Digital Amplifier supports IIS digital audio signal input.

Press Release Summary:



Featuring built-in 24-bit audio DSP, R2J15116FP delivers stereo output to 2 speakers at up to 15 W/channel, and is intended for use in thin flat-screen TVs employing LCD or plasma display panels. It features compact package measuring 7 x 7 mm, uses feedback circuit to stabilize output level during voltage fluctuations, while it's DSP also performs processing for volume control and parametric equalizer. Product also features overcurrent, overheating, and low voltage protection.



Original Press Release:



Renesas Technology to Release Compact, High-Performance R2J15116FP Digital Amplifier Supporting IIS Digital Audio Signal Input



Built-in audio DSP for audio signal processing to enable more compact and low-cost systems

Tokyo, November 27, 2008 Renesas Technology Corp. today announced the development of the R2J15116FP, a compact, high-performance digital amplifier supporting IIS1 digital audio signal input with a built-in 24-bit audio DSP. It is intended for use in thin flat-screen TVs employing LCD or plasma display panels, and sample shipments will begin in December 2008 in Japan.

The R2J15116FP accepts IIS digital audio signal input, performs signal processing using a built-in audio DSP, and amplifies the result with a digital amplifier to deliver stereo output to two speakers at up to 15 watts per channel. Its main features are as follows.

(1) Integrated audio DSP for reduction of mounting area by approximately half (Renesas' comparison)

The design emphasis for thin flat-screen TVs becomes slim, resulting in demand for an audio processing system implemented on highly integrated ICs for compactness. The R2J15116FP integrates a digital amplifier and a 24-bit audio DSP in a single compact package measuring only 7 mm × 7 mm. This reduces the mounting area by about half, compared with the two-package products (Renesas' comparison), and helps reduce the size and cost of the system overall.

(2) Integrated audio DSP allowing detailed tuning of audio characteristics

Thin flat-screen TVs require detailed tuning of their audio systems for different markets and screen sizes. This processing is usually performed in the preceding stage of this digital amplifier by the main DSP, which mainly handles tasks such as surround processing and decoding. This imposes a significant processing load. In the R2J15116FP, in contrast, processing for the volume control and the parametric equalizer2 for optimizing the speaker characteristics is done by the built-in audio DSP. This reduces the load on the main DSP and makes it possible to generate a more varied and higher quality sound environment for video applications.

(3) Achieves superior sound quality

The R2J15116FP achieves better audio signal performance and quality than conventional digital volume control implemented using a DSP, through the use of Renesas Technology's exclusive intelligent volume function, which offers higher resolution when switching the volume level for smoother volume level transitions. The R2J15116FP also uses a feedback circuit to stabilize the output level when the power supply voltage fluctuates, an approach with a proven track record in products employing analog input.

(4) Multiple protection and monitoring functions

Protection functions to prevent problems when this amplifier is in an abnormal state include detection of overcurrent, overheating, and low voltage, all of which were implemented in earlier Renesas products, as well as a new function that provides warning in advance of overheating. This last function automatically lowers the volume to prevent the temperature from rising to a dangerous level. Additional functions include PLL unlock detection, which enhances the safety of signal input to the amplifier, and input signal error detection. This full complement of protection functions simplifies system design and boosts reliability.

Product Background

In recent years, thin flat-screen TVs, typically employing LCD or plasma display panels, have become even slimmer, and at the same time more attention is being paid to their design aesthetics. This has produced a tendency toward the use of smaller and thinner speakers that are less conspicuous when viewed from the front than the types previously used, which extended out prominently from the sides. This has made it more difficult to achieve the same sense of audio volume and presence. On the other hand, larger screen sizes are heightening demand for excellent sound quality. As a result, audio compensation through the use of signal processing has become essential.

Renesas Technology has developed the R2J15116FP, a digital amplifier incorporating a DSP for audio compensation and audio tuning, in response to this demand. It enables the system more efficiently to perform detailed audio tuning of individual product models to match different markets and design characteristics, a task that previously was performed by the main DSP.

The R2J15116FP is Renesas Technology's first digital amplifier designed for digital input. As its input format it supports IIS digital audio signals, the signal format typically output by the DSP in the stage preceding the R2J15116FP, thereby allowing direct connection. The integrated 24-bit audio DSP benefits from the experience and technology accumulated over Renesas Technology's extensive track record of mass producing widely used digital amplifiers designed for a variety of types of analog input. It delivers high-performance audio signal processing and fine-grained audio tuning functionality. The integration of the audio DSP into the same package as the digital amplifier reduces the mounting area and contributes to more compact system size overall.

Product Details

The R2J15116FP digital amplifier for digital input with integrated audio DSP supports digital input in IIS format. The audio signal processing block implements the following compensation functions for audio tuning:

o In addition to the volume control and seven-band parametric equalizer for adjusting speaker frequency characteristics, which are described in the list of features, there is a two-band tone control, a loudness function useful for low- and high-range expansion compensation, a power limiter function that allows setting of a user-defined maximum output level, and a dynamic range control (DRC) function that lowers the signal amplitude without distortion at high volume levels and raises it at low volume levels. Settings for all of these functions can be made flexibly from the MCU via the I2C bus.

The R2J15116FP also implements Renesas Technology's exclusive intelligent volume function (mentioned in the list of features) for improved sound quality. It suppresses amplification of noise components based on the power supply voltage fluctuation ratio, known as the power supply rejection ratio (PSRR), reduces wavering in the volume level, and reduces the distortion ratio, which is important for good sound quality.

As for the necessary level of amplifier performance, the R2J15116FP inherits the performance of previous generations of Renesas Technology products designed for analog input. It delivers low distortion, a high S/N ratio, and a high damping factor. The specifications for all electrical characteristics that affect sound quality are good. Furthermore, the high-performance feedback circuit mentioned in the list of features assures stable output even when the power supply voltage fluctuates, maintains high power amplifier efficiency, and provides ample protection (as mentioned in the list of features). The R2J15116FP uses a compact 48-pin HTQFP package, requires no heat sink, and delivers maximum stereo output of 15 watts per channel.

Renesas Technology plans to extend its product lineup by releasing additional digital amplifiers that accept digital input and varying the list of functions incorporated in the audio DSP, in response to demand for audio signal processing capabilities for thin flat-screen TVs and similar products.

Notes

1. IIS: IIS is a representative pulse code modulation (PCM) format in recent years and a widely used output format for digital audio signals.

2. Parametric equalizer: The equalizer in an audio processing system allows raising or lowering of the gain for specific frequencies of the audio signal. Operation of the equalizer is left to the end user. In a parametric equalizer, the audio frequencies of the audio signal are divided into bands, and the center frequency of each band can be fine tuned by changing the parameter Q (quality factor). The primary reason for providing this functionality in the R2J15116FP is to enable fine-grained adjustment of the speakers' frequency characteristics.

Typical Applications

o Video equipment: LCD TVs, Plasma TVs, PC monitors, etc.

Product Name Package Sample Price [Tax Included] (Yen)

R2J15116FP 48-pin HTQFP 400

Specifications

Item R2J15116FP Specifications

Power supply voltage 3.3 V (pre amplifier stage), 15 V (power amplifier stage)
Max. output power 15 V (8 Ω, THD = 10%, Vcc = 15 V) × 2 channels
Control system I2C bus interface
Package 48-pin HTQFP (size: 7 mm × 7 mm [excluding pins])

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