Reference Design HFRD-34.0 (Rev.3, 05/08)
Maxim Integrated Products
Page 9 of
18
Audio Section Components
Part Number
Functional Description
MAX4550
The MAX4550 serial-interface, programmable, dual 4x2 audio/video crosspoint switch is ideal
for multimedia applications. It contains two identical crosspoint switch arrays, each with four
inputs and two outputs. To improve off-isolation, the additional crosspoint inputs, SA and SB,
can be used as shunts. The output is selectively programmable for clickless or regular mode
operation. A set of internal resistive voltage-dividers supplies DC bias for each output when
using AC-coupled inputs. Additionally, four auxiliary outputs control additional circuitry
through the MAX4550’s 2-wire interface.
Additional information:
www.maxim-ic.com/MAX4550
MAX9728A
The MAX9728A stereo headphone amplifier is designed for display and notebook
applications or portable equipment where board space is at a premium. This device uses a
unique, patented DirectDrive™ architecture to produce a ground-referenced output from a
single supply, thereby eliminating the need for large DC-blocking capacitors. It saves cost,
board space, and component height. The MAX9728A offers an externally adjustable gain and
delivers up to 60mW per channel into a 32
Ω
load with 0.02% THD+N. An 80dB at 1kHz
power-supply rejection ratio (PSRR) allows these devices to operate from noisy digital
supplies without an additional linear regulator. Comprehensive click-and-pop circuitry
suppresses audible clicks and pops at startup and shutdown.
Additional information:
www.maxim-ic.com/MAX9728A
MAX9723
The MAX9723 stereo DirectDrive™ headphone amplifier with BassMax and volume control is
ideal for portable audio applications where space is at a premium and high performance is
essential. The MAX9723 operates from a single 1.8V to 3.6V power supply. The device
includes features that reduce external component count, system cost, and board space; other
features improve audio reproduction. The headphone amplifier uses Maxim’s patented
DirectDrive architecture that produces a ground-referenced output from a single supply,
thereby eliminating the need for large DC-blocking capacitors.
The headphone amplifiers deliver 62mW into a 16
Ω
load, feature low 0.006% THD+N, and
high 90dB PSRR. The MAX9723 features Maxim’s industry-leading click-and-pop
suppression. The BassMax feature boosts the amplifier’s bass response, thus improving
audio reproduction when inexpensive headphones are used. The integrated volume control
features 32 discrete volume levels, eliminating the need for an external potentiometer.
BassMax and the volume control are enabled through the I2C/SMBus™-compatible interface.
Shutdown is controlled through either the hardware or software interfaces.
Additional information:
www.maxim-ic.com/MAX9723