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.
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
MAX9770
Ordering Information
PART
MAX9770ETI
†
MAX9770EUI
†
Lead-free package.
TEMP RANGE
-40
o
C to +85
o
C
-40 C to +85 C
o
o
PIN-PACKAGE
28 TQFN-EP*
28 TSSOP
*EP
= Exposed paddle.
Simplified Block Diagram
V
DD
DirectDrive
STEREO
HEADPHONE
L1IN
L2IN
MONO
Applications
Cellular Phones
PDAs
Compact Notebooks
R1IN
R2IN
GAIN SEL
INPUT SEL
MUTE
SHDN
HPS
CLASS
D
SPKR
(MONO)
MAX9770
Pin Configuration appears at end of data sheet.
________________________________________________________________
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
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)
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
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
Power-Supply Rejection Ratio
PSRR
(Note 4)
V
RIPPLE
= 200mV
P-P
, f = 217Hz
V
RIPPLE
= 200mV
P-P
, f = 1kHz
V
RIPPLE
= 200mV
P-P
, f = 20kHz
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
50
(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
68
50
550
900
1200
0.025
0.03
%
mW
dB
±70
mV
Output Power
P
OUT
Total Harmonic Distortion Plus
Noise
THD+N
R
L
= 8Ω, P
OUT
= 300mW, f = 1kHz
R
L
= 4Ω, P
OUT
= 300mW, f = 1kHz
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
Signal-to-Noise Ratio
SYMBOL
SNR
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
A
V
GAIN1 = 0, GAIN2 = 1
GAIN1 = 1, GAIN2 = 0
GAIN1 = 1, GAIN2 = 1
Gain Accuracy
Speaker Path Off-Isolation
HPS = V
DD
, headphone amplifier active,
f = 1kHz
V
OS
V
DD
= 2.5V to 5.5V
Power-Supply Rejection Ratio
PSRR
(Note 3)
V
RIPPLE
= 200mV
P-P
, f = 217kHz
V
RIPPLE
= 200mV
P-P
, f = 1kHz
V
RIPPLE
= 200mV
P-P
, f = 20kHz
f = 1kHz,
THD+N = 1%
V
DD
= 3.3V
V
DD
= 5V
Total Harmonic Distortion Plus
Noise
Signal-to-Noise Ratio
Crosstalk
Headphone Off-Isolation
THD+N
SNR
R
L
= 32Ω
R
L
= 16Ω
R
L
= 32Ω
R
L
= 16Ω
40
65
102
800
85
6
3
9
0
±5
%
dB
dB
CONDITIONS
R
L
= 8Ω, V
OUT
= 2V
RMS
, A-weighted
980
1280
MIN
TYP
85.9
1100
1450
1220
±120kHz
2000
kHz
%
1220
1620
kHz
MAX
UNITS
dB
MAX9770
HEADPHONE AMPLIFIER (GAIN1 = 1, GAIN2 = 0, HPS = V
DD
)
Output Offset Voltage
±5
76
85
82
56
55
40
60
80
0.015
0.03
101
80
96
%
dB
dB
dB
mW
dB
±10
mV
Output Power
P
OUT
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
_______________________________________________________________________________________
3
1.2W Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
MAX9770
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
Capacitive-Load Drive
SYMBOL
C
L
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
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
CONDITIONS
MIN
TYP
1000
7
4
-2
1
±2.5
%
kV
dB
MAX
UNITS
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:
PSRR is specified with the amplifier inputs connected to GND through C
IN
.
Typical Operating Characteristics
(V
DD
= 3.3V, BW = 22Hz to 22kHz, GAIN1 = 1, GAIN2 = 0, spread-spectrum mode, headphone outputs in phase.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9770 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9770 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
R
L
= 8Ω
MAX9770 toc03
10
V
DD
= +5V
R
L
= 4Ω
1
THD+N (%)
P
OUT
= 25mW
0.1
10
R
L
= 4Ω
10
1
THD+N (%)
THD+N (%)
P
OUT
= 100mW
0.1
1
P
OUT
= 40mW
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
4
_______________________________________________________________________________________
1.2W Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
MAX9770
Typical Operating Characteristics (continued)
(V
DD
= 3.3V, BW = 22Hz to 22kHz, GAIN1 = 1, GAIN2 = 0, spread-spectrum mode, headphone outputs in phase.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY (SPEAKER MODE)
MAX9770 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9770 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
R
L
= 4Ω
10
MAX9770 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 toc07
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER (SPEAKER MODE)
MAX9770 toc08
OUTPUT POWER
vs. LOAD RESISTANCE (SPEAKER MODE)
1.50
OUTPUT POWER (W)
1.25
1.00
0.75
0.50
0.25
0
THD+N = 1%
V
DD
= 5V
f = 1kHz
THD+N = 10%
MAX9770 toc09
100
R
L
= 8Ω
10
100
V
DD
= 5V
f = 1kHz
R
L
= 8Ω
1.75
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
FFM MODE
0.001
0
400
800
1200
1600
OUTPUT POWER (mW)
1
10
LOAD RESISTANCE (Ω)
100
OUTPUT POWER
vs. LOAD RESISTANCE (SPEAKER MODE)
MAX9770 toc10
OUTPUT POWER
vs. SUPPLY VOLTAGE (SPEAKER MODE)
f = 1kHz
R
L
= 8Ω
THD+N = 10%
OUTPUT POWER (W)
1.5
EFFICIENCY (%)
MAX9770 toc11
EFFICIENCY vs. OUTPUT POWER
90
80
70
60
50
40
30
20
10
V
DD
= 5V
f = 1kHz
R
L
= 8Ω
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
MAX9770 toc12
1.0
f = 1kHz
0.8
OUTPUT POWER (W)
THD+N = 10%
0.6
2.0
100
1.0
0.4
THD+N = 1%
0.2
0.5
THD+N = 1%
0
1
10
LOAD RESISTANCE (Ω)
100
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
0
OUTPUT POWER (W)
_______________________________________________________________________________________
5
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