19-3963; Rev 1; 7/09
60mW, DirectDrive, Stereo
Headphone Amplifiers with Shutdown
/MAX9728B
General Description
Features
♦ No Bulky DC-Blocking Capacitors Required
The MAX9728A/MAX9728B stereo headphone ampli-
fiers are designed for display and notebook applica-
tions or portable equipment where board space is at a
premium. These devices use a unique DirectDrive®
architecture to produce a ground-referenced output
from a single supply, eliminating the need for large DC-
blocking capacitors, saving cost, board space, and
component height. The MAX9728A offers an externally
adjustable gain, while the MAX9728B has an internally
preset gain of -1.5V/V. The MAX9728A/MAX9728B
deliver up to 60mW per channel into a 32Ω load and
have low 0.02% THD+N. An 80dB at 1kHz power-sup-
ply rejection ratio (PSRR) allows these devices to oper-
ate from noisy digital supplies without an additional
linear regulator. Comprehensive click-and-pop circuitry
suppresses audible clicks and pops on startup and
shutdown.
♦ Low-Power Shutdown Mode, < 0.1µA
♦ Adjustable Gain (MAX9728A) or Fixed -1.5V/V
Gain (MAX9728B)
♦ Low 0.02% THD+N
♦ High PSRR (80dB at 1kHz) Eliminates LDO
♦ Integrated Click-and-Pop Suppression
♦ 4.5V to 5.5V Single-Supply Operation
♦ Low Quiescent Current (3.5mA)
♦ Available in Space-Saving Packages
12-Pin Thin QFN (3mm x 3mm x 0.8mm)
14-Pin TSSOP (5mm x 4.4mm x 1.1mm)
The MAX9728A/MAX9728B operate from a single 4.5V
to 5.5V supply, consume only 3.5mA of supply current,
feature short-circuit and thermal-overload protection,
and are specified over the extended -40°C to +85°C
temperature range. The devices are available in tiny 12-
pin Thin QFN (3mm x 3mm x 0.8mm) and 14-pin
TSSOP packages (5mm x 4.4mm x 1.1mm).
Ordering Information
PART
GAIN (V/V) PIN-PACKAGE TOP MARK
MAX9728AETC+
MAX9728AEUD+
MAX9728BETC+
MAX9728BEUD+
Adj.
Adj.
-1.5
-1.5
12 TQFN-EP*
14 TSSOP
ABC
—
12 TQFN-EP*
14 TSSOP
ABD
—
Applications
CRT TVs
Note: All devices specified over the -40°C to +85°C operating
Notebook PCs
DVD Players
range.
+Denotes lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Multimedia Monitors
LCD/PDP Displays
DirectDrive is a registered trademark of Maxim Integrated
Product, Inc.
Pin Configurations appear at end of data sheet.
Block Diagrams
MAX9728B
MAX9728A
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
LEFT
AUDIO
INPUT
LEFT
AUDIO
CAPACITORS
INPUT
SHDN
SHDN
RIGHT
RIGHT
AUDIO
INPUT
FIXED GAIN ELIMINATES
AUDIO
EXTERNAL RESISTOR
INPUT
NETWORK
________________________________________________________________ Maxim Integrated Products
1
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.