MAX9787ETI [MAXIM]
2.2W Stereo Audio Power Amplifier with Analog Volume Control; 2.2W立体声音频功率放大器与模拟音量控制
| 型号： | MAX9787ETI |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 2.2W Stereo Audio Power Amplifier with Analog Volume Control |
| 文件： | 总15页 (文件大小：235K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3882; Rev 0; 10/05
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
General Description
Features
♦ Class AB, 2.2W, Stereo BTL Speaker Amplifiers
♦ Analog Volume Control
The MAX9787 combines a stereo, 2.2W audio power
amplifier with an analog volume control in a single device.
A high 90dB PSRR and low 0.01% THD+N ensures clean,
low-distortion amplification of the audio signal.
♦ BEEP Input with Glitch Filter
♦ 5V Single-Supply Operation
The analog volume control can be driven with a poten-
tiometer, an RC-filtered PWM source, or a DAC output.
A BEEP input allows the addition of alert signals from
the controller to the audio path.
♦ High 90dB PSRR
♦ Low-Power Shutdown Mode
♦ Industry-Leading Click-and-Pop Suppression
♦ Low 0.01% THD+N at 1kHz
Industry-leading, click-and-pop suppression eliminates
audible transients during power and shutdown cycles.
Other features include single-supply voltage, a shut-
down mode, logic-selectable gain, thermal-overload,
and output short-circuit protection.
♦ Short-Circuit and Thermal Protection
♦ Selectable-Gain Settings
♦ Space-Saving 28-Pin TQFN (5mm x 5mm x 0.8mm)
The MAX9787 is offered in a space-saving, thermally
efficient, 28-pin, thin QFN (5mm x 5mm x 0.8mm) pack-
age, and is specified over the extended -40°C to +85°C
temperature range.
Applications
Ordering Information
Portable DVD Players
Notebook PCs
Flat-Panel TVs
Tablet PCs
PART
PIN-PACKAGE
PKG CODE
LCD Projectors
MAX9787ETI+
28 TQFN-EP*
T2855N-1
Multimedia Monitors
Note: This device is specified for -40°C to +85°C operation.
+Denotes lead-free package.
*EP = Exposed paddle.
PC Displays
Typical Operating Circuit
Pin Configuration
TOP VIEW
+5V
21 20
19 18
17 16
15
SHDN 22
GAIN2 23
GAIN1 24
14 N.C.
13 N.C.
Σ
12
V
SS
MAX9787
V
25
11 CPV
10 C1N
DD
SS
Σ
GND 26
INR 27
VOL 28
9
8
CPGND
C1P
BEEP
*EP
MAX9787
VOLUME
+
1
2
3
4
5
6
7
THIN QFN
*EXPOSED PAD.
________________________________________________________________ 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.
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V , PV , CPV to GND) .......................+6V
Continuous Input Current (all other pins) ......................... 20mA
DD
DD
DD
GND to PGND..................................................................... 0.ꢀV
Continuous Power Dissipation (T = +70°C)
A
CPV , C1N, V to GND .........................-6.0V to (GND + 0.ꢀV)
28-Pin Thin QFN (derate 2ꢀ.8mW/°C above +70°C) .......1.9W
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+ꢀ00°C
SS
SS
Any Other Pin .............................................-0.ꢀV to (V
+ 0.ꢀV)
DD
Duration of OUT_ Short Circuit to GND or PV ........Continuous
DD
Duration of OUT_+ Short Circuit to OUT_-.................Continuous
Continuous Current (PV , OUT_, PGND) ...........................1.7A
DD
Continuous Current (CPV , C1N, C1P, CPV
V
)......850mA
DD
SS, SS
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
= PV
= CPV
= 5V, GND = PGND = CPGND = 0V, SHDN = V , C
= 1µF, C1 = C2 = 1µF, speaker load
BIAS
DD
DD
DD
DD
terminated between OUT_+ and OUT_-, GAIN1 = GAIN2 = VOL = 0V, T = T
to T
, unless otherwise noted. Typical values are
A
MIN
MAX
at T = +25°C.) (Note 1)
A
PARAMETER
GENERAL
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Bias Voltage
V
, PV
Inferred from PSRR test
4.5
5.5
29
5
V
mA
µA
V
DD
DD
I
14
0.2
1.8
10
DD
I
SHDN = GND
SHDN
V
1.7
10
1.9
BIAS
Switching Time
t
Gain or input switching
Amplifier inputs (Note 2)
µs
kΩ
ms
SW
Input Resistance
R
20
ꢀ0
6
IN
Turn-On Time
t
25
SON
Measured between OUT_+ and OUT_-,
= +25°C
Output Offset Voltage
V
0.4
mV
OS
T
A
PV
or V
= 4.5V to 5.5V (T = +25°C)
75
90
80
DD
DD
A
Power-Supply Rejection Ratio
(Note ꢀ)
PSRR
f = 1kHz, V
= 200mV
RIPPLE P-P
dB
f = 10kHz, V
= 200mV
55
RIPPLE
P-P
R = 8Ω
0.65
1.2
0.8
1.5
2.2
0.01
0.02
L
THD+N = 1%,
f = 1kHz,
Output Power (Note 4)
P
W
%
R = 4Ω
L
OUT
T
A
= +25°C
R = ꢀΩ
L
R = 8Ω, P
= 500mW, f = 1kHz
= 1W, f = 1kHz
L
OUT
Total Harmonic Distortion Plus
Noise
THD+N
R = 4Ω, P
L
OUT
2
_______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
ELECTRICAL CHARACTERISTICS (continued)
(V
= PV
= CPV
= 5V, GND = PGND = CPGND = 0V, SHDN = V , C
= 1µF, C1 = C2 = 1µF, speaker load
BIAS
DD
DD
DD
DD
terminated between OUT_+ and OUT_-, GAIN1 = GAIN2 = VOL = 0V, T = T
to T
, unless otherwise noted. Typical values are
A
MIN
MAX
at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
= 500mW, BW = 22Hz to
OUT
MIN
TYP
MAX
UNITS
R = 8Ω, P
22kHz
L
Signal-to-Noise Ratio
SNR
90
dB
Noise
V
BW = 22Hz to 22kHz, A-weighted
No sustained oscillations
80
200
75
µV
RMS
n
Capacitive-Load Drive
Crosstalk
C
pF
dB
L
L to R, R to L, f = 10kHz
Slew Rate
SR
1.4
6
V/µs
GAIN1 = 0, GAIN2 = 0
GAIN1 = 1, GAIN2 = 0
GAIN1 = 0, GAIN2 = 1
GAIN1 = 1, GAIN2 = 1
7.5
9
Gain (Maximum Volume Setting)
A
dB
VMAX(SPKR)
10.5
CHARGE PUMP
Charge-Pump Frequency
VOLUME CONTROL
VOL Input Impedance
VOL Input Hysteresis
Full-Mute Input Voltage
Channel Matching
f
500
550
600
kHz
OSC
R
100
10
MΩ
mV
V
VOL
(Note 5)
4.29
0.2
A = -25dB to +1ꢀ.5dB
V
dB
BEEP INPUT
Beep Signal Minimum Amplitude
Beep Signal Minimum Frequency
V
R
B
= ꢀꢀkΩ (Note 6)
0.ꢀ
V
P-P
BEEP
f
ꢀ00
Hz
BEEP
LOGIC INPUT (SHDN, GAIN1, GAIN2, VOL)
Logic Input High Voltage
Logic Input Low Voltage
Logic Input Current
V
2
V
V
IH
V
0.8
1
IL
I
µA
IN
Note 1: All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.
Note 2: Guaranteed by design. Not production tested.
Note 3: PSRR is specified with the amplifier input connected to GND through C
.
IN
Note 4: Output power levels are measured with the thin QFN’s exposed paddle soldered to the ground plane.
Note 5: See Table ꢀ for details of the mute levels.
Note 6: The value of R dictates the minimum beep signal amplitude (see the BEEP Input section).
B
_______________________________________________________________________________________
3
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Typical Operating Characteristics
(Measurement BW = 22Hz to 22kHz, T = +25°C, unless otherwise noted.)
A
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
10
1
10
1
10
1
V
= 5V
V
= 5V
V
= 5V
CC
CC
CC
R = 3Ω
R = 4Ω
R = 8Ω
L
L
L
A
V
= 10.5dB
A
= 10.5dB
A = 10.5dB
V
V
OUTPUT POWER = 1.5W
OUTPUT POWER = 1.25W
OUTPUT POWER = 500mW
OUTPUT POWER = 100mW
0.1
0.01
0.1
0.01
0.1
0.01
OUTPUT POWER = 500mW
OUTPUT POWER = 600mW
0.001
0.001
0.001
0.0001
0.0001
0.0001
10
100
1k
10k
100k
10
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
100
10
1
100
10
1
100
10
1
V
= 5V
V
= 5V
CC
L
CC
L
V
V
= 5V
CC
L
V
R = 4Ω
A
R = 8Ω
A = 10.5dB
V
R = 3Ω
A
= 10.5dB
= 10.5dB
f
= 10kHz
f
= 10kHz
IN
IN
f
= 10kHz
0.1
0.1
0.1
IN
0.01
0.01
0.01
f
= 1kHz
2.0
f
= 1kHz
IN
IN
f
= 20Hz
f
= 1kHz
0.8
f
= 20Hz
IN
IN
IN
f
= 20Hz
IN
0.001
0.001
0.001
0
0.5
1.0
1.5
2.5
3.0
0
2.0
0
1.2
0.5
1.0
OUTPUT POWER (W)
1.5
0.2
0.4
0.6
1.0
OUTPUT POWER (W)
OUTPUT POWER (W)
POWER DISSIPATION vs. OUTPUT POWER
OUTPUT POWER
vs. LOAD RESISTANCE
5
4
3
2
1
0
3.0
2.5
2.0
1.5
1.0
0.5
0
V
= 5V
V
= 5V
DD
CC
f = 1kHz
= P
f = 1kHz
= 10.5dB
P
+ P
OUTR
A
OUT
OUTL
V
R = 4Ω
L
THD+N = 10%
THD+N = 1%
R = 8Ω
L
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
OUTPUT POWER (W)
1
10
LOAD RESISTANCE (Ω)
100
4
_______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Typical Operating Characteristics (continued)
(Measurement BW = 22Hz to 22kHz, T = +25°C, unless otherwise noted.)
A
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
CROSSTALK vs. FREQUENCY
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0
V
A
= 200mV
P-P
= 10.5dB
V
V
= 5V
RIPPLE
V
CC
-10
-20
-30
-40
-50
-60
-70
-80
= 200mV
RIPPLE
P-P
OUTPUT REFERRED
R = 4Ω
L
LEFT TO RIGHT
-90
-100
-110
-120
RIGHT TO LEFT
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
TURN-ON RESPONSE
TURN-OFF RESPONSE
MAX9787 toc11
MAX9787 toc12
5V/div
5V/div
SHDN
SHDN
OUT_+
AND
OUT_+
AND
2V/div
2V/div
OUT_-
OUT_-
OUT_+
- OUT_-
OUT_+
- OUT_-
100mV/div
20mV/div
R
= 8Ω
R
= 8Ω
L
L
20ms/div
20ms/div
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
18
16
14
12
10
8
6
4
2
0
4.50
4.75
5.00
5.25
5.50
4.50
4.75
5.00
5.25
5.50
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Pin Description
PIN
NAME
FUNCTION
1
2
INL
Left-Channel Audio Input
BEEP
Audible Alert Beep Input
ꢀ, 19
4
PGND
OUTL+
OUTL-
Power Ground
Left-Channel Positive Speaker Output
Left-Channel Negative Speaker Output
Speaker Amplifier Power Supply
Charge-Pump Power Supply
5
6, 15, 16
7
PV
DD
CPV
DD
8
C1P
Charge-Pump Flying-Capacitor Positive Terminal
Charge-Pump Ground
9
CPGND
C1N
10
Charge-Pump Flying-Capacitor Negative Terminal
11
CPV
Charge-Pump Output. Connect to V
.
SS
SS
12
V
SS
Amplifier Negative Power Supply
1ꢀ, 14
17
N.C.
OUTR-
OUTR+
GND
No Connection. Not internally connected.
Right-Channel Negative Speaker Output
Right-Channel Positive Speaker Output
Ground
18
20, 26
21
BIAS
Common-Mode Bias Voltage. Bypass with a 1µF capacitor to GND.
22
SHDN
GAIN2
GAIN1
Shutdown. Drive SHDN low to disable the device. Connect SHDN to V
Gain Control Input 2
for normal operation.
DD
2ꢀ
24
Gain Control Input 1
25
V
Power Supply
DD
27
INR
VOL
EP
Right-Channel Audio Input
28
Analog Volume Control Input
Exposed Pad. Connect to GND.
EP
6
_______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
required, additional high-frequency ripple attenuation
Detailed Description
can be achieved by increasing the size of C2 (see the
The MAX9787 combines a 2.2W bridge-tied load (BTL)
speaker amplifier and an analog volume control, BEEP
input, and four-level gain control. The MAX9787 features
high 90dB, low 0.01% THD+N, industry-leading click-
pop performance, and a low-power shutdown mode.
Typical Operating Circuit).
BIAS
The MAX9787 features an internally generated, power-
supply independent, common-mode bias voltage of 1.8V
referenced to GND. BIAS provides both click-and-pop
suppression and sets the DC bias level for the amplifiers.
Choose the value of the bypass capacitor as described
in the BIAS Capacitor section. No external load should
be applied to BIAS. Any load lowers the BIAS voltage,
affecting the overall performance of the device.
Each signal path consists of an input amplifier that sets
the gain of the signal path, and feeds the speaker
amplifier (Figure 1). The speaker amplifier uses a BTL
architecture, doubling the voltage drive to the speakers
and eliminating the need for DC-blocking capacitors.
The output consists of two signals, identical in magni-
tude, but 180o out of phase.
Gain Selection
The GAIN1 and GAIN2 inputs set the maximum gain of
the speaker and amplifiers (Table 1). The gain of the
device can vary based upon the voltage at VOL (see
the Analog Volume Control section). However, the max-
imum gain cannot be exceeded.
An analog volume control varies the gain of the ampli-
fiers based on the DC voltage applied at VOL. An under-
voltage lockout prevents operation from an insufficient
power supply. Click-and-pop suppression eliminates
audible transients on startup and shutdown. The ampli-
fiers include thermal-overload and short-circuit protec-
tion. An additional feature of the speaker amplifiers is
that there is no phase inversion from input to output.
Analog Volume Control (VOL)
An analog volume control varies the gain of the device
in ꢀ1 discrete steps based upon the DC voltage
Charge Pump
The MAX9787 features a low-noise charge pump. The
550kHz switching frequency is well beyond the audio
range, and does not interfere with the audio signals.
The switch drivers feature a controlled switching speed
that minimizes noise generated by turn-on and turn-off
transients. Limiting the switching speed of the charge
pump minimizes the di/dt noise caused by the parasitic
bond wire and trace inductance. Although not typically
applied to VOL. The input range of V
is from 0 (full
VOL
volume) to 0.858 x PV
(full mute), with example step
DD
sizes shown in Table 2. Connect the reference of the
device driving VOL (Figure 2) to PV . Since the vol-
DD
ume control ADC is ratiometric to PV , any changes in
DD
Table 1. Gain Settings
SPEAKER MODE
GAIN2
GAIN1
GAIN (dB)
0
0
1
1
0
1
0
1
6
7.5
9
IN_
10.5
OUT_+
BIAS
BIAS
MAX9787
PV
DD
VOLUME
OUT_
V
REF
VOL
CONTROL
DAC
VOL
BIAS
Figure 1. MAX9787 Signal Path
Figure 2. Volume Control Circuit
_______________________________________________________________________________________
7
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Table 2. Volume Levels
V
(V)
SPEAKER MODE GAIN (dB)
VOL
GAIN1 = 0,
GAIN2 = 0
GAIN1 = 1,
GAIN2 = 0
GAIN1 = 0,
GAIN2 = 1
GAIN1 = 1,
GAIN2 = 1
V
*
V
*
V
*
MIN
TYP
MAX
0
0.ꢀ70
0.800
0.915
1.0ꢀ5
1.150
1.265
1.ꢀ85
1.500
1.620
1.7ꢀ5
1.855
1.970
2.090
2.205
2.ꢀ20
2.440
2.555
2.675
2.790
2.910
ꢀ.025
ꢀ.140
ꢀ.260
ꢀ.ꢀ75
ꢀ.495
ꢀ.610
ꢀ.7ꢀ0
ꢀ.845
ꢀ.965
4.080
4.195
4.290
0.742
0.860
0.977
1.094
1.211
1.ꢀ28
1.446
1.56ꢀ
1.680
1.797
1.914
2.0ꢀ2
2.149
2.266
2.ꢀ8ꢀ
2.500
2.617
2.7ꢀ5
2.852
2.969
ꢀ.086
ꢀ.20ꢀ
ꢀ.ꢀ21
ꢀ.4ꢀ8
ꢀ.555
ꢀ.672
ꢀ.789
ꢀ.907
4.024
4.141
4.258
5.000
6
5
7.5
7
9
8.5
8
10.5
10
9.5
9
0.742
0.860
0.977
1.094
1.211
1.ꢀ28
1.446
1.56ꢀ
1.680
1.797
1.914
2.0ꢀ2
2.149
2.266
2.ꢀ8ꢀ
2.500
2.617
2.7ꢀ5
2.852
2.969
ꢀ.086
ꢀ.20ꢀ
ꢀ.ꢀ21
ꢀ.4ꢀ8
ꢀ.555
ꢀ.672
ꢀ.789
ꢀ.907
4.024
4.141
4.258
4
6
ꢀ
5
7.5
7
1
4
8.5
8
-1
ꢀ
6
-ꢀ
1
5
7.5
7
-5
-1
4
-7
-ꢀ
ꢀ
6
-9
-5
1
5
-11
-1ꢀ
-15
-17
-19
-21
-2ꢀ
-25
-27
-29
-ꢀ1
-ꢀꢀ
-ꢀ5
-ꢀ7
-41
-45
-48
-5ꢀ
-57
-61
-65
MUTE
-7
-1
4
-9
-ꢀ
ꢀ
-11
-1ꢀ
-15
-17
-19
-21
-2ꢀ
-25
-27
-29
-ꢀ1
-ꢀ
-5
1
-7
-1
-9
-ꢀ
-11
-1ꢀ
-15
-17
-9
-5
-7
-9
-11
-1ꢀ
-15
-17
-19
-21
-2ꢀ
-25
-27
-29
-ꢀ1
-ꢀꢀ
-ꢀ5
MUTE
-21
-2ꢀ
-2
-27
-29
-ꢀ1
-ꢀꢀ
-ꢀ5
-ꢀ7
-41
-45
MUTE
-ꢀ5
-ꢀ7
-41
-45
-49
-5ꢀ
-57
MUTE
*Based on PV = 5V
DD
8
_______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
PV
are negated. The gain step sizes are not con-
roughly the amplitude of V
times the gain of
BEEP(OUT)
DD
stant; the step sizes are 0.5dB/step at the upper
extreme, 2dB/step in the midrange, and 4dB/step at the
lower extreme. Figure ꢀ shows the transfer function of
the volume control for a 5V supply.
the selected signal path.
The input resistor (R ) sets the gain of the BEEP input
B
amplifier, and thus the amplitude of V
.
BEEP(OUT)
Choose R based on:
B
BEEP Input
An audible alert beep input (BEEP) accepts a mono
system alert signal and mixes it into the stereo audio
V
x R
0.ꢀ
IN
INT
R
≤
B
path. When the amplitude of V
exceeds
BEEP(OUT)
where R
is the value of the BEEP amplifier feedback
800mV
(Figure 4) and the frequency of the beep sig-
INT
P-P
resistor (47kΩ) and V is the BEEP input amplitude.
nal is greater than 400Hz, the beep signal is mixed into
the active audio path (speaker or headphone). If the
IN
Note that the BEEP amplifier can be set up as either an
attenuator, if the original alert signal amplitude is too
large, or set to gain up the alert signal if it is below
signal at V
is either < 800mV
or <400Hz,
BEEP(OUT)
P-P
the BEEP signal is not mixed into the audio path. The
amplitude of the BEEP signal at the device output is
800mV . AC-couple the alert signal to BEEP. Choose
P-P
the value of the coupling capacitor as described in the
Input Filtering section. Multiple beep inputs can be
summed (Figure 4).
VOLUME CONTROL
TRANSFER FUNCTION
20
Shutdown
The MAX9787 features a 0.2µA, low-power shutdown
mode that reduces quiescent current consumption and
extends battery life. Driving SHDN low disables the
drive amplifiers, bias circuitry, and charge pump, and
drives BIAS and all outputs to GND. Connect SHDN to
GAIN1 = GAIN2 = 0
10
0
AUDIO
TAPER POT
-10
-20
-30
-40
-50
-60
-70
-80
V
for normal operation.
DD
MAX9787
Click-and-Pop Suppression
The MAX9787 speaker amplifiers feature Maxim’s com-
prehensive, industry-leading click-and-pop suppres-
sion. During startup, the click-and-pop suppression
circuitry eliminates any audible transient sources inter-
nal to the device. When entering shutdown, both ampli-
fier outputs ramp to GND quickly and simultaneously.
0
1
2
3
4
5
V
(V)
VOL
Figure 3. Volume Control Transfer Function
R
S1
0.47µF
0.47µF
0.47µF
47kΩ
R
INT
SOURCE 1
SOURCE 2
SOURCE 3
47kΩ
R
S2
47kΩ
SPEAKER AMPLIFIER
BEEP
V
OUT(BEEP)
WINDOW
INPUTS
R
S3
47kΩ
DETECTOR
(0.3V THRESHOLD)
P-P
MAX9787
FREQUENCY
DETECTOR
BIAS
(300Hz THRESHOLD)
Figure 4. Beep Input
_______________________________________________________________________________________
9
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Power Dissipation and Heat Sinking
Applications Information
Under normal operating conditions, the MAX9787 can dis-
sipate a significant amount of power. The maximum power
dissipation for each package is given in the Absolute
Maximum Ratings under Continuous Power Dissipation, or
can be calculated by the following equation:
BTL Speaker Amplifiers
The MAX9787 features speaker amplifiers designed to
drive a load differentially, a configuration referred to as
bridge-tied load (BTL). The BTL configuration (Figure 5)
offers advantages over the single-ended configuration,
where one side of the load is connected to ground.
Driving the load differentially doubles the output volt-
age compared to a single-ended amplifier under similar
conditions. Thus, the device’s differential gain is twice
the closed-loop gain of the input amplifier. The effective
gain is given by:
T
− T
A
J(MAX)
P
=
DISSPKG(MAX)
θ
JA
where TJ(MAX) is +150°C, TA is the ambient temperature,
o
and θJA is the reciprocal of the derating factor in C/W
as specified in the Absolute Maximum Ratings section.
For example, θJA of the TQFN package is +42oC/W. For
optimum power dissipation, the exposed paddle of the
package should be connected to the ground plane
(see the Layout and Grounding section).
R
F
A
= 2×
VD
R
IN
Substituting 2 X VOUT(P-P) into the following equation
yields four times the output power due to double the
output voltage:
For 8Ω applications, the worst-case power dissipation
occurs when the output power is 1.1W/channel, result-
ing in a power dissipation of about 1W. In this case, the
TQFN packages can be used without violating the max-
imum power dissipation or exceeding the thermal pro-
tection threshold.
V
OUT(P−P)
V
=
=
RMS
2 2
2
V
RMS
Output Power
The increase in power delivered by the BTL configura-
tion directly results in an increase in internal power dis-
sipation over the single-ended configuration.
P
OUT
R
L
Since the differential outputs are biased at midsupply,
there is no net DC voltage across the load. This elimi-
nates the need for DC-blocking capacitors required for
single-ended amplifiers. These capacitors can be large
and expensive, can consume board space, and can
degrade low-frequency performance.
If the power dissipation for a given application exceeds
the maximum allowed for a given package, either
reduce VDD, increase load impedance, decrease the
ambient temperature, or add heatsinking to the device.
Large output, supply, and ground PC board traces
improve the maximum power dissipation in the package.
1000
V
= 5V
DD
R = 16Ω
V
L
100
10
A
= 3dB
V
+1
-1
OUT(P-P)
OUTPUTS IN PHASE
1
2 x V
V
OUT(P-P)
0.1
0.01
0.001
OUT(P-P)
OUTPUTS 180° OUT OF PHASE
0
25
50
75
100
125
150
OUTPUT POWER (mW)
Figure 5. Bridge-Tied Load Configuration
Figure 6. Total Harmonic Distortion Plus Noise vs. Output Power
with Inputs In/Out of Phase
10 ______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Table 3. Suggested Capacitor Manufacturers
SUPPLIER
Taiyo Yuden
TDK
PHONE
FAX
WEBSITE
www.t-yuden.com
www.component.tdk.com
800-ꢀ48-2496
807-80ꢀ-6100
847-925-0899
847-ꢀ90-4405
Thermal-overload protection limits total power dissipa-
tion in these devices. When the junction temperature
exceeds +160°C, the thermal-protection circuitry dis-
ables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by 15°C.
This results in a pulsing output under continuous ther-
mal-overload conditions as the device heats and cools.
BIAS Capacitor
BIAS is the output of the internally generated DC bias
voltage. The BIAS bypass capacitor, CBIAS, improves
PSRR and THD+N by reducing power supply and other
noise sources at the common-mode bias node, and
also generates the clickless/popless, startup/shutdown
DC bias waveforms for the speaker amplifiers. Bypass
BIAS with a 1µF capacitor to GND.
Power Supplies
The MAX9787 speaker amplifiers are powered from
PVDD. PVDD ranges from 4.5V to 5.5V. VSS is the nega-
tive supply of the amplifiers. Connect VSS to CPVSS. The
charge pump is powered by CPVDD. CPVDD should be
the same potential as PVDD. The charge pump inverts
the voltage at CPVDD, and the resulting voltage
appears at CPVSS. The remainder of the device is pow-
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100mΩ for opti-
mum performance. Low-ESR ceramic capacitors mini-
mize the output resistance of the charge pump. For
best performance over the extended temperature
range, select capacitors with an X7R dielectric. Table 4
lists suggested manufacturers.
ered by VDD
.
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump. A
C1 value that is too small degrades the device’s ability
to provide sufficient current drive, which leads to a loss
of output voltage. Increasing the value of C1 improves
load regulation and reduces the charge-pump output
resistance to an extent. See the Output Power vs.
Charge-Pump Capacitance and Load Resistance
graph in the Typical Operating Characteristics. Above
2.2µF, the on-resistance of the switches and the ESR of
C1 and C2 dominate.
Component Selection
Input Filtering
The input capacitor (CIN), in conjunction with the ampli-
fier input resistance (RIN), forms a highpass filter that
removes the DC bias from an incoming signal (see the
Typical Operating Circuit). The AC-coupling capacitor
allows the amplifier to bias the signal to an optimum DC
level. Assuming zero source impedance, the -ꢀdB point
of the highpass filter is given by:
1
f
=
−ꢀdB
2πR C
Output Capacitor (C2)
The output capacitor value and ESR directly affect the
ripple at CPVSS. Increasing the value of C2 reduces
output ripple. Likewise, decreasing the ESR of C2
reduces both ripple and output resistance. Lower
capacitance values can be used in systems with low
maximum output power levels. See the Output Power
vs. Charge-Pump Capacitance and Load Resistance
graph in the Typical Operating Characteristics.
IN IN
RIN is the amplifier’s internal input resistance value
given in the Electrical Characteristics. Choose CIN such
that f
is well below the lowest frequency of interest.
-ꢀdB
Setting f
too high affects the amplifier’s low-fre-
-ꢀdB
quency response. Use capacitors with low-voltage
coefficient dielectrics, such as tantalum or aluminum
electrolytic. Capacitors with high-voltage coefficients,
such as ceramics, may result in increased distortion at
low frequencies.
______________________________________________________________________________________ 11
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
CPVDD Bypass Capacitor
The CPVDD bypass capacitor (Cꢀ) lowers the output
impedance of the power supply and reduces the
impact of the MAX9787’s charge-pump switching tran-
sients. Bypass CPVDD with Cꢀ, the same value as C1,
and place it physically close to the CPVDD and PGND
(refer to the MAX9750 Evaluation Kit for a suggested
layout).
audio signal. Connect CPGND, PGND, and GND
together at a single point on the PC board. Route
CPGND and all traces that carry switching transients
away from GND, PGND, and the traces and compo-
nents in the audio signal path.
Connect all components associated with the charge
pump (C2 and Cꢀ) to the CPGND plane. Connect VSS
and CPVSS together at the device. Place the charge-
pump capacitors (C1, C2, and Cꢀ) as close to the
device as possible. Bypass PVDD with a 0.1µF capaci-
tor to GND. Place the bypass capacitors as close to the
device as possible.
Powering Other Circuits
from a Negative Supply
An additional benefit of the MAX9787 is the internally
generated negative supply voltage (CPVSS). CPVSS pro-
vides the negative supply for the amplifiers. It can also
be used to power other devices within a design.
Current draw from CPVSS should be limited to 5mA;
exceeding this affects the operation of the amplifier. A
typical application is a negative supply to adjust the
contrast of LCD modules.
Use large, low-resistance output traces. As load imped-
ance decreases, the current drawn from the device out-
puts increase. At higher current, the resistance of the
output traces decrease the power delivered to the load.
For example, when compared to a 0Ω trace, a 100mΩ
trace reduces the power delivered to a 4Ω load from
2.1W to 2W. Large output, supply, and GND traces also
improve the power dissipation of the device.
When considering the use of CPVSS in this manner,
note that the charge-pump voltage of CPVSS is roughly
proportional to PVDD and is not a regulated voltage. The
charge-pump output impedance plot appears in the
Typical Operating Characteristics.
The MAX9787 thin QFN features and exposed thermal
pad on its underside. This pad lowers the package’s
thermal resistance by providing a direct heat conduc-
tion path from the die to the PC board. Connect the
exposed thermal pad to GND by using a large pad and
multiple vias to the GND plane.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Use large traces for the power-supply
inputs and amplifier outputs to minimize losses due to
parasitic trace resistance, as well as route head away
from the device. Good grounding improves audio per-
formance, minimizes crosstalk between channels, and
prevents any switching noise from coupling into the
Chip Information
TRANSISTOR COUNT: 9591
PROCESS: BiCMOS
12 ______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Block Diagram
4.5V TO 5.5V
0.1µF
V
DD
25
6, 15, 16
PV
DD
4.5V TO 5.5V
0.1µF
MAX9787
C
1µF
IN
4
5
OUTL+
OUTL-
GAIN/
VOLUME
CONTROL
INL
1
BTL
AMPLIFIER
LEFT-CHANNEL
AUDIO INPUT
C
1µF
IN
18
OUTR+
GAIN/
VOLUME
CONTROL
INR
27
21
BTL
AMPLIFIER
RIGHT-CHANNEL
AUDIO INPUT
17 OUTR-
BIAS
C
BIAS
1µF
VOL 28
24
GAIN/
VOLUME
CONTROL
GAIN1
V
V
DD
HEADPHONE
DETECTION
GAIN2 23
DD
1µF
47kΩ
BEEP
DETECTION
BEEP
2
SHUTDOWN
CONTROL
SHDN
22
V
DD
CPV
DD
7
3V TO 5.5V
1µF
C1P
8
C1
CHARGE
PUMP
1µF
10
C1N
9
CPGND
3, 19
11
CPV
12
20, 26
GND
V
PGND
SS
SS
C2
1µF
______________________________________________________________________________________ 13
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
D2
D
b
0.10 M
C A B
C
L
D2/2
D/2
k
L
MARKING
AAAAA
E/2
E2/2
C
(NE-1) X
e
L
E2
E
PIN # 1 I.D.
0.35x45°
DETAIL A
e/2
PIN # 1
I.D.
e
(ND-1) X
e
DETAIL B
e
L
C
L
C
L
L1
L
L
e
e
0.10
C
A
0.08
C
C
A3
A1
PACKAGE OUTLINE,
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
1
-DRAWING NOT TO SCALE-
I
21-0140
2
14 ______________________________________________________________________________________
2.2W Stereo Audio Power Amplifier
with Analog Volume Control
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
COMMON DIMENSIONS
EXPOSED PAD VARIATIONS
PKG.
16L 5x5
20L 5x5
28L 5x5
32L 5x5
40L 5x5
L
DOWN
BONDS
ALLOWED
D2
E2
exceptions
PKG.
SYMBOL MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX.
CODES
±0.15
MIN. NOM. MAX. MIN. NOM. MAX.
3.00 3.10 3.20 3.00 3.10 3.20
3.00 3.10 3.20 3.00 3.10 3.20
A
0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80
0.02 0.05 0.02 0.05 0.02 0.05 0.02 0.05 0.02 0.05
0.20 REF. 0.20 REF. 0.20 REF. 0.20 REF. 0.20 REF.
T1655-2
T1655-3
YES
NO
NO
**
**
**
**
A1
0
0
0
0
0
A3
b
T1655N-1 3.00 3.10 3.20 3.00 3.10 3.20
0.25 0.30 0.35 0.25 0.30 0.35 0.20 0.25 0.30 0.20 0.25 0.30 0.15 0.20 0.25
4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10
4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10
T2055-3
T2055-4
3.00 3.10 3.20 3.00 3.10 3.20
3.00 3.10 3.20 3.00 3.10 3.20
YES
NO
D
E
**
YES
T2055-5
T2855-3
T2855-4
T2855-5
3.15 3.25 3.35 3.15 3.25 3.35 0.40
e
0.80 BSC.
0.25
0.65 BSC.
0.25
0.50 BSC.
0.25
0.50 BSC.
0.25
0.40 BSC.
3.15 3.25 3.35 3.15 3.25 3.35
2.60 2.70 2.80 2.60 2.70 2.80
2.60 2.70 2.80 2.60 2.70 2.80
3.15 3.25 3.35 3.15 3.25 3.35
YES
YES
NO
**
**
**
k
L
-
-
-
-
-
-
-
-
0.25 0.35 0.45
0.30 0.40 0.50 0.45 0.55 0.65 0.45 0.55 0.65 0.30 0.40 0.50 0.40 0.50 0.60
L1
-
-
-
-
-
-
-
-
-
-
-
-
0.30 0.40 0.50
NO
YES
YES
T2855-6
T2855-7
**
**
N
ND
NE
16
4
4
20
5
5
28
7
7
32
8
8
40
10
10
2.80
2.60 2.70
2.60 2.70 2.80
T2855-8
3.15 3.25 3.35 3.15 3.25 3.35 0.40
WHHB
WHHC
WHHD-1
WHHD-2
-----
JEDEC
T2855N-1 3.15 3.25 3.35 3.15 3.25 3.35
NO
YES
NO
YES
NO
**
**
**
**
**
**
3.20
3.00 3.10 .20
T3255-3
T3255-4
T3255-5
3.00 3.10
3.00 3.10 3.20 3.00 3.10 .20
3.20
NOTES:
3.00 3.10
3.00 3.10 3.20
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
T3255N-1 3.00 3.10 3.20 3.00 3.10 3.20
T4055-1 3.20 3.30 3.40 3.20 3.30 3.40
YES
**SEE COMMON DIMENSIONS TABLE
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL
CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE
OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1
IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN
0.25 mm AND 0.30 mm FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT EXPOSED PAD DIMENSION FOR
T2855-3 AND T2855-6.
10. WARPAGE SHALL NOT EXCEED 0.10 mm.
11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY.
12. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY.
13. LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION "e", ±0.05.
PACKAGE OUTLINE,
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
2
-DRAWING NOT TO SCALE-
21-0140
I
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
Heaney
相关型号：
MAX9787ETI+
Audio Amplifier, 2 Channel(s), BICMOS, 5 X 5 MM, 0.80 MM HEIGHT, LEAD FREE, MO-220WHHD-1, TQFN-28
MAXIM
MAX9788ETI+C6F
Audio Amplifier, 2.4W, 1 Channel(s), 1 Func, BICMOS, 4 X 4 MM, 0.80 MM HEIGHT, ROHS COMPLIANT, TQFN-28
MAXIM
©2020 ICPDF网 联系我们和版权申明