MAXIM Integrated Products, represented by Arrow , has introduced the MAX9722A and MAX9722B devices into its DirectDrive headphone amplifier series.
The MAX9722 architecture produces a ground-referenced output from a single supply. This eliminates the two dc-blocking capacitors that are typically required between the amplifier and headphone.
The MAX9722 is suitable for portable audio equipment where board space and height must be minimised.
The MAX9722 does not require dc bias voltage to be applied to the headphone-jack ground pin, simplifying end-product design and reliability.
The differential input structure of the MAX9722 allows the amplifier to reject common-mode noise present in a system. The device can also be configured to sense the headphone return potential, eliminating noise caused by ground loops.
The gain of the MAX9722B is set internally to -6dB, which minimises external components, while the gain of the MAX9722A is set with two external resistors.
The MAX9722 operates from a single 2.4V to 5.5V supply, provides 60mW per channel into a 16Ω load, and has only 0.02% THD + N.
The device provides 130mW per channel into a 32Ω load. High, 90dB PSRR allows the amplifier to operate directly from noisy supplies without the need for additional LDOs or filtering.
To optimise power savings, a low-power shutdown mode reduces supply-current consumption to below 100mA. Additionally, eliminating the dc-blocking capacitors improves the amplifier's low-frequency response, allowing full-range audio reproduction which is important for music and video playback.
Comprehensive click-and-pop suppression circuitry ensures fast turn-on/turn-off times without audible glitches. The outputs feature ±8kV ESD protection.
The MAX9722 is available in 16-pin QFN (3mm x 3mm x 0.8mm) and 16-pin TSSOP packages making them ideal for cell phones, smart phones, MP3 players, PDAs, notebook computers, DVD and general portable audio applications.
Specifications are guaranteed over a -40°C to +85°C temperature range.