TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
D
D
D
D
D
D
D
Modulation Scheme Optimized to Operate
Without a Filter
2 W Into a 4-Ω Speaker (THD+N<1%)
<0.2% THD+N at 1.5 W, 1 kHz, Into a 4-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
– PSSR . . . –77 dB
Integrated Depop Circuitry
Short-Circuit Protection (Short to Battery,
Ground, and Load)
–40°C to 85°C Operating Temperature
Range
PW PACKAGE
(TOP VIEW)
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
INN
SHUTDOWN
GAIN0
GAIN1
PVDD
PVDD
OUTP
A2
AGND BYPASS
A6
A1
B1
A7
B7
C1
D1
C7
D7
E1
E7
F1
G1
F7
G7
NC
COSC
ROSC
VDD
PVDD
PVDD
OUTN
PGND
description
(SIDE VIEW)
The TPA2000D1 is a 2-W mono bridge-tied-load
(BTL) class-D amplifier designed to drive a
NC – No internal connection, still requires a pad for the ball.
speaker with at least 4-Ω impedance. The
NOTE: The shaded terminals are used for thermal
amplifier uses TI’s third generation modulation
connections to the ground plane.
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 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 TPA2000D1 is available in the 16-pin TSSOP package (PW) which is capable of driving 2-W continuous
output power level into a 4-Ω load. TPA2000D1 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
TPA2000D1PW
TPA2000D1GQC
† 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., TPA2000D1PWR).
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 2001, 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.
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1
TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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
GQY
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
AGND
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 – E7
F2 – F7
G2 – G7
8, 9
I
High-current grounds (2)
PVDD
E1, E7,
F1, F7
6, 11
I
High-current power supplies (2)
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
2
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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
PACKAGE
PW
TA ≤ 25°C
774 mW
DERATING FACTOR
GQC‡
TBD
‡ Product preview stage of development
6.19 mW/°C
TA = 70°C
495 mW
TA = 85°C
402 mW
TBD
TBD
TBD
recommended operating conditions
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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
0.8
V
85
°C
electrical characteristics at specified free-air temperature, PVDD = 5 V, TA = 25°C (unless otherwise
noted)
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
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,
PVDD = 5.5,
TYP
MAX
UNIT
25
mV
1
µA
1
µA
4
6
mA
0.05
20
µA
77
VI = PVDD
VI = 0 V
dB
operating characteristics, PVDD = 5 V, TA = 25°C, RL = 4 Ω, gain = 6 dB (unless otherwise noted)
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁ
ÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
PARAMETER
TEST CONDITIONS
PO
THD + N
Output power
THD = 1%,
f = 1 kHz,
Total harmonic distortion plus noise
f = 20 Hz to 20 kHz
BOM
kSVR
Maximum output power bandwidth
PO = 1.5 W,
THD = 1%,
Supply ripple rejection ratio
f = 1 kHz,
CBYP = 1 µF
SNR
Signal-to-noise ratio
Vn
Output noise voltage (no-noise weighting filter)
CBYP = 1 µF,
f = <10 Hz to 22 kHz
Zi
Input impedance
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
MIN
TYP
2
MAX
UNIT
W
<0.2%
20
kHz
71
dB
95
dB
40
µV(rms)
>15
kΩ
3
TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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,
PVDD = 3.3,
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 = 4 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,
CBYP = 1 µF
SNR
Signal-to-noise ratio
Vn
Output noise voltage (no-noise weighting filter)
Zi
Input impedance
4
CBYP= 1 µF,
POST OFFICE BOX 655303
f = <10 Hz to 22 kHz
• DALLAS, TEXAS 75265
MIN
TYP
850
MAX
UNIT
mW
<0.2%
20
kHz
61
dB
93
dB
40
µV(rms)
>15
kΩ
TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
APPLICATION INFORMATION
eliminating the output filter with the TPA2000D1
This section will focus on why the user can eliminate the output filter with the TPA2000D1.
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 pre-filtered output varies between positive and negative VDD, where filtered 50% duty cycle yields
0 V 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
OV
–5 V
Current
Figure 1. Traditional Class-D Modulation Scheme’s Output Voltage and Current Waveforms Into an
Inductive Load With No Input
TPA2000D1 modulation scheme
The TPA2000D1 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.
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5
TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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 TPA2000D1 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 TPA2000D1 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 cut-off 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
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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 (POUT). The switching power dissipated in the speaker is the inverse of the measured
efficiency (ηMEASURED) minus the theoretical efficiency (ηTHEORETICAL) all multiplied by POUT.
PSPKR = PSUP – PSUP THEORETICAL (at max output power)
(1)
PSPKR = POUT(PSUP / POUT – PSUP THEORETICAL / POUT) (at max output power)
(2)
PSPKR = POUT(1/ηMEASURED – 1/ηTHEORETICAL) (at max output power)
(3)
The maximum efficiency of the TPA2000D1 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 TPA2000D1 without the filter if the traces from amplifier to speaker are short. The TPA2000D1
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 TPA2000D1 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 TPA2000D1. At the higher gain
settings, the input impedance could increase as high as 115 kΩ.
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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 cutoff frequency will also change by over six times.
Zf
Ci
IN
Input
Signal
Zi
The –3-dB frequency can be calculated using equation 4.
f –3 dB
+ 2p C ǒ1R ø Z Ǔ
i
(4)
i
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
+ 2 p Z1 C
(5)
i i
fc
8
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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
+ 2 p 1Z fc
(6)
i
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 TPA2000D1 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, CBYP
The midrail bypass capacitor (CBYP) is the most critical capacitor and serves several important functions. During
start-up or recovery from shutdown mode, CBYP 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 (CBYP) 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, CBYP should be 10 times larger than Ci.
CBYP ≥ 10 × Ci
(8)
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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 TPA2000D1 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 TPA2000D1 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 TPA2000D1 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
TPA2000D1
1 INP
2
J2
C4
1 µF
1 µF
C1
13 220 pF
8
GAIN1
ROSC
VDD
PVDD
PVDD
OUTP
OUTN
GNDP
GNDN
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
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
APPLICATION INFORMATION
Table 2. TPA2000D1 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, TPA2000D1, audio power amplifier, 2-W, single
channel, class-D
24-pin
TSSOP
1
TI
TPA2000D1PW
† These components are used in the EVM, but they are not required for normal applications.
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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°– 8°
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
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TPA2000D1
2-W FILTERLESS MONO CLASS-D AUDIO POWER AMPLIFIER
SLOS328B – JUNE 2000 – REVISED MAY 2001
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.
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