MAXIM MAX9705 Technical data
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 prevents high-frequency emissions resulting from conventional 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 performance by allowing the output FETs to switch simultaneously without cross-conduction. A patented spreadspectrum modulation scheme eliminates the need for output 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 fixedfrequency (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 interference 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), 10-pin µMAX®, 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.
Applications
Features
♦ Filterless Amplifier Passes FCC-Radiated
Emissions Standards with 24in of Cable
♦ Unique Spread-Spectrum Mode and Active
Emissions Limiting (AEL) Achieves Better than
20dB Margin Under FCC Limits
♦ Zero Dead Time (ZDT) H-Bridge Maintains State-
of-the-Art Efficiency and THD+N
♦ Simple Master-Slave Setup for Stereo Operation
♦ Up to 90% Efficiency
♦ 2.3W into 4Ω (1% THD+N)
♦ Low 0.02% THD+N (P
OUT
= 1W, VDD= 5.0V)
♦ High PSRR (75dB at 217Hz)
♦ Integrated Click-and-Pop Suppression
♦ Low Quiescent Current (5.4mA)
♦ Low-Power Shutdown Mode (0.3µA)
♦ Short-Circuit and Thermal-Overload Protection
♦ Available in Thermally Efficient, Space-Saving
Packages
10-Pin TDFN (3mm x 3mm x 0.8mm)
10-Pin µMAX
12-Bump UCSP (1.5mm x 2mm x 0.6mm)
♦ Pin-for-Pin Compatible with the MAX9700 and
MAX9712
MAX9705
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-3405; Rev 0; 7/05
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.
EVALUATION KIT
AVAILABLE
Cellular Phones
PDAs
MP3 Players
Portable Audio
PART
TEMP RANGE
PIN-
TOP
MARK
MAX9705AETB+T
ACY
MAX9705AEUB+
10 µMAX —
MAX9705AEBC+T
ACH
MAX9705BETB+T
ACX
MAX9705BEUB+
10 µMAX —
MAX9705BEBC+T
ACG
Ordering Information continued at end of data sheet.
µMAX is a registered trademark and UCSP is a trademark of
Maxim Integrated Products, Inc.
+Denotes lead-free package.
Selector Guide appears at end of data sheet.
30.0 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
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
FREQUENCY (MHz)
AMPLITUDE (dBµV/m)
FCC EMI LIMIT
MAXIM'S NEW ULTRA-LOW
OUTPUT SPECTRUM
EMI Spectrum Diagram
查询MAX9705供应商
PACKAGE
-40oC to +85oC 10 TDFN-10
-40oC to +85oC
-40oC to +85oC 12 UCSP-12
-40oC to +85oC 10 TDFN-10
-40oC to +85oC
-40oC to +85oC 12 UCSP-12
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD= PVDD= SHDN = 3.3V, GND = PGND = 0V, SYNC = GND (FFM), RL= ∞, RLconnected between OUT+ and OUT-, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C.) (Notes 1, 2)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VDDto GND..............................................................................6V
PV
DD
to PGND .........................................................................6V
GND to PGND .......................................................-0.3V to +0.3V
PV
DD
to VDD..........................................................-0.3V to +0.3V
All Other Pins to GND.................................-0.3V to (V
DD
+ 0.3V)
Continuous Current Into/Out of PV
DD
/PGND/OUT_........±600mA
Continuous Input Current (all other pins) .........................±20mA
Duration of OUT_ Short Circuit to GND or PV
DD
........Continuous
Duration of Short Circuit Between OUT+ and OUT-.....Continuous
Continuous Power Dissipation (TA= +70°C)
10-Pin TDFN (derate 24.4mW/°C above +70°C) .....1951.2mW
10-Pin µMAX (derate 5.6mW/
o
C above +70°C) .........444.4mW
12-Bump UCSP (derate 6.1mW/°C above +70°C)........484mW
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Bump Temperature (soldering)
Reflow ..........................................................................+235°C
MAX9705
PARAMETER
CONDITIONS
UNITS
GENERAL
Supply Voltage Range V
DD
Inferred from PSRR test 2.5 5.5 V
Quiescent Current I
DD
5.4 7 mA
Shutdown Current I
SHDN
0.3 10 µA
Turn-On Time t
ON
30 ms
Input Resistance R
IN
TA = +25°C 12 20 kΩ
MAX9705A
1.0
MAX9705B
MAX9705C
Input Bias Voltage V
BIAS
Either input
MAX9705D
V
MAX9705A 1.9 2.0 2.1
MAX9705B 3.8 4.0 4.2
MAX9705C 5.7 6.0 6.3
Voltage Gain A
V
MAX9705D 9.5 10
V/V
Output Offset Voltage V
OS
TA = +25°C
mV
Common-Mode Rejection Ratio CMRR fIN = 1kHz, input referred 56 dB
VDD = 2.5V to 5.5V, TA = +25°C 50 75
75
Power-Supply Rejection Ratio
(Note 3)
PSRR
200mV
P-P
ripple
60
dB
RL = 8Ω
Output Power P
OUT
THD+N = 1%,
f
IN
= 1kHz
R
L
= 4Ω
mW
RL = 8Ω,
P
OUT
= 450mW
Total Harmonic Distortion
Plus Noise
fIN = 1kHz, either FFM or
SSM
R
L
= 4Ω,
P
OUT
= 375mW
%
Into shutdown -68
Click/Pop Level K
CP
Peak voltage,
dB
SYMBOL
MIN TYP MAX
THD+N
A-weighted (Notes 3, 4)
0.88
0.73 0.83 0.93
0.61 0.71 0.81
0.48 0.56 0.64
f
= 217Hz
RIPPLE
f
= 20kHz
RIPPLE
Out of shutdown -60.5
±10 ±69
600
950
0.02
0.025
1.12
10.5
MAX9705
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD= PVDD= SHDN = 3.3V, GND = PGND = 0V, SYNC = GND (FFM), RL= ∞, RLconnected between OUT+ and OUT-, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C.) (Notes 1, 2)
Note 1: All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R
L
= 4Ω, L = 33µH.
For R
L
= 8Ω, L = 68µH. For RL= 16Ω, L = 136µH.
Note 3: Inputs AC-coupled to GND.
Note 4: Testing performed with 8Ω resistive load in series with 68µH inductive load connected across BTL output. Mode transitions
are controlled by
SHDN pin. KCPlevel is calculated as 20 x log[(peak voltage under normal operation at rated power
level)/(peak voltage during mode transition, no input signal)]. Units are expressed in dB.
Note 5: SYNC has a 1MΩ resistor to V
REF
= 1.25V.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Output Slew Rate SR
V/µs
Rise/Fall Time
10% to 90% 15 ns
FFM 91
BW = 22Hz
to 22kHz
SSM 89
FFM 93
Signal-to-Noise Ratio SNR V
OUT
= 2V
RMS
SSM 91
dB
SYNC = GND 980
SYNC = float
Oscillator Frequency f
OSC
SYNC = VDD (SSM mode)
kHz
SYNC Frequency Lock Range 800
kHz
Efficiency η P
OUT
= 800mW, fIN = 1kHz, RL = 8Ω 89 %
DIGITAL INPUTS (SHDN, SYNC)
V
IH
2
Input Thresholds
V
IL
0.8
V
SHDN Input Leakage Current 0.1 ±10 µA
SYNC Input Current (Note 5)
±10 µA
ELECTRICAL CHARACTERISTICS
(VDD= PVDD= SHDN = 5V, GND = PGND = 0V, SYNC = GND (FFM), RL= ∞, RLconnected between OUT+ and OUT-, TA= T
MIN
to
T
MAX
, unless otherwise noted. Typical values are at TA= +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Quiescent Current I
DD
7mA
Shutdown Current I
SHDN
µA
f = 217Hz 75
Power-Supply Rejection Ratio PSRR
f = 20kHz 60
dB
RL = 16Ω
RL = 8Ω
Output Power P
OUT
THD+N = 1%,
f = 1kHz
R
L
= 4Ω
mW
RL = 8Ω, P
OUT
= 1.0W
Total Harmonic Distortion
Plus Noise
f = 1kHz, either
FFM or SSM
%
FFM 94
BW = 22Hz to
22kHz
SSM 91
FFM 97
Signal-to-Noise Ratio SNR
V
OUT
=
3V
RMS
A-weighted
SSM 93
dB
176
t
, t
RISE
FALL
A-weighted
1100 1220
1250 1450 1650
1220
±120
2000
-1.25
0.55
200mV
THD+N
ripple
P-P
RL = 4Ω, P
= 1.75W 0.05
OUT
750
1400
2300
0.02
100
00.51.01.5
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9705toc04
OUTPUT POWER (W)
THD+N (%)
VDD = 3.3V
R
L
= 4Ω
fIN = 1kHz
100
01.00.5 2.01.5 2.5 3.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9705toc05
OUTPUT POWER (W)
THD+N (%)
fIN = 1kHz
VDD = 5.0V
R
L
= 4Ω
100
00.40.2 0.80.6 1.0 1.2
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9705toc06
OUTPUT POWER (W)
THD+N (%)
VDD = 3.3V
R
L
= 8Ω
f
IN
= 1kHz
FFM
SSM
100
0.01
10 100 10k 100k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
1
10
MAX9705toc07
FREQUENCY (Hz)
THD+N (%)
1k
VDD = 3.3V
R
L
= 8Ω
P
OUT
= 100mW
P
OUT
= 450mW
100
0.01
10 100 10k 100k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
1
10
MAX9705toc08
FREQUENCY (Hz)
THD+N (%)
1k
VDD = 5.0V
R
L
= 8Ω
P
OUT
= 250mW
P
OUT
= 1W
100
0.01
10 100 10k 100k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
1
10
MAX9705toc09
FREQUENCY (Hz)
THD+N (%)
1k
VDD = 2.5V
R
L
= 4Ω
P
OUT
= 50mW
P
OUT
= 300mW
MAX9705
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VDD= 3.3V, SYNC = VDD(SSM), differential input, TA= +25°C, unless otherwise noted.)
100
00.40.81.00.2 0.6 1.2
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9705toc01
OUTPUT POWER (W)
THD+N (%)
fIN = 1kHz
VDD = 3.3V
R
L
= 8Ω
100
0 0.5 1.0 1.5 2.0
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9705toc02
OUTPUT POWER (W)
THD+N (%)
fIN = 1kHz
VDD = 5.0V
R
L
= 8Ω
100
0 0.2 0.4 0.6 0.8
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9705toc03
OUTPUT POWER (W)
THD+N (%)
fIN = 1kHz
VDD = 2.5V
R
L
= 4Ω
MAX9705
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VDD= 3.3V, SYNC = VDD(SSM), differential input, TA= +25°C, unless otherwise noted.)
100
0.01
10 100 10k 100k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
1
10
MAX9705toc10
FREQUENCY (Hz)
THD+N (%)
1k
VDD = 3.3V
R
L
= 4Ω
P
OUT
= 100mW
P
OUT
= 800mW
100
0.01
10 100 10k 100k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
1
10
MAX9705toc11
FREQUENCY (Hz)
THD+N (%)
1k
VDD = 5.0V
R
L
= 4Ω
P
OUT
= 250mW
P
OUT
= 1.75W
100
0.01
10 100 10k 100k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
0.1
1
10
MAX9705toc12
FREQUENCY (Hz)
THD+N (%)
1k
VDD = 3.3V
R
L
= 8Ω
P
OUT
= 450mW
FFM
SSM
100
00.5 1.51.0 2.0 2.5
10
1
0.1
0.01
0.001
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. COMMON-MODE VOLTAGE
MAX9705toc13
COMMON-MODE VOLTAGE (V)
THD+N (%)
VDD = 3.3V to 5V
f
IN
= 1kHz
P
OUT
= 500mW
GAIN = 6dB
R
L
= 8Ω
0
30
20
10
40
50
60
70
80
90
100
00.40.2 0.6 0.8 1.0
EFFICIENCY
vs. OUTPUT POWER
MAX9705toc14
OUTPUT POWER (W)
EFFICIENCY (%)
VDD = 3.3V
f
IN
= 1kHz
RL = 8Ω
R
L
= 4Ω
0
30
20
10
40
50
60
70
80
90
100
01.00.5 1.5 2.0 2.5 3.0
EFFICIENCY
vs. OUTPUT POWER
MAX9705toc15
OUTPUT POWER (W)
EFFICIENCY (%)
VDD = 5.0V
f
IN
= 1kHz
RL = 8Ω
RL = 4Ω
0
30
20
10
40
50
60
70
80
90
100
2.5 3.53.0 4.0 4.5 5.0 5.5
EFFICIENCY
vs. SUPPLY VOLTAGE
MAX9705toc16
SUPPLY VOLTAGE (V)
EFFICIENCY (%)
fIN = 1kHz
THD+N = 1%
RL = 8Ω
RL = 4Ω
0
30
20
10
40
50
60
70
80
90
100
800 12001000 1400 1600 1800 2000
EFFICIENCY
vs. SYNC FREQUENCY
MAX9705toc17
SYNC FREQUENCY (kHz)
EFFICIENCY (%)
VDD = 3.3V
f
IN
= 1kHz
THD+N = 1%
RL = 8Ω
RL = 4Ω
0
30
20
10
40
50
60
70
80
90
100
800 12001000 1400 1600 1800 2000
EFFICIENCY
vs. SYNC FREQUENCY
MAX9705toc18
SYNC FREQUENCY (kHz)
EFFICIENCY (%)
VDD = 5.0V
f
IN
= 1kHz
THD+N = 1%
RL = 8Ω
RL = 4Ω
-140
-120
-100
-80
-60
-40
-20
0
20
051015 20
SPREAD-SPECTRUM-MODE OUTPUT
SPECTRUM vs. FREQUENCY
MAX9705 toc25
FREQUENCY (kHz)
AMPLITUDE (dBV)
RL = 8Ω
V
DD
= 5.0V
f
IN
= 1kHz
A-WEIGHTED
MAX9705
2.3W, Ultra-Low-EMI, Filterless,
Class D Audio Amplifier
6 _______________________________________________________________________________________
0
0.6
0.4
0.2
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.5 3.53.0 4.0 4.5 5.0 5.5
OUTPUT POWER
vs. SUPPLY VOLTAGE
MAX9705toc19
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
fIN = 1kHz
R
L
= 8Ω
THD+N = 1%
THD+N = 10%
0
1.5
1.0
0.5
2.0
2.5
3.0
3.5
2.5 3.53.0 4.0 4.5 5.0 5.5
OUTPUT POWER
vs. SUPPLY VOLTAGE
MAX9705toc20
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
fIN = 1kHz
R
L
= 4Ω
THD+N = 1%
THD+N = 10%
4.0
0
1 100 1000
OUTPUT POWER
vs. LOAD RESISTANCE
1.5
1.0
3.0
2.0
3.5
0.5
2.5
MAX9705 toc21
LOAD RESISTANCE (Ω)
OUTPUT POWER (W)
10
fIN = 1kHz
Z
LOAD
= 33µH IN
SERIES WITH R
L
THD+N = 1%
3.3V
5.0V
0
-10
-100
10 100 10k 100k
POWER-SUPPLY REJECTION
RATIO vs. FREQUENCY
-90
-50
-70
-80
-40
-60
-20
-30
MAX9705 toc22
FREQUENCY (Hz)
PSRR (dB)
1k
VDD = 3.3V
V
IN
= 200mV
P-P
RL = 8Ω
-140
-120
-100
-80
-60
-40
-20
0
20
051015 20
FIXED-FREQUENCY-MODE OUTPUT
SPECTRUM vs. FREQUENCY
MAX9705 toc23
FREQUENCY (kHz)
AMPLITUDE (dBV)
RL = 8Ω
V
DD
= 5.0V
f
IN
= 1kHz
BW = 22Hz to 22kHz
-140
-120
-100
-80
-60
-40
-20
0
20
051015 20
SPREAD-SPECTRUM-MODE OUTPUT
SPECTRUM vs. FREQUENCY
MAX9705 toc24
FREQUENCY (kHz)
AMPLITUDE (dBV)
RL = 8Ω
V
DD
= 5.0V
f
IN
= 1kHz
BW = 22Hz to 22kHz
Typical Operating Characteristics (continued)
(VDD= 3.3V, SYNC = VDD(SSM), differential input, TA= +25°C, unless otherwise noted.)
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