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3W/CH FILTERLESS STEREO CLASS-D AUDIO AMPLIFIER
Description
The PAM8404 is a 3W high efficiency filterless Class-D audio
amplifier in 4mmX4mm and 2mmX2mm wafer chip scale (WCSP)
packages that requires few external components.
Features like 89% efficiency, -63dB PSRR, improved RF-rectification
immunity, and very small PCB area make the PAM8404 Class-D
amplifier ideal for cellular handset and PDA applications.
In cellular handsets, the earpiece, speaker phone, and melody ringer
can each be driven by the PAM8404. The PAM8404 allows
independent gain by summing signals from seperate sources, and
has as low as 43µV noise floor.
PAM8404 is available in QFN 4mmx4mm and WCSP 2mmx2mm
packages.
Features
3W Output at 10% THD with a 4 Load and 5V Supply
Supply Voltage from 2.5V to 5.5V
Efficiency Up to 89%
Superior Low Noise without Input
Few External Components to Save the Space and Cost
Short Circuit Protection
Thermal Shutdown
Space Saving Packages :
2mm X 2mmWCSP
4mm X 4mm Thin QFN
Pb-Free Packages
Applications
Pin Assignments
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PAM8404
LCD Monitor / TV Projector
Notebook Computers
Portable Speakers
Portable DVD Players, Game Machines
Cellular Phones/Speaker Phones
PAM8404
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Typical Applications Circuit
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PAM8404
Pin Descriptions
Pin
Name
G1 1 B2 Gain Select (MSB)
OUTL+ 2 A3 Left Channel Positive Differential Output
PVDD 313 A2 Power Supply (Must be Same Voltage as AVDD)
PGND 412 C4 Power Ground
OUTL- 5 A4 Left Channel Negative Differential Output
NC 610 — Not Connected
SDL 7 B4 Left Channel Shutdown Terminal (active low)
SDR 8 B3 Right Channel Shutdown Terminal (active low)
AVDD 9 D2 Analog Supply (Must be Same Voltage as PVDD)
OUTR- 11 D4 Right Channel Negative Differential Output
OUTR+ 14 D3 Right Channel Positive Differential Output
G0 15 C2 Gain Select (LSB)
INR+ 16 D1 Right Channel Positive Input
INR- 17 C1 Right Channel Negative Input
AGND 18 C3 Analog Ground
INL- 19 B1 Left Channel Negative Input
INL+ 20 A1 Left Channel Positive Input
QFN4x4 WCSP2x2
PAM8404
Document number: DSxxxxx Rev. 1 - 1
Pin Number
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Function
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Functional Block Diagram
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PAM8404
Absolute Maximum Ratings (@T
These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may
affect device reliability. All voltages are with respect to ground.
Parameter Rating Unit
Supply Voltage 6.0
Input Voltage
Maximum Junction Temperature 150
Storage Temperature -65 to +150
Soldering Temperature 250, 10sec
Recommended Operating Conditions (@T
Parameter Rating Unit
Supply Voltage Range 2.5 to 5.5 V
Operation Temperature Range -40 to +85 °C
Junction Temperature Range -40 to +125 °C
PAM8404
Document number: DSxxxxx Rev. 1 - 1
= +25°C, unless otherwise specified.)
A
-0.3 to V
+0.3
DD
= +25°C, unless otherwise specified.)
A
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V
°C
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PAM8404
Thermal Information
Parameter Package Symbol Max Unit
Thermal Resistance (Junction to Ambient)
Thermal Resistance (Junction to Case)
WCSP2x2-16
QFN4x4-20 31
WCSP2x2-16
QFN4x4-20 13
JA
JC
Electrical Characteristics (@T
= +25°C, AVDD = PVDD = 5V, GND = PGND = 0V, unless otherwise specified.)
A
QFN4X4-20
Symbol Parameter Test Conditions Min Typ Max Units
VDD
Supply Power
THD+N = 10%, f = 1kHz, R
= 4
L
THD+N = 1%, f = 1kHz, RL = 4
PO
Output Power
THD+N = 10%, f = 1kHz, RL = 8
THD+N = 1%, f = 1kHz, RL = 8
= 5.0V, Po = 0.5W, RL = 8
V
DD
V
= 3.6V, Po = 0.5W, RL = 8
THD+N
Total Harmonic Distortion Plus
Noise
PSRR Power Supply Ripple Rejection
CS
Crosstalk
SNR Signal-to-Noise
VN
Output Noise
DD
V
= 5.0V, Po = 1W, RL = 4
DD
V
= 3.6V, Po = 1W, RL = 4
DD
V
= 5.0V, Inputs AC-Grounded with
DD
= 1.0F
C
IN
V
= 5V, Po = 0.5W, RL = 4,
DD
Gv = 23dB
V
= 5V, V
DD
= 5V, Inputs AC-Grounded with
V
DD
= 1F
C
IN
= 1VGv = 23dB
ORMS
BW 22Hz – 22kHz No A-weighting 59
Dyn Dynamic Range
Efficiency
Quiescent Current
IQ
ISD
R
DS(ON)
Shutdown Current
Static Drain-to-Source On-State
Resistor
fsw Switching Frequency
VOS
Output Offset Voltage
Gain Closed-Loop Voltage Gain
OTP Over Temperature Protection
OTH Over Temperature Hysterisis 50
V
= 5V, THD = 1%
DD
R
= 8, THD = 10%
L
RL = 4, THD = 10%
= 5.0V
V
DD
V
= 3.6V
DD
V
= 5.5V VSD = 0.3V
DD
I
= 500mA,VGS = 5V
DS
V
= 3V to 5V
DD
V
= 0V, V
IN
V
= 5V, RL = 4, f = 1kHz
DD
DD
= 5V
No Load, Junction Temperature
64
—
°C/W
2.5 5.5 V
= 5.0V
V
DD
VDD = 3.6V
= 5.0V
V
DD
VDD = 3.6V
= 5.0V
V
DD
VDD = 3.6V
= 5.0V
V
DD
VDD = 3.6V
f = 1kHz
f = 1kHz
f = 100kHz -48
f = 1kHz -63
3
1.5
2.35
1.2
1.7
0.9
1.4
0.7
0.15
0.27
0.23
0.24
W
W
W
W
%
%
dB
f = 1kHz -93 dB
A-weighting 87 dB
A-weighting 43
µV
A-weighting 97 dB
f = 1kHz
No load
89
84
11
6
%
mA
< 1 µA
PMOS 250
NMOS 170
m
300 kHz
10 mV
G0 = L, G1 = L 6
G0 = H, G1 = L 12
G0 = L, G1 = H 18
dB
G0 = H, G1 = H 24
V
= 5V
DD
150
°C
PAM8404
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PAM8404
Electrical Characteristics (@T
WCSP2x2-16
Symbol Parameter Test Conditions Min Typ Max Units
VDD
PO
THD+N
PSRR Power Supply Ripple Rejection
CS
SNR Signal-to-Noise
VN
Dyn Dynamic Range
ISD
R
DS(ON)
fsw Switching Frequency
VOS
Gain Closed-Loop Voltage Gain
OTP Over Temperature Protection
OTH Over Temperature Hysterisis 50
PAM8404
Document number: DSxxxxx Rev. 1 - 1
Supply Power
Output Power
Total Harmonic Distortion Plus
Noise
Crosstalk
Output Noise
Efficiency
Quiescent Current
IQ
Shutdown Current
Static Drain-to-Source On-State
Resistor
Output Offset Voltage
= +25°C, AVDD = PVDD = 5V, GND = PGND = 0V, unless otherwise specified.)
A
= 5.0V
V
THD+N = 10%, f = 1kHz, R
= 4
L
THD+N = 1%, f = 1kHz, RL = 4
THD+N = 10%, f = 1kHz, RL = 8
THD+N = 1%, f = 1kHz, RL = 8
= 5.0V, Po = 0.5W, RL = 8
V
DD
V
= 3.6V, Po = 0.5W, RL = 8
DD
V
= 5.0V, Po = 1W, RL = 4
DD
V
= 3.6V, Po = 1W, RL = 4
DD
V
= 5.0V, Inputs AC-Grounded with
DD
C
= 1.0F
IN
V
= 5.0V, Po = 0.5W, RL = 4,
DD
Gv = 23dB
V
= 5V, V
DD
= 5V, Inputs AC-Grounded with
V
DD
= 0.47F
C
IN
= 1VGv = 23dB
ORMS
DD
VDD = 3.6V
= 5.0V
V
DD
VDD = 3.6V
= 5.0V
V
DD
VDD = 3.6V
= 5.0V
V
DD
VDD = 3.6V
f = 1kHz
f = 1kHz
f = 217kHz -50 dB
f = 1kHz -70 dB
A-weighting 85 dB
A-weighting 34
2.5 5.5 V
2.2
1.2
1.8
1
1.5
0.8
1.2
0.6
0.3
0.4
0.3
0.2
W
W
W
W
%
%
µV
BW 22Hz – 22kHz No A-weighting 54
V
= 5V, THD = 1%
DD
R
= 8, THD = 10%
L
RL = 4, THD = 10%
= 5.0V
V
DD
V
= 3.6V
DD
V
= 2.5V to 5.5V VSD = 0.3V
DD
I
= 500mA,VGS = 5V
DS
V
= 5V
DD
V
= 0V, V
IN
DD
= 5V
A-weighting 98 dB
f = 1kHz
No load
85
75
12
7
%
mA
< 1 µA
PMOS 500
NMOS 460
m
300 kHz
20 mV
G0 = L, G1 = L 6
V
= 5V, RL = 4, f = 1kHz
DD
G0 = H, G1 = L 12
G0 = L, G1 = H 18
dB
G0 = H, G1 = H 24
No Load, Junction Temperature
V
= 5V
DD
150
°C
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Typical Performance Characteristics (@T
QFN4X4-20
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= +25°C, unless otherwise specified.)
A
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PAM8404
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Typical Performance Characteristics (cont.) (@T
QFN4X4-20
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= +25°C, unless otherwise specified.)
A
PAM8404
PAM8404
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Typical Performance Characteristics (cont.) (@T
QFN4X4-20
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= +25°C, unless otherwise specified.)
A
PAM8404
PAM8404
Document number: DSxxxxx Rev. 1 - 1
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Typical Performance Characteristics (cont.) (@T
WCSP2x2-16
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= +25°C, unless otherwise specified.)
A
PAM8404
PAM8404
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Typical Performance Characteristics (cont.) (@T
WCSP2x2-16
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= +25°C, unless otherwise specified.)
A
PAM8404
PAM8404
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Typical Performance Characteristics (cont.) (@T
WCSP2x2-16
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= +25°C, unless otherwise specified.)
A
PAM8404
PAM8404
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Application Information
Test Setup for Performance Testing
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PAM8404
Notes: 1. The AP AUX-0025 low pass filter is necessary for class-D amplifier measurement with AP analyzer.
2. Two 22H inductors are used in series with load resistor to emulate the small speaker for efficiency measurement.
Gain Settin
The gain of PAM8404 can be selected as 6,12,18 or 24 dB utilizing the G0 and G1 gain setting pins. The gains showed in the following table are
realized by changing the input resistors inside the amplifier. The input impedance changes with the gain setting.
Table 1. Gain Setting
G1 G0
0 0 2 6 28.1
0 1 4 12 17.3
1 0 8 18 9.8
1 1 16 24 5.2
For optimal performance the gain should be set to 2x (R
voltage at the input making the inputs less susceptible to noise. In addition to these features, lower value of Gain minimizes pop noise.
Gain
(V/V)
Gain
(dB)
Input
Impedance
(kΩ)
= 150k). Lower gain allows the PAM8404 to operate at its best, and keeps a high
I
Input Capacitors (CI)
In the typical application, an input capacitor, CI, is required to allow the amplifier to bias the input signal to the proper DC level for optimum
operation. In this case, C
It is important to consider the value of C
specification calls for a flat bass response are down to 200Hz, the equation is reconfigured as follows:
When input resistance variation is considered, the C
capacitor is the leakage path from the input source through the input network (C
voltage at the input to the amplifier that reduces useful headroom, especially in high gain applications.
f
C
C
I
PAM8404
Document number: DSxxxxx Rev. 1 - 1
and the input impedance RI form a high-pass filter with the corner frequency determined by the follow equation:
I
1
R2
C
I
I
as it directly affects the low frequency performance of the circuit. When Ri i s 28.1k and the
I
1
R2
f
C
I
is 28nF, so one would likely choose a value of 33nF. A further consideration for this
I
, RI + RF) to the load. This leakage current creates a DC offset
I
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Application Information
Input Capacitors (CI) (cont.)
For this reason, a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the
capacitor should face the amplifier input in most applications as the DC level is held at V
Please note that it is important to confirm the capacitor polarity in the application.
If the corner frequency is within the audio band, the capacitors should have a tolerance ±10% or better, because any mismatch in capacitance
cause an impedance mismatch at the corner frequency and below.
Decoupling Capacitor (CS)
The PAM8404 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output total harmonic
distortion (THD) as low as possible. Power supply decoupling also prevents the oscillations causing by long lead length between the amplifier
and the speaker.
The optimum decoupling is achieved by using two different types of capacitors that target on different types of noise on the power supply leads.
For higher frequency transients, spikes, or digital hash on the line, a good low equivalent series-resistance (ESR) ceramic capacitor, typically
1µF, is placed as close as possible to the device each V
large ceramic capacitor of 10µF or greater placed near the audio power amplifier is recommended.
and PVDD pin for the best operation. For filtering lower frequency noise signals, a
DD
How to Reduce EMI
Most applications require a ferrite bead filter for EMI elimination as shown at Figure 1. The ferrite filter reduces EMI of around 1MHz and higher.
When selecting a ferrite bead, choose one with high impedance at high frequencies and low impedance at low frequencies.
/2, which is likely higher than the source DC level.
DD
Figure 1. Ferrite Bead Filter to Reduce EMI
Shutdown Operation
In order to reduce power consumption while not in use, the PAM8404 contains shutdown circuitry to turn off the amplifier's bias circuitry. It
features independent shutdown controls for each channel. This shutdown turns the amplifier off when logic low is placed on the SDx pin. By
switching the shutdown pin to GND, the PAM8404 supply current draw will be minimized in idle mode.
Short Circuit Protectrion (SCP)
The PAM8404 has short circuit protection circuitry on the outputs to prevent the device from damage when output-to-output shorts or output-to-
GND shorts occur. When a short circuit occurs, the device immediately goes into shutdown state. Once the short is removed, the device will be
reactivated.
Over Temperature Protection (OTP)
Thermal protection on the PAM8404 prevents the device from damage when the internal die temperature exceeds +150°C. There is a +15°C
tolerance on this trip point from device to device. Once the die temperature exceeds the set point, the device will enter the shutdown state and
the outputs are disabled. This is not a latched fault. The thermal fault is cleared once the temperature of the die decreased by 50°C. This large
hysteresis will prevent motor boating sound well and the device begins normal operation at this point with no external system interaction.
PAM8404
Document number: DSxxxxx Rev. 1 - 1
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Application Information
POP and Click Circuitry
The PAM8404 contains circuitry to minimize turnon and turn-off transients or “click and pops”, where turn-on refers to either power supply turnon
or device recover from shutdown mode. When the device is turned on, the amplifiers are internally muted. An internal current source ramps up
the internal reference voltage. The device will remain in mute mode until the reference voltage reach half supply voltage V
reference voltage is stable, the device will begin full operation. For the best power-off pop performance, the amplifier should be set in shutdown
mode prior to removing the power supply voltage.
PCB Layout Guidelines
Grouding
It is recommended to use plane grounding or separate grounds. Do not use one line connecting power GND and analog GND. Noise currents in
the output power stage need to be returned to output noise ground and nowhere else. When these currents circulate elsewhere, they may get
into the power supply, or the signal ground, etc, even worse, they may form a loop and radiate noise. Any of these instances results in degraded
amplifier performance. The output noise ground that the logical returns for the output noise currents associated with Class-D switching must tie
to system ground at the power exclusively. Signal currents for the inputs, reference need to be returned to quite ground. This ground only ties to
the signal components and the GND pin. GND then ties to system ground.
Power Supply Line
Same as the ground, VDD and PVDD need to be separately connected to the system power supply. It is recommended that all the trace could be
routed as short and thick as possible. For the power line layout, just imagine water stream, any barricade placed in the trace (shown in Figure 2)
could result in the bad performance of the amplifier.
/2. As soon as the
DD
Figure 2. Power Line
Component Placement
Decoupling capacitors-As previously described, the high-frequency 1F decoupling capacitors should be placed as close to the power supply
terminals (V
the PV
Input capacitors need to be placed very close to input pins.
Output filter - The ferrite EMI filter should be placed as close to the output terminals as possible for the best EMI performance, and the capacitors
used in the filters should be grounded to system ground.
PAM8404
Document number: DSxxxxx Rev. 1 - 1
and PVDD) as possible. Large bulk power supply decoupling capacitors (10F or greater) should be placed near the PAM8404 on
DD
terminal.
DD
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Ordering Information
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PAM8404
Part Number Part Marking Package Type Standard Package
PAM8404ZER
PAM8404KGR
Marking Information
FR
YW
P8404
XXXYW
WCSP-16 3000 Units/Tape&Reel
QFN4x4-20L 3000 Units/Tape&Reel
PAM8404
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Package Outline Dimensions (All dimensions in mm.)
QFN4X4-20
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PAM8404
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Package Outline Dimensions (cont.) (All dimensions in mm.)
WCSP2x2-16
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PAM8404
PAM8404
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IMPORTANT NOTICE
LIFE SUPPORT
PAM8404
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