Class D audio amplifier targets flat panel tv markets

ON Semiconductor has introduced a new Class D stereo audio amplifier with efficiency levels up to 87%.The NCS8353 is designed for the flat panel tv market and is said to eliminate the need for the inclusion of a heatsink in the system design.

The device can be powered from the existing 24V backlight rail in the tv system and is capable of delivering a continuous output power of up to 20W per channel into an 8ohm bridge tied load. According to ON, the pwm technique utilised within the Class D architecture permits filterless operation in certain circumstances by using the speakers themselves as an LC filter. This is said to significantly improve total bill of material costs. "The flat panel tv market is highly competitive and manufacturers need to be able to differentiate themselves from their rivals," said Josh Warner, marketing manager for signal and interface products at ON Semiconductor. "Highly integrated, featured packed amplifier devices, such as the NCS8353, facilitate more streamlined tv designs and offer development teams a greater degree of flexibility, as well as making sure the system is better protected from short circuits or extreme temperatures." According to Warner, an integrated digital power limiter can be set using two external bits to deliver a specific output (10, 12, 15 or 20W). This is designed to protect the tv speakers from high amplitude input spikes. A shutdown function has been implemented to reduce the quiescent current drawn by the amplifier to 100µA typical, while the mute feature is said to ensure that audio is not present at the output during audio source switching. Four selectable gain ranges are supported: 20, 26, 32 and 36dB.