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PDF MAX9705 Data sheet ( Hoja de datos )
| Número de pieza | MAX9705 | |
| Descripción | 2.3W Ultra-Low-EMI Filterless Class D Audio Amplifier | |
| Fabricantes | Maxim Integrated Products | |
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19-3405; Rev 3; 5/09
EVAALVUAAILTAIOBNLEKIT
www.DataSheet4U.com
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
General Description
The MAX9705 3rd-generation, ultra-low EMI, mono, Class
D audio power amplifier provides Class AB performance
with Class D efficiency. The MAX9705 delivers 2.3W into
a 4Ω load and offers efficiencies above 85%. Active
emissions limiting (AEL) circuitry greatly reduces EMI by
actively controlling the output FET gate transitions under
all possible transient output-voltage conditions. AEL pre-
vents high-frequency emissions resulting from conven-
tional Class D free-wheeling behavior in the presence of
an inductive load. Zero dead time (ZDT) technology
maintains state-of-the-art efficiency and THD+N perfor-
mance by allowing the output FETs to switch simultane-
ously without cross-conduction. A patented spread-
spectrum modulation scheme eliminates the need for out-
put filtering found in traditional Class D devices. These
design concepts reduce an application’s component
count and extend battery life.
The MAX9705 offers two modulation schemes: a fixed-
frequency (FFM) mode and a spread-spectrum (SSM)
mode that further reduces EMI-radiated emissions due to
the modulation frequency. The MAX9705 oscillator can
be synchronized to an external clock through the SYNC
input, allowing the switching frequency to be externally
defined. The SYNC input also allows multiple MAX9705s
to be cascaded and frequency locked, minimizing inter-
ference due to clock intermodulation. The device utilizes
a fully differential architecture, a full-bridged output, and
comprehensive click-and-pop suppression. The gain of
the MAX9705 is set internally (MAX9705A: 6dB,
MAX9705B: 12dB, MAX9705C: 15.6dB, MAX9705D:
20dB), further reducing external component count.
The MAX9705 is available in 10-pin TDFN (3mm x 3mm x
0.8mm), and 12-bump UCSP™ (1.5mm x 2mm x 0.6mm)
packages. The MAX9705 is specified over the extended
-40°C to +85°C temperature range.
Cellular Phones
PDAs
Applications
MP3 Players
Portable Audio
Selector Guide appears at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
Features
o Filterless Amplifier Passes FCC-Radiated
Emissions Standards with 24in of Cable
o Unique Spread-Spectrum Mode and Active
Emissions Limiting (AEL) Achieves Better than
20dB Margin Under FCC Limits
o Zero Dead Time (ZDT) H-Bridge Maintains State-
of-the-Art Efficiency and THD+N
o Simple Master-Slave Setup for Stereo Operation
o Up to 90% Efficiency
o 2.3W into 4Ω (1% THD+N)
o Low 0.02% THD+N (POUT = 1W, VDD = 5.0V)
o High PSRR (75dB at 217Hz)
o Integrated Click-and-Pop Suppression
o Low Quiescent Current (5.4mA)
o Low-Power Shutdown Mode (0.3µA)
o Short-Circuit and Thermal-Overload Protection
o Available in Thermally Efficient, Space-Saving
Packages
10-Pin TDFN (3mm x 3mm x 0.8mm)
12-Bump UCSP (1.5mm x 2mm x 0.6mm)
o Pin-for-Pin Compatible with the MAX9700 and
MAX9712
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
TOP
MARK
MAX9705AETB+T -40oC to +85oC 10 TDFN
ACY
MAX9705AEBC+T -40oC to +85oC 12 UCSP
ACH
MAX9705BETB+T -40oC to +85oC 10 TDFN
ACX
MAX9705BEBC+T -40oC to +85oC 12 UCSP
ACG
Ordering Information continued at end of data sheet.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
EMI Spectrum Diagram
50.0
45.0
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
30.0
FCC EMI LIMIT
MAXIM'S NEW ULTRA-LOW
OUTPUT SPECTRUM
60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0
FREQUENCY (MHz)
________________________________________________________________ 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.
1 page  
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2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
Typical Operating Characteristics (continued)
(VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted. Typical Operating Characteristics for 4Ω
load condition apply to the MAX9705_ETB+T only.)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
100
VDD = 3.3V
RL = 4Ω
10
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
100
VDD = 5.0V
RL = 4Ω
10
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
100
VDD = 3.3V
RL = 8Ω
POUT = 450mW
10
1 POUT = 100mW
POUT = 800mW
0.1
POUT = 250mW
1
POUT = 1.75W
0.1
1
0.1
FFM
SSM
0.01
10
100 1k
10k
FREQUENCY (Hz)
0.01
100k 10
100 1k
0.01
10k 100k
10
FREQUENCY (Hz)
100 1k
10k
FREQUENCY (Hz)
100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. COMMON-MODE VOLTAGE
100
VDD = 3.3V to 5V
fIN = 1kHz
10 POUT = 500mW
GAIN = 6dB
RL = 8Ω
1
0.1
0.01
0.001
0
0.5 1.0 1.5 2.0
COMMON-MODE VOLTAGE (V)
2.5
100
90
80
70
60
50
40
30
20
10
0
2.5
EFFICIENCY
vs. SUPPLY VOLTAGE
RL = 8Ω
RL = 4Ω
fIN = 1kHz
THD+N = 1%
3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
5.5
100
90
80
70
60
50
40
30
20
10
0
0
EFFICIENCY
vs. OUTPUT POWER
RL = 8Ω
RL = 4Ω
VDD = 3.3V
fIN = 1kHz
0.2 0.4 0.6 0.8
OUTPUT POWER (W)
1.0
100
90
80
70
60
50
40
30
20
10
0
800
EFFICIENCY
vs. SYNC FREQUENCY
RL = 8Ω
RL = 4Ω
VDD = 3.3V
fIN = 1kHz
THD+N = 1%
1000 1200 1400 1600 1800 2000
SYNC FREQUENCY (kHz)
100
90
80
70
60
50
40
30
20
10
0
0
EFFICIENCY
vs. OUTPUT POWER
RL = 8Ω
RL = 4Ω
VDD = 5.0V
fIN = 1kHz
0.5 1.0 1.5 2.0 2.5
OUTPUT POWER (W)
3.0
100
90
80
70
60
50
40
30
20
10
0
800
EFFICIENCY
vs. SYNC FREQUENCY
RL = 8Ω
RL = 4Ω
VDD = 5.0V
fIN = 1kHz
THD+N = 1%
1000 1200 1400 1600 1800 2000
SYNC FREQUENCY (kHz)
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
tSW tSW
tSW
tSW
VIN-
VIN+
OUT-
OUT+
tON(MIN)
VOUT+ - VOUT-
Figure 2. MAX9705 Output with an Input Signal Applied (SSM Mode)
Filterless Modulation/Common-Mode Idle
The MAX9705 uses Maxim’s unique, patented modula-
tion scheme that eliminates the LC filter required by
traditional Class D amplifiers, improving efficiency,
reducing component count, and conserving board
space and system cost. Conventional Class D amplifiers
output a 50% duty cycle square wave when no signal is
present. With no filter, the square wave appears across
the load as a DC voltage, resulting in a finite load cur-
rent, increasing power consumption. When no signal is
present at the input of the MAX9705, the outputs switch
as shown in Figure 3. Because the MAX9705 drives the
speaker differentially, the two outputs cancel each other,
resulting in no net idle-mode voltage across the speak-
er, minimizing power consumption.
Efficiency
Efficiency of a Class D amplifier is attributed to the
region of operation of the output stage transistors. In a
Class D amplifier, the output transistors act as current-
steering switches and consume negligible additional
power. Any power loss associated with the Class D out-
put stage is mostly due to the I2R loss of the MOSFET
on-resistance and supply current.
The theoretical best efficiency of a linear amplifier is
78%; however, that efficiency is only exhibited at peak
output powers. Under normal operating levels (typical
music reproduction levels), efficiency falls below 30%,
whereas the MAX9705 still exhibits >70% efficiencies
under the same conditions (Figure 4).
Shutdown
The MAX9705 has a shutdown mode that reduces power
consumption and extends battery life. Driving SHDN low
places the MAX9705 in a low-power (0.3µA) shutdown
mode. Connect SHDN to VDD for normal operation.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MAX9705.PDF ] | |
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