by more than 10% compared with conventional products, thereby reducing power consumption.
|
|
|
|
|
|
| Development Background |
|
|
|
|
YAMAHA has worked to commercialize digital amplifier chips in the 2.5W–100W per channel range that offer superior sound quality and low power consumption since becoming the first semiconductor maker in Japan to develop a 2.5W/channel stereo digital amplifier chip in October 2001.
In recent years, mobile phones and portable audio devices have increasingly been equipped with stereo speakers, facilitating the enjoyment of stereophonic audio in such formats as MP3, which is a standard compression method for digital sound, including Chaku-Melo and Chaku-Uta. As a result, device makers have started using digital amplifiers with low power consumption in a drive to make their products portable, beginning with mobile phones, by making them smaller and to extend their battery life.
The YDA139 meets the need for high-efficiency, ultra-small stereo amplifiers that enable portable devices to deliver superior sound quality. Also, because it is equipped with the ‘pure pulse direct speaker drive circuit,’ which delivers high-quality, high-efficiency filter-less output, the YDA139 reduces the number of external components.
|
|
|
|
|
|
| Key Features |
|
|
|
|
| 1. |
All-in-one 2.5W/channel digital amplifier chip
The YDA139 is a 25-pin wafer-level chip-size packaging (WLCSP) integrated circuit with an ultra-small angle of 2.6. It supports both analog and digital signals, enabling mixing playback of both. It has a pulse-width modulation circuit (Note 2), employs the ‘pure pulse direct speaker drive circuit,’ internal-excited clock oscillation circuit (Note 3), a pop noise reduction circuit (Note 4), an overload protection circuit (Note 5), and other functions required of digital amplifiers.
|
| 2. |
High-efficiency ‘pure pulse direct speaker drive circuit’ that delivers superior sound quality
Conventional digital amplifier chips use an LC filter to remove the pulse modulation signal, which is contained in the output signal, for direct speaker connection. However, the use of an LC filter reduces sound quality and the space requirement for mounting the LC filter has become a problem.
The YDA139 uses a ‘pure pulse direct speaker drive circuit’ to control the pulse modulation signal in the output signal, thereby eliminating the need for an LC filter. Because the YDA139 enables filter-less, direct connection to the speaker, it eliminates the problems of degraded sound quality and additional mounting space associated with the use of LC filters.
Also, degradation of sound quality due to the reacting voltage of the speaker’s voice coil and to fluctuations in the power supply voltage is ameliorated, thereby enhancing functionality and sound quality.
|
| 3. |
Achievement of high-performance sound on par with hi-fi stereo units at lower power consumption
Compared with digital amplifier chips in the same class, the YDA139 delivers high-performance sound on a par with hi-fi stereo units, achieving distortion + noise of 0.02% and an S/N ratio of 97dB or greater.
|
| 4. |
Reduction of external components
The YDA139 enables the elimination of external LC filters, according to application, thereby reducing the number of external resistance and capacity components by up to half.
|
|
|
|
|
|
|
| Major Specifications |
|
|
|
|
| Functions/specifications |
All-in-one digital amplifier chip with single power supply
Input: Digital/analog
Output: 2.5W x 2 channels at 4
VDD=5V
Max. efficiency: 90%+
THD + N: Min. 0.02%, 10% @ 2.5W output
S/N: 97dB or greater, 1Vrms sensitivity time control
|
Operating/power supply
voltage |
2.5–5.0W |
| Process |
CMOS process |
| Package |
25-pin WLCSP (2.6 mm) |
Figure 1: Operation of YDA139’s ‘pure pulse direct speaker drive circuit’ |
|
|
|
|
|
| Notes |
|
|
|
|
| 1. |
Digital amplifier
Conventional analog amplifiers boost wattage by using an analog electric waveform in proportion to the size of the music signal, thereby driving the speaker. In contrast, digital amplifiers convert the music signal into high-speed digital pulse signals, thereby boosting wattage and driving the speaker.
Because digital amplifiers boost wattage using digital pulse signals with a value of either ‘1’ or ‘0,’ power source usage efficiency is high compared with analog systems, enabling considerable output power with little power consumption and little generation of heat.
|
| 2. |
Pulse-width modulation circuit
The pulse-width modulation circuit converts the voltage magnitude of the music signal into long and short digital pulses. Output is in the form of a pulse width signal that has been modulated from a music signal using digital pulse frequencies.
|
| 3. |
Internal-excited clock oscillation circuit
The Internal-excited clock oscillation circuit enables automated clock oscillation without the use of external oscillation elements, such as a crystal oscillator.
|
| 4. |
Pop noise reduction circuit
The pop noise reduction circuit reduces the ‘popping’ noise generated by the speaker when the amplifier chip is turned on and off.
|
| 5. |
Overload protection circuit
The overload protection circuit monitors output current from the digital amplifier chip and shuts down operation when there is an abnormal power surge, such as when there is a short in the speaker.
|
The products and companies mentioned in this press release are registered trademarks of YAMAHA CORPORATION. |
|
|
 |
For further information, please contact
YAMAHA CORPORATION
Public & Investor Relations Group,
Public Relations Division
Mr. Mike Tanaka
TEL +81-3-5488-6601
FAX +81-3-5488-5060
|
|
|
|
|
|
|
