PAM8301 Filterless Class-D Mono Audio Amplifier Key Features General Description n 1.5W Output at 10% THD with a 8 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 Tiny SOT23-6 Package n Pb-Free Package The PAM8301 is a 1.5W 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 PAM8301 is much better than that of class-AB cousins. It can optimize battery life thus is ideal for portable applications. The PAM8301 is available in SOT23-6 package. Applications n n n n n n PMP/MP4 GPS Portable Speakers Walkie Talkie Handsfree phones/Speaker Phones Cellular Phones Typical Application VDD 10μF 5 1μF VDD 3 Audio OUT+ 6 IN 0.1μF PAM8301 Shutdown 4 OUT- 1 /SD GND 2 Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 1 PAM8301 Filterless Class-D Mono Audio Amplifier Block Diagram VDD VDD/2 + - IN DRIVER RI +OUT -OUT MODULATOR RF THERMAL PROTECTION INTERNAL OSCILLATOR SHUTDOWN SD CURRENT PROTECTION OSC GND Pin Configuration & Marking Information TOP VIEW SOT23-6 6 5 4 FP: Product Code of PAM8301 X: Internal Code Y: Year W: Week FPXYW 1 Pin Number 2 3 Pin Name Description 1 OUT- Negative Output 2 GND Ground 3 IN Input 4 SD Shutdown, active low 5 VDD Power Supply 6 OUT+ Positive Output Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 2 PAM8301 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 Operation Temperature Range........ -40 °C to 85 °C Junction Temperature Range.........-40 °C to 125 °C Thermal Information Parameter Symbol Package Maximum Thermal Resistance (Junction to Case) θJC SOT23-6 130 Thermal Resistance (Junction to Ambient) θJA SOT23-6 250 Unit °C/W Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 3 PAM8301 Filterless Class-D Mono Audio Amplifier Electrical Characteristic V DD=5V, Gain = 24dB, R L=8 Ω, T A=25 °C，unless otherwise noted. PARAMETER Supply Voltage Range SYMBOL CONDITIONS VDD IQ No Load Shutdown Current ISHDN VSHDN=0V SHDN Input High V SH SHDN Input Low VSL Resistance Output Power Total Harmonic Distortion Plus Noise Power Supply Ripple Rejection RDS(ON) PO THD+N PSRR Gain Gv Noise Vn Oscillator Frequency fOSC Peak Efficiency η TYP 2.5 Quiescent Current Drain-Source On-State MIN 4 MAX UNITS 5.5 V 8 mA 1 μA 1.2 0.4 IDS =100mA f=1kHz P MOSFET 0.45 N MOSFET 0.20 THD+N=1% 1.2 THD+N=10% 1.5 RL = 8Ω，PO=200mW 0.2 RL = 8Ω，PO=0.5W 0.3 No input, f=1kHz, Vpp=200mV 45 W % dB 24 dB 180 A-weighting 120 f =20 to 20kHz Ω 50 No A-weighting f=1kHz V μV 200 250 300 kHz 85 88 % 78 dB Signal to Noise Ratio SNR Over Temperature Protection OTP 135 °C Over Temperature Hysteresis OTH 30 °C Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 4 PAM8301 Filterless Class-D Mono Audio Amplifier Typical Performance Characteristic T A=25°C,unless otherwise noted. 2. Frequency VS Temperature 1. Frequency VS Supply Voltage 258 350 256 300 252 F r e q u e n c y (k H z ) Frequency (kHz) 254 250 248 246 244 242 250 200 150 100 50 240 238 2 3 4 5 0 6 0 20 40 60 Supply Voltage (V) 100 120 140 Temperature 3.Efficiency VS Output Power 4.Efficiency VS Output Power 100% 90% R L=8 Ω, V DD=3.6V/5V 85% 95% 80% 90% 75% 85% Efficiency Efficiency 80 70% 65% R L=16 Ω, V DD=3.6V/5V 80% 75% 70% 60% VDD=5V 55% VDD=5V VDD=3.6V 65% VDD=3.6V 60% 50% 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 200 Output Pow er (mW) 600 800 1000 1200 Output Pow e r(m W) 5. THD+N VS Output Power 6. THD+N VS Output Power 50 20 400 200 R L=8 Ω, Gain=23dB, f=1kHz, V DD=3.6V/5V 100 3.6 5 50 V V 20 R L=16 Ω, Gain=23dB, f=1kHz, V DD=3.6V/5V/5.5V 10 5 3.6V 5V 10 % 2 % 5 1 2 0.5 1 0.5 0.2 0.1 20m 0.2 50m 100m 200 m 500 m 1 2 0.1 20m 3 50m 100m 200m 500m 1 2 3 W W Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 5 . PAM8301 Filterless Class-D Mono Audio Amplifier Typical Performance Characteristic T A=25°C,unless otherwise noted. 7. THD+N VS Frequency 10 5 8. THD+N VS Frequency 10 R L=8 Ω , Gain=23dB, Cin=0.1 μ F, V DD=5V,Po=500mW 5 R L=16 Ω, Gain=23dB, Cin=0.1 μ F, V DD=5V,Po=500mW 2 2 1 % 1 % 0.5 0.5 0.2 0.2 0.1 0.1 0.06 20 0.05 50 100 200 500 1k 2k 5k 10k 0.03 20 20k 50 100 200 500 9. THD+N VS Frequency R L=8 Ω, Gain=23dB, Cin=0.1 μ F, V DD=3.6V,Po=200mW 5 10k 20k R L=16 Ω, Gain=23dB, Cin=0.1 μ F, V DD=3.6V,Po=200mW 2 1 % 1 0.5 0.5 0.2 0.2 0.08 20 5k 10. THD+N VS Frequency 2 % 2k 10 10 5 1k Hz Hz 50 100 200 500 1k 2k 5k 10k 0.08 20 20k 50 100 200 500 1k 2k 5k 10k 20k 5k 10k 20k Hz Hz 11. Frequency Response 12. Noise Floor + 50 +0 R L=16 Ω, Cin=0.1 μ F,V DD=5V Inputs floating, R L=8 Ω, Cin=0.1 μ F,V DD=5V + 45 -20 + 40 + 35 -40 d B r + 30 -60 d B V -80 A + 20 + 25 -100 + 15 -120 + 10 +5 +0 20 -140 50 100 200 500 1k 2k 5k 10k 20 20k 50 100 200 500 1k 2k Hz Hz Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 6 PAM8301 Filterless Class-D Mono Audio Amplifier Typical Performance Characteristic T A=25°C unless otherwise noted. 14.EMI vs Frequency 13. PSRR +0 - 10 T TT T R L=8 Ω, Gain=23dB, V DD=5V,Input floating R L=8 Ω, Gain=23dB, V DD=5V, Po=500 mW - 20 - 30 - 40 dB - 50 - 60 - 70 - 80 - 90 - 100 20 50 100 200 500 1k 2k 5k 10k Hz . Test Setup for Performance Testing PAM8301 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 7 PAM8301 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 PAM8301 has two internal amplifier stages. The first stage's gain is externally con figurable, while the second stage's is internally fixed. The closed-loop 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 PAM8301 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 a ff e c t s l o w f r e q u e n c y r e s p o n s e . O p t i m u m 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-series-resistance (ESR) ceramic capacitor, typically 1.0μF is good, placing it as close as possible to the device VDD terminal. For filtering lower-frequency noise signals, a capacitor of 10μF or A VD=20*log [2*(R f/R i)] The PAM8301 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: fC = larger, closely located to near the audio power amplifier is recommended. 1 Shutdown Operation (2p RiCi) In order to reduce shutdown power consumption, the PAM8301 contains shutdown circuitry for turn off the amplifier. This shutdown feature turns the amplifier off when a logic low is applied on the SHDOWN pin. By switching the shutdown pin over to GND, the PAM8301 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: Ci = 1 (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 PAM8301 incorporates circuitry to detect low on or off voltage. When the supply voltage drops to 2.1V or below, the PAM8301 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 8 PAM8301 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 9 PAM8301 Filterless Class-D Mono Audio Amplifier Ordering Information PAM8301 X X X Number of pins Pin Type Pin Configuration Pin Configuration Package Type Number of pins A: A: SOT23-6 F: 6 1: OUT2: GND 3: IN 4: SD 5: VDD 6: OUT+ Part Number Marking Package Type Standard Package PAM8301AAF FPXYW SOT23-6 3,000 Units/Tape & Reel Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 10 PAM8301 Filterless Class-D Mono Audio Amplifier Outline Dimensions SOT23-6 A A E E1 D e e1 SEE VIEWS c WITH PLANTING A A2 b SECTION A-A 0.25 A1 BASE METAL GAUGE PLANE SEATING PLANE θ L L1 VIEW B Symbol Spec A A1 1.20±0.25 0.10±0.05 A2 b c D E 1.10±0.2 0.40±0.1 0.15±0.07 2.90±0.1 2.80±0.2 Symbol E1 e e1 L L1 θ Spec 1.60±0.1 0.95BSC 1.90BSC 0.55±0.25 0.60REF 4°±4° Unit: Millimeter Power Analog Microelectronics , Inc www.poweranalog.com 09/2008 Rev 1.2 11