PAM8006
10W STEREO CLASS-D AUDIO POWER AMPLIFIER
Description
The PAM8006 is a 10W (per channel) stereo Class-D audio amplifier with fixed gain which offers low THD+N, low EMI, and good PSRR producing high-quality sound reproduction.
The PAM8006 runs off from a 7.5V to 18V supply at much higher efficiency than competitors’ ICs.
The PAM8006 only requires very few external components, significantly saving cost and board space.
The PAM8006 is available in a 32pin QFN 5mm*5mm and TSSOP-28PP package.
Features
? 10W @ 10%THD/ Channel Output into a 8? Load at 13V ? Power Supply Range: 7.5V to 18V ? Low SNR: 95dB ? Over 90% Efficiency
? With Shutdown/Mute Function
? Over Current , Thermal, Short-Circuit Protection and UVLO ? Low THD+N
? Low Quiescent Current ? Pop Noise Suppression
? Small Package Outlines: Thin 32-pin QFN 5mm*5mm and TSSOP-28PP Package
? RoHS Pass and Green Package
Applications
? Flat Monitor /LCD TVs ? Multi-media Speaker System ?
DVD players, Game machines
? Boom Box ? Music instruments
Pin Assignments
Typical Applications Circuit
Pin Descriptions
Pin Name
Pin Number
Function
QFN5x5 TSSOP-25
RINN 2 5 Negative differential audio input for right channel. RINP 3 6 Positive differential audio input for right channel. NC 1, 8, 17, 24 — Not Connected AVDD 5 8 5VAnalog V DD MUTE 4 7 A logic high on this pin disables the outputs and a logic low enables the outputs. LINP 6 9 Positive differential audio input for left channel. LINN 7 10 Negative differential audio input for left channel. PGNDL 9, 16 11, 18 Power ground for left channel H-bridge. PVCCL 10, 15 12, 17 Power supply for left channel H-bridge not connected to PVCCRor AVCC. LOUTN 11 13 Class-D 1/2-H-bridge negative output for left channel. BSLN 12 14 Bootstrap I/O for left channel, negative high-side FET. BSLP 13 15 Bootstrap I/O for left channel, positive high-side FET. LOUTP 14 16 Class-D 1/2-H-bridge posi tive output for left channel.
COSC 18 19
I/O for charge/discharging currents onto capacitor for ramp generator triangle
wave biased at V2P5.
AVCC 22 23 High-voltage analog power supply (7.5V to 18V).
V2P5 19 20
2.5V Reference for analog cells, as well as reference for unused audio input
when using single-ended inputs.
AGND 20 21 Analog GND
SD 23 24
Shutdown signal for IC (low = shutdown, high = operational). TTL logic levels with
compliance to V CC .
VCLAMP 21 22 Internally generated voltage supply bootstrap capacitors. PGNDR 25, 32 4, 25 Power ground for right channel H-br idge. PVCCR 26, 31 3, 26 Power supply for right channel H-bridge not connected to PVCCL or AVCC. ROUTP 27 27 Class-D 1/2-H-bridge posi tive output for right channel. BSRP 28 28 Bootstrap I/O for right channel, positive high-side FET. BSRN 29 1 Bootstrap I/O for right channel, negative high-side FET. POUTN 30 2 Class-D 1/2-H-bridge negative output for right channel.
Functional Block Diagram
Absolute Maximum Ratings (@T A = +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.
Recommended Operating Conditions (@T A = +25°C, unless otherwise specified.)
Thermal Information
Parameter Package Symbol Max Unit
Thermal Resistance (Junction to Ambient) QFN 5x5
θJA
18.1 °C/W
TSSOP-28PP 27.8
Thermal Resistance (Junction to Case) QFN 5x5
θJC
7.6 TSSOP-28PP 14.4 Internal Power Dissipation (T A = +25°C) QFN 5x5 P D
5.52
W TSSOP-28PP 3.60
The exposed PAD must be soldered to a thermal land on the PCB
Electrical Characteristics (@T A = +25°C, V CC = 12V, G V = 24dB, R L = 8?, unless otherwise specified.)
Symbol Parameter
Test Conditions Min Typ Max Units
V CC
Supply Power 7.5 12 18 V P O
Continuous Output Power
THD+N = 0.1%, f = 1kHz, R L = 8?
5 W THD+N = 1.0%, f = 1kHz, R L = 8?
8 W THD+N = 10%, f = 1kHz, R L = 8?, V CC = 13V 10 W THD+N = 10%, f = 1kHz, R L = 4? (Note 1)
15 W THD+N Total Harmonic Distortion Plus Noise Po = 5W, f = 1kHz, R L = 8? 0.1 % I CC Quiescent Current
(No Load) 20 30 mA I SD Shutdown Quiescent Current in Shutdown Mode
SHUTDOWN = 0V 4 10 μA
R DS(ON) Static Drain-to-Source On-State Resistor
V CC = 12V I O = 1A T A = +25°C
High Side 300 m ? Low Side 300
Total 600
PSRR Power Supply Ripple Rejection 1V PP Ripple, f = 1kHz,
Input AC-Coupled to Ground -60 dB f OSC Oscillator Frequency
C OSC = 220pF
250 V N Output Integrated Noise Floor 20Hz to 22kHz, A-Weighting
-90 μV C S
Crosstalk
P O = 3W, R L = 8?, f = 1kHz
-80 dB SNR
Signal-to-Noise
Maximum Outout @ THD+N < 0.5%, f = 1kHz 95 dB |V OS |
Output Offset Voltage (Measured Differentially) INN and INP Connected Together 30 mV V2P5 2.5V Bias Voltage
No Load
2.5
AVDD
Internal Analog Supply Voltage
V CC = 7.5 to 18 5 5.5 OTS Over Temperature Shutdown
150
°C
OTH Temperature Hysterisis
40
Note:
1. Heat sink is required for high power output.
Typical Performance Characteristics (@T A = +25°C, R L = 8?, V CC = 12V, G V = 24dB, unless otherwise specified.)
Typical Performance Characteristics (cont.) (@T A = +25°C, R L = 8?, V CC = 12V, G V = 24dB, unless otherwise specified.)
Application Information
Power and Heat Dissipation
Choose speakers that are able to stand large output power from the PAM8006. Otherwise, speaker may suffer damage.
Heat dissipation is very important when the device works in full power operation. Two factors affect the heat dissipation, the efficiency of the device that determines the dissipation power, and the thermal resistance of the package that determines the heat dissipation capability.
In operation, some of power is dissipated to the resistors. Power Dissipation: P LOSS = (P O *(1-η)/η)*2
The PAM8006’s efficiency is 90% with 10W ouput and 8? load. The dissipation power is 2.22W.
Thermal resistance of junction to ambient of the QFN package is 18.1°C/W and the junction temperature T J = P LOSS *θJA +T A , where T A is ambient temperature. If the ambient temperature is +85°C, the QFN’s junction temperature
T J = 2.22*18.1 + 85 = +125°C
which is lower than +150°C rated junction temperature.
If the rated workable junction temperature is +150°C, the relationship between ambient temperature and permitted P LOSS is shown in below diagram.
From the diagram, it can be found that when the device works at 10W/8? load the dissipation power is 1.1W per channel, 2.2W total, the permitted ambient temperature is over +100°C. This is proven by actual test. The PAM8006 can work in full output power under +85°C ambient temperature.
Heat Dissipation in PCB Design
Generally, class-D amplifiers are high efficiency and need no heat sink. For high power ones that has high dissipation power, the heat sink may also not necessary if the PCB is carefully designed to achieve good heat dissipation by the PCB itself.
Dual-Side PCB
To achieve good heat dissipation, the PCB’s copper plate should be thicker than 0.035mm and the copper plate on both sides of the PCB should be utilized for heat sink.
The thermal pad on the bottom of the device should be soldered to the plate of the PCB, and via holes, usually 9 to 16, should be drilled in the PCB area under the device and deposited copper on the vias should be thick enough so that the heat can be dissipated to the other side of the plate. There should be no insulation mask on the other side of the copper plate. It is better to drill more vias on the PCB around the device if possible.
Application Information (cont.)
4-Layer PCB
If it is 4-layer PCB, the two middle layers of grounding and power can be employed for heat dissipation, isolating them into serval islands to avoid short between ground and power.
Consideration for EMI
Filters are not required if the traces from the amplifier to the speakers are short (< 20cm). But most applications require a ferrite bead filter as shown in below figure. The ferrite bead filter reduces EMI of around 1MHz and higher to meet the FCC and CE's requirements. It is recommended to use a ferrite bead with very low impedances at low frequencies and high impedance at high frequencies (above 1MHz).
The EMI characteristics are as follows after employing the ferrite bead.
Vertical Polarization
Horizontal Polarization
MUTE Operation
The MUTE pin is an input for controlling the output state of the PAM8006. A logic high on this pin disables the outputs and low enables the outputs. This pin may be used as a quick disable or enable of the outputs.
For power saving, the SD pin should be used to reduce the quiescent current to the absolute minimum level.
Shutdown Operation
The PAM8006 employs a shutdown operation mode to reduce supply current to the absolute minimum level during periods of non-use to save power. The SD input terminal should be held high during normal operation when the amplifier is in use. Pulling SD low causes the outputs to mute and the amplifier to enter a low-current state. SD should never be left unconnected to prevent the amplifier from unpredictable operation.
For the best power-off pop performance, the amplifier should be set in shutdown mode prior to removing the power supply voltage.
Application Information (cont.)
Internal 2.5V Bias Generator Capacitor Selection
The internal 2.5V bias generator (V2P5) provides the internal bias for the preamplifier stage. The external input capacitors and this internal reference allow the inputs to be biased within the optimal common-mode range of the input preamplifiers.
The selection of the capacitor value on the V2P5 terminal is critical for achieving the best device performance. During startup or recovery from shutdown state, the V2P5 capacitor determines the rate at which the amplifier starts up. When the voltage on the V2P5 capacitor equals 0.75 x V2P5, or 75% of its final value, the device turns on and the Class-D outputs start switching. The startup time is not critical for the best de-pop performance since any heard pop sound is the result of the Class-D output switching-on other than that of the startup time. However, at least a 0.47μF capacitor is recommended for the V2P5 capacitor.
Another function of the V2P5 capacitor is to filter high frequency noise on the internal 2.5V bias generator.
Power Supply Decoupling, C S
The PAM8006 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 oscillations caused by long lead between the amplifier and the speaker. The optimum decoupling is achieved by using two capacitors 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-seriesresistance (ESR) ceramic capacitor, typically 1μF, is recommended, placing as close as possible to the device’s VCC lead. To filter lowerfrequency noises, a large aluminum electrolytic capacitor of 10μF or greater is recommended, placing near the audio power amplifier. The 10μF capacitor also serves as a local storage capacitor for supplying current during large signal transients on the amplifier outputs.
BSN and BSP Capacitors
The full H-bridge output stages use NMOS transistors only. They therefore require bootstrap capacitors for the high side of each output to turn on correctly. A at least 220nF ceramic capacitor, rated for at least 25V, must be connected from each output to its corresponding bootstrap input. Specifically, one 220nF capacitor must be connected from xOUTP to xBSP, and another 220nF capacitor from xOUTN to xBSN. It is recommended to use 1μF BST capacitor to replace 220nF (pin15, pin16, pin35 and pin36) for lower than 100Hz applications.
VCLAMP Capacitors
To ensure that the maximum gate-to-source voltage for the NMOS output transistors not exceeded, two internal regulators are used to clamp the gate voltage. Two 1μF capacitors must be connected from VCLAMP to ground and must be rated for at least 25V. The voltages at the VCLAMP terminals vary with V CC and may not be used to power any other circuitry.
Internal Regulated 5-V Supply (AVDD)
The AVDD terminal is the output of an internallygenerated 5V supply, used for the oscillator, preamplifier. It requires a 0.1μF to 1μF capacitor, placed very close to the pin to Ground to keep the regulator stable. The regulator may not be used to power any external circuitry.
Differential Input
The differential input stage of the amplifier eliminates noises that appear on the two input lines of the channel. To use the PAM8006 with a differential source, connect the positive lead of the audio source to the INP input and the negative lead from the audio source to the INN input. To use the PAM8006 with a single-ended source, acground the INP input through a capacitor equal in value to the input capacitor on INN and apply the audio source to the INN input. In a single-ended input application, the INP input should be acgrounded at the audio source other than at the device input for best noise performance.
Using Low-ESR Capacitors
Low-ESR capacitors are recommended throughout this application section. A real (with respect to ideal) capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance the more the real capacitor behaves as an ideal capacitor.
Short-Circuit Protection
The PAM8006 has short circuit protection circuitry on the outputs to prevent damage to the device when output-to-output shorts, output-to-GND shorts, or output-to-VCC shorts occur. Once a short-circuit is detected on the outputs, the output drive is immediately disabled. This is a latched fault and must be reset by cycling the voltage on the SD pin to a logic low and back to the logic high state for normal operation. This will clear the short-circuit flag and allow for normal operation if the short was removed. If the short was not removed, the protection circuitry will again activate.
Application Information (cont.)
Selection of C OSC and Frequency Setting
The switching frequency is determined by the values of components connected to C OSC and calculated as follows:
f OSC = 22 / (C OSC *R)
R is the internal resistor and the vaule is 400k ? and with ±20% tolerance.The frequency may varies from 200kHz to 300kHz by adjusting the values of C OSC . The recommended value is C OSC = 220pF for a switching frequency of 250kHz.
Selection of Gain and Input Signal Amplitude
The PAM8006 has two internal amplifier stages with fixed gain. The pre-amp stage gain is 10X, while the second stage gain is 5X.
The pre-amp is powered internally by the 5V value of AVDD. At maximum pre-amp gain operation for avoiding the pre-amp saturation, it's worth noting that the peak value of input signal (V P ) shouldn't exceed 250mV when the THD+N of PAM8006 is lower than 1%; and the V P value shouldn't exceed 300mV when the THD+N is lower than 10%. Total gain is calculated as follows:
Gain = 20log[100k/(10k+RIN)*5]
(R IN is external input resistor.)
Thermal Protection
Thermal protection on the PAM8006 prevents damage to the device 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 set thermal point, the device enters into 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 is reduced by +40°C. The device begins normal operation at this point without external system intervention.
Test Setup for Performance Testing
Notes: 2. The Audio Precision(AP) AUX-0025 low pass filter is necessary for Class-D amplifier measurement with AP analyzer.
3. Two 22μH inductors are used in series with load resistor to emulate the small speaker for effic iency measurement.
Ordering Information
Part Number Part Marking Package Type
Standard Package
PAM8006TR PAM8006 XATYWWLL QFN5x5 3000 Units/Tape&Reel PAM8006HR
PAM8006 XATYWWLL
TSSOP-28PP 2500 Units/Tape&Reel
Marking Information
Package Outline Dimensions (All dimensions in mm.)
QFN5x5-32
Package Outline Dimensions (cont.) (All dimensions in mm.)
TSSOP-28PP
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