Class-G amplifiers operate at low supply voltages for the majority of audio-signal levels, but are able to increase dynamic range temporarily when high signal levels are received. This enhances energy efficiency and reduces overall power consumption. As a result, Toshiba’s new amplifier achieves significantly higher efficiency than conventional class-A/B alternatives while retaining inherently low audio distortion. It will also allow customers to build ultra low-power headphone amplifiers while avoiding the high costs and complex filtering associated with a class-D amplifier.
The TC94B15WBG has been designed to minimise component count and board space. Built-in DC/DC converter circuitry facilitates direct connection to the battery; an integrated Sigma-Delta DAC stage with digital and low-pass filtering supports the I2S digital interface; and there is no requirement for output coupling capacitors. In addition, internal volume control (with muting) enhances the system dynamic range, allowing adjustment from -63db to 0dB in 32 steps while further reducing the need for external components. An integrated I2C port provides a convenient, industry-standard interface for volume control and diagnostic monitoring.
The device delivers high audio performance, with a typical THD+N rating of less than 0.02% and a typical SNR of 92dB. Typical quiescent current is down to just 1.8mA, while a 1µA standby mode allows designers to use power management to further increase system energy efficiency for maximum battery lifetime. Analogue voltage supply (AVDD) and digital voltage supply (DVDD) ranges are 1.65V to 1.95V and 2.3V to 4.8V respectively.
Supplied in a miniature 20-pin 0.4mm-pitch wafer-level chip-scale package (WCSP), the TC94B15WBG has dimensions of just 2.43mm x 2.03mm.