PAM8008DR - DIODES INC - Datasheet.Live

PAM8008

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3W STEREO CLASS-D with DC VOLUME,

POWER LIMIT and ANTI-SATURATION

Description

The PAM8008 is a 3W, Class-D audio amplifier. Advanced 64-step

DC volume control minimizes external components and allows

speaker volume control.

Integrated power limit technology which suppress the output signal

clip automatically due to the over level input signal. It offers low

THD+N and protect speaker.

Integrated anti-saturation technology which suppress the output

signal clip automatically when supply voltage changes. It offers low

THD+N, to produce high-quality sound reproduction.

PAM8008 has an additional noise reduction circuit which achieves

6dB noise attenuation. This circuit may help eliminate external

filtering, thereby saving the board space and components cost.

The PAM8008 features SCP (short circuit protection), OTP and

thermal shutdown.

The PAM8008 is available in SOP-16L package.

Features

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

• 2.4W Output at 1% THD with a 4 Load and 5V Power Supply

• Filterless, Low Quiescent Current and Low EMI

• Low THD+N

• Power Limit Function to Protect Speaker when Occuring Large

Input

• 64-Step DC Volume Control from -80dB to +20dB

• 6dB Effective Noise Reduction

• Superior Low Noise: 60µV

• Minimize Pop/Clip Noise

• High Efficiency Up to 90%

• Auto Recovery Short Circuit Protection

• Thermal Shutdown

• Pb-Free Package

Pin Assignments

Applications

• LCD Monitors / TV Projectors

• Notebook/All-In-One Computers

• Portable Speakers

• Portable DVD Players, Game Machines

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Typical Applications Circuit

Pin Descriptions

Number

Name Function

1 SD

Full Chip ShutdownControl Input (active low).

2 BYPASS

Bias Voltage for Power Amplifiers.

3 RINN

Negative Input of Right Channel Power Amplifier.

4 PL

Connect PL to GND for Power Limit Setting.

5, 12, 13 GND Ground Connection.

6 LINN

Negative Input of Left Channel Power Amplifier.

7 VOLUME

DC Volume Control to Set the Gain of Class-D.

8 MUTE

Mute Control Input (active high).

9 LOUTP

Positive Output of Left Channel Power Amplifier.

10, 15 VDD Power Supply.

11 LOUTN

Negative Output of Lef t Channel Power Amplifier.

14 ROUTN

Negative Output of Right Channel Power Amplifier.

16 ROUTP

Positive Output of Right Channel Power Amplifier.

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Functional Block Diagram

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

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 V

Input Voltage -0.3 to VDD +0.3

Operational Junction Temperature -40 to +125

°C

Storage Temperature -65 to +150

Soldering Temperature 300, 5 sec

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

Parameter Rating Unit

Supply Voltage Range 2.5 to 5.5 V

Ambient OperationTemperature Range -20 to +85 °C

Junction Temperature Range -20 to +125

Thermal Information

Parameter Package Symbol Max Unit

Thermal Resistance (Junction to Ambient) SOP-16L θJA 110 °C/W

Thermal Resistance (Junction to Case) SOP-16L θJC 23

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Electrical Characteristics (@TA = +25°C, VDD = 5V, Gain = Maximum, RL = 8Ω, unless otherwise specified.)

Parameter Symbol Test Conditions Min Typ Max Units

Supply Voltage Range VDD 2.5 5.5 V

Quiescent Current IQ No Load 8 mA

Output Offset Voltage VOS No Load 10 mV

Drain-Source On-State Resistance RDS(ON) I

DS = 0.5A P MOSFET 0.31 Ω

N MOSFET 0.21

Output Power PO THD+N = 1%

f = 1kHz

RL = 8Ω 1.4 W

RL = 4Ω 2.4

Total Harmonic Distortion Plus Noise THD+N RL = 8Ω, PO = 0.85W, f = 1KHz 0.08 %

RL = 4Ω, PO = 1.75, f = 1KHz 0.08

Power Supply Ripple Rejection PSRR Input AC-GND, f = 1KHz, VPP = 200mV 70 dB

Channel Separation CS PO = 1W, f = 1KHz -95 dB

Oscillator Frequency fOSC 200 250 300 kHz

Efficiency η PO = 1.1W, f =1 kHz, RL = 8Ω 87 %

PO = 2.4W, f =1 kHz, RL = 4Ω 83 %

Noise VN Input AC-GND A-Weighting 60 µV

No A-Weighting 80

Signal Noise Ratio SNR f = 20 - 20kHz, THD = 1% 95 dB

Turn-On Time TON VDD = 5V, CBYP = 1µF 1.2 S

Mute Current IMUTE MUTE = VDD 4 10 mA

Shutdown Current ISD VSD = 0V 1 µA

Logic Input High VIH 1.4 V

Logic Input Low VIL 0.6

Over Temperature Protection OTP 150 °C

Over Temperature Hysteresis OTH 40 °C

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Typical Performance Characteristics (@TA = +25°C, VDD = 5V, GV = 20dB, RL = 8Ω, unless otherwise specified.)

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Typical Performance Characteristics (cont.) (@TA = +25°C, VDD = 5V, GV = 20dB, RL = 8Ω, unless otherwise specified.)

PAM8008

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Typical Performance Characteristics (cont.) (@TA = +25°C, VDD = 5V, GV = 20dB, RL = 8Ω, unless otherwise specified.)

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Typical Performance Characteristics (cont.) (@TA = +25°C, VDD = 5V, GV = 20dB, RL = 8Ω, unless otherwise specified.)

Table 1. DC Volume Control

STEP Gain (dB) Volume (V) STEP Gain (dB) Volume (V)

1 19.84 0 to 0.201 33 6.60 2.461 to 2.533

2 19.42 0.201 to 0.275 34 6.24 2.533 to 2.605

3 19.00 0.275 to 0.347 35 5.88 2.605 to 2.678

4 18.60 0.347 to 0.419 36 5.51 2.678 to 2.751

5 18.21 0.419 to 0.491 37 5.16 2.751 to 2.823

6 17.83 0.491 to 0.563 38 4.79 2.823 to 2.897

7 17.46 0.563 to 0.633 39 4.43 2.897 to 2.969

8 16.92 0.633 to 0.701 40 4.06 2.969 to 3.043

9 16.40 0.701 to 0.771 41 3.70 3.043 to 3.114

10 15.90 0.771 to 0.849 42 3.33 3.114 to 3.186

11 15.41 0.849 to 0.929 43 2.96 3.186 to 3.259

12 14.93 0.929 to 1.005 44 2.58 3.259 to 3.332

13 14.47 1.005 to 1.079 45 2.21 3.332 to 3.403

14 14.02 1.079 to 1.153 46 1.83 3.403 to 3.476

15 13.58 1.153 to 1.225 47 1.44 3.476 to 3.551

16 13.15 1.225 to 1.297 48 1.05 3.551 to 3.621

17 12.72 1.297 to 1.371 49 0.66 3.621 to 3.695

18 12.30 1.371 to 1.443 50 0.26 3.695 to 3.767

19 11.89 1.443 to 1.517 51 -0.14 3.767 to 3.839

20 11.49 1.517 to 1.589 52 -1.19 3.839 to 3.909

21 11.09 1.589 to 1.661 53 -2.27 3.909 to 3.979

22 10.70 1.661 to 1.733 54 -3.19 3.979 to 4.045

23 10.31 1.733 to 1.807 55 -5.18 4.045 to 4.116

24 9.92 1.807 to 1.879 56 -7.16 4.116 to 4.195

25 9.55 1.879 to 1.951 57 -9.11 4.195 to 4.273

26 9.17 1.951 to 2.025 58 -11.01 4.273 to 4.347

27 8.80 2.025 to 2.097 59 -17.13 4.347 to 4.421

28 8.42 2.097 to 2.169 60 -22.95 4.421 to 4.493

29 8.06 2.169 to 2.243 61 -29.07 4.493 to 4.565

30 7.69 2.243 to 2.315 62 -33.50 4.565 to 4.637

31 7.33 2.315 to 2.389 63 -39.33 4.637 to 4.708

32 6.69 2.389 to 2.461 64 -58.62 4.708 to Max

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Application Information

Power Limit Function

When connect Pin 4 to GND or floating, the PAM8008 power is limited at 2.5W. Different from other company’s power limit, the power limit circuit

of PAM8008 sets a limit on the output peak voltage, and the value is lower than the supply voltage (VDD), it means the THD+N always lower than

10% when power limit works. When the PAM8008 enters in power limit mode, the gain changes depending on the input audio signal amplitude

and the attack, release time. The gain changes constantly as the audio signal increase or decrease. Every gain step size is about 0.4dB. If the

audio signal has near-constant amplitude or the maximum attenuation is 20dB, the gain does not change.

Anti-Saturation Function

When connect Pin 4 to high, the PAM8008 enters power limit or anti-saturation mode. Which mode is selected depending on VDD and input

audio signal amplitude. If the VDD < = 5V, it enters anti-saturation mode. If the VDD > 5V, it enters power limit mode. In anti-saturation mode, the

power is 2.3W and the THD+N is lower than 1% when VDD = 5V. If connect Pin 4 to VDD/2, it can disable power limit and antisaturation function.

Table 2. PAM8008 Power Limit and Anti-Saturation Varible Description

Varible Description Value

Gain The max gain when the PAM8008 is not in power limit

and anti-saturation mode.

20dB

(Maximum)

Attack Time The minimum time between two gain decrements. 128µs

Release Time The minimum time between two gain increments. 256mS

Table 3. PAM8008 Power Limit and Anti-Saturation Mode Setting

PL Mode

PL = Floating or

PL = 0V to 0.2V Power Limit

PL = 0.8V to VDD/2 Power Limit and

Anti-Saturation Off

PL = 3.8V to VDD VDD > 5V, Power Limit

VDD < = 5V, Anti-Saturation

Noise Reduction Function

The gain of PAM8008 will reduce 6dB when there is no audio at the input of the amplifier for 8s. The gain will recover until the input signal is

above the noise threshold.The noise threshold is set by internal voltage.

Mute Operation

The MUTE pin is an input for controlling the Class-D output state of the PAM8008. A logic low on this pin enables the outputs, and a logic high

on this pin disables 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-down.

Shutdown Operation

In order to reduce power consumption while not in use, the PAM8008 contains shutdown circuit to tur n off the amplifier's bias circuit. The

amplifier is turned off when logic low is placed on the SD pin. By connecting the SD pin to GND, the PAM8008 supply current will be minimized

in idle mode. The SD pin can be left floating due to the internal pull-up.

For the best power on/off pop performance, the amplifier should be placed in the Mute mode prior to turning on/off the

power supply.

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Application Information (cont.)

Power Supply Decoupling

The PAM8008 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 also prevents oscillations caused by long lead between the amplifier and the speaker. The

optimum decoupling is achieved by using two capacitiors of different types that target 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 resisitance (ESR) ceramic capacitor, typically 0.1µF,

is recommended, placing as close as possible to the device’s VDD lead. For filtering lower-frequency noise signals, a large capacitor of 10µF

(ceramic) or greater placed near the audio power amplifier is recommended.

Input Capacitior (CI)

Large input capacitors are both expensive and spce hungrt for portale 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 inout capacitior may not increase actual system performance. In this case, input

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

CΠ

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

reach its quiescent DC voltage (norminally ½ VDD). This charge comes from the internal circuit via the 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 (CBYP)

Analog Reference Bypass Capacitor (CBYP) is the most critical capacitor and serves several important functions. During start-up or recovery from

shutdown mode, CBYP determines the rate at which the amplifier starts up. The second function is to reduce noise produced by the power supply

caused by 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 (CBYP) of 0.47µF to 1.0µF is recommended for the best THD and noise performance. Increasing the bypass

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

Under Voltage Lock-Out

The PAM8008 incorporates circuitry designed to detect when the supply voltage is low. When the supply voltage drops to 2.2V or below, the

PAM8008 outputs are disable, and the device comes out of this state and starts to normal functional once VDD ≥ 2.4V.

Short Circuit Protection (SCP)

The PAM8008 has short circuit protection circuitry on the outputs that prevents the device from damage when output-to-output and output-to-

GND short. 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 PAM8008 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 +40°C. This large hysteresis will prevent motor

boating sound well. The device begins normal operation at this point without external system interaction.

How to Reduce EMI (Electro Magnetic Interference)

A simple solution is to put an additional capacitor 1000µF at power supply terminal for power line coupling if the traces from amplifier to speakers

are short (< 20CM).

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Application Information (cont.)

How to Reduce EMI (Electro Magnetic Interference) (cont.)

Most applications required a ferrite bead filter as shown at Figure 1. The ferrite filter reduces EMI around 1MHz and higher. When selecting a

ferrite bead, choose one with high impedance at high frequencies, and low impedance at low frequencies (MH2012HM221-T).

Figure 1: Ferrite Bead Filter to Reduce EMI

PCB Layout Guidelines Grounding

At this stage it is paramount to notice the necessity of separate grounds. Noise currents in the output power stage need to be returned to output

noise ground and nowhere else. Were these currents to circulate elsewhere, they may get into the power supply, the signal ground, etc, worse

yet, they may form a loop and radiate noise. Any of these cases results in degraded amplifier performance. The logical returns for the output

noise currents associated with Class-D switching are the respective GND pins for each channel. The switch state diagram illustrates that GND is

instrumental in nearly every switch state. This is the perfect point to which the output noise ground trace should return. Also note that output

noise ground is channel specific. A two channel amplifier has two seperate channels and consequently must have two seperate output noise

ground traces. The layout of the PAM8008 offers separate GND connections for each channel and in some cases each side of the bridge.

Output noise grounds must be tied to system ground at the power in exclusively. Signal currents for the inputs, reference, etc need to be

returned to quite ground. This ground is only tied to the signal components and the GND pin, and GND then tied to system ground.

Test Setup for Performance Testing (Class D)

1. When the PAM8008 works with LC filters, it should be connected with the speaker before it's powered on, otherwise it will be damaged easily.

2. When the PAM8008 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 absolute maximum rating of the PAM8008 operation voltage is 6.0V. When the PAM8008 is powered with four battery cells, it should be

noted that the voltage of four new dry or alkaline batteries is over 6V, higher than its maximum operation voltage, which probably make the

device damaged. Therefore, it's recommended to use either four Ni-MH (Nickel Metal Hydride) rechargeable batteries or three dry or alkaline

batteries.

4. The input signal should not be too high, if too high, it will cause the clipping of output signal when increasing the volume. Because the DC

volume control of the PAM8008 has big gain, it will make the device damaged.

5. When testing the PAM8008 without LC filters b y using resistor instead of speaker as the output load, the test results, e.g. THD or efficiency,

will be worse than those using speaker as load.

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.

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Ordering Information

Part Number Package Type Standard Package

PAM8008DR SOP-16L 2500 Units/Tape&Reel

Marking Information

PAM8008

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Package Outline Dimensions (All dimensions in mm.)

SOP-16L

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