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MAX97200BEWC+T [MAXIM]

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MAX97200BEWC+T
型号： MAX97200BEWC+T
厂家： MAXIM INTEGRATED PRODUCTS    MAXIM INTEGRATED PRODUCTS
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19-4981; Rev 2; 3/11  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
General Description  
The MAX97200 is a 45mW Class H headphone amplifier  
that runs from a single low 1.8V supply voltage and employs  
Maxim’s second-generation DirectDrivetechnology.  
Features  
S Second-Generation DirectDrive Technology  
S Dynamic, Class H, Dual Mode Charge Pump  
S Low Voltage Operation, V = 1.8V  
PVIN  
The MAX97200 features a Dual ModeK internal charge  
pump to generate the power rails for the amplifier. The  
charge-pump output can be QPVIN/2 or QPVIN depend-  
ing on the amplitude of the output signal. When the out-  
put voltage is low, the power-supply voltage is QPVIN/2.  
When the output signal demands larger output voltage,  
the charge pump switches modes so that a greater  
power-supply voltage is realized and more output power  
can be delivered to the load.  
S Low Quiescent Current, 1.15mA (typ) at V  
=
PVIN  
1.8V  
S Eliminates Large Output DC-Blocking Capacitors  
S Industry-Leading Click-and-Pop Performance  
S High-Fidelity, SNR 105dB (5.6µV Output Noise)  
S Output Power 34mW into 32I (THD+N 1%)  
S Output Power 45mW into 16I (THD+N 10%)  
S Tiny, 12-Bump, 1.27mm x 1.65mm (0.4mm Lead  
Second-generation DirectDrive technology improves  
power consumption when compared to first-generation  
DirectDrive amplifiers. The MAX97200 can be powered  
from a regulated 1.8V and have similar power consump-  
tion to a traditional DirectDrive amplifier that is powered  
from 0.9V.  
Pitch) WLP Package  
Ordering Information/  
Selector Guide  
GAIN  
(dB)  
PIN-  
PACKAGE  
TOP  
MARK  
PART  
Maxim’s DirectDrive architecture uses an inverting  
charge pump to derive a negative voltage supply. The  
headphone amplifier is powered between the positive  
supply and the generated negative rail. This scheme  
allows the audio output signal to be biased about  
ground, eliminating the need for large DC-blocking  
capacitors between the amplifier output and the head-  
phone load.  
MAX97200AEWC+  
MAX97200BEWC+  
3
0
12 WLP  
12 WLP  
ABF  
ABG  
Note: All devices operate over the -40°C to +85°C tempera-  
ture range.  
+Denotes a lead(Pb)-free and RoHS-compliant package.  
Low-output offset voltage provides very good click-and-  
pop performance both into and out of shutdown. High  
signal-to-noise ratio maintains system fidelity.  
Typical Operating Circuit  
The MAX97200 is available in a tiny, 12-bump wafer  
level packaging (WLP 1.27mm x 1.65mm) with a small,  
0.4mm lead pitch and specified over the -40NC to +85NC  
extended temperature range.  
MAX97200  
LEFT AUDIO  
INPUT  
LEFT AUDIO OUTPUT  
Applications  
APPLICATIONS  
PROCESSOR  
SHDN  
Cellular Phones  
Smartphones  
MP3 Players  
VoIP Phones  
RIGHT AUDIO  
INPUT  
RIGHT AUDIO  
OUTPUT  
CHARGE  
PUMP  
DirectDrive is a registered trademark of Maxim Integrated  
Products, Inc.  
Dual Mode is a trademark of Maxim Integrated Products, Inc.  
_______________________________________________________________ Maxim Integrated Products  
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,  
or visit Maxim’s website at www.maxim-ic.com.  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
ABSOLUTE MAXIMUM RATINGS  
PVIN or PVDD to PGND .......................................-0.3V to +2.2V  
GND to PGND ......................................................-0.3V to +0.3V  
PVSS to PGND .....................................................-2.2V to +0.3V  
OUT_ and IN_ to GND ............. (PVSS - 0.2V) to (PVDD + 0.2V)  
C1P, C1N ...................................................Cap connection only  
SHDN to GND .........................................................-0.3V to +4V  
Output Short-Circuit Current .....................................Continuous  
Thermal Limits (Note 1)  
Continuous Power Dissipation (T = +70NC)  
A
12-Bump WLP (derate 13.7mW/NC above +70NC)....1095mW  
Junction Temperature .................................................+150NC  
Operating Temperature Range.......................... -40NC to +85NC  
Storage Temperature Range............................ -65NC to +150NC  
Soldering Temperature (reflow) ......................................+260NC  
Multiple Layer PCB  
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-  
tion 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.  
PACKAGE THERMAL CHARACTERISTICS (Note 1)  
Junction-to-Ambient Thermal Resistance (B )..............73NC/W  
JA  
Junction-to-Case Thermal Resistance (B ) ..................30NC/W  
CA  
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-  
layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.  
ELECTRICAL CHARACTERISTICS  
(V  
PVIN  
= 1.8V, V  
= V  
= 0V, V  
= 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, T = T  
to T , unless otherwise noted.  
MAX  
PGND  
GND  
SHDN  
A
MIN  
Typical values are at T = +25NC.) (Note 2)  
A
PARAMETER  
SYMBOL  
CONDITIONS  
Guaranteed by PSRR  
MIN  
TYP  
MAX  
UNITS  
POWER SUPPLY  
Supply Voltage Range  
UVLO Rising  
PVIN  
1.62  
1.36  
1.80  
1.48  
1.46  
1.15  
1.16  
0.2  
1.98  
1.58  
V
V
V
UVLO Falling  
Inputs grounded, T = +25NC, no load  
1.7  
A
Quiescent Supply Current  
I
mA  
DD  
16Iload, inputs grounded, T = +25NC  
A
Shutdown Current  
Turn-On Time  
FA  
I
V
= 0V, T = +25NC  
SHDN A  
SHDN  
t
0.6  
1
ms  
ON  
CHARGE PUMP  
Oscillator Frequency  
f
f
V
V
= 0V, T = +25NC  
78  
83  
88  
kHz  
kHz  
OSC1  
OSC2  
OUT  
OUT  
A
Oscillator Frequency  
Oscillator Frequency  
= 0.2V, R = J, f = 1kHz  
665  
L
IN  
f
V
V
= 0.5V, R = J, f = 1kHz  
500  
kHz  
V
OSC3  
OUT  
OUT  
L
IN  
= 0.2V, R = J  
PVIN/2  
L
Positive Output Voltage  
Negative Output Voltage  
V
PVDD  
V
V
V
= 0.5V, R = J  
PVIN  
-PVIN/2  
-PVIN  
OUT  
OUT  
OUT  
L
= 0.2V, R = J  
L
V
V
PVSS  
= 0.5V, R = J  
L
R = J, output voltage at which the  
L
QPVIN  
x
0.08  
charge pump switches modes, V  
OUT  
Output Voltage Threshold  
V
TH1  
V
rising, transition from 1/8 to normal  
frequency  
2
______________________________________________________________________________________  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
ELECTRICAL CHARACTERISTICS (continued)  
(V  
PVIN  
= 1.8V, V  
= V  
= 0V, V  
= 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, T = T  
to T , unless otherwise noted.  
MAX  
PGND  
GND  
SHDN  
A
MIN  
Typical values are at T = +25NC) (Note 2)  
A
PARAMETER  
SYMBOL  
CONDITIONS  
R = J, output voltage at which the  
MIN  
TYP  
MAX  
UNITS  
L
QPVIN  
x
0.24  
charge pump switches modes, V  
OUT  
Output Voltage Threshold  
V
TH2  
V
rising, transition from high-efficiency  
mode to high-power mode  
Time it takes for the charge pump to  
transition from high-power mode to  
t
32  
20  
ms  
HOLD  
high-efficiency mode; R = J  
L
Charge-Pump Mode Transition  
Timeouts (Figure 2)  
Time it takes for the charge pump to  
transition from high-efficiency mode to high-  
t
Fs  
RISE  
power mode (90% of its value); R = J  
L
AMPLIFIER  
MAX97200A  
MAX97200B  
2.75  
2.92  
0
3.09  
Voltage Gain  
A
dB  
V
-0.17  
+0.17  
R = 10kI, THD+N = 1%  
1.295  
1.44  
L
Maximum Output Voltage  
V
PK  
R = 10kI, THD+N = 10%  
L
Channel-to-Channel Gain  
Matching  
Q0.1  
dB  
mV  
kI  
Total Output Offset Voltage  
V
T
= +25NC  
A
Q0.1  
10  
Q0.3  
14  
OS  
MAX97200A  
MAX97200B  
6
Input Resistance  
R
IN  
7.2  
62  
12  
16.8  
V
= 1.62V to 1.98V, T = +25NC  
83  
PVDD  
A
f
f
f
= 217Hz  
= 1kHz  
96  
IN  
IN  
IN  
Power-Supply Rejection Ratio  
PSRR  
dB  
100mV  
ripple  
94  
P-P  
= 20kHz  
61  
R = 10kI  
0.16  
34  
L
Output Power  
P
THD+N = 1%  
R = 10kI  
R = 32I  
L
mW  
OUT  
R = 16I  
L
45  
Line Output Voltage  
V
1
V
RMS  
LINE  
L
R = 16I, P  
= 0.1mW, f = 1kHz (Note 3)  
0.02  
0.003  
0.008  
5.6  
105  
L
OUT  
IN  
Total Harmonic Distortion Plus  
Noise  
THD+N  
R = 16I, P  
L
= 10mW, f = 1kHz (Note 4)  
OUT IN  
%
R = 10kI, V  
L
= 1V, f = 1kHz (Note 4)  
IN  
OUT  
Output Noise  
V
N
Inputs grounded, A-weighted, MAX97200B  
A-weighted, MAX97200B  
FV  
Signal-to-Noise Ratio  
SNR  
dB  
R = 32I, peak  
L
Into shutdown  
80  
68  
voltage, A-weighted,  
32 samples/second,  
MAX97200B  
Click-and-Pop Level  
V
CP  
dBV  
Out of shutdown  
Crosstalk  
X
TALK  
R = 16I, 1kHz, P = 5mW  
L OUT  
94  
dB  
pF  
Maximum Capacitive Load  
200  
_______________________________________________________________________________________  
3
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
ELECTRICAL CHARACTERISTICS (continued)  
(V  
PVIN  
= 1.8V, V  
= V  
= 0V, V  
= 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, T = T  
to T , unless otherwise noted.  
MAX  
PGND  
GND  
SHDN  
A
MIN  
Typical values are at T = +25NC) (Note 2)  
A
PARAMETER  
SYMBOL  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
DIGITAL INPUT (SHDN)  
Input High Voltage  
Input Low Voltage  
V
1.4  
V
V
IH  
V
0.4  
+1  
+1  
+1  
IL  
-1  
-1  
-1  
V
V
V
= 4V, T = +25NC  
A
SHDN  
SHDN  
SHDN  
I
IH  
Input Leakage Current  
FA  
= 1.8V, T = +25NC  
A
I
IL  
= 0V, T = +25NC  
A
Note 2: All specifications are 100% tested at T = +25NC. Temperature limits are guaranteed by design.  
A
Note 3: V  
Note 4: V  
= 0.9V, V  
= 1.8V, V  
= -0.9V.  
= -1.8V.  
PVDD  
PVDD  
PVSS  
PVSS  
Typical Operating Characteristics  
(V  
PVIN  
= 1.8V, V  
= V  
= 0V, V  
= 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, both channels driven in phase, T = +25NC,  
PGND  
GND  
SHDN A  
unless otherwise noted.)  
THD+N vs. OUTPUT POWER  
THD+N vs. OUTPUT POWER  
THD+N vs. OUTPUT VOLTAGE  
100  
10  
100  
10  
100  
10  
R = 16I  
L
R = 32I  
L
R = 10kI  
L
1
1
1
0.1  
0.1  
0.1  
f
= 100Hz  
f = 100Hz  
IN  
IN  
f
= 100Hz  
f = 1kHz  
IN  
IN  
f
IN  
= 1kHz  
0.01  
0.001  
0.01  
0.001  
0.01  
0.001  
f
= 1kHz  
= 6kHz  
IN  
f
= 6kHz  
40  
IN  
f
= 6kHz  
f
IN  
IN  
0
10 20 30 40 50 60 70 80  
(mW)  
0
10  
20  
30  
(mW)  
50  
60  
0
0.5  
1.0  
1.5  
2.0  
2.5  
P
OUT  
P
V
(V  
)
OUT  
OUT RMS  
THD+N vs. FREQUENCY  
THD+N vs. FREQUENCY  
THD+N vs. FREQUENCY  
10  
1
10  
1
10  
1
R = 16I  
L
R = 32I  
L
R = 10kI  
L
0.1  
0.1  
0.1  
V
= 0.868V  
RMS  
OUT  
P
= 20mW  
OUT  
P
= 20mW  
OUT  
0.1  
V
OUT  
= 1.12V  
RMS  
P
OUT  
= 25mW  
0.01  
0.001  
0.01  
0.001  
0.01  
0.001  
P
= 2mW  
P
1
= 25mW  
10  
OUT  
OUT  
P
= 2mW  
0.1  
V
= 0.316V  
0.1  
OUT  
OUT  
RMS  
0.01  
1
FREQUENCY (kHz)  
10  
100  
0.01  
100  
0.01  
1
FREQUENCY (kHz)  
10  
100  
FREQUENCY (kHz)  
4
______________________________________________________________________________________  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Typical Operating Characteristics (continued)  
(V  
PVIN  
= 1.8V, V  
= V  
= 0V, V  
= 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, both channels driven in phase, T = +25NC,  
SHDN A  
PGND  
GND  
unless otherwise noted.)  
OUTPUT POWER  
vs. LOAD RESISTANCE  
POWER CONSUMPTION  
vs. OUTPUT POWER  
OUTPUT POWER vs. LOAD RESISTANCE  
AND CHARGE-PUMP CAPACITOR  
80  
70  
60  
50  
40  
30  
20  
10  
0
80  
70  
60  
50  
40  
30  
20  
10  
0
160  
140  
120  
100  
80  
10% THD + N  
C = C = C = 1µF  
1
2
3
C = C = C = .47µF  
1
2
3
C = C = C = 2.2µF  
1
2
3
60  
1% THD + N  
40  
20  
0
1
10  
100  
1000  
10,000  
10  
100  
1000  
10,000  
1
10  
100  
LOAD RESISTANCE (I)  
LOAD RESISTANCE (I)  
OUTPUT POWER (mW)  
POWER DISSIPATION  
vs. OUTPUT POWER  
SUPPLY CURRENT  
vs. SUPPLY VOLTAGE  
SHUTDOWN SUPPLY CURRENT  
vs. SUPPLY VOLTAGE  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
1.20  
1.15  
1.10  
1.05  
1.00  
0.95  
0.90  
0.85  
0.80  
0.20  
0.18  
0.16  
0.14  
0.12  
0.1  
RL = J  
RL = J  
R = 16I  
L
R = 32I  
L
0.08  
0.06  
0.04  
0.02  
0
1
10  
OUTPUT POWER (mW)  
100  
1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00  
SUPPLY VOLTAGE (V)  
1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00  
SUPPLY VOLTAGE (V)  
POWER-SUPPLY REJECTION RATIO  
vs. FREQUENCY  
CROSSTALK vs. FREQUENCY  
5mW 16I  
IN-BAND OUTPUT SPECTRUM  
0
-20  
0
-20  
0
-10  
V
= 200mV  
P-P  
RIPPLE  
OUTPUT POWER = 5mW  
R = 16I  
L
f = 1kHz  
-20  
-30  
-40  
-40  
-40  
-60  
-50  
-60  
-60  
-80  
-70  
-100  
-120  
-140  
-160  
-80  
-80  
-90  
-100  
-120  
-100  
-110  
-120  
0.01  
0.1  
1
10  
100  
0.01  
0.1  
1
10  
100  
20 50 100 200 500 1k 2k  
FREQUENCY (Hz)  
5k 10k 20k  
FREQUENCY (kHz)  
FREQUENCY (Hz)  
_______________________________________________________________________________________  
5
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Typical Operating Characteristics (continued)  
(V  
PVIN  
= 1.8V, V  
= V  
= 0V, V  
= 1.8V, C1 = C2 = C3 = 1FF, C4 = 10FF, both channels driven in phase, T = +25NC,  
SHDN A  
PGND  
GND  
unless otherwise noted.)  
SUPPLY MODE SWITCHING  
TURN-ON RESPONSE  
MAX97200 toc16  
MAX97200 toc17  
R = 16I  
L
PVDD  
PVSS  
OUTPUT  
SHDN  
20ms/div  
400µs/div  
TURN-OFF RESPONSE  
MAX97200 toc18  
OUTPUT  
SHDN  
400µs/div  
6
______________________________________________________________________________________  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Pin Configuration  
TOP VIEW  
MAX97200  
1
2
3
4
A
B
C
OUTR  
PVSS  
C1N  
C1P  
OUTL  
INL  
SHDN  
INR  
GND  
PGND  
PVIN  
PVDD  
WLP  
Pin Description  
BUMP  
A1  
NAME  
OUTR  
PVSS  
C1N  
FUNCTION  
Right Amplifier Output  
A2  
Negative Charge-Pump Output. Connect a 1FF capacitor between PVSS and PGND.  
Charge-Pump Flying Cap Negative Connection. Connect 1FF capacitor between C1N and C1P.  
Charge-Pump Flying Cap Positive Connection. Connect 1FF capacitor between C1P and C1N.  
Left Amplifier Output  
A3  
A4  
C1P  
B1  
OUTL  
B2  
Active-Low Shutdown  
SHDN  
GND  
PGND  
INL  
B3  
Signal Ground. Connect to PGND.  
B4  
Power Ground. Connect to GND.  
C1  
C2  
C3  
C4  
Left Audio Input  
INR  
Right Audio Input  
PVDD  
PVIN  
Positive Charge-Pump Output. Bypass to PGND with 1FF.  
Main Power-Supply Connection. Bypass to PGND with 10FF.  
_______________________________________________________________________________________  
7
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Maxim’s second-generation DirectDrive architecture  
Detailed Description  
uses a charge pump to create an internal negative sup-  
The MAX97200 is a 45mW Class H headphone ampli-  
ply voltage. This allows the headphone outputs of the  
fier that runs from a single low 1.8V supply voltage  
MAX97200 to be biased at GND while operating from a  
and employs Maxim’s second-generation DirectDrive  
single supply (Figure 1). Without a DC component, there  
is no need for the large DC-blocking capacitors. Instead  
technology.  
Maxim’s DirectDrive architecture uses an inverting  
charge pump to derive a negative voltage supply. The  
headphone amplifier is powered between the positive  
supply and the generated negative rail. This scheme  
allows the audio output signal to be biased about  
ground, eliminating the need for large DC blocking  
capacitors between the amplifier output and the head-  
phone load.  
of two large (220FF typ) capacitors, the MAX97200  
charge pump requires 3 small ceramic capacitors, con-  
serving board space, reducing cost, and improving the  
frequency response of the headphone amplifier.  
V
OUT  
V
DD  
Second-generation DirectDrive technology improves  
power consumption when compared to first-generation  
DirectDrive amplifiers. The MAX97200 can be powered  
from a regulated 1.8V supply and have similar power  
consumption to a traditional DirectDrive amplifier that is  
powered from 0.9V.  
V
/ 2  
V
DD  
DD  
GND  
The MAX97200 features a dual-mode internal charge  
pump to generate the power rails for the DirectDrive  
amplifier. The charge-pump output can be QPVIN/2 or  
QPVIN depending on the amplitude of the output signal.  
When the output voltage is low the power-supply volt-  
age is QPVIN/2. When the output signal demands larger  
output voltage, the charge pump switches modes so  
that a greater power-supply voltage is realized and more  
output power can be delivered to the load.  
CONVENTIONAL DRIVER BIASING SCHEME  
V
OUT  
+V  
DD  
DirectDrive Headphone Amplifier  
Traditional single-supply headphone amplifiers have  
outputs biased at a nominal DC voltage (typically half  
the supply). Large coupling capacitors are needed to  
block this DC bias from the headphone. Without these  
capacitors, a significant amount of DC current flows to  
the headphone, resulting in unnecessary power dis-  
sipation and possible damage to both headphone and  
headphone amplifier.  
GND  
2V  
DD  
-V  
DD  
DirectDrive BIASING SCHEME  
Figure 1. Traditional Amplifier vs. MAX97200 DirectDrive  
Output  
8
______________________________________________________________________________________  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Dual Mode Charge Pump  
The MAX97200’s Dual Mode, charge pump outputs  
either QPVIN/2 in high-efficiency mode or QPVIN in high-  
power mode, resulting in a power-supply differential of  
1.8V or 3.6V. The charge-pump mode changes based  
on the level of the output signal needed. When the  
output voltage is small, the voltage rails are reduced to  
minimize power consumption. When the output voltage  
is large, the voltage rails are increased to accommodate  
the larger output need.  
The switch from high-power mode to high-efficiency  
mode occurs 32ms (typ) after the threshold is crossed.  
Built-in hysteresis keeps the charge pump from erratic  
mode switching when the output voltage is near the high  
and low thresholds.  
Click-and-Pop Suppression  
In conventional single-supply audio amplifiers, the out-  
put-coupling capacitor contributes significantly to audi-  
ble clicks and pops. Upon startup, the amplifier charges  
the coupling capacitor to its bias voltage, typically half  
the supply. Likewise, on shutdown, the capacitor is dis-  
charged. This results in a DC shift across the capacitor,  
which appears as an audible transient at the speaker.  
Since the MAX97200 does not require output coupling  
capacitors, this problem does not arise. Additionally,  
the MAX97200 features extensive click-and-pop sup-  
pression that eliminates any audible transient sources  
internal to the device.  
High-power mode is similar to Maxim’s traditional  
DirectDrive architecture and is best suited for loads  
that require high voltage swing. High-efficiency mode  
improves power consumption by reducing the power-  
supply voltage across the amplifier’s output stage by  
half. The reduced power-supply voltage is good for idle  
conditions or low-signal level conditions into a head-  
phone.  
Class H Operation  
The MAX97200’s internal Class H amplifier uses a class  
AB output stage with multiple, discrete power supplies.  
This result’s in two power-supply differentials of 1.8V and  
3.6V generated from a single 1.8V external supply. The  
PVIN/2 power-supply differential is used when the output  
voltage requirements are low, and the output is below  
Typically, the output of the device driving the MAX97200  
has a DC bias of half the supply voltage. At startup, the  
input-coupling capacitor, C , is charged to the pream-  
IN  
plifier’s DC bias voltage through the MAX97200 input  
resistor, R . This DC shift across the capacitor results  
IN  
in an audible click-and-pop. The MAX97200 precharges  
the input capacitors when power is applied to ensure  
that no audible clicks or pops are heard when SHDN is  
pulled high.  
V
TH2  
as seen in Figure 2. The higher supply differential  
is used when the output voltage exceeds the high  
threshold V , maximizing output power and voltage  
TH2  
Shutdown  
The MAX97200 features a 1FA, low-power shutdown  
mode that reduces quiescent current consumption and  
extends battery life. Shutdown is controlled by the SHDN  
input. Driving the SHDN input low disables the drive  
amplifiers and charge pump and sets the headphone  
amplifier output resistance to 100I.  
swing. The transition time from high-efficiency mode to  
high-power mode occurs when the threshold is crossed.  
V
PVDD  
Applications Information  
Component Selection  
IN_  
Input-Coupling Capacitor  
The input capacitor (C ), in conjunction with the ampli-  
IN  
V
fier input resistance (R ), forms a highpass filter that  
PVSS  
IN_  
removes the DC bias from the incoming signal. The  
AC-coupling capacitor allows the amplifier to bias the sig-  
nal to an optimum DC level. Assuming zero source imped-  
ance, the -3dB point of the highpass filter is given by:  
10ms/div  
1
f-  
=
Figure 2. Inverting and Split Mode Transitions  
3dB  
2πR C  
IN IN  
_______________________________________________________________________________________  
9
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
R
is the amplifier’s input resistance value. Choose C  
Additional RF immunity can also be obtained from rely-  
ing on the self-resonant frequency of capacitors as  
it exhibits the frequency response similar to a notch  
filter. Depending on the manufacturer, 10pF to 20pF  
capacitors typically exhibit self resonance at RF frequen-  
cies. These capacitors when placed at the input pins  
can effectively shunt the RF noise at the inputs of the  
MAX97200. For these capacitors to be effective, provide  
a low-impedance, low-inductance path from the capaci-  
tors to the ground plane. Do not use microvias to con-  
nect to the ground plane as these vias do not conduct  
well at RF frequencies. Figure 3 shows headphone RF  
immunity with a well laid out PCB.  
IN  
IN  
such that f  
interest. Setting f  
is well below the lowest frequency of  
-3dB  
too high affects the amplifier’s low  
-3dB  
frequency. Capacitors with higher voltage coefficients,  
such as ceramics, result in increased distortion at low  
frequencies.  
Charge-Pump Capacitor Selection  
Use capacitors with an ESR less than 100mI 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.  
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. Connect a 1FF capacitor between C1P  
and C1N.  
HEADPHONE RF IMMUNITY  
vs. FREQUENCY  
0
-10  
-20  
-30  
-40  
-50  
Output Capacitors (C2, C3)  
The output capacitor value and ESR directly affect the  
ripple at PVSS. Increasing the value of C2 and C3 reduc-  
es output ripple. Likewise, decreasing the ESR of C2 and  
C3 reduces both ripple and output resistance. Lower  
capacitance values can be used in systems with low  
maximum output power levels. Connect a 1FF capaci-  
tor between PVDD and PGND. Connect a 1FF capacitor  
between PVSS and PGND.  
-60  
-70  
RIGHT CHANNEL  
LEFT CHANNEL  
-80  
-90  
-100  
1000  
1500  
2000  
2500  
3000  
FREQUENCY (MHz)  
RF Susceptibility  
Improvements to both layout and component selec-  
tion can decrease the MAX97200 susceptibility to RF  
noise and prevent RF signals from being demodulated  
into audible noise. Trace lengths should be kept below  
¼ of the wavelength of the RF frequency of interest.  
Minimizing the trace lengths prevents the traces from  
functioning as antennas and coupling RF signals into the  
MAX97200. The wavelength (λ) in meters is given by:  
Figure 3. Headphone RF Immunity  
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 heat away  
from the device. Good grounding improves audio per-  
formance, minimizes crosstalk between channels, and  
prevents switching noise from coupling into the audio  
signal. Connect PGND and GND together at a single  
point on the PCB. Route PGND and all traces that carry  
switching transients away from GND, and the traces and  
components in the audio signal path.  
λ = c/f  
where c = 3 x 108 m/s, and f is the RF frequency of  
interest.  
Route audio signals to the middle layers of the PCB to  
allow the ground planes above and below to shield them  
from RF interference. Ideally, the top and bottom layers  
of the PCB should primarily be ground planes to create  
effective shielding.  
Connect C2 to the PGND plane. Place the charge-pump  
capacitors (C1, C2) as close as possible to the device.  
Bypass PVDD with a 1FF capacitor to PGND. Place the  
bypass capacitors as close as possible to the device.  
10 _____________________________________________________________________________________  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Simplified Functional Diagram  
Chip Information  
PROCESS: BiCMOS  
1.8V  
C4  
10µF  
PVIN  
C4  
MAX97200  
R
FB  
PVDD  
INL C1  
INR C2  
B1 OUTL  
A1 OUTR  
R
R
IN  
IN  
PVSS  
SHDN  
B2  
B3  
R
FB  
A2 PVSS  
CHARGE  
PUMP  
GND  
C2  
1µF  
C3  
PGND PVDD  
B4  
A3  
C1N  
A4  
C1P  
C3  
1µF  
C1  
1µF  
______________________________________________________________________________________ 11  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Package Information  
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note  
that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix  
character, but the drawing pertains to the package regardless of RoHS status.  
LAND  
PATTERN NO.  
PACKAGE TYPE  
PACKAGE CODE  
OUTLINE NO.  
21-0449  
12 WLP  
W121A1+1  
Refer to Application Note 1891  
12 _____________________________________________________________________________________  
Low-Power, Low-Offset, Dual Mode, Class H  
DirectDrive Headphone Amplifier  
Revision History  
REVISION REVISION  
PAGES  
CHANGED  
DESCRIPTION  
NUMBER  
DATE  
1/10  
3/10  
3/11  
0
1
2
Initial release  
—
2
Removed shutdown current max value  
Corrected crosstalk data in TOC 14  
5
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  
13  
©
2011 Maxim Integrated Products  
Maxim is a registered trademark of Maxim Integrated Products, Inc.  

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