STMicroelectronics has announced a compact Class D power amplifier chip intended for the new generation of mobile phones and other products seeking to provide higher audio power output while preserving and extending battery life. The new TS4962 will provide 3W of output power into a 4-ohm loudspeaker when operating on a 5V power supply, and achieves an outstanding 88% efficiency -- far higher than that of the Class AB amplifiers commonly used in mobile phones today.
The TS4962 is designed to operate over a wide 2.4V to 5.5V supply voltage range. Its quiescent current with no input signal is 2.3mA typical, and Standby current when powered down using its active-low control line is just 10nA. Pop and Click reduction circuitry provides low on/off switching noise while allowing the amplifier to start within 5ms. The gain is set using two external resistors.
A fully differential design reduces RF rectification effects and eliminates the need for a bypass capacitor. Output power is 3W into 4 ohms or 1.75W into 8 ohms, at 10% maximum THD+N (Total Harmonic Distortion plus Noise), on a 5V supply. At 1% maximum THD+N, output power is 2.3W into 4 ohms on a 5V supply, or 0.75W on a 3V supply. Signal to noise ratio is typically 85dB.
This physically small amplifier is ideal for use in mobile phones and speakerphones -- where its high efficiency will result in longer talk-times -- as well as for bringing new features to PDAs and laptop computers. It is available in a lead-free, 1.6mm square, 9-bump flip-chip package, and is supported by a development board, which includes the device pre-mounted onto a flip-chip to DIP adapter for easier handling during evaluation. Available in production volume now the device is priced at $0.55 in quantities of 5000 pieces.