A Product Line of Diodes Incorporated PAM8008 3W STEREO CLASS-D with DC VOLUME, POWER LIMIT and ANTI-SATURATION Description Pin Assignments 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 * Applications * LCD Monitors / TV Projectors * Notebook/All-In-One Computers * Portable Speakers * Portable DVD Players, Game Machines 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: 60V * Minimize Pop/Clip Noise * High Efficiency Up to 90% * Auto Recovery Short Circuit Protection * Thermal Shutdown * Pb-Free Package PAM8008 Document number: DSxxxxx Rev. 1 - 0 1 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Typical Applications Circuit Pin Descriptions Pin Number 1 2 3 4 5, 12, 13 6 7 8 9 10, 15 11 14 16 Pin Name SD BYPASS RINN PL GND LINN VOLUME MUTE LOUTP VDD LOUTN ROUTN ROUTP Function Full Chip ShutdownControl Input (active low). Bias Voltage for Power Amplifiers. Negative Input of Right Channel Power Amplifier. Connect PL to GND for Power Limit Setting. Ground Connection. Negative Input of Left Channel Power Amplifier. DC Volume Control to Set the Gain of Class-D. Mute Control Input (active high). Positive Output of Left Channel Power Amplifier. Power Supply. Negative Output of Lef t Channel Power Amplifier. Negative Output of Right Channel Power Amplifier. Positive Output of Right Channel Power Amplifier. PAM8008 Document number: DSxxxxx Rev. 1 - 0 2 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Functional Block Diagram Absolute Maximum Ratings (@TA = +25C, 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 Supply Voltage Input Voltage Operational Junction Temperature Storage Temperature Soldering Temperature Rating 6.0 Unit V -0.3 to VDD +0.3 -40 to +125 -65 to +150 300, 5 sec C Recommended Operating Conditions (@TA = +25C, unless otherwise specified.) Parameter Supply Voltage Range Ambient OperationTemperature Range Junction Temperature Range Rating 2.5 to 5.5 -20 to +85 -20 to +125 Unit V C Thermal Information Package Symbol Max Thermal Resistance (Junction to Ambient) Parameter SOP-16L JA 110 Thermal Resistance (Junction to Case) SOP-16L JC 23 PAM8008 Document number: DSxxxxx Rev. 1 - 0 3 of 14 www.diodes.com Unit C/W October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Electrical Characteristics (@TA = +25C, VDD = 5V, Gain = Maximum, RL = 8, unless otherwise specified.) Parameter Supply Voltage Range Quiescent Current Output Offset Voltage Drain-Source On-State Resistance Output Power Symbol IQ VOS No Load RDS(ON) PO THD+N Power Supply Ripple Rejection PSRR Channel Separation CS Oscillator Frequency fOSC Noise Signal Noise Ratio VN SNR Turn-On Time TON Mute Current IMUTE Shutdown Current ISD Logic Input High VIH Logic Input Low VIL OTP OTH Over Temperature Protection Over Temperature Hysteresis PAM8008 Document number: DSxxxxx Rev. 1 - 0 Min Typ 2.5 No Load Total Harmonic Distortion Plus Noise Efficiency Test Conditions VDD IDS = 0.5A 5.5 Units V 8 mA 10 mV P MOSFET N MOSFET 0.31 0.21 RL = 8 1.4 RL = 4 2.4 RL = 8, PO = 0.85W, f = 1KHz 0.08 RL = 4, PO = 1.75, f = 1KHz 0.08 THD+N = 1% f = 1kHz Max Input AC-GND, f = 1KHz, VPP = 200mV 70 PO = 1W, f = 1KHz -95 200 250 W % dB dB 300 kHz PO = 1.1W, f =1 kHz, RL = 8 87 % PO = 2.4W, f =1 kHz, RL = 4 A-Weighting Input AC-GND No A-Weighting f = 20 - 20kHz, THD = 1% 83 % VDD = 5V, CBYP = 1F 1.2 60 80 95 4 MUTE = VDD VSD = 0V V dB S 10 mA 1 A 1.4 0.6 150 40 4 of 14 www.diodes.com V C C October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Typical Performance Characteristics (@TA = +25C, VDD = 5V, GV = 20dB, RL = 8, unless otherwise specified.) PAM8008 Document number: DSxxxxx Rev. 1 - 0 5 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Typical Performance Characteristics (cont.) (@TA = +25C, VDD = 5V, GV = 20dB, RL = 8, unless otherwise specified.) PAM8008 Document number: DSxxxxx Rev. 1 - 0 6 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Typical Performance Characteristics (cont.) (@TA = +25C, VDD = 5V, GV = 20dB, RL = 8, unless otherwise specified.) PAM8008 Document number: DSxxxxx Rev. 1 - 0 7 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Typical Performance Characteristics (cont.) (@TA = +25C, VDD = 5V, GV = 20dB, RL = 8, unless otherwise specified.) Table 1. DC Volume Control STEP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Gain (dB) 19.84 19.42 19.00 18.60 18.21 17.83 17.46 16.92 16.40 15.90 15.41 14.93 14.47 14.02 13.58 13.15 12.72 12.30 11.89 11.49 11.09 10.70 10.31 9.92 9.55 9.17 8.80 8.42 8.06 7.69 7.33 6.69 PAM8008 Document number: DSxxxxx Rev. 1 - 0 Volume (V) 0 to 0.201 0.201 to 0.275 0.275 to 0.347 0.347 to 0.419 0.419 to 0.491 0.491 to 0.563 0.563 to 0.633 0.633 to 0.701 0.701 to 0.771 0.771 to 0.849 0.849 to 0.929 0.929 to 1.005 1.005 to 1.079 1.079 to 1.153 1.153 to 1.225 1.225 to 1.297 1.297 to 1.371 1.371 to 1.443 1.443 to 1.517 1.517 to 1.589 1.589 to 1.661 1.661 to 1.733 1.733 to 1.807 1.807 to 1.879 1.879 to 1.951 1.951 to 2.025 2.025 to 2.097 2.097 to 2.169 2.169 to 2.243 2.243 to 2.315 2.315 to 2.389 2.389 to 2.461 STEP 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 8 of 14 www.diodes.com Gain (dB) 6.60 6.24 5.88 5.51 5.16 4.79 4.43 4.06 3.70 3.33 2.96 2.58 2.21 1.83 1.44 1.05 0.66 0.26 -0.14 -1.19 -2.27 -3.19 -5.18 -7.16 -9.11 -11.01 -17.13 -22.95 -29.07 -33.50 -39.33 -58.62 Volume (V) 2.461 to 2.533 2.533 to 2.605 2.605 to 2.678 2.678 to 2.751 2.751 to 2.823 2.823 to 2.897 2.897 to 2.969 2.969 to 3.043 3.043 to 3.114 3.114 to 3.186 3.186 to 3.259 3.259 to 3.332 3.332 to 3.403 3.403 to 3.476 3.476 to 3.551 3.551 to 3.621 3.621 to 3.695 3.695 to 3.767 3.767 to 3.839 3.839 to 3.909 3.909 to 3.979 3.979 to 4.045 4.045 to 4.116 4.116 to 4.195 4.195 to 4.273 4.273 to 4.347 4.347 to 4.421 4.421 to 4.493 4.493 to 4.565 4.565 to 4.637 4.637 to 4.708 4.708 to Max October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 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 Gain Attack Time Release Time Description The max gain when the PAM8008 is not in power limit and anti-saturation mode. The minimum time between two gain decrements. The minimum time between two gain increments. Value 20dB (Maximum) 128s 256mS Table 3. PAM8008 Power Limit and Anti-Saturation Mode Setting PL PL = Floating or PL = 0V to 0.2V Mode 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. PAM8008 Document number: DSxxxxx Rev. 1 - 0 9 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 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 0.1F, is recommended, placing as close as possible to the device's VDD lead. For filtering lower-frequency noise signals, a large capacitor of 10F (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, fC = 1 2RI CI 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 1/2 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 0.47F to 1.0F 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-toGND 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 +150C. 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 +40C. 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 1000F at power supply terminal for power line coupling if the traces from amplifier to speakers are short (< 20CM). PAM8008 Document number: DSxxxxx Rev. 1 - 0 10 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 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 22H inductors are used in series with load resistor to emulate the small speaker for efficiency measurement. PAM8008 Document number: DSxxxxx Rev. 1 - 0 11 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Ordering Information Part Number PAM8008DR Package Type SOP-16L Standard Package 2500 Units/Tape&Reel Marking Information PAM8008 Document number: DSxxxxx Rev. 1 - 0 12 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 Package Outline Dimensions (All dimensions in mm.) SOP-16L PAM8008 Document number: DSxxxxx Rev. 1 - 0 13 of 14 www.diodes.com October 2012 (c) Diodes Incorporated A Product Line of Diodes Incorporated PAM8008 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, 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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Copyright (c) 2012, Diodes Incorporated www.diodes.com PAM8008 Document number: DSxxxxx Rev. 1 - 0 14 of 14 www.diodes.com October 2012 (c) Diodes Incorporated Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Diodes Incorporated: PAM8008DR