19-3134; Rev 1; 9/05
1.2W, Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
General Description
The MAX9770/MAX9772 combine a mono, filterless,
Class D speaker amplifier and stereo DirectDrive
TM
headphone amplifiers in a single device. The MAX9770/
MAX9772 operate from a single 2.5V to 5.5V supply
and include features that reduce external component
count, system cost, board space, and offer improved
audio reproduction.
The speaker amplifiers make 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 amplifiers deliver
1.2W into an 8Ω load while offering efficiencies above
85%. A spread-spectrum modulation scheme reduces
radiated emissions caused by the modulation frequency.
Furthermore, the MAX9770/MAX9772 oscillators can be
synchronized to an external clock through the SYNC
input, avoiding possible problem frequencies inside a
system. The speaker amplifier features THD+N as low as
0.025%, 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 85dB 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/MAX9772 include internally set, logic-
selectable gain, and a comprehensive input mul-
tiplexer/mixer, allowing 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, while the MAX9772 is offered in a
tiny (2.54mm x 2.54mm x 0.62mm) 25-bump chip-scale
package (UCSP™). The MAX9770/MAX9772 feature
thermal-overload and output short-circuit protection,
and are specified over the extended -40°C to +85°C
temperature range.
Features
♦
1.2W Filterless Class D Amplifiers Pass FCC
Class B Radiated EMI Standards with 100mm of
Cable
♦
Patented Spread-Spectrum Mode Offers 5dB EMI
Improvement over Conventional Methods
♦
80mW DirectDrive Headphone Amplifier
Eliminates Bulky DC-Blocking Capacitors
♦
High 85dB PSRR at 217Hz
♦
85% Efficiency
♦
Low 0.015% THD+N
♦
Industry-Leading Click-and-Pop Suppression
♦
Integrated 2-Way Input Mixer/Multiplexer
(MAX9772)
♦
Integrated 3-Way Input Mixer/Multiplexer
(MAX9770)
♦
Logic-Adjustable Gain
♦
Short-Circuit and Thermal Protection
♦
Available in Space-Saving, Thermally Efficient
Packages
MAX9770/MAX9772
Ordering Information
PART
MAX9770ETI+
MAX9770EUI
PIN-
PACKAGE
28 TQFN-EP*
28 TSSOP
PKG
SELECTABLE
CODE
INPUTS
T2855N-1 2 stereo, 1 mono
U28-1
B25-1
2 stereo, 1 mono
1 stereo, 1 mono
MAX9772EBA-T
5 x 5 UCSP
Note:
All devices specified over the -40°C to +85°C operating
temperature range.
*EP
= Exposed paddle.
+
Denotes lead-free package.
Pin Configuration appears at end of data sheet.
Simplified Block Diagram
V
DD
DirectDrive
STEREO
HEADPHONE
IN1L
IN2L*
MONO
IN1R
IN2R*
GAIN SEL
INPUT SEL
MUTE
SHDN
HPS
CLASS
D
SPKR
(MONO)
Applications
Cellular Phones
Compact Notebooks
UCSP is a trademark of Maxim Integrated Products, Inc.
PDAs
MAX9770/MAX9772
*MAX9770 ONLY.
________________________________________________________________
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.
1.2W, Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
MAX9770/MAX9772
ABSOLUTE MAXIMUM RATINGS
GND to PGND to CPGND......................................-0.3V to +0.3V
V
DD
to PV
DD
to CPV
DD
..........................................-0.3V to +0.3V
V
DD
to GND ...........................................................................+6V
PV
DD
to PGND .......................................................................+6V
CPV
DD
to CPGND..................................................................+6V
CPV
SS
to CPGND....................................................................-6V
SV
SS
to GND ...........................................................................-6V
C1N..........................................(PV
SS
- 0.3V) to (CPGND + 0.3V)
HPOUT_ to GND ....................................................................±3V
All Other Pins to GND.................................-0.3V to (V
DD
+ 0.3V)
Continuous Current Into/Out of:
PV
DD
, PGND, OUT_ ......................................................600mA
PV
SS
..............................................................................260mA
Duration of HPOUT_ Short Circuit to V
DD
, PV
DD
,
GND, PGND ...........................................................Continuous
Duration of Short Circuit Between
HPOUTL and HPOUTR ..........................................Continuous
Duration of OUT_ Short Circuit to V
DD
, PV
DD
, GND, PGND ..10s
Duration of Short Circuit Between OUT+ and OUT-...............10s
Continuous Power Dissipation (T
A
= +70°C)
5 x 5 UCSP (derate 15.85mW/°C above +70°C) .........1.268W
28-Pin TQFN (derate 20.8mW/°C above +70°C) .......1667mW
28-Pin TSSOP (derate 12.8mW°C above +70°C) ......1026mW
Junction Temperature ......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering) Reflow............................+235°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
= CPV
DD
= 3.3V, GND = PGND = CPGND = 0V,
SHDN
= 3.3V, C1 = C2 = 1µF, C
BIAS
= 0.047µF, SYNC = GND, R
L
=
∞,
speaker load connected between OUT+ and OUT-, headphone load connected between HPOUT_ and GND, T
A
= T
MIN
to T
MAX
,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Shutdown to Full Operation
Input Impedance
Bias Voltage
Feedthrough
V
DD
I
DD
I
SHDN
t
ON
R
IN
V
BIAS
From any unselected input to any output,
f = 10kHz
V
OS
V
DD
= 2.5V to
5.5V, T
A
= +25°C
Power-Supply Rejection Ratio
PSRR
(Note 4)
MAX9770
MAX9772
50
48
70
68
50
550
900
1200
mW
dB
(Note 3)
MONO
INL_, INR_
7
14
1.1
Inferred from PSRR test
No load
SHDN
= HPS = GND
Headphone mode
Speaker mode
2.5
5.5
5.2
0.1
50
10
20
1.25
70
1.4
5.5
10
7.5
10
V
mA
µA
ms
kΩ
V
dB
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SPEAKER AMPLIFIER (GAIN1 = GAIN2 = V
DD
, HPS = GND)
Output Offset Voltage
±15
70
±70
mV
V
RIPPLE
= 200mV
P-P
, f = 217Hz
V
RIPPLE
= 200mV
P-P
, f = 1kHz
V
RIPPLE
= 200mV
P-P
, f = 20kHz
Output Power
P
OUT
f = 1kHz,
THD+N = 1%,
GAIN1 = 1,
GAIN2 = 0
V
DD
= 3.3V
V
DD
= 5V
R
L
= 8Ω
R
L
= 4Ω
R
L
= 8Ω
2
_______________________________________________________________________________________
1.2W, Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= CPV
DD
= 3.3V, GND = PGND = CPGND = 0V,
SHDN
= 3.3V, C1 = C2 = 1µF, C
BIAS
= 0.047µF, SYNC = GND, R
L
=
∞,
speaker load connected between OUT+ and OUT-, headphone load connected between HPOUT_ and GND, T
A
= T
MIN
to T
MAX
,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Total Harmonic Distortion Plus
Noise
Signal-to-Noise Ratio
SYMBOL
CONDITIONS
R
L
= 8Ω, P
OUT
= 300mW, f = 1kHz
THD+N
R
L
= 4Ω, P
OUT
= 300mW, f = 1kHz
MAX9772, R
L
= 8Ω, P
OUT
= 500mW,
f = 1kHz
R
L
= 8Ω, V
OUT
= 2V
RMS
, A-weighted
SYNC = GND
Output Switching Frequency
f
S
SYNC = FLOAT
SYNC = V
DD
SYNC Frequency Lock Range
Efficiency
η
P
O
= 1000mW, f = 1kHz
GAIN1 = 0, GAIN2 = 0
Gain (MAX9770)
A
V
GAIN1 = 0, GAIN2 = 1
GAIN1 = 1, GAIN2 = 0
GAIN1 = 1, GAIN2 = 1
GAIN1 = 0, GAIN2 = 0
GAIN1 = 0, GAIN2 = 1
GAIN1 = 1, GAIN2 = 0
GAIN1 = 1, GAIN2 = 1
HPS = V
DD
, headphone amplifier active,
f = 1kHz
Peak voltage, A-
weighted, 32
samples per second
(Notes 4, 5)
MAX9770
MAX9772
V
DD
= 2.5V to 5.5V, T
A
= +25°C
MAX9770, V
RIPPLE
= 200mV
P-P
,
f = 217Hz
MAX9772, V
RIPPLE
= 200mV
P-P
,
f = 217Hz
V
RIPPLE
= 200mV
P-P
, f = 1kHz
V
RIPPLE
= 200mV
P-P
, f = 20kHz
T
A
= +25°C,
f = 1kHz,
THD+N = 1%
(Note 3)
V
DD
= 3.3V
V
DD
= 5V
R
L
= 32Ω
R
L
= 16Ω
R
L
= 32Ω
R
L
= 16Ω
40
65
76
75
85
82
56
55
40
60
80
mW
dB
Into shutdown
Out of shutdown
Into mute
Out of mute
800
85
6
3
9
0
15.6
12
20
6
±5
102
-76
-55
-83
-69
±5
±10
±14
dB
980
1280
MIN
TYP
0.025
0.03
0.1
85.9
1100
1450
1220
±120kHz
2000
kHz
%
1220
1620
kHz
dB
%
MAX
UNITS
MAX9770/MAX9772
SNR
Gain (MAX9772)
A
V
dB
Gain Accuracy
Speaker Path Off-Isolation
%
dB
Click-and-Pop Level
K
CP
dB
HEADPHONE AMPLIFIER (GAIN1 = 1, GAIN2 = 0, HPS = V
DD
)
Output Offset Voltage
V
OS
mV
Power-Supply Rejection Ratio
PSRR
(Note 4)
Output Power
P
OUT
_______________________________________________________________________________________
3
1.2W, Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
MAX9770/MAX9772
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
= CPV
DD
= 3.3V, GND = PGND = CPGND = 0V,
SHDN
= 3.3V, C1 = C2 = 1µF, C
BIAS
= 0.047µF, SYNC = GND, R
L
=
∞,
speaker load connected between OUT+ and OUT-, headphone load connected between HPOUT_ and GND, T
A
= T
MIN
to T
MAX
,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
Total Harmonic Distortion Plus
Noise
Signal-to-Noise Ratio
Crosstalk
Headphone Off-Isolation
SYMBOL
THD+N
SNR
CONDITIONS
R
L
= 32Ω, P
OUT
= 50mW, f = 1kHz
R
L
= 16Ω, P
OUT
= 35mW, f = 1kHz
R
L
= 32Ω, V
OUT
= 300mV
RMS
,
BW = 22Hz to 22kHz
Between channels, f = 1kHz,
V
IN
= 200mV
P-P
HPS = GND, speaker amplifier active,
f = 1kHz
Peak voltage, A-
weighted, 32
samples per second
(Notes 4, 5)
GAIN1 = 0, GAIN2 = 0
Gain
A
V
GAIN1 = 0, GAIN2 = 1
GAIN1 = 1, GAIN2 = 0
GAIN1 = 1, GAIN2 = 1
Gain Accuracy
ESD Protection
Input Voltage High
Input Voltage Low
Input Leakage Current (Note 6)
HPS Input Current
V
IH
V
IL
SYNC input
All other logic inputs
HPS = GND
HPOUTR, HPOUTL, IEC Air Discharge
2
0.8
±25
±1
-10
±8
DIGITAL INPUTS (SHDN, SYNC, HPS, GAIN_, SEL_)
V
V
µA
µA
Into shutdown
Out of shutdown
Into mute
Out of mute
MIN
TYP
0.015
0.03
101
80
96
-58
-53
-92
-73
1000
7
4
-2
1
±2.5
%
kV
dB
MAX
UNITS
%
dB
dB
dB
Click-and-Pop Level
K
CP
dBV
Capacitive-Load Drive
C
L
pF
Note 1:
All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2:
Speaker amplifier testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For
R
L
= 4Ω, L = 47µH. For R
L
= 8Ω, L = 68µH.
Note 3:
Guaranteed by design, not production tested.
Note 4:
Inputs AC-coupled to GND.
Note 5:
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 to GND. Mode transitions are controlled by
SHDN.
K
CP
level is calculated as: 20 x log [(peak voltage during mode transition, no input signal)/(peak voltage under normal operation at
rated power level)]. Units are expressed in dB. Measured with V
DD
= 5V.
Note 6:
SYNC has a 200kΩ resistor to V
REF
= 1.25V.
4
_______________________________________________________________________________________
1.2W, Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
MAX9770/MAX9772
Typical Operating Characteristics
(MAX9770 V
DD
= 3.3V, BW = 22Hz to 22kHz, GAIN1 = 1, GAIN2 = 0, spread-spectrum mode, headphone outputs in phase, unless
otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9770/72 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9770/72 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
R
L
= 8Ω
MAX9770/72 toc03
10
V
DD
= +5V
R
L
= 4Ω
1
THD+N (%)
10
R
L
= 4Ω
10
1
THD+N (%)
P
OUT
= 25mW
THD+N (%)
P
OUT
= 100mW
0.1
1
P
OUT
= 40mW
0.1
0.1
0.01
P
OUT
= 1000mW
0.01
P
OUT
= 500mW
0.01
P
OUT
= 400mW
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9770/72 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9770/72 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
R
L
= 4Ω
10
MAX9770/72 toc06
10
V
DD
= 5V
P
OUT
= 1W
R
L
= 8Ω
1
THD+N (%)
100
V
DD
= 5V
R
L
= 8Ω
10
100
THD+N (%)
1
f = 1kHz
0.1
f = 20Hz
THD+N (%)
1
f = 1kHz
f = 20Hz
0.1
0.1
SSM MODE
0.01
FFM MODE
0.01
0.001
f = 10kHz
0.01
0.001
f = 10kHz
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0
400
800
1200
1600
0
200
OUTPUT POWER (mW)
800
600
400
OUTPUT POWER (mW)
1000
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9770/72 toc07
MAX9772
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
R
L
= 8Ω
10
THD+N (%)
f
IN
= 1kHz
1
f
IN
= 20Hz
0.1
MAX9770/72 toc08
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
V
DD
= 5V
f = 1kHz
R
L
= 8Ω
MAX9770/72 toc09
100
R
L
= 8Ω
10
100
100
10
THD+N (%)
1
f = 20Hz
THD+N (%)
f = 1kHz
1
SSM MODE
0.1
0.1
0.01
f = 10kHz
0.001
0
200
400
600
800
OUTPUT POWER (mW)
0.01
0
200
400
600
800
1000
OUTPUT POWER (mW)
f
IN
= 10kHz
0.01
FFM MODE
0.001
0
400
800
1200
1600
OUTPUT POWER (mW)
_______________________________________________________________________________________
5
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