19-3681; Rev 0; 12/05
KIT
ATION
EVALU
BLE
AVAILA
3-Channel, 2.3W, Filterless Class D Amplifiers
with Active Crossover
General Description
The MAX9706/MAX9707 combine three high-efficiency
Class D amplifiers with an active crossover to provide
stereo highpass outputs, and a mono lowpass output.
All three channels deliver up to 2.3W at 1% THD+N per
channel into 4Ω when operating from a 5V supply.
An internal active filter processes the stereo inputs (left
and right) into stereo highpass and mono lowpass out-
puts. The crossover frequency is pin-selectable to four
different frequencies to accommodate a variety of
speaker configurations. The internal Class D amplifiers
feature low-EMI, spread-spectrum outputs. No output
filters are required.
The MAX9706 features Maxim’s DirectDrive™ headphone
amplifier, providing ground-referenced headphone out-
puts without the need for bulky DC-coupling capacitors.
The headphone outputs are capable of delivering
95mW per channel into 16Ω from a 3.3V supply, and
are protected against ESD up to ±8kV.
The MAX9706/MAX9707 feature pin-programmable
gain, synchronization inputs and outputs, and a shut-
down mode that reduces supply current to less than
1µA. All amplifiers feature click-and-pop suppression
circuitry. Both devices are fully specified over the -40°C
to +85°C extended temperature range and are avail-
able in the thermally enhanced 36-pin (6mm x 6mm x
0.8mm) thin QFN package.
Features
♦
Triple Class D Amplifiers Deliver 3 x 2.3W into 4Ω
♦
Internal Active Crossover Filter with Adjustable
Crossover Frequency
♦
Low-EMI, Spread-Spectrum Modulation
♦
Low 0.02% THD+N
♦
High PSRR (71dB)
♦
DirectDrive Headphone Amplifier (MAX9706)
♦
Enhanced Click-and-Pop Suppression
♦
Input and Output Modulator Synchronization
♦
Low-Power Shutdown Mode
♦
Up To 90% Efficiency
♦
Space-Saving (6mm x 6mm x 0.8mm) 36-Pin Thin
QFN Package
MAX9706/MAX9707
Ordering Information
PART
MAX9706ETX+
MAX9707ETX+
HP AMP
Yes
No
PIN-PACKAGE
36 Thin QFN
36 Thin QFN
PKG CODE
T3666N-1
T3666N-1
+Denotes
lead-free package.
Note:
These devices operate over the -40°C to +85°C temper-
ature range.
Functional Diagrams and Pin Configurations appear at end
of data sheet.
Applications
Notebook Audio Solutions
2.1 Speaker Solutions
Desktop PCs
Multimedia Monitors
Portable DVD Players
Table-Top LCD TVs
Block Diagram
MAX9706
MAX9707
FULL-RANGE
TRANSDUCERS
AUDIO IN
AUDIO IN
FULL-RANGE
TRANSDUCERS
LOW-FREQUENCY
TRANSDUCER
FREQUENCY
SELECT
HEADPHONE
LOW-FREQUENCY
TRANSDUCER
FREQUENCY
SELECT
SHDN
SHDN
________________________________________________________________
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.
3-Channel, 2.3W, Filterless Class D Amplifiers
with Active Crossover
MAX9706/MAX9707
ABSOLUTE MAXIMUM RATINGS
V
DD
, PV
DD
, HPV
DD
, CPV
DD
to GND ........................-0.3V to +6V
GND to PGND, CPGND.........................................-0.3V to +0.3V
CPV
SS
, V
SS
to GND..................................................-6V to +0.3V
C1N to GND ...........................................(CPV
SS
- 0.3V) to +0.3V
C1P to GND ...........................................-0.3V to (CPV
DD
+ 0.3V)
HPL, HPR.....................................................................-3V to +3V
All Other Pins to GND.................................-0.3V to (V
DD
+ 0.3V)
OUT_+, OUT_ -, Short Circuit to GND or PV
DD ...........
Continuous
OUT_+ Short Circuit to OUT_-....................................Continuous
HPR, HPL Short Circuit to GND..................................Continuous
MONO_OUT Short Circuit to GND or V
DD ....................
Continuous
Continuous Current (PV
DD
, OUT_+, OUT_-, PGND).............1.7A
Continuous Current (MONO_OUT, CPV
DD
, C1N, C1P,
CPGND, CPV
SS
, V
SS
, HPV
DD
, HPR, HPL) ......................0.85A
Continuous Current (all other pins) .....................................20mA
Continuous Power Dissipation (T
A
= +70°C)
Single-Layer Board
36-Pin TQFN (derate 26.3mW/°C above +70°C) .......2105mW
Multilayer Board
36-Pin TQFN (derate 35.7mW/°C above +70°C) .......2857mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
DD
= PV
DD
= HPV
DD
= 5V, GND = PGND = CPGND = 0V,
SHDN
= V
DD
, GAIN1 = GAIN2 = GND (SPKR = +9dB, HP = 0dB), HPS =
GND, FS0 = FS1 = GND (800Hz), MGAIN = float (-6dB), SYNC_IN = V
DD
(SSM), speaker load R
L
connected between OUT_+ and
OUT_-, unless otherwise noted, R
L
=
∞.
Headphone load R
LH
connected between HPR/HPL to GND, R
LH
=
∞.
C
BIAS
= 1µF to GND,
C1 = 1µF, C2 = 1µF. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values at T
A
= +25°C.) (Note 1)
PARAMETER
Speaker Amplifier Supply Voltage
Range
Headphone Amplifier Supply
Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Input Resistance
Turn-On Time, Shutdown to Full
Operation
SYMBOL
CONDITIONS
MIN
4.5
3.0
25
7
0.5
15
Speaker mode
Headphone mode (MAX9706)
R
L
= 8Ω, THD+N = 1%
R
L
= 4Ω, THD+N = 1%
P
OUT
= 1W,
bandwidth = 22Hz to
22kHz (Note 2)
R
L
= 8Ω, P
OUT
= 1W
(Note 2)
R
L
= 8Ω
R
L
= 4Ω
Bandwidth =
22Hz to 22kHz
A-weighted
V
DD
= PV
DD
= 4.5V to 5.5V, T
A
= +25°C
Power-Supply Rejection Ratio
PSRR
100mV
P-P
ripple
(Note 3)
f = 2kHz, OUTL_, OUTR_
f = 100Hz, OUTM_
50
25
87
87
1.4
2.3
0.06
%
0.07
87
92
71
51
65
dB
TYP
MAX
5.5
5.5
35
12
3
35
UNITS
V
V
mA
µA
kΩ
ms
V
DD
, PV
DD
Inferred from PSRR test
HPV
DD
,
CPV
DD
I
DD
I
SHDN
R
IN
Inferred from PSRR test (MAX9706)
Speaker mode
Headphone mode, HPS = V
DD
(MAX9706)
SHDN
= GND
SPEAKER AMPLIFIERS (OUTL_, OUTR_, OUTM_)
Output Power (Note 2)
Total Harmonic Distortion Plus
Noise
P
OUT
W
THD+N
Signal-to-Noise Ratio
SNR
dB
2
_______________________________________________________________________________________
3-Channel, 2.3W, Filterless Class D Amplifiers
with Active Crossover
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= HPV
DD
= 5V, GND = PGND = CPGND = 0V,
SHDN
= V
DD
, GAIN1 = GAIN2 = GND (SPKR = +9dB, HP = 0dB), HPS =
GND, FS0 = FS1 = GND (800Hz), MGAIN = float (-6dB), SYNC_IN = V
DD
(SSM), speaker load R
L
connected between OUT_+ and
OUT_-, unless otherwise noted, R
L
=
∞.
Headphone load R
LH
connected between HPR/HPL to GND, R
LH
=
∞.
C
BIAS
= 1µF to GND,
C1 = 1µF, C2 = 1µF. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values at T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
GAIN2 = 0
Speaker Path Gain (Note 4)
GAIN2 = 0
GAIN2 = 1
GAIN2 = 1
Channel-to-Channel Gain
Tracking
MGAIN = GND
MONO Gain Offset (Note 5)
MGAIN = float
MGAIN = V
DD
Crosstalk
Maximum Capacitive Load
Efficiency
C
L
η
Right to left, left to right, f
IN
= 10kHz,
P
OUT
= 1W
No sustained oscillations
R
L
= 8Ω, P
OUT
= 3 x 1W, f = 800Hz
R
L
= 4Ω, P
OUT
= 3 x 1W, f = 800Hz
FFM, SYNC_IN = GND
Class D Center Frequency
Class D Spreading Bandwidth
SYNC_IN Frequency Lock Range
Output Offset Voltage
Click-and-Pop Level
CROSSOVER FILTERS
Cutoff Frequency Accuracy
(Note 7)
FS0 = 0
Crossover Frequency
f
XO
FS0 = 0
FS0 = 1
FS0 = 1
Left-to-Right Cutoff Frequency
Tracking
FS1 = 0
FS1 = 1
FS1 = 0
FS1 = 1
800
1066.7
1600
2133.3
±0.5
%
Hz
±15
%
V
OS
K
CP
OUT_+ to OUT_-
Peak voltage,
A-weighted, 32 samples
per second (Note 6)
Into shutdown
Out of shutdown
f
OSC
FFM, SYNC_IN = float
SSM, SYNC_IN = V
DD
SSM mode, SYNC_IN = V
DD
1000
14
47
dBV
50
955
1140
CONDITIONS
GAIN1 = 0
GAIN1 = 1
GAIN1 = 0
GAIN1 = 1
MIN
TYP
9
10.5
12
13.5
0.3
-4.5
-6
-7.5
70
200
90
88
1100
1340
1150
±50
1500
kHz
kHz
mV
1270
1540
kHz
dB
pF
%
dB
%
dB
MAX
UNITS
MAX9706/MAX9707
_______________________________________________________________________________________
3
3-Channel, 2.3W, Filterless Class D Amplifiers
with Active Crossover
MAX9706/MAX9707
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= HPV
DD
= 5V, GND = PGND = CPGND = 0V,
SHDN
= V
DD
, GAIN1 = GAIN2 = GND (SPKR = +9dB, HP = 0dB), HPS =
GND, FS0 = FS1 = GND (800Hz), MGAIN = float (-6dB), SYNC_IN = V
DD
(SSM), speaker load R
L
connected between OUT_+ and
OUT_-, unless otherwise noted, R
L
=
∞.
Headphone load R
LH
connected between HPR/HPL to GND, R
LH
=
∞.
C
BIAS
= 1µF to GND,
C1 = 1µF, C2 = 1µF. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values at T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
HEADPHONE AMPLIFIERS (MAX9706) (HPS = V
DD
)
Output Power
P
OUT
HPV
DD
= 3.3V to 5V,
T
A
= +25°C, THD+N = 1%
(Notes 2, 7)
V
OUT
= 1V
RMS
, f = 1kHz,
bandwidth = 22Hz to
22kHz
V
OUT
= 1V
RMS
HPV
DD
= 3V to 5.5V
Power-Supply Rejection Ratio
PSRR
f = 1kHz, 100mV
P-P
ripple (Note 3)
f = 20kHz, 100mV
P-P
ripple (Note 3)
Headphone Path Gain (Note 8)
Output Offset Voltage
Crosstalk
Slew Rate
Maximum Capacitive Load
HPS Pullup Impedance
Debounce Time
Output Impedance in Shutdown
Charge-Pump Switching
Frequency
Click-and-Pop Level
f
CP
Peak voltage,
A-weighted, 32 samples
per second (Note 6)
Into shutdown
Out of
shutdown
HPS = GND or
SHDN
= GND
C
L
No sustained oscillations
V
OSHP
GAIN2 = 0
GAIN2 = 1
HP_ to GND, T
A
= +25°C
HPL to HPR, HPR to HPL, f
IN
= 1kHz,
P
OUT
= 32mW, R
L
= 32Ω
R
L
= 32Ω
R
L
= 16Ω
R
L
= 32Ω
R
L
= 16Ω
Bandwidth =
22Hz to 22kHz
A-weighted
70
35
50
mW
95
0.02
%
0.04
96
100
90
80
65
0
3
±0.7
-60
0.5
300
600
65
1.4
f
OSC
/ 2
52
52
dBV
±3
dB
mV
dB
V/µs
pF
kΩ
ms
kΩ
kHz
dB
Total Harmonic Distortion Plus
Noise
THD+N
Signal-to-Noise Ratio
SNR
dB
K
CP
LINE-LEVEL MONO OUTPUT (MONO_OUT)
MONO_OUT Signal-Path Gain
Output Impedance
Maximum Output Level
Total Harmonic Distortion Plus
Noise
Maximum Capacitive Load
THD+N
C
L
R
L
= 10kΩ
V
OUT
= 1V
RMS
, f
IN
= 100Hz, R
L
= 10kΩ,
bandwidth = 22Hz to 22kHz
No sustained oscillations
0
0.1
1
0.01
200
dB
Ω
V
RMS
%
pF
4
_______________________________________________________________________________________
3-Channel, 2.3W, Filterless Class D Amplifiers
with Active Crossover
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= HPV
DD
= 5V, GND = PGND = CPGND = 0V,
SHDN
= V
DD
, GAIN1 = GAIN2 = GND (SPKR = +9dB, HP = 0dB), HPS =
GND, FS0 = FS1 = GND (800Hz), MGAIN = float (-6dB), SYNC_IN = V
DD
(SSM), speaker load R
L
connected between OUT_+ and
OUT_-, unless otherwise noted, R
L
=
∞.
Headphone load R
LH
connected between HPR/HPL to GND, R
LH
=
∞.
C
BIAS
= 1µF to GND,
C1 = 1µF, C2 = 1µF. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values at T
A
= +25°C.) (Note 1)
PARAMETER
Input-Voltage High
Input-Voltage Low
Input Leakage Current
Input Current
Pullup Impedance
DIGITAL OUTPUT (SYNC_OUT)
Output-Voltage High
Output-Voltage Low
V
OH
V
OL
I
OH
= 1mA
I
OL
= 1mA
V
DD
x
0.9
V
DD
x
0.1
V
V
SYMBOL
V
INH
V
INL
GAIN1, GAIN2, FS0, FS1,
SHDN
SYNC_IN, MGAIN
SYNC_IN, MGAIN
200
CONDITIONS
MIN
2
0.8
±1
±50
TYP
MAX
UNITS
V
V
µA
µA
kΩ
DIGITAL INPUTS (GAIN1, GAIN2, FS0, FS1,
SHDN,
SYNC_IN, MGAIN)
MAX9706/MAX9707
Note 1:
Note 2:
Note 3:
Note 4:
All devices are 100% tested at T
A
= +25°C. Limits over temperature are guaranteed by design.
Measured at 2kHz for OUTL_, OUTR_, HPL, and HPR; measured at 100Hz for OUTM_.
PSRR is measured with the inputs AC-grounded.
Left/right signal-path gain is defined as:
(
V
OUT _
+
)
−
(
V
OUT _
−
)
V
IN _
MONO signal-path gain is defined as:
(
V
OUTM
+
)
−
(
V
OUTM
−
)
(
V
INL
)
+
(
V
INR
)
Note 5:
MONO gain offset is measured with respect to speaker-path gain.
Note 6:
Speaker mode testing performed with an 8Ω resistive load in series with a 68µH inductive load connected across BTL output.
Headphone mode testing performed with a 32Ω resistive load connected between HP_ and GND. Mode transitions are controlled
by
SHDN.
Note 7:
Headphone-path gain is defined as:
V
HP
V
IN _
Note 8:
Guaranteed by design only.
_______________________________________________________________________________________
5
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