AP4809 ANACHIP | Alldatasheet
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Stereo Headphone Amplifier With Shutdown Mode This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product. Rev. 1.0 Sep 29, 2004 Features - Operate from 3V to 7V Single Supply Voltage - High Signal-to-Noise ratio - High Slew Rate - Large Output Voltage Swing - Low Distortion - Low Power Consumption - Switch On/Off Click suppression - Excellent Power Supply Ripple Rejection - SOP-8, PDIP-8 and MSOP-8 Pb-Free Packages Applications - CD-ROM, DVD-ROM - MP3 Player - Battery Powered Devices - Personal Computers Pin Assignments SOP-8L/PDIP-8L (Top View) IN1- GND BYPASS Vo2 Vo1 VDD SHUTDOWN IN2- MSOP-8L (Top View) IN1- GND BYPASS Vo2 Vo1 VDD SHUTDOWN IN2- General Description The AP4809 is a stereo power amplifier in an 8-pin SOP package capable of delivering 70mW continuous average power per channel into 32 Ω loads with less than 0.1% (THD+N) from a 5V power supply. Amplifier gain is externally configured by means of two resistors per input channel. It was designed specially to provide high quality output power with a minimal amount of external components and is therefore optimally suited for low-power portable systems. Pin Descriptions Pin No. Pin Name Description
1 Vo1 Output 1
2 IN1- Inverting input 1
3 BYPASS Tap to voltage divider for
internal mid-rail bias supply.
4 GND Ground
5 SHUTDOWN Logic low to put chip in
shutdown mode.
6 IN2- Inverting input 2
7 Vo2 Output 2
8 V DD Positive power supply
Ordering Information Package Packing S : SOP-8L N: PDIP-8L M: MSOP-8L AP4809 X Blank : Tube A : Taping X
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Absolute Maximum Ratings (TA=25oC) Symbol Parameter Max. Unit VDD Supply Voltage 7 V TJ Junction Temperature 150 oC TS Soldering Temperature, 10 Seconds 250 oC TA Operating Ambient Temperature Range -40 to 85 oC TSTG Storage Temperature Range -65 to 150 oC VESD ESD Susceptibility (Note 1) 2000 V Note 1: Human Body Model, C=100pF, R=1500Ω, 3 positive pulses and 3 Negative Pulses. Electrical Characteristics (TA=25oC, VDD=5V, fi=1KHz, RL=32Ω) Symbol Parameter Test Condition Min. Typ. Max. Unit VDD Supply Voltage 2.5 - 5.5 V IDD Supply Current V IN=0V, IO=0A - 3 5 mA PTOT Total Power Dissipation V IN=0V, IO=0A - 10 20 mW VI(OS) Input Offset Voltage V IN=0V - 5 - mV IBIAS Input Bias Current - 10 - pA VCM Common Mode Voltage 0 - 3.5 V GV Open-Loop Voltage Gain R L=5KΩ - 80 - dB IO Max. Output Current THD+N < 0.1% - 80 - mA VSHUT Shutdown Enabled Shutdown Pin Voltage - - 0.7 V VSHUT Shutdown Disabled Shutdown Pin Voltage 0.9 - - V RO Output Resistance - 0.3 - Ω PSRR Power Supply Ripple Rejection - 75 - dB αS Channel Separation R L=32Ω - 80 - dB THD+N Total Harmonic Distortion + Noise RL=32Ω VO=3.2VP-P (at 0 dB) - 0.02 - % SNR Signal-TO-Noise Ratio V O=3.2VP-P (at 0 dB) - 105 - dB fG Unity Gain Frequency Open Loop, R L=5KΩ - 6 - MHz PO Output Power R L=32Ω, THD+N=0.1% - 75 - mW SR Slew Rate Unity Gain Inverting - 6 - V/µs
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Typical Performance Characteristics
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Typical Performance Characteristics Test Circuit Shutdown Control Vo2 Vo1 IN1-Vi1 Vi2 CI 10uF CI 10uF BYPASS IN2- SHUTDOWNFrom Shutdown Control Circuit Ri Ri 450K 450K Rf Rf CS 100uF CC 220uF CC 220uF 20K 20K 100 100 CS 0.1uF CB 10uF VDD / 2 Vo1 Vo2 VDD VDD Ω Ω Ω Ω ΩΩ
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Application Information 1. Input Capacitor, CI In the typical application, an input capacitor, C i, is required to allow the amplifier to bias the input signal to the proper dc level for optimum operation. In this case, C i and Ri form a high-pass filter with the corner frequency determined in following equation (1). fco(highpass) = CiRi2π 1 (1) The value of Ci is important to consider, as it directly affects the low frequency performance of the circuit. Consider the example where R i is 15k Ω and the specification calls for a flat bass response down to 20Hz. Equation (1) is reconfigured as below: Ci = fRi2π s)co(highpas (2) In this example, C i is 0.5 µF, so one would likely choose a value in the range of 1 µF to 2.2 µF. A further consideration for this capacitor is the leakage path from the input source through the input network i, C i) and the feedback resistor (R f) 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 applications (>10). For this reason a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications, as the dc level there is held at V DD/2, which is likely higher than th e source dc level. It is important to confirm the capacitor polarity in the application. 2. Power Supply Decoupling, C S The AP4809 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure that the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents oscillations for long lead lengths 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-series-resistance (ESR) ceramic capacitor, typically 0.1 µF, placed as close as possible to the device V DD lead, works best. For filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near the power amplifier is recommended. 3. Mid-rail Bypass Capacitor, C B In the consideration of reducing the start-up pop, the mid-rail voltage should rise at a sub-sonic rate; that is, less than the rise time of 20Hz waveform and slower than the charging rate of both C i & C C. The relationship shown in equation (3) should be maintained to keep the noise as low as possible. Where C B is the value of bypass capacitor and RSOURCE is the equivalent source impedance of the voltage divider (the parallel combination of the two resistors) RC SOURCEB × RiCi 1 < < RR CL (3) The bypass capacitor, C B, serves several important functions. During start-up, CB determines the rate at which the amplifier starts up. This helps to push the start-up pop noise into the sub-audible range (so slow it can not be heard). 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 mid-rail generation circuit internal to the amplifier. The capacitor is fed from the resistor divider with equivalent resistance of R SOURCE. On selection of bypass capacitor, C B, ceramic or tantalum low-ESR capacitors are recommended for the best THD and noise performance. 4. Output Coupling Capacitor, C C In the typical single-supply single-ended (SE) configuration, an output coupling capacitor (C C) is required to block the dc bias at the output of the amplifier, thus preventing dc currents in the load. As with the input coupling capacitor, the output coupling capacitor and impedance of the load form a high-pass filter governed by equation (4). f(out high) = CR2π CL (4) The main disadvantage, from a performance standpoint, is that the typically small load impedances drive the low-frequency corner higher. Large values of C C are required to pass low frequencies into the load. The output coupling capacitor required in single-supply SE mode also places additional constraints on the selection of other components in the amplifier circuit. With the rules described earlier still valid, add the following relationship:
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Application Information (Continued)
4.1 Output Pull-Down Resistor, RC + RO
Placing a 100Ω resistor, RC, from the output side of the coupling capacitor to ground insures the coupling capacitor, CC, is charged before a plug is inserted into the jack. Without this resistor, the coupling capacitor would charge rapidly upon insertion of a plug, leading to an audible pop in the headphones. Placing a 20kΩ resistor, R O, from the output of the IC to ground insures that the coupling capacitor fully discharges at power down. If the supply is rapidly cycled without this capacitor, a small pop may be audible in 10kΩ loads.
4.2 Using Low-ESR Capacitors
Low-ESR capacitors are recommended throughout this application. A real 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 like an ideal capacitor. Marking Information ( Top View ) Logo Part number ID code: internal Year: "01" = 2001 Xth week: 01~52 ~1 4 AP4809 YY WW X "02" = 2002 SOP-8L/PDIP-8L Logo Part number ID code: internal M: Month (A~L) 4809 YM X (Top View) Date code: Y: Year : 0~9 MSOP-8L
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Package Information (1) Package Type: SOP-8L VIEW "A" L C VIEW "A" H E A A2A1Be D 7 (4X) 0.015x45 7 (4X) y A1 0.10 - 0.25 0.040 - 0.100 θ 0O - 8 O 0 O - 8 O
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Package Information(Continued) (2) Package Type: PDIP-8L D 7 (4X) AL A2A1 B2B1 B eS 15 (4X) E C eB E-PIN O0.118 inch PIN #1 INDENT O0.025 DEEP 0.006-0.008 inch
Stereo Headphone Amplifier With Shutdown Mode Anachip Corp Package Information (Continued) (3) Package Type: MSOP-8L E D L GAGE PLANE 0.25 DETAIL A b A y C θ DETAIL A e 12 (4x) 0.038DP SURFACE POLISHED PIN 1 INDICATOR 0.45 mmφ A1 0.05 - 0.15 0.002 - 0.006 θ 0º 3º 6º 0º 3º 6º