Diodes PAM8406 User Manual

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Description

The PAM8406 is a 5W audio amplifier with an alternative option

between Class-D and Class-AB output which makes PAM8406 very

ideally for the applications efficiency-EMI compatible.

PAM8406 offers low THD+N, high SNR allowing it to achieve high-

quality sound reproduction. The fully differential output wi th new filter

less architecture (Class-D Mode) allows the device to drive the

speaker directly, requiring no low-pass output filters and DC blocking

capacitors, thus to save the system cost and PCB area.

The efficiency of the PAM8406 is up to 90%. It can extend the battery

life, ideally for portable applications. The PAM8406 is fully protected

against faults with short circuit protection and thermal protection.

The PAM8406 is available in SOP-16L/SOP-16(EP) package.

Features

ALTERNATIVE 5W STEREO AUDIO AMPLIFIER

Pin Assignments

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 Alternative Output: Class-D or Class-AB

 5W Output at 10% THD with a 2Ω Load and 5V Power Supply

at Class-D Mode

 3W Output at 10% THD with a 4Ω Load and 5V Power Supply

 Filterless, Low Quiescent Current and No EMI

 Low THD+N at Fully Output Range

 Superior Low Noise

 Efficiency up to 90% with Class-D Mode

 No Pop At Turn-on/off

 Fully Short Circuit Protection With Auto Recovery

 Thermal Shutdown

 Few External Components to Save the Space and Cost

 SOP-16L/SOP-16(EP) Package

Typical Applications Circuit

Applications

 LCD TVs

 Mutimedia Speakers

 AM/FM System

 DABs

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Pin Descriptions

Pin

Number

1 +OUT_L Left Channel Positive Output

2 PGNDL Power GND

3 -OUT_L Left Channel Negative Output

4 PVDDL Power VDD

5 MUTE Mute Control Input (active low)

6 VDD Analog VDD

7 INL Left Channel Input

8 VREF Internal analog reference, connect a bypass capacitor from VREF to GND.

9 MODE High: Class-D; Low: Class-AB

10 INR Right Channel Input

11 GND Analog GND

12 SHND Shutdown Control Input (active low)

13 PVDDR Power VDD

14 -OUT_R Right Channel Negative Output

15 PGNDR Power GND

16 +OUT_R Right Channel Positive Output

Pin

Name

Functional Block Diagram

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Function

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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

Operation Temperature Range -40 to +85

Maximum Junction Temperature 150

Operation Junction Temperature -40 to +125

Storage Temperature -65 to +150

Soldering Temperature 300, 5 sec

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

= +25°C, unless otherwise specified.)

A

-0.3 to V

+0.3V

DD

= +25°C, unless otherwise specified.)

A

V

°C

Thermal Information

Parameter Package Symbol Max Unit

Thermal Resistance (Junction to Ambient) SOP-16

Thermal Resistance (Junction to Case) SOP-16

θ

JA

θ

JC

110

23

°C/W

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Electrical Characteristics

(@TA = +25°C, VDD = 5V, Gain = 24dB, RL = 8Ω, both Class-AB and D mode, unless otherwise specified.)

Symbol Parameter Test Conditions Min Typ Max Units

VDD

PO

THD+N

GV

PSRR

CS

SNR Signal-to-Noise Ratio

VN

PAM8406

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Supply Voltage 2.5 5.5 V

5.0

2.6

1.3

4.0

2.0

1.0

3.14

1.5

0.76

2.55

1.45

0.63

1.8

0.92

0.44

1.6

0.76

0.36

0.15

0.11

0.15

0.11

0.15

0.11

dB

90

85

80

10

8

6

25

15

10

Output Power

Total Harmonic
Distortion Plus Noise

Closed Loop Gain

Power Supply Ripple
Rejection

Crosstalk

Output Noise

η Efficiency

Quiescent Current

IQ

Quiescent Current

THD+N = 10%, f = 1KHz, R

= 2Ω

L

(Class-D)

THD+N = 1%, f = 1KHz, RL = 2Ω

(Class-D)

THD+N = 10%, f = 1KHz, RL = 4Ω

THD+N = 1%, f = 1KHz, RL = 4Ω

THD+N = 10%, f = 1KHz, RL = 8Ω

THD+N = 1%, f = 1KHz, RL = 8Ω

= 5.0V, PO = 0.1W to 1W , RL = 8Ω

V

DD

VDD = 3.6V, PO = 0.05W to 0.5W, RL = 8Ω

VDD = 5.0V, PO = 0.1W to 2W, RL = 4Ω

VDD = 3.6V, PO = 0.05W to 2W, RL = 4Ω

VDD = 5.0V, PO = 0.1W to 2W, RL = 2Ω

(Class-D)

VDD = 3.6V, PO = 0.05W to 1W, RL = 2Ω

(Class-D)

VDD = 3V to 5V

= 5.0V, Inputs AC-Grounded with CIN =

V

DD

0.47µF

V

= 5.0V, PO = 0.5W, RL = 8Ω,

DD

= 24db

G

V

V

= 5.0V, THD = 1%, GV = 24db

DD

VDD = 5.0V, Inputs AC-Grounded

R

= 8Ω, THD = 10%

L

RL = 4Ω, THD = 10%

RL = 2Ω, THD = 10%

V

= 5.0V

DD

VDD = 3.6V

VDD = 2.5V

V

= 5.0V

DD

VDD = 3.6V

VDD = 2.5V

= 5.0V

V

DD

VDD = 3.6V

VDD = 2.5V

= 5.0V

V

DD

VDD = 3.6V

VDD = 2.5V

= 5.0V

V

DD

VDD = 3.6V

VDD = 2.5V

= 5.0V

V

DD

VDD = 3.6V

VDD = 2.5V

= 5.0V

V

DD

VDD = 3.6V

VDD = 2.5V

= 5.0V

V

DD

VDD = 3.6V

VDD = 2.5V

f = 1kHz

f = 1kHz

f = 1kHz

f = 100Hz -70

f = 1kHz -65

f = 1kHz -95 dB

f = 1kHz 90 dB

A-Weighting 100

No A-Weighting 150

Class D Mode

f = 1kHz

No Load

No Load

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W

W

W

W

W

W

%

%

%

dB

µV

%

mA

mA

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Electrical Characteristics (cont.)

(@TA = +25°C, VDD = 5V, Gain = 24dB, RL = 8Ω, both Class-AB and D mode, unless otherwise specified.)

Symbol Parameter Test Conditions Min Typ Max Units

I

MUTE

ISD

R

DS(ON)

fSW

VOS

VIH

VIL

VIH

VIL

VIH

VIL

OTP

OTH

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Muting Current

Shutdown Current

Static Drain-to-Source
On-State Resistor

Switching Frequency

Output Offset Voltage

Enable Input High
Voltage

Enable Input Low
Voltage

MUTE Input High
Voltage

MUTE Input Low
Voltage

MODE Input High
Voltage

MODE Input Low
Voltage

Over Temperature
Protection

Over Temperature
Hysterisis

VDD = 5.0V V

VDD = 2.5V to 5.5V VSD = 0.3V

IDS = 500mA, VGS = 5V

VDD = 2.5V to 5.5V

Input AC-GND, VDD = 5.0V

VDD = 5.0V

VDD = 5.0V

VDD = 5.0V

VDD = 5.0V

VDD = 5.0V

VDD = 5.0V

No Load, Junction Temperature

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= 0.3V

MUTE

PMOS 180

NMOS 140

Class-D 250 kHz

V

= 5.0V

DD

2.4 mA

< 1 µA

mΩ

10 mV

1.4
V

0.4

1.4
V

0.4

1.4
V

0.4

150

°C

30

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Typical Performance Characteristics

(@TA = +25°C, VDD = 5V, Gain = 24dB, RL = 8Ω, both Class-AB and D mode, unless otherwise specified.)

PAM8406

PAM8406

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Typical Performance Characteristics (cont.)

(@TA = +25°C, VDD = 5V, Gain = 24dB, RL = 8Ω, both Class-AB and D mode, unless otherwise specified.)

PAM8406

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Typical Performance Characteristics (cont.)

(@TA = +25°C, VDD = 5V, Gain = 24dB, RL = 8Ω, both Class-AB and D mode, unless otherwise specified.)

PAM8406

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Application Information

Application Note

1. When the PAM8406 works in Class-D with LC filters, it should be connected with the speaker before it's powered on, otherwise it will be
damaged easily.

2. When the PAM8406 works without LC filters, it's better to add a ferrite chip bead at the outgoing line of speaker for suppressing the possible
electromagnetic interference.

3. The recommended operating voltage is 5.5V. When the PAM8406 is powered with four battery cells, it should be noted that the voltage of four
new dry or alkaline batteries is over 6.0V, higher than its operation voltage, which will probably damage the device. Therefore, it's
recommended to use either four Ni-MH (Nickel Metal Hydride) rechargeable batteries or 3 dry or alkaline batteries.

4. One should not make the input signal too large. Large signal can cause the clipping of output signal when increasing the volume. This will
damage the device because of big gain of the PAM8406.

Test Setup for Performance Testing

Notes: 1. The AP AUX-0025 low pass filter is necessary for Class-D amplifier measurement with AP analyzer.

2. Two 22μH inductors are used in series with load resistor to emulate the small speaker for efficiency measurement.

Maximum Gain

As shown in block diagram (Page 2), the PAM8406 has two internal amplifier stages. The first stage's gain is externally configurable, while the

second stage's is internally fixed. The closed-loop gain of the first stage is set by selecting the ratio of R

fixed at 2x.The output of amplifier 1 serves as the input to amplifier 2, thus the two amplifiers produce signals identical in magnitude, but different

in phase by 180°. Consequently, the differential gain for the IC is

A

The PAM8406 sets maximum R

= 20*log [2*(RF/RI)]

VD

=142kΩ, minimum RI =18kΩ, so the maximum closed-gain is 24dB.

F

to RI while the second stage's gain is

F

Mode Selection

When mode pin high, it features Class-D; mode pin low, it’s class AB. Mode pin can’t be floating.

Mute Operation

The MUTE pin is an input for controlling the output state of the PAM8406. A logic low on this pin disables the outputs, and a logic high on this pin

enables the outputs. This pin may be used as a quick disable or enable of the outputs without a volume fade. Quiescent current is listed in the

electrical characteristic table. The MUTE pin can be left floating due to the internal pull-up.

Shutdown Operation

In order to reduce power consumption while not in use, the PAM8406 contains shutdown circuitry to turn off the amplifier's bias circuitry. This

shutdown feature turns the amplifier off when logic low is applied to the SHDN pin. By switching the SHDN pin connected to GND, the PAM8406

supply current draw will be minimized in idle mode. The SHDN pin can be left floating due to the internal pull-up.

PAM8406

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Application Information (cont.)

Power Supply Decoupling

The PAM8406 is a high performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output THD and

PSRR as low as possible. Power supply decoupling affects low frequency response. Optimum decoupling is achieved by using two capacitors of

different types targeting to 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 1.0μF, works best, placing it as close as possible to the device V

terminal. For filtering lower frequency noise signals, a large capacitor of 20μF (ceramic) or greater is recommended, placing it near the audio

power amplifier.

Input Capacitor (CI)

Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certain sized capacitor is needed to couple in low

frequencies without severe attenuation. But in many cases the speakers used in portable systems, whether internal or external, have little ability

to reproduce signals below 100Hz to 150Hz. Thus, using a large input capacitor may not increase actual system performance. In this case, input

capacitor (C

In addition to system cost and size, click and pop performance is affected by the size of the input coupling capacitor, C

capacitor requires more charge to reach its quiescent DC voltage (nominally 1/2 V

feedback and is apt to create pops upon device enable. Thus, by minimizing the capacitor size based on necessary low frequency response,

turn-on pops can be minimized.

Analog Reference Bypass Capacitor (C

The Analog Reference Bypass Capacitor (C

from shutdown mode, C

supply coupling into the output drive signal. This noise is from the internal analog reference to the amplifier, which appears as degraded PSRR

and THD+N.

A ceramic bypass capacitor (C

bypass capacitor reduces clicking and popping noise from power on/off and entering and leaving shutdown.

) and input resistance (RI) of the amplifier form a high-pass filter with the corner frequency determined by equation below,

I

1



f

C

R2



C

I

I

. A larger input coupling

I

). This charge comes from the internal circuit via the

DD

)

BYP

) is the most critical capacitor and serves several important functions. During start-up or recovery

BYP

determines the rate at which the amplifier starts up. The second function is to reduce noise caused by the power

BYP

) with values of 0.47μF to 1.0μF is recommended for the best THD and noise performance. Increasing the

BYP

Under Voltage Lock-Out (UVLO)

The PAM8406 incorporates circuitry designed to detect low supply voltage. When the supply voltage drops to 2.0V or below, the PAM8406

outputs are disabled, and the device comes out of this state and starts to normal function when V

≥ 2.2V.

DD

Short Circuit Protection (SCP)

The PAM8406 has short circuit protection circuitry on the outputs to prevent damage to the device when output-to-output or output-to-GND short

occurs. When a short circuit is detected on the outputs, the outputs are disabled immediately. If the short was removed, the device activates

again.

Over Temperature Protection

Thermal protection on the PAM8406 prevents the device from damage when the internal die temperature exceeds +150°C. There is a 15 degree

tolerance on this trip point from device to device. Once the die temperature exceeds the thermal set point, the device outputs are disabled. This

is not a latched fault. The thermal fault is cleared once the temperature of the die is reduced by 30°C. This large hysteresis will prevent motor

boating sound well and the device begins normal operation at this point without external system intervention.

DD

PAM8406

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Ordering Information

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PAM8406

Part Number Part Marking Package Type Standard Package

PAM8406DR

PAM8406ER

Marking Information

PAM8406

XATYWWLL

PAM8406

XATYWWLL

SOP-16 2500 Units/Tape&Reel

SOP-16(EP) 2500 Units/Tape&Reel

PAM8406

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Package Outline Dimensions (All dimensions in mm.)

SOP-16

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Package Outline Dimensions (All dimensions in mm.)

SOP-16(EP)

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PAM8406

PAM8406

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IMPORTANT NOTICE

LIFE SUPPORT

PAM8406

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