PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Key Features General Description n 2.5W Output at 10% THD with a 4 Ω Load and 5V Power Supply n Filterless, Low Quiescent Current and Low EMI n High Efficiency up to 88% n Superior Low Noise n Short Circuit Protection n Thermal Shutdown n Few External Components to Save Space and Cost n MSOP-8, SOP-8 and DFN3x3 Packages Available n Pb-Free Package The PAM8302A is a 2.5W class-D mono audio amplifier. Its low THD+N feature offers highquality sound reproduction. The new filterless architecture allows the device to drive speaker directly instead of using low-pass output filters, therefore save system cost and PCB area. With the same number of external components, the efficiency of the PAM8302A is much better than that of class-AB cousins. It can optimize battery life thus is ideal for portable applications. The PAM8302A is available in MSOP-8, SOP-8 and DFN3x3 packages. Applications n n n n n n PMP/MP4 GPS Portable Speakers Walkie Talkie Handsfree phones/Speaker Phones Cellular Phones Typical Application 1μF 6 VDD Ci Ri IN- 4 INVO- 8 Differential Input Ci 3 IN+ ON PAM8302A Ri 1 IN+ VO+ 5 /SD OFF GND 7 Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 1 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Block Diagram VDD IN+ VO+ DRIVER MODULATOR VO- IN- THERMAL PROTECTION INTERNAL OSCILLATOR SHUTDOWN SD SHORT PROTECTION OSC GND Pin Configuration & Marking Information Top View DFN3x3 Top View MSOP-8/SOP-8 SD 1 IN+ 3 P8302A XXXXYW NC 2 IN- 4 8 VO- SD 1 7 GND NC 2 6 VDD IN+ 3 5 VO+ IN- 4 P8302A XXXXYW 8 VO- 7 GND 6 VDD 5 VO+ Pin Number 1 Pin name SD Description Shutdown terminal ,active low 2 NC No connection 3 IN+ Positive differential input 4 IN- Negative differential input 5 VO+ Positive BTL output 6 VDD Analog power supply 7 GND Ground 8 VO- Negative BTL output X: Internal Code Y: Year W: Week Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 2 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Absolute Maximum Ratings 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 . Supply Voltage at no Input Signal...................6.6V Input Voltage.............................-0.3V to V DD +0.3V Maximum Junction Temperature..................150 ° C Storage Temperature.....................-65 ° C to 150 ° C Soldering Temperature....................... 300 ° C ,5sec Recommended Operating Conditions Supply voltage Range........................ 2.5V to 5.5V Max. Supply Voltage (for Max. duration of 30 minutes)................................................6.0V Ambient Operation Temperature Range......................................... -40 ° C to 85 ° C Junction Temperature Range.........-40 ° C to 125 ° C Thermal Information Parameter Thermal Resistance (Junction to ambient) Symbol θJA Package Maximum Unit SOP-8 115 °C/W MSOP-8 180 °C/W DFN 3x3-8 47.9 °C/W Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 3 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Electrical Characteristic V DD=5V, Gain = 24dB, R L=4 Ω, T A=25 ° C，unless otherwise noted. PARAMETER Supply Voltage Range SYMBOL CONDITIONS VDD IQ No Load Shutdown Current ISHDN VSHDN=0V Peak Efficiency Total Harmonic Distortion Plus Noise Gain Power Supply Ripple Rejection PO 4 f=1kHz, RL=4Ω VDD=5V 2.50 THD+N=10% VDD=3.6V 1.25 f=1kHz, RL=4Ω VDD=5V 2.00 THD+N=1% VDD=3.6V 0.95 f=1kHz, RL=8Ω VDD=5V 1.50 THD+N=10% VDD=3.6V 0.80 F=1kHz, RL=8Ω VDD=5V 1.30 THD+N=1% VDD=3.6V 0.65 η THD+N f=1kHz 85 RL = 8Ω，PO=0.1W, f=1kHz 0.30 RL = 8Ω，PO=0.5W, f=1kHz 0.45 RL = 4Ω，PO=0.1W, f=1kHz 0.35 RL = 4Ω，PO=0.5W, f=1kHz 0.40 Gv PSRR TYP 2.5 Quiescent Current Output Power MIN No input, f=1kHz, Vpp=200mV 45 MAX UNITS 5.5 V 8 mA 1 μA W 88 % % 24 dB 50 dB Dynamic Range Dyn f=20 to 20kHz 90 dB Signal to Noise Ratio SNR f =20 to 20kHz 80 dB No A-weighting 180 A-weighting 120 Noise Vn Oscillator Frequency fOSC Drain-Source On-State Resistance RDS(ON) 200 IDS=100mA 250 P MOSFET 0.45 N MOSFET 0.20 μV 300 kHz Ω 1.2 V SHDN Input High VS H SHDN Input Low VSL Over Temperature Protection OTP 135 °C Over Temperature Hysteresis OTH 30 °C 0.4 V Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 4 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Typical Performance Characteristics O T A=25 C, unless otherwise noted. THD+N VS Output Power R L=4 Ω , Gain=23dB, f=1kHz THD+N VS Output Power R L=8 Ω , Gain=23dB, f=1kHz 50 50 V DD= 3 . 6 V 20 V DD= 3 . 6 V 20 10 10 V DD= 4 . 2 V 5 % V DD= 4 . 2 V 5 % 2 2 1 1 0.5 0.5 V DD= 5 V 0.2 0.1 20m 50m 100 m 200 m 500 m 1 2 0.2 V DD= 5 V 0.1 20m 3 50m 100 m W 500 m 1 2 3 W THD+N VS Frequency R L=8 Ω , Cin=0.1 μ F, Gain=23dB, V DD=3.6V THD+N VS Frequency R L=8 Ω , Cin=0.1 μ F, Gain=23dB, V DD=5V 10 10 5 5 Po=200mW 2 2 1 1 % 200 m 0.5 Po=500mW 0.5 % Po=500mW 0.2 0.2 0.1 0.1 0.05 0.05 Po=200mW 0.02 0.02 20 50 100 200 500 1k 2k 5k 10k 0.01 20 20k 50 100 200 Hz 10 1k 2k 5k 10k 20k Hz THD+N VS Frequency R L=4 Ω , Cin=0.1 μ F, Gain=23dB, V DD=5V 10 5 5 2 2 1 THD+N VS Frequency R L=4 Ω , Cin=0.1 μ F, Gain=23dB, V DD=3.6V Po=200mW 1 Po=500mW 0.5 500 % % 0.5 Po=500mW 0.2 0.2 0.1 Po=200mW 0.05 0.1 0.05 0.02 0.01 20 50 100 200 500 1k 2k 5k 10k 0.02 20 20k Hz 50 100 200 500 1k 2k 5k 10k 20k Hz Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 5 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Typical Performance Characteristics O T A=25 C, unless otherwise noted. 350 7 Oscillator Frequency (kHz) Q uiescent Current(mA) 8 Quiescent Current VS Temperature No input, No Load, V DD=5.0V 6 5 4 3 2 1 0 0 50 100 Frequency VS Temperature No input, No Load, V DD=5.0V 300 250 200 150 100 50 0 150 0 50 Temperature 0.4 Supply Current VS Output Power R l=8 Ω +33 μ H 0.7 0.25 0.2 0.15 0.1 VDD=3.6V VDD=5V 0.05 0 0 Supply Current VS Output Power V DD=5.0V 500 1000 1500 0.5 0.4 0.3 0.2 Load=8ohm+33uH 0.1 L=4ohm+33uH 0 2000 0 500 Output Power(mW) 1000 1500 2000 2500 3000 Output Power(mW) Output Power VS. Supply Voltage R l=8 Ω 3.5 Output Power VS. Supply Voltage R l=4 Ω 3 Output Power(W) 2 O u tp u t Po w er(W) 150 0.6 0.3 Supply Current(A) Supply Current(A) 0.35 2.5 100 Temperature 1.5 1 0.5 THD=1% THD=10% 3 3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8 5 2 1.5 1 0.5 0 2.8 2.5 0 2.5 5.2 5.4 Supply Voltage(V) THD+N=1% THD+N=10% 3 3.5 4 4.5 5 5.5 Supply Voltage(V) Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 6 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Typical Performance Characteristics O T A=25 C, unless otherwise noted. 95% 90% 90% 85% 85% Efficiency Efficiency 95% Efficiency VS Output Power V DD=5.0V 80% 75% 70% 80% 75% 70% Load=8ohm+33uH 65% Efficiency VS Output Power R l=8 Ω+33μΗ Vin=5V Vin=3.6V 65% Load=4ohm+33uH 60% 60% 0 500 1000 1500 2000 2500 0 3000 500 Output Pow er(m W) 4.5 350 Oscillator Frequency (kHz) Quiescent Current(mA) 3.5 3 2.5 2 1.5 1 0.5 3.5 4 4.5 5 300 250 200 150 100 50 0 2.5 5.5 Supply Voltage (V) 0.16 2000 Frequency VS. Supply Voltage 4 3 1500 Output Pow er(m W) Quiescent Current VS. Supply Voltage No load 0 2.5 1000 3 3.5 4 4.5 5 5.5 Supply V oltage (V ) Power Dissipation VS. Output Power R l=8 Ω Power Dissipation(W) 0.14 0.12 0.10 0.08 0.06 0.04 VDD=5V VDD=3.6V 0.02 0.00 0 500 1000 1500 2000 Output Pow e r(W) Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 7 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Test Setup for Performance Testing PAM8302A Demo Board Load +OUT AP System One Generator Input AP Low Pass Filter GND -OUT AP System One Analyzer AUX-0025 VDD Power Supply Notes 1. The AP AUX-0025 low pass filter is necessary for every 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. Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 8 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Application Information Maximum Gain capacitor is the best choice. When a polarized capacitor is 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. As shown in block diagram (page 2), the PAM8302A has two internal amplifier stages. The first stage's gain is externally con figurable, while the second stage's is internally fixed. The closedloop gain of the first stage is set by selecting the ratio of R f to R i while the second stage's gain is 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 Power Supply Decoupling (Cs) The PAM8302A 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 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 1.0μF is good, placing it as close as possible to the device VDD terminal. For filtering lowerfrequency noise signals, a capacitor of 10μF or A VD=20*log [2*(R f/R i)] The PAM8302A sets maximum R f=80k Ω , minimum R i=10k Ω , so the maximum closed-gain is 24dB. Input Capacitors (Ci) In typical application, an input capacitor, Ci, is required to allow the amplifier to bias input signals to a proper DC level for optimum operation. In this case, Ci and the minimum input impedance Ri (10k internal) form a high pass filter with a corner frequency determined by the following equation: 1 fC = (2p RiCi) larger, closely located to near the audio power amplifier is recommended. Shutdown Operation In order to reduce shutdown power consumption, the PAM8302A contains shutdown circuitry for turn off the amplifier. This shutdown feature turns the amplifier off when a logic low is applied on the SD pin. By switching the shutdown pin over to GND, the PAM8302A supply current draw will be minimized in idle mode. It is important to choose the value of Ci as it directly affects low frequency performance of the circuit, for example, when an application requires a flat bass response as low as 100Hz. Equation is reconfigured as follows: 1 Ci = (2p Rifc ) For the best power on/off pop performance, the amplifier should be set in the shutdown mode prior to power on/off operation. As the input resistance is variable, for the Ci value of 0.16 μ F, one should actually choose the Ci within the range of 0.1 μ F to 0.22 μ F. A further consideration for this capacitor is the leakage path from the input source through the input network (Ri, RF,Ci) to the load. This leakage current creates a DC offset voltage at the input to the amplifier that reduces useful headroom, especially in high gain application. For this reason, a low leakage tantalum or ceramic Under Voltage Lock-out (UVLO) The PAM8302A incorporates circuitry to detect low on or off voltage. When the supply voltage drops to 2.1V or below, the PAM8302A goes into a state of shutdown, and the device comes out of its shutdown state and starts to normal operation by reset the power supply or SD pin. Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 9 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier How to Reduce EMI (Electro Magnetic Interference) A simple solution is to put an additional capacitor 1000 μ F at power supply terminal for power line coupling if the traces from amplifier to speakers are short (<20CM). Most applications require a ferrite bead filter as shown at Figure 1. The ferrite filter depresses EMI of around 1MHz and higher. When selecting a ferrite bead, choose one with high impedance at high frequencies and low impedance at low frequencies. Ferrite Bead OUT+ 220pF Ferrite Bead OUT220pF Figure 1: Ferrite Bead Filter to reduce EMI Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 10 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Ordering Information PAM8302A X X X X Shipping Package Number of pins Package Type Pin Configuration P in Co n fig uratio n A: Package Typ e Nu mb er o f p ins S: M SO P C: 8 D : SOP 1: SD 2: NC Y: D FN 3X 3 3: IN+ 4: IN5: VO + 6: VDD 7: G ND 8: VO - Part Number Package Type MOQ/Shipping Package PAM8302AASCR MSOP-8 2,500 Units/Tape & Reel PAM8302AADCR SOP-8 2,500 Units/Tape & Reel PAM8302AAYCR DFN3x3-8 3,000 Units/Tape & Reel Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 11 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Outline Dimensions MSOP-8 REF Millimeter 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 L 0.65BSC 0.40 0.70 Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 12 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Outline Dimensions DFN 3x3 DFN Note: All dimensions are in Millimeters. Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 13 PAM8302A 2.5W Filterless Class-D Mono Audio Amplifier Outline Dimensions - REF DIMENSIONS Millimeters C A B G Min Max A 5.80 6.20 B 4.80 5.00 C 3.80 4.00 D 0º 8º E 0.40 0.90 F 0.19 0.25 M 0.10 0.25 H 0.35 0.49 L 1.35 1.75 J 0.375 REF K 45º G 1.27 TYP D H F K 0.25 L M J E Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 14