MAXIM Integrated Products, represented in Australia by Arrow Electronics , has released the MAX9850, a stereo audio DAC. It has built-in DirectDrive headphone amplifiers and operates from any 1.8V to 3.6V single supply.
It is optimised for low-voltage operation and delivers 30mW of output power from a 1.8V supply. It is designed to meet the board-space and performance requirements of portable devices such as cell phones, MP3 players and portable DVD players.It uses the company's DirectDrive architecture that produces a ground-referenced output from a single supply, eliminating the two bulky dc-blocking capacitors commonly used between the amplifier and the headphone. The removal of the two large caps makes more efficient use of board space.
Driving the audio signal directly to the headphone enhances the low-frequency response of the system, leading to full-range audio reproduction. This is especially important for music and video playback. The DirectDrive architecture does not require the headphone jack to be biased to a dc voltage and it allows a conventional, grounded chassis design, simplifying system design and improving long-term reliability.
The output-clocking circuitry derives all common audio rates from an arbitrary master clock up to 40MHz. The flexible architecture uses any available system clock and eliminates the need for an external PLL and multiple crystal oscillators. The device supports sample rates from 8kHz to 48kHz in both master and slave modes.
The device supports common I2C-compatible audio interfaces. Stereo-audio line inputs are provided either to mix analogue audio with the digital input stream, or to drive the headphone or line outputs directly. A PSRR rate of 100dB allows the part to operate directly from noisy supplies, eliminating the need for a dedicated LDO. To simplify the design and reduce system cost further, the MAX9850 has -73dB to +6dB volume control that uses I2C to adjust the gain of the output amplifier and eliminate the need for an external potentiometer.
The MAX9850 is available in a 5mm x 5mm, 28-pin TQFN package that is suitable for portable audio applications. It operates over the industrial temperature range from -40ºC to 85ºC.