MAXIM MAX9730EBPT

19-0701; Rev 0; 12/06
KIT
ATION
EVALU
E
L
B
AVAILA
2.4W, Single-Supply, Class G Power Amplifier
The MAX9730 features a mono Class G power amplifier
with an integrated inverting charge-pump power supply.
The charge pump can supply up to 500mA of peak output current over a 2.7VDC to 5.5VDC supply voltage
range, guaranteeing up to 2.4W output power into an
8Ω load. The 2.4W output power allows for transient
audio content to remain unclipped as the battery rail collapses over time.
The MAX9730 maximizes battery life by offering highperformance efficiency. Maxim’s proprietary output
stage provides efficiency levels greater than Class AB
devices without the EMI penalties commonly associated with Class D amplifiers. High efficiency allows the
MAX9730 to be packaged in a UCSP™ package without derating the output power handling capability.
The device utilizes fully differential inputs and outputs,
comprehensive click-and-pop suppression, shutdown
control, and soft-start circuitry. The MAX9730 is fully
specified over the -40°C to +85°C extended temperature range and is available in ultra-small, lead-free,
20-bump UCSP (2mm x 2.5mm) and 28-pin TQFN
(4mm x 4mm) packages.
Applications
MP3 Players
Personal Media Players
Handheld Gaming
Consoles
Cell Phones
Smartphones
Notebook Computers
Features
o 2.7V to 5.5V Operation
o Integrated Charge-Pump Power Supply
o 63% Efficiency (VCC = 5V, POUT = 1W)
o 2.4W Output Power into 8Ω at VCC = 3.3V
o Up to 2.4W Instantaneous Output Power into 8Ω
o Clickless/Popless Operation
o Small Thermally Efficient Packages
2mm x 2.5mm 20-Bump UCSP
4mm x 4mm 28-Pin TQFN
Ordering Information
PART
TEMP RANGE
PINPACKAGE
MAX9730EBP+T*
-40°C to +85°C 20 UCSP-20
MAX9730ETI
-40°C to +85°C 28 TQFN-EP**
PKG
CODE
B20-7
T2844-1
+Denotes lead-free package.
*Future product—contact factory for availability.
**EP = Exposed pad.
Typical Application Circuit/Functional Diagram and Pin
Configurations appear at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
Simplified Block Diagram
2.7V TO 5.5V
VCC
CPVDD
FB+
MAX9730
CIN
RIN+
RFB+
IN+
IN-
CIN
RIN-
CLASS G
OUTPUT
STAGE
+
-
OUT+
OUT-
RFBCHARGE
PUMP
FBGND
CPGND
________________________________________________________________ Maxim Integrated Products
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
MAX9730
General Description
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
ABSOLUTE MAXIMUM RATINGS
(Voltages with respect to GND.)
VCC, CPVDD .............................................................-0.3V to +6V
PVSS, SVSS ...............................................................-6V to +0.3V
CPGND..................................................................-0.3V to +0.3V
OUT+, OUT-...................................(SVSS - 0.3V) to (VCC + 0.3V)
IN+, IN-, FB+, FB- ......................................-0.3V to (VCC + 0.3V)
C1N..........................................(PVSS - 0.3V) to (CPGND + 0.3V)
C1P.......................................(CPGND - 0.3V) to (CPVDD + 0.3V)
FS, SHDN ...................................................-0.3V to (VCC + 0.3V)
Continuous Current Into/Out of
OUT+, OUT-, VCC, GND, SVSS .....................................800mA
CPVDD, CPGND, C1P, C1N, PVSS .................................800mA
Any Other Pin ..................................................................20mA
Duration of OUT+, OUT- Short Circuit to
VCC, GND, CPVDD, CPGND ..................................Continuous
Continuous Power Dissipation (TA = +70°C)
20-Bump UCSP (derate 10.3mW/°C above +70°C) .....827mW
28-Pin TQFN (derate 20.8mW/°C above +70°C) ........1667mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................+300°C
Bump Temperature (soldering) Reflow............................+235°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
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 =
10µF; speaker load resistors (RL) are terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL
Supply Voltage Range
VCC
Quiescent Current
ICC
Inferred from PSRR test
2.7
8
Chip Power Dissipation
PDISS
VOUT = 2.8VRMS, f = 1kHz, RL = 8Ω
0.9
Shutdown Current
ISHDN
SHDN = GND
0.3
Time from shutdown or power-on to full
operation
50
Turn-On Time
tON
Input DC Bias Voltage
VBIAS
Charge-Pump Oscillator
Frequency (Slow Mode)
fOSC
Maximum Capacitive Load
IN_ inputs
1.1
V
12
mA
5
µA
W
ms
1.24
1.4
ILOAD = 0mA (slow mode)
55
83
110
ILOAD > 100mA (normal mode)
230
330
430
VIH
1.4
CL
SHDN Input Threshold (Note 3)
5.5
200
VIL
kHz
pF
0.4
SHDN Input Leakage Current
V
±1
V
µA
SPEAKER AMPLIFIER
Output Offset Voltage
Common-Mode Rejection Ratio
Click-and-Pop Level
2
VOS
CMRR
VCP
TA = +25°C
±3
TMIN ≤ TA ≤ TMAX
±15
±20
mV
fIN = 1kHz (Note 4)
68
dB
Peak voltage into/out of shutdown
A-weighted, 32 samples per second
(Notes 5, 6)
-52
dBV
_______________________________________________________________________________________
2.4W, Single-Supply, Class G Power Amplifier
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 =
10µF; speaker load resistors (RL) are terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2)
PARAMETER
Voltage Gain
SYMBOL
AV
Continuous Output Power
POUT
CONDITIONS
(Notes 4, 7)
THD+N = 1%, f = 1kHz,
RL = 8Ω
f = 1kHz, 1% THD+N,
ZL = 1µF + 10Ω
Output Voltage
VOUT
f = 10kHz, 1% THD+N,
ZL = 1µF + 10Ω, no
load
11.5
PSRR
Signal-to-Noise Ratio
Dynamic Range
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
THD+N
SNR
DR
MAX
UNITS
12
12.5
dB
2.4
VCC = 4.2V
1.67
VCC = 3.6V
1.25
VCC = 3.0V
0.8
VCC = 5V
7.1
VCC = 4.2V
5.9
VCC = 3.6V
5.1
VCC = 3.0V
4.2
VCC = 5V
6.5
VCC = 4.2V
5.4
VCC = 3.6V
4.7
VCC = 3.0V
3.8
63
77
f = 1kHz, 200mVP-P ripple
77
0.007
RL = 8Ω, VOUT = 1kHz / 1W
0.12
(Note 9)
W
dB
58
RL = 8Ω, VOUT = 1kHz / 400mW
VOUT = 0.5W, inputs to GND by C1N,
A-weighted
VRMS
77
f = 217Hz, 200mVP-P ripple
f = 20kHz, 200mVP-P ripple
Total Harmonic Distortion Plus
Noise
TYP
VCC = 5V
VCC = 2.7V to 5.5V
Power-Supply Rejection Ratio
(Note 4)
MIN
95
22Hz to 22kHz
96
A-weighted
99
%
dB
dB
All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.
Testing performed with resistive and inductive loads to simulate an actual speaker load. For dynamic speakers,
RL = 8Ω, 68µH.
Designed for 1.8V logic.
RIN_ and RFB_ have 0.5% tolerance.
Amplifier inputs AC-coupled to GND.
Testing performed at room temperature with 8Ω resistive load in series with 68µH inductive load connected across BTL
output for speaker amplifier. Mode transitions are controlled by SHDN. VCP is the peak output transient expressed in dBV.
Voltage gain is defined as: [VOUT+ - VOUT-] / [VIN+ - VIN-].
Mode A tone burst tested at full amplitude for one cycle and half amplitude for nine cycles. Mode B tone burst tested at
full amplitude for three cycles and half amplitude for seven cycles. Full amplitude is defined as 1% THD+N at full battery
(VCC = 4.2V). Electrical Characteristics table targets must be met at THD+N = 1% for one cycle (Mode A) and THD+N <
5% for three cycles (Mode B).
Dynamic range is calculated by measuring the RMS voltage difference between a -60dBFS output signal and the noise
floor, then adding 60dB. Full scale is defined as the output signal needed to achieve 1% THD+N.
_______________________________________________________________________________________
3
MAX9730
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 =
10µF, RL = 8Ω; speaker load resistors (RL) are terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX,
unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2)
POUT = 0.37W
1
10
MAX9730 toc03
0.001
0.01
100
POUT = 0.83W
0.01
0.001
0.1
0.01
POUT = 2.08W
0.1
0.01
0.001
0.1
1
10
0.01
100
0.1
1
10
100
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
VCC = 3.6V
fIN = 10kHz
fIN = 10kHz
1
fIN = 1kHz
0.1
0.01
0.01
0.01
fIN = 20Hz
0.001
0.001
0.5
1.0
1.5
0.1
fIN = 20Hz
fIN = 20Hz
0.001
fIN = 1kHz
THD+N (%)
THD+N (%)
fIN = 1kHz
0
VCC = 5V
1
0.1
MAX9730 toc06
fIN = 10kHz
10
MAX9730 toc05
VCC = 3V
1
10
MAX9730 toc04
10
0
0.5
1.0
1.5
0
2.0
0.5
1.0
1.5
2.0
2.5
OUTPUT POWER (W)
OUTPUT POWER (W)
OUTPUT POWER (W)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
POWER EFFICIENCY
vs. OUTPUT POWER
POWER EFFICIENCY
vs. OUTPUT POWER
-20
70
70
MAX9730 toc08
VRIPPLE = 200mVP-P
MAX9730 toc07
0
-10
60
60
50
-40
-50
-60
3.5
50
EFFICIENCY (%)
EFFICIENCY (%)
-30
3.0
MAX9730 toc09
THD+N (%)
1
0.1
POUT = 0.33W
0.01
VCC = 5V
THD+N (%)
0.1
10
POUT = 0.93W
1
POUT = 0.69W
THD+N (%)
THD+N (%)
VCC = 3.6V
MAX9730 toc02
VCC = 3V
1
10
MAX9730 toc01
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
PSRR (dB)
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
40
30
20
40
30
20
-70
-90
10
0
0.01
0.1
1
FREQUENCY (kHz)
4
VCC = 3V
fIN = 1kHz
10
-80
10
100
VCC = 3.6V
fIN = 1kHz
0
0
0.5
1.0
OUTPUT POWER (W)
1.5
0
0.5
1.0
OUTPUT POWER (W)
_______________________________________________________________________________________
1.5
2.4W, Single-Supply, Class G Power Amplifier
POWER EFFICIENCY
vs. OUTPUT POWER
MAX9730 toc12
MAX9730 toc11
MAX9730 toc10
60
SHDN
5V/div
SHDN
5V/div
OUT+ - OUT500mV/div
OUT+ - OUT500mV/div
50
40
30
20
10
VCC = 5V
fIN = 1kHz
0
0
1
3
2
10ms/div
10ms/div
OUTPUT POWER (W)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT (mA)
8
6
4
MAX9730 toc14
10
1.0
0.9
SHUTDOWN CURRENT (μA)
MAX9730 toc13
12
0.8
0.7
0.6
0.5
0.4
0.3
0.2
2
0.1
0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
6.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
OUTPUT POWER
vs. SUPPLY VOLTAGE
OUTPUT POWER
vs. LOAD RESISTANCE
3.0
MAX9730 toc15
4.0
3.5
3.0
3.0
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
10% THD+N
2.5
2.0
1% THD+N
1.5
fIN = 1kHz
POUT AT 1% THD+N
2.5
6.0
MAX9730 toc16
0
OUTPUT POWER (W)
EFFICIENCY (%)
SHUTDOWN WAVEFORM
STARTUP WAVEFORM
70
2.0
VCC = 5V
1.5
1.0
1.0
0.5
0.5
VCC = 3.6V
fIN = 1kHz
0
0
2.5
3.0
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
5.5
6.0
0
20
40
60
80
100
LOAD RESISTANCE (Ω)
_______________________________________________________________________________________
5
MAX9730
Typical Operating Characteristics (continued)
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 =
10µF, RL = 8Ω; speaker load resistors (RL) are terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX,
unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2)
Typical Operating Characteristics (continued)
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 =
10µF, RL = 8Ω; speaker load resistors (RL) are terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX,
unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2)
MAX9730 toc17
20
POUT = 1W
18
16
OUT+
5V/div
MAX9730 toc18
FREQUENCY RESPONSE
CLASS G OUTPUT WAVEFORM
14
GAIN (dB)
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
OUT5V/div
12
10
8
6
OUT+ - OUT10V/div
4
2
1% THD+N
0
10
200μs/div
100
1k
10k
100k
FREQUENCY (Hz)
Pin Description
PIN
6
NAME
FUNCTION
TQFN
UCSP
1
B2
SHDN
2, 5, 6, 8, 11, 17,
19, 23, 25, 28
—
N.C.
3
A2
C1P
4
A3
CPVDD
7
A4
FB-
Negative Amplifier Feedback
Shutdown
No Connection. No internal connection.
Charge-Pump Flying Capacitor, Positive Terminal. Connect a 4.7µF
capacitor between C1P and C1N.
Charge-Pump Positive Supply
9
A5
IN-
Negative Amplifier Input
10
B5
IN+
Positive Amplifier Input
12
B4
FB+
Positive Amplifier Feedback
13
C5
FS
Charge-Pump Frequency Set. Connect a 100kΩ resistor from FS to
GND to set the charge-pump switching frequency.
14, 22
D1, D5
VCC
Supply Voltage. Bypass with a 10µF capacitor to GND.
15, 21
C2, C4
SVSS
Amplifier Negative Power Supply. Connect to PVSS.
16
D4
OUT-
Negative Amplifier Output
18
D3
GND
Ground
20
D2
OUT+
24
C1
PVSS
26
B1
C1N
27
A1
CPGND
EP
—
EP
Positive Amplifier Output
Charge-Pump Output. Connect a 10µF capacitor between PVSS and
CPGND.
Charge-Pump Flying Capacitor, Negative Terminal. Connect a 4.7µF
capacitor between C1N and C1P.
Charge-Pump Ground. Connect to GND.
Exposed Pad. Connect the TQFN EP to GND.
_______________________________________________________________________________________
2.4W, Single-Supply, Class G Power Amplifier
ply range. In this range, the operation of the device is
identical to a traditional single-supply Class AB amplifier where:
ILOAD = IN1
The MAX9730 Class G power amplifier with inverting
charge pump is the latest in linear amplifier technology. The Class G output stage offers the performance
of a Class AB amplifier while increasing efficiency to
extend battery life. The integrated inverting charge
pump generates a negative supply capable of delivering up to 500mA.
As the output signal increases, so a wider supply is
needed, the device begins its transition to the higher supply range (VCC to SVSS) for the large signals. To ensure a
seamless transition between the low and high supply
ranges, both of the lower transistors are on so that:
ILOAD = IN1 + IN2
The Class G output stage and the inverting charge pump
allow the MAX9730 to deliver an output power that is up
to four times greater than a traditional single-supply linear
amplifier. This allows the MAX9730 to maintain 0.8W into
an 8Ω load as the battery rail collapses.
As the output signal continues to increase, the transition to the high supply is complete. The device then
operates in the higher supply range, where the operation of the device is identical to a traditional dual-supply Class AB amplifier where:
ILOAD = IN2
Class G Operation and Efficiency
The MAX9730 Class G amplifier is a linear amplifier that
operates within a low (VCC to GND) and high (VCC to
SVSS) supply range. Figure 1 illustrates the transition
from the low to high supply range. For small signals,
the device operates within the lower (VCC to GND) sup-
During operation, the output common-mode voltage of
the MAX9730 adjusts dynamically as the device transitions between supply ranges.
BTL CLASS G SUPPLY TRANSITION
VCC
VCC
IP
ON
P
VCC
IP
ON
RL
IN1
N1
ON
N2
OFF
P
IP
ON
RL
IN1
IN2
N1
ON
N2
ON
P
RL
IN2
N1
OFF
N2
ON
SVSS
SVSS
SVSS
LOW SUPPLY RANGE OPERATION
IP = IN1
SUPPLY TRANSITION
IP = IN1 + IN2
HIGH SUPPLY RANGE OPERATION
IP = IN2
Figure 1. Class G Supply Transition
_______________________________________________________________________________________
7
MAX9730
Detailed Description
Utilizing a Class G output stage with an inverting
charge pump allows the MAX9730 to realize a 2.4W
output power with a 5V supply.
The theoretical best efficiency of a linear amplifier is
78%; however, that efficiency is only exhibited at peak
output powers. Under normal operating levels (typical
music reproduction levels), efficiency falls below 30%,
whereas the MAX9730 still exhibits 50% efficiency
under the same conditions.
Inverting Charge Pump
The MAX9730 features an integrated charge pump with
an inverted supply rail that can supply greater than
700mA over the positive 2.7V to 5.5V supply range. In
the case of the MAX9730, the charge pump generates
the negative supply rail (PVSS) needed to create the
higher supply range, which allows the output of the
device to operate over a greater dynamic range as the
battery supply collapses over time.
Shutdown Mode
The MAX9730 has a shutdown mode that reduces
power consumption and extends battery life. Driving
SHDN low places the MAX9730 in a low-power (0.3µA)
shutdown mode. Connect SHDN to V CC for normal
operation.
Click-and-Pop Suppression
The MAX9730 Class G amplifier features Maxim’s comprehensive, industry-leading click-and-pop suppression. During startup, the click-and-pop suppression
circuitry eliminates any audible transient sources internal to the device.
Applications Information
Differential Input Amplifier
The MAX9730 features a differential input configuration,
making the device compatible with many CODECs, and
offering improved noise immunity over a single-ended
input amplifier. In devices such as PCs, noisy digital
signals can be picked up by the amplifier’s input
traces. The signals appear at the amplifiers’ inputs as
common-mode noise. A differential input amplifier
amplifies the difference of the two inputs, and signals
common to both inputs are canceled out. When configured for differential inputs, the voltage gain of the
MAX9730 is set by:
⎡ ⎛ RFB _ ⎞ ⎤
A V = 20 log⎢4 × ⎜
⎟ ⎥ (dB)
⎢⎣ ⎝ RIN _ ⎠ ⎥⎦
where AV is the desired voltage gain in dB. RIN+ should
be equal to RIN- and RFB+ should be equal to RFB-. The
Class G output stage has a fixed gain of 4V/V (12dB). Any
gain or attenuation set by the external input stage resistors
will add to or subtract from this fixed gain. See Figure 3.
MAX9730
EFFICIENCY vs. CLASS AB
MAX9730 fig02
100
90
80
EFFICIENCY (%)
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
70
RFB+
MAX9730
CIN-
60
RIN+
IN+
50
IN-
40
30
CINTRADITIONAL CLASS AB
20
MAX9730
FB+
+
-
RINRFB-
10
FB-
0
0
0.5
1.0
1.5
2.0
OUTPUT POWER (W)
Figure 2. MAX9730 Efficiency vs. Class AB Efficiency vs.
Class D Efficiency
8
Figure 3. Gain Setting
_______________________________________________________________________________________
CLASS G
OUTPUT
STAGE
2.4W, Single-Supply, Class G Power Amplifier
RFB + RFB −
=
RIN+
RIN−
and
CIN+ = CIN−
Component Selection
Input-Coupling Capacitor
The AC-coupling capacitors (CIN_) and input resistors
(RIN_) form highpass filters that remove any DC bias from
an input signal (see the Typical Application
Circuit/Functional Diagram). CIN_ blocks DC voltages
from the amplifier. The -3dB point of the highpass filter,
assuming zero source impedance due to the input signal
source, is given by:
Hold Capacitor (C2)
The output capacitor value and ESR directly affect the
ripple at PVSS. Increasing C2 reduces output ripple.
Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. A 10µF capacitor is recommended.
Charge-Pump Frequency Set Resistor (RFS)
The charge pump operates in two modes. When the
charge pump is loaded below 100mA, it operates in a
slow mode where the oscillation frequency is reduced
to 1/4 of its normal operating frequency. Once loaded,
the charge-pump oscillation frequency returns to normal operation. In applications where the design may be
sensitive to the operating charge-pump oscillation frequency, the value of the external resistor RFS can be
changed to adjust the charge-pump oscillation frequency (see Figure 4).
1
(Hz)
2π × RIN _ × CIN _
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 50mΩ for optimum performance. Low-ESR ceramic capacitors minimize 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
CHARGE-PUMP OSCILLATION
FREQUENCY vs. RFS
600
ILOAD > 100mA
550
MAX9730 fig04
Choose CIN so that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the
amplifier’s low frequency response. Use capacitors with
low-voltage coefficient dielectrics. Aluminum electrolytic,
tantalum, or film dielectric capacitors are good choices
for AC-coupling capacitors. Capacitors with high-voltage
coefficients, such as ceramics (non-C0G dielectrics),
can result in increased distortion at low frequencies.
CHARGE-PUMP OSCILLATION FREQUENCY (kHz)
f−3dB =
to provide sufficient current drive. Increasing the value
of C1 improves load regulation and reduces the chargepump output resistance to an extent. Above 1µF, the onresistance of the switches and the ESR of C1 and C2
dominate. A 4.7µF capacitor is recommended.
500
450
400
350
300
250
200
50
75
100
125
150
RFS (kΩ)
Figure 4. Charge-Pump Oscillation Frequency vs. RFS
_______________________________________________________________________________________
9
MAX9730
In differential input configurations, the common-mode
rejection ratio (CMRR) is primarily limited by the external resistor and capacitor matching. Ideally, to achieve
the highest possible CMRR, the following external components should be selected where:
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
Thermal Considerations
The copper polygon to which the exposed pad is
attached should have multiple vias to the opposite side
of the PCB, where they connect to GND. Make this
polygon as large as possible within the system’s constraints.
Class G amplifiers provide much better efficiency and
thermal performance than a comparable Class AB
amplifier. However, the system’s thermal performance
must be considered with realistic expectations and
include consideration of many parameters. This section
examines Class G amplifiers using general examples to
illustrate good design practices.
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, PCB techniques,
bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability
testing results, go to the Maxim website at www.maximic.com/ucsp for the application note, UCSP—A WaferLevel Chip-Scale Package.
TQFN Considerations
The exposed pad is the primary route of keeping heat
away from the IC. With a bottom-side exposed pad, the
PCB and its copper become the primary heatsink for
the Class G amplifier. Solder the exposed pad to a
large copper polygon that is connected to the ground
plane.
Typical Application Circuit/Functional Diagram
VDD
0.1μF
14, 22
(D1, D5) 4 (A3)
1 (B2)
VCC
SHDN
*
CPVDD
12 (B4) FB+
MAX9730
CIN
1μF
RIN10kΩ
RFB+
10kΩ
10 (B5) IN+
+
9 (A5) INCIN
1μF
RIN10kΩ
OUT+ 20 (D2)
CLASS G
OUTPUT
STAGE
-
OUT- 16 (D4)
RFB10kΩ
GND
18 (D3)
( ) UCSP PACKAGE
FS 13 (C5)
CHARGE
PUMP
7 (A4) FBCPGND
27 (A1)
C1P
C1N
26 (B1)
PVSS
3 (A2) 24 (C1)
C1
4.7μF
RFS
100kΩ
SVSS
15, 21
(C2, C4)
C2
10μF
DEVICE SHOWN WITH AV = 12dB
*SYSTEM-LEVEL REQUIREMENT TYPICALLY 10μF
10
______________________________________________________________________________________
2.4W, Single-Supply, Class G Power Amplifier
TOP VIEW
(BUMP SIDE DOWN)
N.C.
CPGND
C1N
N.C.
PVSS
N.C.
VCC
27
26
25
24
23
22
+
28
TOP VIEW
MAX9730
SHDN
1
21
SVSS
N.C.
2
20
OUT+
C1P
3
19
N.C.
CPVDD
4
18
GND
N.C.
5
17
N.C.
N.C.
6
16
OUT-
15
SVSS
8
9
10
11
12
13
14
IN-
IN+
N.C.
FB+
FS
VCC
7
EP*
N.C.
FB-
MAX9730
1
2
3
4
5
CPGND
C1P
CPVDD
FB-
IN-
C1N
SHDN
FB+
IN+
PVSS
SVSS
SVSS
FS
VCC
OUT+
OUT-
VCC
A
B
C
D
GND
UCSP
THIN QFN
*EXPOSED PAD.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
11
MAX9730
Pin Configurations
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.)
24L QFN THIN.EPS
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
PACKAGE OUTLINE,
12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
21-0139
12
______________________________________________________________________________________
E
1
2
2.4W, Single-Supply, Class G Power Amplifier
PACKAGE OUTLINE,
12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
21-0139
E
2
2
______________________________________________________________________________________
13
MAX9730
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.)
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.)
5x4 UCSP.EPS
MAX9730
2.4W, Single-Supply, Class G Power Amplifier
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.