TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 D Modulation Scheme Optimized to Operate PW PACKAGE (TOP VIEW) Without a Filter D 4 mm × 4 mm MicroStar Junior BGA and D D D D D TSSOP Package Options 1 W Into an 8-Ω Speaker (THD+N<1%) <0.2% THD+N at 1 W, 1 kHz, Into an 8-Ω Load Extremely Efficient Third Generation 5-V Class-D Technology: – Low-Supply Current (No Filter) . . . 4 mA – Low-Supply Current (Filter) . . . 7.5 mA – Low-Shutdown Current . . . 0.05 µA – Low-Noise Floor . . . 40 µVRMS (No-Weighting Filter) – Maximum Efficiency Into 8 Ω, 75 – 85% – 4 Internal Gain Settings . . . 6 – 23.5 dB – PSRR . . . –77 dB Integrated Depop Circuitry Short-Circuit Protection (Short to Battery, Ground, and Load) INP INN SHUTDOWN GAIN0 GAIN1 PVDD OUTP PGND 1 2 3 4 5 6 7 8 BYPASS AGND COSC ROSC VDD PVDD OUTN PGND 16 15 14 13 12 11 10 9 MicroStar Juniort (GQC) Package (TOP VIEW) INP AGND BYPASS A6 A2 INN SHUTDOWN GAIN0 GAIN1 PVDD PVDD OUTP A7 NC B7 COSC C7 A1 B1 C1 D1 ROSC D7 VDD E7 PVDD F7 PV DD G7 E1 F1 G1 OUTN PGND description (SIDE VIEW) The TPA2001D1 is a 1-W mono bridge-tied-load (BTL) class-D amplifier designed to drive a speaker with at least 8-Ω impedance. The NC – No internal connection, still requires a pad for the ball. amplifier uses TI’s third generation modulation NOTE: The shaded terminals are used for thermal technique, which results in improved efficiency connections to the ground plane. and SNR. It also allows the device to be connected directly to the speaker without the use of the LC output filter commonly associated with class-D amplifiers (this will result in EMI which must be shielded at the system level). These features make the device ideal for use in devices where high-efficiency is needed to extend battery run time. The gain of the amplifier is controlled by two input terminals, GAIN1, and GAIN0. This allows the amplifier to be configured for a gain of 6, 12, 18, and 23.5 dB. The differential input terminals are high-impedance CMOS inputs, and can be used as summing nodes. The class-D BTL amplifier includes depop circuitry to reduce the amount of turnon pop at power up, and when cycling SHUTDOWN. The TPA2001D1 is available in the 16-pin TSSOP and MicroStar Junior BGA packages that will drive 1 W of continuous output power into an 8-Ω load. TPA2001D1 operates over an ambient temperature range of –40°C to 85°C. AVAILABLE OPTIONS PACKAGED DEVICES TSSOP (PW)† GQC‡ TA – 40°C to 85°C TPA2001D1PW TPA2001D1GQCR † The PW package is available taped and reeled. To order a taped and reeled part, add the suffix R to the part number (e.g., TPA2001D1PWR). ‡ The GQC package is only available taped and reeled. Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. MicroStar Junior is a trademark of Texas Instruments. Copyright 2002, Texas Instruments Incorporated This document contains information on products in more than one phase of development. The status of each device is indicated on the page(s) specifying its electrical characteristics. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 functional block diagram VDD AGND VDD PVDD Gain Adjust INN + _ _ Deglitch Logic Gate Drive OUTN + _ + PGND + _ PVDD + _ Gain Adjust INP _ Deglitch Logic + Gate Drive OUTP PGND SD SHUTDOWN GAIN1 2 GAIN0 Gain Biases and References Start-Up Protection Logic Ramp Generator COSC ROSC BYPASS Thermal OC Detect VDD ok Terminal Functions TERMINAL NAME I/O NO. DESCRIPTION GQC PW A3 – A5, B2 – B6 C2 – C6 D2 – D4 15 I Analog ground BYPASS A6 16 I Connect capacitor to ground for BYPASS voltage filtering. COSC B7 14 I Connect capacitor to ground to set oscillation frequency. GAIN0 C1 4 I Bit 0 of gain control (TTL logic level) GAIN1 D1 5 I Bit 1 of gain control (TTL logic level) INN A1 2 I Negative differential input INP A2 1 I Positive differential input OUTN G7 10 O Negative BTL output OUTP G1 7 O Positive BTL output PGND D5, D6 E2 – E6 F2 – F6 G2 – G6 8, 9 I High-current grounds PVDD E1, E7, F1, F7 6, 11 I High-current power supplies ROSC C7 13 I Connect resistor to ground to set oscillation frequency. SHUTDOWN B1 3 I Places the amplifier in shutdown mode if a TTL logic low is placed on this terminal, and normal operation if a TTL logic high is placed on this terminal. VDD D7 12 I Analog power supply AGND 2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage, VDD, PVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 5.5 V Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to VDD +0.3 V Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (see Dissipation Rating Table) Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 40°C to 85°C Operating junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 40°C to 150°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. DISSIPATION RATING TABLE TA ≤ 25°C 774 mW DERATING FACTOR PW 6.19 mW/°C TA = 70°C 495 mW TA = 85°C 402 mW GQC 2.61 W 20.9 mW/°C 1.67 W 1.36 W PACKAGE recommended operating conditions ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply voltage, VDD, PVDD High-level input voltage, VIH GAIN0, GAIN1, SHUTDOWN Low-level input voltage, VIL GAIN0, GAIN1, SHUTDOWN MIN MAX 2.7 5.5 2 Operating free-air temperature, TA – 40 UNIT V V 0.7 V 85 °C electrical characteristics at specified free-air temperature, PVDD = 5 V, TA = 25°C (unless otherwise noted) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ PARAMETER TEST CONDITIONS |VOS| Output offset voltage (measured differentially) PSRR Power supply rejection ratio |IIH| High-level input current |IIL| Low-level input current IDD Supply current, no filter (with or without speaker load) IDD(SD) Supply current, shutdown mode MIN VI = 0 V, AV = any gain PVDD = 4.9 V to 5.1 V PVDD = 5.5 V, PVDD = 5.5 V, TYP MAX mV 1 µA 1 µA 4 6 mA 0.05 20 µA 77 VI = PVDD VI = 0 V GAIN0, GAIN1, SHUTDOWN = 0 V UNIT 25 dB operating characteristics, PVDD = 5 V, TA = 25°C, RL = 8 Ω, gain = 6 dB (unless otherwise noted) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ PARAMETER TEST CONDITIONS PO THD + N Output power THD = 1%, f = 1 kHz Total harmonic distortion plus noise Maximum output power bandwidth PO = 1 W, THD = 1% f = 20 Hz to 20 kHz BOM kSVR Supply ripple rejection ratio f = 1 kHz, C(BYP) = 1 µF SNR Signal-to-noise ratio Vn Output noise voltage (no noise weighting filter) ZI Input impedance C(BYP) = 1 µF, POST OFFICE BOX 655303 f = <10 Hz to 22 kHz • DALLAS, TEXAS 75265 MIN TYP 1 MAX UNIT W <0.1% 20 kHz 71 dB 95 dB 40 µV(rms) >15 kΩ 3 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 electrical characteristics at specified free-air temperature, PVDD = 3.3 V, TA = 25°C (unless otherwise noted) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ PARAMETER TEST CONDITIONS |VOS| Output offset voltage (measured differentially) PSRR Power supply rejection ratio |IIH| High-level input current |IIL| Low-level input current IDD Supply current, no filter (with or without speaker load) IDD(SD) Supply current, shutdown mode MIN VI = 0 V, AV = any gain PVDD = 3.2 V to 3.4 V PVDD = 3.3 V, PVDD = 3.3 V, TYP MAX UNIT 25 mV 1 µA 1 µA 4 6 mA 0.05 20 µA 61 VI = PVDD VI = 0 V dB operating characteristics, PVDD = 3.3 V, TA = 25°C, RL = 8 Ω, gain = 6 dB (unless otherwise noted) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ PARAMETER TEST CONDITIONS PO THD + N Output power THD = 1%, f = 1 kHz Total harmonic distortion plus noise Maximum output power bandwidth PO = 55 mW, THD = 0.7% f = 20 Hz to 20 kHz BOM kSVR Supply ripple rejection ratio f = 1 kHz, C(BYP) = 1 µF SNR Signal-to-noise ratio Vn Output noise voltage (no noise weighting filter) ZI Input impedance 4 C(BYP) = 1 µF, POST OFFICE BOX 655303 f = <10 Hz to 22 kHz • DALLAS, TEXAS 75265 MIN TYP 400 MAX UNIT mW <0.1% 20 kHz 61 dB 93 dB 40 µV(rms) >15 kΩ TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION eliminating the output filter with the TPA2001D1 This section will focus on why the user can eliminate the output filter with the TPA2001D1. effect on audio The class-D amplifier outputs a pulse-width modulated (PWM) square wave, which is the sum of the switching waveform and the amplified input audio signal. The human ear acts as a band-pass filter such that only the frequencies between approximately 20 Hz and 20 kHz are passed. The switching frequency components are much greater than 20 kHz, so the only signal heard is the amplified input audio signal. traditional class-D modulation scheme The traditional class-D modulation scheme, which is used in the TPA005Dxx family, has a differential output where each output is 180 degrees out of phase and changes from ground to the supply voltage (VDD). Therefore, the differential prefiltered output varies between positive and negative VDD, where filtered 50% duty cycle yields 0 volts across the load. The traditional class-D modulation scheme with voltage and current waveforms is shown in Figure 1. Note that even at an average of 0 V across the load (50% duty cycle), the current to the load is high causing high loss thus, causing a high supply current. OUTP OUTN +5 V Differential Voltage Across Load 0V –5 V Current Figure 1. Traditional Class-D Modulation Scheme’s Output Voltage and Current Waveforms Into an Inductive Load With No Input TPA2001D1 modulation scheme The TPA2001D1 uses a modulation scheme that still has each output switching from 0 to the supply voltage. However, OUTP and OUTN are now in phase with each other with no input. The duty cycle of OUTP is greater than 50% and OUTN is less than 50% for positive voltages. The duty cycle of OUTP is less than 50% and OUTN is greater than 50% for negative voltages. The voltage across the load sits at 0 V throughout most of the switching period greatly reducing the switching current, which reduces any I2R losses in the load. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION OUTP OUTN Differential Voltage Across Load Output = 0 V +5 V 0V –5 V Current OUTP OUTN Differential Voltage Output > 0 V +5 V 0V Across Load –5 V Current Figure 2. The TPA2001D1 Output Voltage and Current Waveforms Into an Inductive Load efficiency: why you must use a filter with the traditional class-D modulation scheme The main reason that the traditional class-D amplifier needs an output filter is that the switching waveform results in maximum current flow. This causes more loss in the load, which causes lower efficiency. The ripple current is large for the traditional modulation scheme because the ripple current is proportional to voltage multiplied by the time at that voltage. The differential voltage swing is 2 × VDD and the time at each voltage is half the period for the traditional modulation scheme. An ideal LC filter is needed to store the ripple current from each half cycle for the next half cycle, while any resistance causes power dissipation. The speaker is both resistive and reactive, whereas an LC filter is almost purely reactive. The TPA2001D1 modulation scheme has very little loss in the load without a filter because the pulses are very short and the change in voltage is VDD instead of 2 × VDD. As the output power increases, the pulses widen making the ripple current larger. Ripple current could be filtered with an LC filter for increased efficiency, but for most applications the filter is not needed. An LC filter with a cutoff frequency less than the class-D switching frequency allows the switching current to flow through the filter instead of the load. The filter has less resistance than the speaker that results in less power dissipated, which increases efficiency. 6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION effects of applying a square wave into a speaker Audio specialists have advised for years not to apply a square wave to speakers. If the amplitude of the waveform is high enough and the frequency of the square wave is within the bandwidth of the speaker, the square wave could cause the voice coil to jump out of the air gap and/or scar the voice coil. A 250-kHz switching frequency, however, is not significant because the speaker cone movement is proportional to 1/f2 for frequencies beyond the audio band. Therefore, the amount of cone movement at the switching frequency is very small. However, damage could occur to the speaker if the voice coil is not designed to handle the additional power. To size the speaker for added power, the ripple current dissipated in the load needs to be calculated by subtracting the theoretical supplied power (PSUP THEORETICAL) from the actual supply power (PSUP) at maximum output power (PO). The switching power dissipated in the speaker is the inverse of the measured efficiency (ηMEASURED) minus the theoretical efficiency (ηTHEORETICAL) all multiplied by PO. PSPKR = PSUP – PSUP THEORETICAL (at max output power) (1) PSPKR = PO(PSUP / PO – PSUP THEORETICAL / PO) (at max output power) (2) PSPKR = PO(1/ηMEASURED – 1/ηTHEORETICAL) (at max output power) (3) The maximum efficiency of the TPA2001D1 with an 8-Ω load is 85%. Using equation 3 with the efficiency at maximum power (78%), we see that there is an additional 106 mW dissipated in the speaker. The added power dissipated in the speaker is not an issue as long as it is taken into account when choosing the speaker. when to use an output filter Design the TPA2001D1 without the filter if the traces from amplifier to speaker are short. The TPA2001D1 passed FCC and CE radiated emissions with no shielding with speaker wires eight inches long or less. Notebook PCs and powered speakers where the speaker is in the same enclosure as the amplifier are good applications for class-D without a filter. A ferrite bead filter can often be used if the design is failing radiated emissions without a filter, and the frequency sensitive circuit is greater than 1 MHz. This is good for circuits that just have to pass FCC and CE because FCC and CE only test radiated emissions greater than 30 MHz. If choosing a ferrite bead, choose one with high impedance at high frequencies, but very low impedance at low frequencies. Use an output filter if there are low frequency (<1 MHz) EMI sensitive circuits and/or there are long leads from amplifier to speaker. gain setting via GAIN0 and GAIN1 inputs The gain of the TPA2001D1 is set by two input terminals, GAIN0 and GAIN1. The gains listed in Table 1 are realized by changing the taps on the input resistors inside the amplifier. This causes the input impedance, ZI, to be dependent on the gain setting. The actual gain settings are controlled by ratios of resistors, so the actual gain distribution from part-to-part is quite good. However, the input impedance may shift by 30% due to shifts in the actual resistance of the input resistors. For design purposes, the input network (discussed in the next section) should be designed assuming an input impedance of 20 kΩ, which is the absolute minimum input impedance of the TPA2001D1. At the higher gain settings, the input impedance could increase as high as 115 kΩ. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 7 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION Table 1. Gain Settings AMPLIFIER GAIN (dB) INPUT IMPEDANCE (kΩ) TYP TYP 6 104 1 12 74 0 18 44 1 23.5 24 GAIN0 GAIN1 0 0 0 1 1 input resistance Each gain setting is achieved by varying the input resistance of the amplifier, which can range from its smallest value to over six times that value. As a result, if a single capacitor is used in the input high-pass filter, the –3 dB or cut-off frequency will also change by over six times. ZF Ci Input Signal IN ZI The –3 dB frequency can be calculated using equation 4. fc + 1 2p Z C i I (4) input capacitor, Ci In the typical application an input capacitor (Ci) is required to allow the amplifier to bias the input signal to the proper dc level for optimum operation. In this case, Ci and the input impedance of the amplifier (ZI) form a high-pass filter with the corner frequency determined in equation 5. –3 dB fc + (5) 1 2 p ZI Ci fc 8 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION input capacitor, Ci (continued) The value of Ci is important, as it directly affects the bass (low frequency) performance of the circuit. Consider the example where ZI is 20 kΩ and the specification calls for a flat bass response down to 80 Hz. Equation 5 is reconfigured as equation 6. Ci + 1 2p Z I f c (6) In this example, Ci is 0.1 µF, so one would likely choose a value in the range of 0.1 µF to 1 µF. If the gain is known and will be constant, use ZI from Table 1 to calculate Ci. A further consideration for this capacitor is the leakage path from the input source through the input network (Ci) and the feedback network 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. 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 VDD/2, which is likely higher than the source dc level. Note that it is important to confirm the capacitor polarity in the application. Ci must be 10 times smaller than the bypass capacitor to reduce clicking and popping noise from power on/off and entering and leaving shutdown. After sizing Ci for a given cutoff frequency, size the bypass capacitor to 10 times that of the input capacitor. Ci ≤ CBYP / 10 (7) power supply decoupling, CS The TPA2001D1 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure 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 VDD lead works best. For filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near the audio power amplifier is recommended. midrail bypass capacitor, C(BYP) The midrail bypass capacitor (C(BYP)) is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, C(BYP) 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 midrail generation circuit internal to the amplifier, which appears as degraded PSRR and THD+N. Bypass capacitor (C(BYP)) values of 0.47-µF to 1-µF ceramic or tantalum low-ESR capacitors are 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. To have minimal pop, C(BYP) should be 10 times larger than Ci. C(BYP) ≥ 10 × Ci (8) POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 9 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION differential input The differential input stage of the amplifier cancels any noise that appears on both input lines of the channel. To use the TPA2001D1 EVM 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 TPA2001D1 with a single-ended source, ac ground the INN input through a capacitor and apply the audio single to the input. In a single-ended input application, the INN input should be ac-grounded at the audio source instead of at the device input for best noise performance. shutdown modes The TPA2001D1 employs a shutdown mode of operation designed to reduce supply current (IDD) to the absolute minimum level during periods of nonuse for battery-power conservation. The SHUTDOWN input terminal should be held high during normal operation when the amplifier is in use. Pulling SHUTDOWN low causes the outputs to mute and the amplifier to enter a low-current state, IDD(SD) = 1 µA. SHUTDOWN should never be left unconnected because amplifier operation would be unpredictable. using low-ESR capacitors Low-ESR capacitors are recommended throughout this application section. A real (as opposed 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 like an ideal capacitor. evaluation circuit OUT+ C2 IN– C3 IN+ 1 µF 1 µF SHUTDOWN R3 120 kΩ R2 120 kΩ R4 120 kΩ U1 TPA2001D1 1 INP 2 J2 C4 1 µF 1 µF C1 13 220 pF 8 GAIN1 ROSC VDD PVDD PVDD OUTP OUTN PGND PGND S1 12 11 R1 120 kΩ VDD C6 1 µF 10 9 OUT– C5 1 µF GND GND NOTE: R1, R2, and R3 are used in the EVM but are not required for normal applications. 10 15 4 GAIN0 7 C8 10 µF AGND C7 14 6 VDD INN 16 3 SHUTDOWN COSC 5 J1 BYPASS POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 APPLICATION INFORMATION Table 2. TPA2001D1 Evaluation Bill of Materials SIZE QUANTITY MANUFACTURER C1 – C6 REFERENCE Capacitor, ceramic, 1 µF, +80%/–20%, Y5V, 16 V DESCRIPTION 0805 6 Murata GRM40-Y5V105Z16 PART NUMBER C7 Capacitor, ceramic, 10 µF, +80%/–20%, Y5V, 16 V 1210 1 Murata GRM235-Y5V106Z16 C8 R1†, R2†, R3†, R4 Capacitor, ceramic, 220 pF, ±10%, XICON, 50 V 0805 1 Mouser 140-CC501B221K Resistor, chip, 120 kΩ, 1/10 W, 5%, XICON 0805 4 Mouser 260–120K U1 IC, TPA2001D1, audio power amplifier, 2-W, single channel, class-D 24 pin TSSOP 1 TI TPA2001D1PW † These components are used in the EVM, but they are not required for normal applications. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 11 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 MECHANICAL DATA PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0,30 0,19 0,65 14 0,10 M 8 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 7 0°–ā8° A 0,75 0,50 Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 8 14 16 20 24 28 A MAX 3,10 5,10 5,10 6,60 7,90 9,80 A MIN 2,90 4,90 4,90 6,40 7,70 9,60 DIM 4040064/F 01/97 NOTES: A. B. C. D. 12 All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion not to exceed 0,15. Falls within JEDEC MO-153 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TPA2001D1 1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338B – SEPTEMBER 2000 – REVISED AUGUST 2002 MECHANICAL DATA GQC (S-PBGA-N48) PLASTIC BALL GRID ARRAY 4,10 3,90 SQ 3,00 TYP 0,50 0,50 G F E D C B A 1 2 3 4 5 6 7 (BOTTOM VIEW) 0,68 0,62 1,00 MAX Seating Plane 0,35 0,25 0,05 M 0,21 0,08 0,11 4200460/C 10/00 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. MicroStar Junior BGA configuration Falls within JEDEC MO-225 MicroStar Junior BGA is a trademark of Texas Instruments. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 13 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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