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New Speaker Driver Equipped with 'Pure Pulse Direct Speaker Drive Circuit' Delivers Best Sound Quality in its Class
10W, Two-channel digital amplifier chip supports filter-less output
YAMAHA Digital Amplifier Chip YDA138
~Improves sound quality, reduces power consumption, and reduces number of components~ |
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YAMAHA Digital Amplifier Chip (YDA138)
Sample price: ¥630(including tax)
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YAMAHA CORPORATION (with its head office in 10-1, Nakazawa-cho, Hamamatsu-shi, Shizuoka; President: Shuji Ito) announces that it started shipping samples of its YDA138 two-channel output digital amplifier chip on November 8, 2004 (Monday). A 10W, two-channel output digital amplifier (Note 1), the YDA138 is designed for application in devices that require superior sound quality, including flat-panel televisions, LCD PC monitors, portable audio devices, and PC speakers.
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| Sample Price and Launch Date Product name |
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| Product name |
Product no. |
Sample price |
Shipment date
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| YAMAHA two-channel output digital amplifier chip |
YDA138 |
¥630(including tax)
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November 11, 2004 (Monday)
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Initial shipment volume (tentative): 200,000 per month |
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| Product Overview |
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The YDA138 is a 10W digital amplifier chip equipped with the ‘pure pulse direct speaker driver circuit,’ YAMAHA’s new speaker drive circuit that delivers superior sound quality. The YDA138 boasts the lowest level of distortion and low noise while reducing the number of external components.
In conventional digital amplifier chips, the speaker is connected directly to an LC filter (a low-pass filter comprised of a coil L and condenser C), which eliminates the modulating signal contained in the output signal. The YDA138 features the ‘pure pulse direct speaker drive circuit,’ which is a scaled-down LC filter that enables the chip to drive the speaker through a direct connection. This setup eliminates sound degradation associated with the use of LC filters and reduces the number of LC filter components (Figure 1).
Moreover, conventional, filter-less digital amplifier chips designed solely to reduce the number of LC filter components suffer two shortcomings. One is that the reacting voltage of the speaker’s voice coil degrades sound quality. The other is that fluctuations in the power supply voltage distorts the pulse output signal and creates noise. The ‘pure pulse direct speaker drive circuit’ greatly reduces signal distortion and noise, thereby providing a direct-drive capability. As a result, the YDA138 demonstrates significant improvement in terms of distortion and noise compared with conventional filter-less, 10W digital amplifier chips.
The YDA138 also greatly reduces power consumption, using one-fourth or less power than existing 10W analog amplifier chips, enabling the use of a smaller external heat sink, which is necessary in analog amplifier chips.
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| Development Background |
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YAMAHA has worked to commercialize digital amplifiers that deliver superior sound quality since it developed the YDA131 chip in October 2001, becoming the first semiconductor maker in Japan to make a 2.5W/channel, two-channel digital amplifier chip.
In recent years, flat-panel televisions, LCD PC monitors, portable audio equipment, PC speakers, and other such devices have become increasingly thinner and smaller, prompting makers to see ways to conserve space and reduce heat generation. At the same time, they have sought solutions that provide better playback of audio and visual data and enhanced sound quality.
The YDA138 features YAMAHA’s new ‘pure pulse direct speaker drive circuit, aimed at meeting demand for an ultra-small digital amplifier that delivers superior sound quality. While achieving the lowest distortion and noise levels of any 10W digital amplifier, the YDA138 curtails the size of such external components as LC filters and heat sinks.
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| Key Features |
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| 1. |
All-in-one 10W two-channel digital amplifier chip
The YDA138 is a 42-pin shrink small outline package (SSOP) that provides heat dissipation at the high level required by digital amplifiers. It also includes such essential elements as an analog signal input circuit, a pulse width modulation circuit (Note 2), a ‘pure pulse direct speaker drive circuit,’ an internal/external excitation clock oscillation circuit (Note 3), a pop noise reduction circuit (Note 4), a master/slave drive circuit (Note 5), a carrier frequency hopping circuit (Note 6), an overload protection circuit, and a headphone amplifier.
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High-efficiency pure pulse direct speaker drive circuit that delivers superior sound quality
In conventional digital amplifier chips, the speaker is connected directly to an LC filter, which eliminates the modulating signal contained in the output signal. However, sound degradation associated with the LC filter and mounting space for LC filter components are problematic.
The YDA138 controls the pulse modulation signal in the output signal using YAMAHA’s new ‘pure pulse direct speaker drive circuit,’ which enables the use of a scaled-down LC filter and filter-less operation through a direct connection between the amplifier chip and the speaker, thereby eliminating sound degradation associated with the use of LC filters.
Moreover, the YDA138 delivers superior quality through enhanced functions that ameliorate the degradation of sound quality due to the reacting voltage of the speaker’s voice coil and due to fluctuations in power supply voltage.
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High-efficiency pure pulse direct speaker drive circuit that delivers superior sound quality
Compared with digital amplifier chips in the same class, the YDA139 delivers high-performance sound on par with hi-fi stereo units, achieving distortion + noise of 0.02% and an S/N ratio of 100dB or greater.
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Fewer external components
Depending on the application, the YDA138 makes it possible to eliminate such external components as the LC filter, headphone amplifier, gain resistor, transducer, and heat sink.
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Built-in monaural operation mode
The two-channel output-enabled YDA138 is equipped with a monoaural operation mode, which is capable of a maximum output of 20W @ 4.
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| Major Specifications |
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| Functions/specifications |
All-in-one digital amplifier chip with single power supply
Output: 2CH x 10W@8Ω /1CH×20W@4Ω (monaural mode) VDD =12V
THD + N min. 0.02%, 10% @10W output
S/N 100dB or higher @ 1Vrms sensitivity
Built-in headphone amplifier
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| Operating/power supply voltage |
9–12 volts
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| Process |
CMOS process
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| Package |
42-pin SSOP with internal heat sink
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Figure 1: Operation of YDA138’s Pure Pulse Direct Speaker Drive Circuit |
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| Notes |
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| 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.
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Pulse-width modulation(PWM) circuit
The pulse-width modulation circuit converts the magnitude of the voltage in the music signal into long and short digital pulses. Output (the PWM signal) is in the form of a pulse width signal that has been modulated from a music signal using digital pulse frequencies.
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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. It also allows the selection of other excitation modes that use external oscillation elements. The internal-excited mode reduces the number of external chip components, while the other external excitation mode enables carrier frequency hopping and a multi-channel structure using a master/slave connection.
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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.
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Master/slave operation circuit
The master/slave operation circuit has a multi-channel system construction that is enabled by synchronous operation and connection through the ‘other excitation mode’ of multiple YDA138 chips.
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Carrier frequency hopping circuit
The carrier frequency hopping circuit switches the carrier frequency (i.e., the digital amplifier chip pulse modulation frequency), thereby reducing radio channel reception interference.
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The products mentioned in this press release are registered trademarks of YAMAHA CORPORATION. |
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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
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