The MAX9729 stereo DirectDrive™ headphone amplifier
features bass boost, volume control, an input mux,
and an I²C/SMBus™-compatible serial interface. This
makes the MAX9729 ideal for portable audio applications
where space is at a premium and performance is
essential. The MAX9729 operates from a single 1.8V to
3.6V, and uses Maxim's patented† DirectDrive architecture,
eliminating the need for large DC-blocking capacitors.
The headphone amplifiers deliver 52mW into a
32Ω load, feature low 0.03% THD+N, and high 90dB
PSRR. Maxim's industry-leading click-and-pop suppression
circuitry reduces audible transients during
power and shutdown cycles.
The BassMax feature boosts the bass response of the
amplifier, improving audio reproduction for low-end
headphones. The integrated volume control features 32
discrete volume levels along with a ramping function to
ensure smooth transitions during shutdown cycles and
input selection. The MAX9729's eight programmable
maximum gain settings allow for a wide range of input
signal levels. A 3:1 multiplexer/mixer allows the selection
and summation of multiple stereo input signal sources.
The MAX9729 also includes a dedicated BEEP input
with independent attenuation control. BassMax, volume
control, gain settings, and input selection are controlled
using the I²C/SMBus-compatible serial interface. A low-power,
5µA shutdown mode is controlled through an
external logic input or the serial interface.
The MAX9729 consumes only 4.8mA of supply current,
provides short-circuit and thermal-overload protection,
and is specified over the -40°C to +85°C extended temperature
range. The MAX9729 is available in a spacesaving
28-pin thin QFN package (5mm x 5mm x 0.8mm).
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