Rainbow Electronics MAX9729 User Manual

General description, Features, Ordering information

General Description

The MAX9729 stereo DirectDrive™ headphone amplifi-
er features bass boost, volume control, an input mux,
and an I

C/SMBus™-compatible serial interface. This

makes the MAX9729 ideal for portable audio applica-
tions 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 architec-

ture, eliminating the need for large DC-blocking capaci-
tors. 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 sup-
pression 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 I

C/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 tem-
perature range. The MAX9729 is available in a space-
saving 28-pin thin QFN package (5mm x 5mm x 0.8mm).

Features

♦ DirectDrive Headphone Amplifier Eliminates

Bulky DC-Blocking Capacitors

♦ 3:1 Input Multiplexer with Digital-Fade Circuitry
♦ Software-Enabled Bass Boost
♦ 32-Step Integrated Volume Control
♦ Beep Input with Programmable Output Level
♦ Low Quiescent Current
♦ Industry-Leading Click-and-Pop Suppression
♦ I

C-Compatible 2-Wire Interface

♦ Short-Circuit Protection
♦ 1.8V to 3.6V Single-Supply Operation
♦ Available in Space-Saving, Thermally Efficient

28-Pin TQFN-EP (5mm x 5mm x 0.8mm)

MAX9729

Stereo Headphone Amplifier with BassMax,

Volume Control, and Input Mux

________________________________________________________________

Maxim Integrated Products

19-0857; Rev 0; 7/07

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Ordering Information

Note: This device is specified over the -40°C to +85°C operating
temperature range.
+

Denotes lead-free package.

*Last digit of slave address is pin programmable.
**EP = Exposed pad.

PART

PIN-
PACKAGE

SLAVE

ADDRESS*

PKG

CODE

MAX9729ETI+

28 TQFN-EP**

101000_

T2855-5

SMBus is a trademark of Intel Corp.

†

U.S. Patent # 7,061,327

Pin Configuration appears at end of data sheet.

C INTERFACE

MUX

MIXER

FADER

CONTROL

VOLUME

CONTROL

BassMax

1.8V TO 3.6V

SCL

SDA

INL1

INL2

INL3

INR1

INR2

INR3

BEEP

OUTL

BML

BMR

MAX9729

PGA

OUTR

PGA

Simplified Block Diagram

Portable CD/DVD/MD
Players

Cell Phones

MP3/PMP Players

Automotive Rear Seat
Entertainment (RSE)

Flat-Panel TVs

Applications