Fixed Gain Class-D Audio Power Amplifier Saves Space in Portable Applications

By integrating the external input resistors and very closely matching them, the new TI devices enable designers to reduce overall board size by approximately 50 percent. The devices also improve PSRR (Power Supply Rejection Ratio) by 20dB and CMRR (Common-mode Rejection Ratio) by 12dB, compared to designing with 5 percent matched external resistors that are the commonly used in portable consumer electronics to reduce cost.



With the TPA203xD1 family of devices, TI delivers 88 percent efficient Class-D audio power amplifiers capable of driving 2.75 W from a 5V power supply into 4 ohms with a low 27 mVrms A-weighted noise floor. The amplifiers come in a compact 1.5 x 1.5 mm Wafer Chip Scale Package (WCSP) that eliminates bond wires and lead frames required for QFN and BGA packaging, and they consume only 2.5 mm x 1.7 mm printed circuit board area.



"As more and more portable audio customers are making the move to Class-D amplifiers, TI's expertise and innovative products are proving to be a tremendous asset in this competitive market," said Nicholas

Holland, high performance analog marketing manager at Texas Instruments. "The TPA203xD1 amplifiers provide more than 2.5x power efficiency compared to Class-AB for customers who want to extend battery life and provide a better audio experience while using less board space."



In addition to shrinking board size and reducing system cost, integrating the external input resistors and closely matching them allows for a substantial improvement of some of the key performance

metrics for power amplifiers, such as CMRR and PSRR. CMRR reflects how well an amplifier cancels noise that is common on its inputs, such as nearby RF transmissions that may manifest as an audible buzz. PSRR reflects how well the amplifier rejects noise present on the power supply. With a typical CMRR of -69 dB and PSRR at 217 Hz of -73 dB, TPA203xD1 amplifiers are ideal for various wireless portable applications, which typically have noisy environments. TPA203xD1 devices are pin-compatible with the TPA2010D1 audio power amplifier, together meeting the amplification needs for a wide range of portable audio applications. TPA203xD1 devices fix the output gain and eliminate external resistors to optimize performance and efficiency, while the TPA2010D1 is available for applications requiring variable gain.



The TPA2032D1, TPA2033D1, and TPA2034D1 offer fixed gain amplification of 2 V/V (6 dB), 3 V/V (9.5 dB), and 4V/V (12 dB) respectively. Available now in production volumes, TPA203xD1 devices cost $0.60 each in 1,000 unit quantities and in a lead-free 1.5 x 1.5 mm WCSP. An evaluation module (EVM) is available to support all three devices.