MAX9720 Datasheet, PDF (1/21 Pages) Maxim Integrated Products – 50mW, DirectDrive, Stereo Headphone Amplifier with SmartSense and Shutdown

19-2859; Rev 0; 4/03
50mW, DirectDrive, Stereo Headphone
Amplifier with SmartSense and Shutdown
General Description
The MAX9720 stereo headphone amplifier combines
Maxim’s patented DirectDrive architecture and
SmartSense™, an automatic mono/stereo detection fea-
ture. Conventional headphone amplifiers require a bulky
DC-blocking capacitor between the headphone and the
amplifier. DirectDrive produces a ground-referenced out-
put from a single supply, eliminating the need for large
DC-blocking capacitors, saving cost, board space, and
component height.
SmartSense automatically detects the presence of a
short at either the left or right amplifier output. Under a
fault condition, the shorted output is automatically dis-
abled and the stereo input signal is automatically mixed
and routed to the remaining active channel. This feature
is useful in cell phone and PDA applications where a
variety of headphone jacks with unknown loads can be
inserted into the headphone jack socket. SmartSense
prevents both damage to the amplifier and eliminates
battery drain into a shorted load.
The MAX9720 delivers up to 50mW per channel into a
16Ω load and has an ultra-low 0.003% THD+N. A high
(92dB at 217kHz) power-supply rejection ratio (PSRR)
allows the device to operate from noisy digital supplies
without additional power conditioning. The gain of the
MAX9720 is set internally, further reducing component
count. Two gain options are available (-1V/V, MAX9720A
and -1.41V/V, MAX9720B). The headphone outputs
include a comprehensive click-and-pop circuitry that
eliminates audible glitches on startup and shutdown. A
shutdown mode provides a fast 250µs turn-on time.
The MAX9720 operates from a single 1.8V to 3.6V
supply and consumes only 5mA of supply current. The
MAX9720 also features thermal overload protection,
and is specified over the extended -40°C to +85°C tem-
perature range. The MAX9720 is available in a tiny
(2mm x 2mm x 0.6mm) 16-bump chip-scale package
(UCSP™) and a 16-pin TSSOP package.
Applications
PDAs
Cellular Phones
MP3 Players
Notebook PCs
Smart Phones
Tablet PCs
Portable Audio Equipment
Features
o DirectDrive Eliminates Bulky DC-Blocking
Capacitors
o SmartSense Automatic Short Detection
o Low 5mA Quiescent Current
o Fixed Gain Eliminates External Feedback Network
MAX9720A: -1V/V
MAX9720B: -1.41V/V
o 50mW per Channel Output Power
o Ultra-Low 0.003% THD+N
o High PSRR (92dB at 217Hz)
o Integrated Click-and-Pop Suppression
o 1.8V to 3.6V Single-Supply Operation
o Thermal Overload Protection
o Available in Space-Saving Packages
16-Bump UCSP (2mm x 2mm x 0.6mm)
16-Pin TSSOP
Ordering Information
PART
TEMP RANGE
MAX9720AEBE-T
MAX9720BEBE-T
MAX9720AEUE
MAX9720BEUE
-40^oC to +85^oC
-40^oC to +85^oC
-40^oC to +85^oC
-40^oC to +85^oC
PIN/BUMP-
PACKAGE
16 UCSP-16
16 UCSP-16
16 TSSOP
16 TSSOP
GAIN
(V/V)
-1
-1.41
-1
-1.41
Simplified Block Diagram
R_IN
+
3.6V TO 1.8V
SUPPLY
MAX9720
SmartSense
R_OUT
HPS
MODE1
MODE2
ALERT
SmartSense and UCSP are trademarks of Maxim Integrated
L_OUT
Products, Inc.
L_IN
Pin Configuration and Typical Application Circuit appear at
end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.