Diodes PAM8304 User Manual

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Description

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PAM8304

3W MONO CLASS D AUDIO AMPLIFIER

Pin Assignments

The PAM8304 is a mono filter-less Class-D amplifier with high SNR

and differential input that helps eliminate noise. The PAM8304

supports 2.8V to 6V operation make it idea for up to 4 cells alkaline

battery applications. The PAM8304 is capable of driving speaker

loads as low as 3Ω speaker with a 5V supply maximizing the output

power.

Features like greater than 90% efficiency and small PCB area make

the PAM8304 Class-D amplifier ideal for portable applications. The

output uses a filter-less architecture minimizing the number of

external components and PCB area whilst providing a high

performance, simple and lower cost system.

The PAM8304 features short circuit protection, thermal shutdown and

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under voltage lock-out.

The PAM8304 is available in DFN3030-8L and MOP-8L packages.

Features

 Supply Voltage from 2.8V to 6.0 V

 3Ω Driving Capability

 3.0W@10% THD Output with a 4Ω Load and 5V Supply

 High Efficiency up to 90% @1W with an 8Ω Load

 Shutdown Current <1μA

 Superior Low Noise without Input

 Short Circuit Protection

 Thermal Shutdown

 Available in Space Saving DFN3030-8L and MSOP-8L

Packages

 Pb-Free Package

DFN3X3-8L

To p V i ew

1

OUT +

2

PVDD

VDD

3

4

IN- IN+

MSOP-8L

To p V i e w

OUT +

1

PVDD

2

VDD

3

IN- IN+

4

Applications

 MP4/MP3

 GPS

 Set-Top-Box

 Tablets/Digital Photo Frame

 Electronic Dictionary

 Portable Game Machines

XXXYW

XXXYW

OUT-

8

P8304

P8304

GND

7

6

SD

5

OUT-

8

GND

7

6

SD

5

Typical Applications Circuit

DD

1Fμ

VDD

OUT+

OUT-

GND

VIN

/SD

0.1 Fμ

0.1 Fμ

IN+

IN-

/SD

PVDD

PAM8304

PGND

PAM8304

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Pin Descriptions

Pin Name MSOP-8L/DFN3x3-8L Function

OUT+ 1 Positive BTL Output

PVDD 2 Power Supply

VDD 3 Analog Power Supply

IN- 4 Negative Differential Input

IN+ 5 Positive Differential Input

/SD 6 Shutdown Terminal, Active Low

GND 7 Ground

OUT- 8 Negative BTL Output

Exposed Pad — NC

Functional Block Diagram

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PAM8304

VDD

IN+

PWM

Modulator

OSC

Protection

IN-

SD

-

+

SD

Bias and

Vref

Absolute Maximum Ratings

Parameter Rating Unit

Supply Voltage (VDD) 6.5 V

Input Voltage (IN+, IN-, /SD) -0.3 to VDD +0.3 V

Storage Temperature -65 to +150 °C

Maximum Junction Temperature 150 °C

Recommended Operating Conditions (@T

(@TA = +25°C, unless otherwise specified.)

= +25°C, unless otherwise specified.)

A

UVLO

Startup

Gate

Drive

Gate

Drive

SC

Protect

OTP

PVDD

OUT +

OUT-

GND

Symbol Parameter Min Max Unit

VDD Supply Voltage 2.8 6.0 V

TA Operating Ambient Temperature Range -40 +85 °C

TJ Junction Temperature Range -40 +125 °C

PAM8304

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Electrical Characteristics (@TA=25°C, VDD=5V, Gain=18dB, RL=L(33μH)+R+L(33μH), unless otherwise noted.)

Symbol Parameter Test Conditions Min Typ Max Unit

VDD Supply Voltage 2.8 6.0 V

3.0

2.4

1.75

1.40

0.17

0.14

-68

170

93

325 mΩ

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THD+N = 10%, f = 1kHz,
R = 4Ω

THD+N = 1%, f = 1kHz,
R = 4Ω

Po Output Power

THD+N = 10%, f = 1kHz,
R = 8Ω

THD+N = 1%, f = 1kHz,
R = 8Ω

VDD = 5.0V, Po = 1W, R = 8Ω

THD+N

PSRR

Dyn Dynamic Range VDD = 5V,THD = %, R = 8Ω f=1kHz 95 dB

Vn Output Noise Inputs ac-grounded

η Efficiency

IQ Quiescent Current VDD = 5V No Load 5 mA

Isd Shutdown Current VDD = 2.8V to 5V /SD=0V 1 μA

Rdson

fsw Switching Frequency VDD = 2.8V to 5V 400 kHz

Gv Closed-loop Gain VDD = 2.8V to 5V 300K/Rin V/V

Vos Output Offset Voltage Input ac-ground, VDD = 5V 50 mV

VIH SD Input High Voltage VDD = 5V 1.4

VIL SD Input Low Voltage VDD = 5V 1.0

Total Harmonic
Distortion Plus
Noise

Power Supply Ripple
Rejection

Static Drain-to Source On­state Resistor

VDD = 3.6V, Po = 0.1W, R = 8Ω 0.16

VDD = 3.2V, Po =0.1W, R = 8Ω 0.14

VDD = 5.0V, Po = 0.5W, R = 4Ω

VDD = 3.6V, Po = 0.2W, R = 4Ω 0.16

VDD = 3.2V, Po = 0.1W, R = 4Ω 0.17

VDD = 3.6V, Inputs ac-grounded
with C = 1μF

RL = 8Ω,THD = 10%

RL = 4Ω,THD = 10% 86

High Side PMOS,I = 500mA VDD=5.0V

Low Side NMOS,I = 500mA VDD=5.0V 200 mΩ

VDD = 5.0V

VDD = 3.6V 1.5

VDD = 3.2V 1.2

VDD = 5.0V

VDD = 3.6V 1.25

VDD = 3.2V 1.0

VDD = 5.0V

VDD = 3.6V 0.90

VDD = 3.2V 0.70

VDD = 5.0V

VDD = 3.6V 0.72

VDD = 3.2V 0.60

f = 1kHz

f = 1kHz

f=217Hz

f=1kHz -70

f=10kHz -67

No A
weighting

A-weighting 130

f=1kHz

PAM8304

W

W

W

W

%

%

dB

μV

%

V

PAM8304

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PAM8304

Performance Characteristics (@TA=25°C, VDD=5V, Gain=18dB, RL=L(33μH)+R+L(33μH), unless otherwise noted.)

THD+N Vs. Output Power (RL=4Ω) THD+N Vs. Output Power (RL=8Ω)

20

10

5

VDD=5.0V

2

%

1

0.5

VDD=3.6V

0.2

0.1
1m 52m 5m 10m 20m 50m 100m 200m 500m 1 2

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W

THD+N Vs. Frequency PSRR Vs. Frequency

10

Po=300mW

5

2

1

0.5

%

0.2

0.1

0.05

0.02
20 20k50 100 200 500 1k 2k 5k 10k

VDD=5.0V

VDD=3.6V

Hz

Frequency Response Noise Floor

+20

+19.5

+19

+18.5

+18

+17.5

+17

+16.5

+16

d

+15.5

B

+15

g

+14.5

A

+14

+13.5

+13

+12.5

+12

+11.5

+11

+10.5

+10

20 20k50 100 200 500 1k 2k 5k 10k

Hz

VDD=5.0V

PAM8304

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20

10

5

2

%

1

0.5

0.2

0.1
1m 32m 5m 10m 20m 50m 100m 200m 500m 1 2

+0

-10

-15

-20

-25

-30

-35

d

-40

B

-45

-50

-55

-60

-65

-70

-75

-80

+20

+10

+0

-10

-20

-30

-40

d

B

-50

r

-60

A

-70

-80

-90

-100

-110

-120

T

-5

VDD=5.0V

20 20k50 100 200 500 1k 2k 5k 10k

VDD=5.0V

20 20k50 100 200 500 1k 2k 5k 10k

VDD=5.0V

VDD=3.6V

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Hz

Hz

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Performance Characteristics (@TA=25°C, VDD=5V, Gain=18dB, RL=L(33μH)+R+L(33μH), unless otherwise noted.)

Efficiency Vs. Output Power (RL=4Ω) Efficiency Vs. Output Power (RL=8Ω)

PAM8304

NEW PRODUCT

Quiescent Current Vs. Supply Voltage OSC Frequency Vs. Supply Voltage

Start-up Response Shutdown Response

PAM8304

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PAM8304

Application Information

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, Ci and the minimum input impedance Ri form a high-pass filter with the corner frequency determined in the follow equation:

f

It is important to consider the value of Ci as it directly affects the low frequency performance of the circuit. For example, when Ri is 150kΩ and the

specification calls for a flat bass response down to 150Hz. The equation is reconfigured as followed to determine the value of Ci:

Ci

When input resistance variation is considered, if Ci is 7nF one would likely choose a value of 10nF. A further consideration for this capacitor is the

leakage path from the input source through the input network (Ci, Ri and Rf) to the load. This leakage current creates a DC offset voltage at the

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input to the amplifier that reduces useful headroom, especially in high gain applications. 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 VDD/2, which is likely higher than the source DC level. Please note that it is important to confirm the

capacitor polarity in the application.

Decoupling Capacitor (CS )

The PAM8304 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.

Optimum decoupling is achieved by using two different types of capacitors that target different types of noise on the power supply leads. Higher

frequency transients, spikes or digital hash should be filtered with a good low equivalent-series-resistance (ESR) ceramic capacitor with a value of

typically 1μF. This capacitor should be placed as close as possible to the VDD pin of the device. Lower frequency noise signals should be filtered

with a large ceramic capacitor of 10μF or greater. It's recommended to place this capacitor near the audio power amplifier.

How to Reduce EMI

Most applications require a ferrite bead filter for EMI elimination as shown in Figure 1. The ferrite filter reduces EMI around 1MHz and higher.

When selecting a ferrite bead it should be chosen with high impedance at high frequencies but low impedance at low frequencies.

OUT+

Ferrite Bead

1

C





2RiCi





2Rf



1

ic



200pF

Ferrite Bead

OUT-

200pF

Figure 1 Ferrite Bead Filter to Reduce EMI

PAM8304

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PAM8304

Application Information (cont.)

Shutdown Operation

In order to reduce power consumption while not in use the PAM8304 contains amplifier shutdown circuitry. When a logic low or ground is applied

to the /SD pin the PAM8304 will enter a standby mode and supply current drawn will be minimized.

Under Voltage Lock-out (UVLO)

The PAM8304 incorporates circuitry designed to detect low supply voltage. When the supply voltage drops to 2.0V or below, the PAM8304 goes

into a state of shutdown. The device returns to normal operation only when VDD is higher than 2.5V.

Short Circuit Protection (SCP)

The PAM8304 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 prevents the device from damage. When the internal die temperature exceeds a typical of 150°C the device will enter a

shutdown state and the outputs are disabled. This is not a latched fault, once the thermal fault is cleared and the temperature of the die decreased

NEW PRODUCT

by 40°C the device will restart with no external system interaction.

Anti-POP and Anti-Click Circuitry

The PAM8304 contains circuitry to minimize turn-on and turn-off transients or “click and pops”, where turn-on refers to either power supply turn-on

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. As soon as the 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.

PAM8304

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Ordering Information

PAM8304 X X X

S: MSOP

Part Number Package Standard Package

PAM8304AYR DFN3030-8L 3,000Units/Tape&Real

PAM8304ASR MSOP-8L 2,500Units/Tape&Real

NEW PRODUCT

Pin Configuration

A: 8 Pin Y: DFN3030 R: Tape & Real

Marking Information

Package Type

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PAM8304

Shipping Package

DFN3030 /MOP8

PAM8304: Product Code

X: Internal Code

Y: Year

W: Week

PAM8304

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Package Outline Dimensions (All dimensions in mm.)

Package: DFN3030

DFN

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PAM8304

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PAM8304

Document number: DS36589 Rev. 1 - 2

Unit: Millimete

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Package Outline Dimensions (All dimensions in mm.)

Package: MSOP

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PAM8304

NEW PRODUCT

Millimeter

REF

Min Max

A -- 1.10

A1 0.05 0.15

A2 0.78 0.94

b 0.22 0.38

c 0.08 0.23

D 2.90 3.10

E 2.90 3.10

E1 4.75 5.05

e 0.65BSC

L 0.40 0.70

PAM8304

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PAM8304

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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).

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2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the

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PAM8304

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