MAX9770 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – 1.2W Low-EMI, Filterless, Mono Class D Amplifier with Stereo DirectDrive Headphone Amplifiers

19-3134; Rev 0; 5/04
1.2W Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
General Description
The MAX9770 combines a mono, filterless, Class D
speaker amplifier and stereo DirectDrive headphone
amplifiers in a single device. The MAX9770 operates
from a single 2.5V to 5.5V supply and includes features
that reduce external component count, system cost,
board space, and offer improved audio reproduction.
The speaker amplifier makes use of Maxim’s patented
Class D architecture, providing Class AB performance
with Class D efficiency, conserving board space, and
extending battery life. The speaker amplifier delivers
1.2W into an 8Ω load while offering efficiencies above
85%. A spread-spectrum scheme reduces radiated
emissions caused by the modulation frequency.
Furthermore, the MAX9770 oscillator can be synchro-
nized to an external clock through the SYNC input,
avoiding possible problem frequencies inside a system.
The speaker amplifier features a low 0.025% THD+N,
high 70dB PSRR, and SNR in excess of 90dB.
The headphone amplifiers feature Maxim’s patented
DirectDrive architecture that produces a ground-refer-
enced output from a single supply, eliminating the need
for large DC-blocking capacitors. The headphone ampli-
fiers deliver up to 80mW into a 16Ω load, feature low
0.015% THD+N, high 80dB PSRR, and ±8kV ESD-pro-
tected outputs. A headphone sense input detects the
presence of a headphone, and automatically configures
the amplifiers for either speaker or headphone mode.
The MAX9770 includes internally set, logic-selectable
gain, and a comprehensive input multiplexer/mixer, allow-
ing multiple audio sources to be selected and for true
mono reproduction of a stereo source in speaker mode.
Industry-leading click-and-pop suppression eliminates
audible transients during power and shutdown cycles. A
low-power shutdown mode decreases supply current
consumption to 0.1µA, further extending battery life.
The MAX9770 is offered in space-saving, thermally effi-
cient 28-pin TQFN (5mm x 5mm x 0.8mm) and 28-pin
TSSOP packages. The MAX9770 features thermal-over-
load and output short-circuit protection, and is specified
over the extended -40°C to +85°C temperature range.
Applications
Cellular Phones
PDAs
Compact Notebooks
Pin Configuration appears at end of data sheet.
Features
♦ 1.2W Filterless Class D Amplifier Passes FCC
Class B Radiated Emissions Standards with
100mm of Cable
♦ Unique Spread-Spectrum Mode Offers 5dB
Emissions Improvement Over Conventional
Methods
♦ 80mW DirectDrive Headphone Amplifier
Eliminates Bulky DC-Blocking Capacitors
♦ High 80dB PSRR at 217Hz
♦ 85% Efficiency
♦ Low 0.015% THD+N
♦ Industry-Leading Click-and-Pop Suppression
♦ Integrated 3-Way Input Mixer/Multiplexer
♦ Logic-Selectable Gain
♦ Short-Circuit and Thermal Protection
♦ ±8kV ESD-Protected Headphone Outputs
♦ Low-Power Shutdown Mode
♦ Available in Space-Saving, Thermally Efficient
Packages
28-Pin TQFN (5mm x 5mm x 0.8mm)
28-Pin TSSOP
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX9770ETI^†
-40^oC to +85^oC
28 TQFN-EP*
MAX9770EUI
-40^oC to +85^oC
28 TSSOP
†_{Lead-free package.}
*EP = Exposed paddle.
Simplified Block Diagram
V_DD
L1IN
L2IN
MONO
DirectDrive
STEREO
HEADPHONE
R1IN
R2IN
GAIN SEL
INPUT SEL
MUTE
SHDN
HPS
CLASS
D
MAX9770
SPKR
(MONO)
________________________________________________________________ Maxim Integrated Products 1
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1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.