Nippon Precision Circuits, Inc. (NPC*) has completed development of two class D speaker amplifiers, the compact SM6801AB model and the SM6802AB stereo mode. Sample units of the SM6801AB are being shipped, while the SM6802AB is in full production and shipping.

The SM6801AB and SM6802AB are housed in a small package made possible by a reduction in internal functions. The small packaging answers persistent customer demand for a small PC board area in portable systems. In addition, the SM6802AB integrates stereo input/output functions on a single chip, a response to the trend in cellular telephones in which a stereo output feature has become the de facto standard.

Both products have a selectable dynamic range compression function, a feature of NPC class D amplifiers. This function automatically tracks the input level in real-time operation and optimizes the output level. The SM6801AB and SM6802AB also have an input equalizer pin that corrects the frequency characteristics of speakers when the products are mounted on a PC board. With this feature, users no longer need to worry about speaker selection because sound pressure comparable to that of large-size speakers can be obtained from compact speakers.

The features of the SM6801AB and SM6802AB make these products a good choice for driving speakers in systems such as cellular telephones and PDAs that require ever greater compactness and efficiency. The output stage is BTL (Balanced Transformer Less) output, and an output waveform that reverses only the modulated components enables direct driving of dynamic speakers without use of an LC filter. Additionally, the slim dielectric speakers can be driven by simply connecting a series resistor to the output. The miniaturization of the amplifier circuit is due largely to the peripheral circuitry, which can consist of only a chip capacitor.

The SM6801AB and SM6802AB are ideal for creating portable systems that, while small, thin, and power-efficient, increase the average sound pressure from speakers.

NPC is developing more Class D amplifiers that satisfy the needs of the customers, supporting various applications.

^*: Corporate Headquaters: 15-6, Nihombashi-kabutocho, Chuo-ku, Tokyo 103-0026, Japan President: Yoshifumi Gomi

Name	Samples shipment date	Unit price of samples	Full production shipment date	Planned production
SM6801AB	July 2005	200 yen/unit (210 yen with tax)	August 2005	500 thousand units/month
SM6802AB	N/A	300 yen/unit (315 yen with tax)	June 2005	500 thousand units/month