TPA2001D1 TI | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 13
Technical content
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002 1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 /C0068Modulation Scheme Optimized to Operate Without a Filter /C0068TSSOP Package Options /C00681 W Into an 8-Ω Speaker (THD+N<1%) /C0068<0.2% THD+N at 1 W, 1 kHz, Into an 8-Ω Load /C0068Extremely Efficient Third Generation 5-V Class-D Technology: – Low-Supply Current (No Filter)...4 m A – Low-Supply Current (Filter). . . 7.5 mA – Low-Shutdown Current. . . 0.05 µA – Low-Noise Floor...4 0 µV RMS (No-Weighting Filter) – Maximum Efficiency Into 8 Ω , 75 – 85% – 4 Internal Gain Settings...6 – 23.5 dB – PSRR . . . –77 dB /C0068Integrated Depop Circuitry /C0068Short-Circuit Protection (Short to Battery, Ground, and Load)
description
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 amplifier uses TI’s third generation modulation technique, which results in improved efficiency 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 results 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 package that drives 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 T PACKAGED DEVICES TA TSSOP (PW) † –40°C to 85°C TPA2001D1PW † 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). Copyright 2002, Texas Instruments Incorporated 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. INP INN SHUTDOWN GAIN0 GAIN1 PV DD OUTP PGND BYPASS AGND COSC ROSC V DD PV DD OUTN PGND PW PACKAGE (TOP VIEW) PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Drive_ Gate Drive Gain Adjust Gain Adjust Start-Up Protection Logic OC Detect Thermal VDD ok Ramp Generator Biases and ReferencesGain AGNDVDD VDD PV DD INN OUTN PGND PV DD OUTP PGND INP SHUTDOWN GAIN1 GAIN0 COSC ROSC BYPASS SD Deglitch Logic Deglitch Logic Terminal Functions TERMINAL NAME NO. I/O DESCRIPTION NAME GQC PW AGND 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 PV DD 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
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002 3POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† † 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 PACKAGE TA ≤ 25°C DERATING FACTOR TA = 70°C TA = 85°C PW 774 mW 6.19 mW/°C 495 mW 402 mW recommended operating conditions MIN MAX UNIT ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply voltage, VDD, PVDD ÁÁÁ ÁÁÁ 2.7 ÁÁÁ ÁÁÁ 5.5 ÁÁÁ ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ High-level input voltage, VIH ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ GAIN0, GAIN1, SHUTDOWN ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Low-level input voltage, VIL ÁÁÁÁÁÁÁÁÁÁ GAIN0, GAIN1, SHUTDOWN ÁÁÁ ÁÁÁ 0.7 ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Operating free-air temperature, TA ÁÁÁ ÁÁÁ –40 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ electrical characteristics at specified free-air temperature, PVDD = 5 V, TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁ ÁÁÁ |VOS | ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Output offset voltage (measured differentially) ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ VI = 0 V, A V = any gain ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV ÁÁÁ ÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ PV DD = 4.9 V to 5.1 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁ ÁÁÁ |IIH| ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ High-level input current ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ PV DD = 5.5 V, V I = PVDD ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA ÁÁÁ ÁÁÁ |IIL| ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Low-level input current ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ PV DD = 5.5 V, V I = 0 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA ÁÁÁ ÁÁÁ IDD ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, no filter (with or without speaker load) ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mA ÁÁÁ ÁÁÁ IDD(SD) ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, shutdown mode ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ GAIN0, GAIN1, SHUTDOWN = 0 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.05 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA operating characteristics, PVDD = 5 V, TA = 25°C, RL = 8 Ω, gain = 6 dB (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Output power ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 1%, ÁÁÁÁÁÁ ÁÁÁÁÁÁ f = 1 kHz ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ W ÁÁÁÁ ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Total harmonic distortion plus noise ÁÁÁÁÁÁ ÁÁÁÁÁÁ PO = 1 W, ÁÁÁÁÁÁ ÁÁÁÁÁÁ f = 20 Hz to 20 kHz ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ <0.1% ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ BOM ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 1% ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kHz ÁÁÁÁ kSVR ÁÁÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁÁ f = 1 kHz, ÁÁÁÁÁÁ C (BYP) = 1 µF ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ SNR ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Signal-to-noise ratio ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ Vn ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Output noise voltage (no noise weighting filter) ÁÁÁÁÁÁ ÁÁÁÁÁÁ C (BYP) = 1 µF, ÁÁÁÁÁÁ ÁÁÁÁÁÁ f = <10 Hz to 22 kHz ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µV(rms) ÁÁÁÁ ÁÁÁÁ ZI ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Input impedance ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ >15 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kΩ
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics at specified free-air temperature, PVDD = 3.3 V, TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ |VOS | ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Output offset voltage (measured differentially) ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ VI = 0 V, A V = any gain ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV ÁÁÁÁ ÁÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ PV DD = 3.2 V to 3.4 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ |IIH| ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ High-level input current ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ PV DD = 3.3 V, V I = PVDD ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA ÁÁÁÁ ÁÁÁÁ |IIL| ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Low-level input current ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ PV DD = 3.3 V, V I = 0 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA ÁÁÁÁ ÁÁÁÁ IDD ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, no filter (with or without speaker load) ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mA ÁÁÁÁ ÁÁÁÁ IDD(SD) ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, shutdown mode ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.05 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA operating characteristics, PVDD = 3.3 V, TA = 25°C, RL = 8 Ω, gain = 6 dB (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Output power ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 1%, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ f = 1 kHz ÁÁ ÁÁ ÁÁÁ ÁÁÁ 400 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mW ÁÁÁÁ ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Total harmonic distortion plus noise ÁÁÁÁÁÁ ÁÁÁÁÁÁ PO = 55 mW, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ f = 20 Hz to 20 kHz ÁÁ ÁÁ ÁÁÁ ÁÁÁ <0.1% ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ BOM ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 0.7% ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kHz ÁÁÁÁ ÁÁÁÁ kSVR ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁÁ ÁÁÁÁÁÁ f = 1 kHz, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ C (BYP) = 1 µF ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ SNR ÁÁÁÁÁÁÁÁÁÁÁÁ Signal-to-noise ratio ÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ Vn ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Output noise voltage (no noise weighting filter) ÁÁÁÁÁÁ ÁÁÁÁÁÁ C (BYP) = 1 µF, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ f = <10 Hz to 22 kHz ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µV(rms) ÁÁÁÁ ÁÁÁÁ ZI ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Input impedance ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁ ÁÁ ÁÁÁ ÁÁÁ >15 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kΩ
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002 5POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
eliminating the output filter with the TPA2001D1 This section focuses 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 (V DD ). 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. 0 V –5 V +5 V Current OUTP Differential Voltage Across Load OUTN Figure 1. Traditional Class-D Modulation Scheme’s Output Voltage and Current Waveforms Into an The TPA2001D1 uses a modulation scheme that still has each output switching from 0 to the supply voltage.
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
–5 V +5 V Current OUTP OUTN Differential Voltage Across Load 0 V –5 V +5 V Current OUTP OUTN Differential Voltage Across Load Output = 0 V Output > 0 V Figure 2. The TPA2001D1 Output Voltage and Current Waveforms Into an Inductive Load resistive and reactive, whereas an LC filter is almost purely reactive. most applications the filter is not needed. dissipated, which increases efficiency.
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002 7POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 effects of applying a square wave into a speaker Audio specialists advise 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/f 2 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 (P SUP 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 . (1)PSPKR = PSUP – PSUP THEORETICAL (at max output power) (2)PSPKR = PO (PSUP / PO – PSUP THEORETICAL / PO ) (at max output power) (3)PSPKR = PO (1/ηMEASURED – 1/ηTHEORETICAL ) (at max output power) 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 .
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
8 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Table 1. Gain Settings or cutoff frequency also changes by over six times. The –3 dB frequency can be calculated using equation 4. high-pass filter with the corner frequency determined in equation 5.
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002 9POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 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. C i /C00431 2/C0112ZIfc (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 V DD /2, which is likely higher than the source dc level. Note that it is important to confirm the capacitor polarity in the application. C i 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. (7)C i ≤ CBYP / 10 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 V DD 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. (8)C (BYP) ≥ 10 × Ci
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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 INP INN SHUTDOWN GAIN0 GAIN1 PV DD OUTP PGND BYPASS AGND COSC ROSC VDD PV DD OUTN PGND TPA2001D1 1 µF 1 µF 1 µF 220 pF R1 120 kΩ 1 µFC3 1 µF 1 µF 10 µF 120 kΩ 120 kΩ OUT+ VDD OUT – IN– IN+ VDD 120 kΩ SHUTDOWN GND GND NOTE: R1, R2, and R3 are used in the EVM but are not required for normal applications.
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002 11POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 Table 2. TPA2001D1 Evaluation Bill of Materials
1 TI TPA2001D1PW
† These components are used in the EVM, but they are not required for normal applications.
1-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER SLOS338D – SEPTEMBER 2000 – REVISED DECEMBER 2002
12 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE
14 PINS SHOWN
0,65 M0,10 0,10 0,25 0,50 0,75 0,15 NOM Gage Plane 9,80 9,60 7,90 7,70 2016 6,60 6,40 4040064/F 01/97 0,30 6,60 6,20 0,19 4,30 4,50 0,15 A 1,20 MAX 5,10 4,90 3,10 2,90 A MAX A MIN DIM PINS ** 0,05 4,90 5,10 Seating Plane 0°–/C02578° NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. C. Body dimensions do not include mold flash or protrusion not to exceed 0,15. D. Falls within JEDEC MO-153
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. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third–party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright 2002, Texas Instruments Incorporated