October 2, 2003

YAMAHA YDA 137 YAMAHA Digital Amplifier IC Sample Shipments to Begin October 20

Maximum 5W/2-channel digital amplifier IC
Highest electric output and sustainable sound quality in VDD=5V class

YAMAHA CORPORATION (head office: Nakazawa-cho 10-1, Hamamatsu-shi, Shizuoka; President: Shuji Ito) will begin sample shipments of its YDA137 maximum 5W/2-channel digital amplifier IC (Note 1) on October 20, 2003. The product is for high-quality audio performance with LCD televisions, LCD monitors for PCs, portable audio equipment, PC speakers, and other applications.

Sample Prices and Launch Schedule

Name	Code#	Sample price	Shipment date
YAMAHA Digital Amplifier IC	YDA137	¥500	October 20

Initial sales planned: 200,000 units/month

Product Overview

The YDA137 is a digital amplifier IC that operates on a single 5V power supply, enabling much greater electrical output than earlier models. It has the driving capability associated with low-impedance load min. 2Ω and has maximum 5W/2-channel output. Also, thanks to YAMAHA's proprietary circuit technologies, it has the lowest distortion and the lowest noise levels of any IC in its class. Both distortion and noise output are less than half those of existing digital amplifier ICs in its equivalent class. Electricity consumption is as little as a quarter that of analog amplifier ICs, eliminating the need for external radiator-board attachments normally used with analog ICs.

Background for Product Development

In October 2001, YAMAHA launched the YDA131 IC, becoming the first domestic semiconductor manufacturer to introduce a digital amplifier IC with 2.5W/2-channel/4Ω force. The new YDA137 model is superior to the YDA131, with higher electrical output through improved metal-oxide semiconductor (MOS) transistors and lower switching impedance. In turn, the output current improves sound quality and increases output power to roughly double using a 28-pin thin-shrink small outline package (TSSOP).

The digital amplifier has better operating efficiency, lower electricity consumption, and lower heat emission than current analog amplifiers. It enables greater compactness, lowers power consumption and the number of batteries required, extends battery life, and improves sound quality. In addition, reduced heat sink and radiation space, and the elimination of air-cooling fans free space for equipment's exterior design, enabling unprecedented new designs for audio equipment.

LCD televisions, PC LCD monitors, portable audio equipment, PC speakers, and other electronic goods have been flattened in recent years, creating needs for greater component compactness and lower heat emission. At the same time, consumers want higher output and better sound quality for playing video and music software. Higher output generally requires similarly high increases in voltage levels. However, even though YDA137 has a low 5V power supply, its digital amplification technique utilizing significantly strengthened power MOS transistors enhances current output. The stronger current enables maximum output of 5W with low distortion for low-impedance (2Ω) speakers.

The YDA137 targets demand for small, high-quality audio digital amplifiers. It is expected to be installed in flat, space-saving speakers with limited voltage for use with LCD TVs, PC LCD monitors, and portable audio equipment.

Special Features

1.	All-in-one 5W/2-channel digital amplifier IC Analog signal input circuits, pulse width-modulation circuits (Note 2), bridge-tied load (BTL) output circuits (Note 3), self-oscillating circuits (Note 4), overcurrent protection circuits, pop-noise suppression circuits (Note 5), headphone amps, and other components necessary for digital amplifiers are combined in an extremely small 28-pin TSSOP.
2.	Single 5V power supply amplifier IC with highest output capabilities in its class Existing single 5V amplifier ICs have current output load impedance of 4Ω and 2W output. However, YAMAHA's proprietary loss-reduction CMOS design techniques improve amplification, enabling maximum output of 5W with output load impedance of 2Ω.(more than double the rate for digital amplifier ICs in its class)
3.	Performance features matching high-fidelity audio components YAMAHA's independently developed circuit technology reduces the distortion rate to 0.02% (1.5W output), less than half the rate for other digital amplifier ICs in its class. The signal-to-noise ratio (S/N) is more than 100dB, matching levels for high-fidelity audio components.
4.	High operating efficiency, energy-saving, and low-heat emissions The YDA137 has maximum power efficiency of about 82% with output load impedance of 3Ω, up to three times higher than for existing analog amplifiers. Electricity consumption during operation is as little as a quarter as much, and electricity loss from amp heat emission is as low as one-seventh as much (YAMAHA measurements). As such, the product is more efficient, consumes less energy, and emits less heat.

Main Specifications

Main functions, specifications	All-in-one digital amplifier IC Output: 5W/CH @ 2Ω, 3W/CH @ 3Ω, 2.5W/CH @ 4Ω, 5V power supply S/N more than 100dB, at 1 Vrms Total harmonic distortion: 0.02% @ 1.5W output Maximum efficiency: About 82% @ 3Ω Headphone amplifier installation
Power voltage range during operation	3–5.5V
Process	CMOS
Package	28-pin TSSOP

Notes:

1.	Digital amplifier Audio amplifiers use analog voltage waves equivalent in size to music signals and amplify them electronically in the same waveform for delivery to speakers. In contrast, digital amplifiers first transform musical signals by size into high-speed digital signals. After amplification with powerful electric digital pulse signals, the speakers pick up only the musical signals. Digital signals can be transformed in several ways. For example, the width of the digital pulse can be lengthened and shortened or the digital pulse density can be increased or reduced. These methods are called D-type and switching amplification, respectively. Since digital amps amplify power with on and off digital signals only, power efficiency is much higher than for analog amps. Digital amplification makes much more efficient use of power than analog does, consuming less energy and emitting less heat for greater power output. Whereas operating efficiency is 30–50% for analog amplifiers, it is much higher (around 80%) for digital ones. When batteries are used as the main power source, longevity is five-to-six-fold higher.
2.	Pulse width-modulation circuits The circuits lengthen and shorten the widths of digital pulses, amplifying the voltage of sound signals.
3.	BTL output circuits These are digital signal output circuits carrying loads with positive and negative polarities.
4.	Self-oscillating circuits These are circuits capable of clock oscillation without using liquid-crystal oscillators and other oscillator attachments. They can reduce the number of component attachments to ICs.
5.	Pop-noise suppression circuits These circuits suppress the popping sound that normally occurs when amplifier ICs are turned on and off.

*All product names and company names mentioned in this newsletter are protected under YAMAHA copyrights and trademarks.

For inquiries about the information presented here, please contact:

Public Relations Div., Corporate Communications Group
Mr.Tanaka

Takanawa 2-17-11, Minato-ku,
Tokyo 108-8568, Japan
TEL: +81-3- 5488-6601