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TPA2028D1
SLOS660C – JANUARY 2010 – REVISED OCTOBER 2015
TPA2028D1 3-W Mono Class-D Audio Amplifier With Fast Gain Ramp SmartGain™
AGC/DRC
1 Features
3 Description
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The TPA2028D1 device is a mono, filter-free Class-D
audio power amplifier with volume control, fast gain
ramp SmartGain™, dynamic range compression
(DRC), and automatic gain control (AGC). It is
available in a 1.63 mm × 1.63 mm wafer chip-scale
package (DSBGA).
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Fast AGC Start-up Time: 5 ms
Pinout Compatible with TPA2018D1
Filter-Free Class-D Architecture
3 W Into 4 Ω at 5 V (10% THD+N)
880 mW Into 8 Ω at 3.6 V (10% THD+N)
Power Supply Range: 2.5 V to 5.5 V
Flexible Operation With/Without I2C™
Programmable DRC/AGC Parameters
Digital I2C™ Volume Control
Selectable Gain from –28 dB to 30 dB in 1-dB
Steps (when compression is used)
Selectable Attack, Release and Hold Times
4 Selectable Compression Ratios
Low Supply Current: 1.8 mA
Low Shutdown Current: 0.2 μA
High PSRR: 80 dB
AGC Enable/Disable Function
Limiter Enable/Disable Function
Short-Circuit and Thermal Protection
Space-Saving Package
– 1.63 mm × 1.63 mm Nano-Free™ DSBGA
(YZF)
The DRC/AGC function in the TPA2028D1 device is
programmable through a digital I2C interface. The
DRC/AGC function can be configured to automatically
prevent distortion of the audio signal and enhance
quiet passages that are normally not heard. The
DRC/AGC can also be configured to protect the
speaker from damage at high power levels and
compress the dynamic range of music to fit within the
dynamic range of the speaker. The gain can be
selected from –28 dB to +30 dB in 1-dB steps. The
TPA2028D1 is capable of driving 3 W at 5 V into a
4-Ω load or 880 mW at 3.6 V into an 8-Ω load. The
device features hardware and software shutdown
controls and also provides thermal and short-circuit
protection. The TPA2028D1 has a faster AGC gain
ramp during start-up than TPA2018D1.
In addition to these features, a fast start-up time and
small package size make the TPA2028D1 an ideal
choice for cellular handsets, PDAs and other portable
applications.
Device Information(1)
2 Applications
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Wireless or Cellular Handsets and PDAs
Portable Navigation Devices
Portable DVD Player
Notebook PCs
Portable Radio
Portable Games
Educational Toys
USB Speakers
PART NUMBER
PACKAGE
TPA2028D1
DSBGA (9)
BODY SIZE (NOM)
1.63 mm x 1.63 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Application Diagram
To Battery
10 mF
PVDD
TPA2028D1
Analog
CIN 1 mF
(Optional)
OUT+
Baseband
IN-
or
IN+
CODEC
OUT2
I C Clock
Digital
BaseBand
2
I C Data
Master Enable
SCL
SDA
EN
PGND
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
TPA2028D1
SLOS660C – JANUARY 2010 – REVISED OCTOBER 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
9
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
4
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
4
5
5
5
5
6
6
7
Absolute Maximum Ratings .....................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Operating Characteristics..........................................
I2C Timing Requirements..........................................
Typical Characteristics ..............................................
Parameter Measurement Information ................ 12
Detailed Description ............................................ 13
9.1 Overview ................................................................. 13
9.2 Functional Block Diagram ....................................... 13
9.3 Feature Description................................................. 13
9.4 Device Functional Modes........................................ 24
9.5 Programming .......................................................... 25
9.6 Register Maps ......................................................... 26
10 Application and Implementation........................ 31
10.1 Application Information.......................................... 31
10.2 Typical Application ............................................... 31
11 Power Supply Recommendations ..................... 33
11.1 Power Supply Decoupling Capacitors................... 33
12 Layout................................................................... 34
12.1 Layout Guidelines ................................................. 34
12.2 Layout Example .................................................... 35
12.3 Efficiency and Thermal Considerations ................ 35
13 Device and Documentation Support ................. 37
13.1
13.2
13.3
13.4
13.5
Device Support......................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
37
37
37
37
37
14 Mechanical, Packaging, and Orderable
Information ........................................................... 37
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (August 2012) to Revision C
•
Page
Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional
Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section ............................... 1
Changes from Revision A (March 2011) to Revision B
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Added Figure 28 .................................................................................................................................................................. 11
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Added ENABLE/DISABLE AMPLIFIER section ................................................................................................................... 24
Changes from Original (January 2010) to Revision A
•
2
Page
Table 4, Changed Register 1, Bit7 From: 0 To: 1 ............................................................................................................... 26
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5 Device Comparison Table
DEVICE NUMBER
SPEAKER CHANNELS
SPEAKER AMP TYPE
OUTPUT POWER (W)
PSRR (dB)
TPA2012D2
Stereo
Class D
2.1
71
TPA2015D1
Mono
Class D
2
85
TPA2026D2
Stereo
Class D
3.2
80
TPA2028D1
Mono
Class D
3
80
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6 Pin Configuration and Functions
YZF Package
9-Pin DSBGA
Top View
PGND
SCL
SDA
A1
A2
A3
OUT+
EN
IN+
B1
B2
B3
OUT-
PVDD
IN-
C1
C2
C3
Pin Functions
PIN
I/O/P (1)
DESCRIPTION
NAME
NO.
EN
B2
I
Enable terminal (active high)
IN+
B3
I
Positive audio input
IN–
C3
I
Negative audio input
OUT+
B1
O
Positive differential output
OUT–
C1
O
Negative differential output
PGND
A1
P
Power ground
PVDD
C2
P
Power supply
SCL
A2
I
I2C clock interface
SDA
A3
I/O
I2C data interface
(1)
I = Input, O = Output, P = Power
7 Specifications
7.1 Absolute Maximum Ratings (1)
over operating free-air temperature range (unless otherwise noted).
VDD
Supply voltage
Input voltage
MIN
MAX
UNIT
PVDD
–0.3
6
V
EN, IN+, IN–
–0.3
VDD+0.3
V
SDA, SCL
–0.3
6
V
Continuous total power dissipation
RLOAD
Minimum load resistance
TA
Operating free-air temperature
TJ
Operating junction temperature
Tstg
Storage temperature
(1)
4
See Thermal Information
3.2
Ω
–40
85
°C
–40
150
°C
–65
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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7.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
MIN
VDD Supply voltage
PVDD
2.5
VIH
High-level input voltage
EN, SDA, SCL
1.3
VIL
Low-level input voltage
EN, SDA, SCL
TA
Operating free-air temperature
NOM
MAX
UNIT
5.5
V
V
–40
0.6
V
85
°C
7.4 Thermal Information
TPA2028D1
THERMAL METRIC (1)
YZF (DSBGA)
UNIT
9 PINS
RθJA
Junction-to-ambient thermal resistance
9
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
0.7
°C/W
RθJB
Junction-to-board thermal resistance
70
°C/W
ψJT
Junction-to-top characterization parameter
3.3
°C/W
ψJB
Junction-to-board characterization parameter
69.7
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
n/a
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
7.5 Electrical Characteristics
at TA = 25°C, VDD = 3.6 V, SDZ = 1.3 V, and RL = 8 Ω + 33 μH (unless otherwise noted).
PARAMETER
VDD
ISDZ
ISWS
IDD
TEST CONDITIONS
Supply voltage range
Shutdown quiescent current
Software shutdown quiescent
current
Supply current
MIN
TYP
MAX
2.5
UNIT
3.6
5.5
EN = 0.35 V, VDD = 2.5 V
0.1
1
EN = 0.35 V, VDD = 3.6 V
0.2
1
EN = 0.35 V, VDD = 5.5 V
0.3
1
EN = 1.3 V, VDD = 2.5 V
35
50
EN = 1.3 V, VDD = 3.6 V
50
70
EN = 1.3 V, VDD = 5.5 V
75
100
VDD = 2.5 V
1.5
2.5
VDD = 3.6 V
1.7
2.7
VDD = 5.5 V
2
3.5
300
325
kHz
1
µA
fSW
Class D Switching Frequency
IIH
High-level input current
VDD = 5.5 V, EN = 5.8 V
275
IIL
Low-level input current
VDD = 5.5 V, EN = –0.3 V
tSTART
Start-up time
2.5 V ≤ VDD ≤ 5.5 V no pop, CIN ≤ 1 μF
POR
Power on reset ON threshold
POR
Power on reset hysteresis
CMRR
Input common mode rejection
Voo
Output offset voltage
–1
V
µA
µA
mA
µA
5
2
ms
2.3
V
0.2
V
RL = 8 Ω, Vicm = 0.5 V and Vicm = VDD – 0.8 V,
differential inputs shorted
–75
dB
VDD = 3.6 V, AV = 6 dB, RL = 8 Ω, inputs ac
grounded
1.5
10
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Electrical Characteristics (continued)
at TA = 25°C, VDD = 3.6 V, SDZ = 1.3 V, and RL = 8 Ω + 33 μH (unless otherwise noted).
PARAMETER
ZOUT
PSRR
TEST CONDITIONS
MIN
Output Impedance in shutdown
mode
EN = 0.35 V
Gain accuracy
Compression and limiter disabled, Gain = 0 to 30 dB
Power supply rejection ratio
VDD = 2.5 V to 4.7 V
TYP
MAX
2
UNIT
kΩ
–0.5
0.5
–80
dB
dB
7.6 Operating Characteristics
at TA = 25°C, VDD = 3.6 V, EN = 1.3 V, RL = 8 Ω +33 μH, and AV = 6 dB (unless otherwise noted).
PARAMETER
kSVR
power-supply ripple rejection ratio
TEST CONDITIONS
MIN
TYP
VDD = 3.6 Vdc with ac of 200 mVPP at 217 Hz
faud_in = 1 kHz; PO = 550 mW; VDD = 3.6 V
0.1%
faud_in = 1 kHz; PO = 1.25 W; VDD = 5 V
0.1%
THD+N
Total harmonic distortion + noise
NfonF
Output integrated noise
Av = 6 dB
42
NfoA
Output integrated noise
Av = 6 dB floor, A-weighted
30
FR
Frequency response
Av = 6 dB
Pomax
Maximum output power
faud_in = 1 kHz; PO = 710 mW; VDD = 3.6 V
1%
faud_in = 1 kHz; PO = 1.4 W; VDD = 5 V
1%
20
Efficiency
UNIT
dB
μV
μV
20000
Hz
THD+N = 10%, VDD = 5 V, RL = 8 Ω
1.72
W
THD+N = 10%, VDD = 3.6 V, RL = 8 Ω
880
mW
THD+N = 1%, VDD = 5 V, RL = 8 Ω
1.4
W
THD+N = 1% , VDD = 3.6 V, RL = 8 Ω
710
mW
THD+N = 1% , VDD = 5 V, RL = 4 Ω
2.5
W
3
W
THD+N = 10% , VDD = 5 V, RL = 4 Ω
η
MAX
–70
THD+N = 1%, VDD = 3.6 V, RL = 8 Ω, PO= 0.71 W
91%
THD+N = 1%, VDD = 5 V, RL = 8 Ω, PO = 1.4 W
93%
7.7 I2C Timing Requirements
For I2C Interface Signals Over Recommended Operating Conditions (unless otherwise noted)
MIN
MAX
UNIT
400
kHz
fSCL
Frequency, SCL
tW(H)
Pulse duration, SCL high
0.6
μs
tW(L)
Pulse duration, SCL low
1.3
μs
tSU(1)
Setup time, SDA to SCL
100
ns
th1
Hold time, SCL to SDA
10
ns
t(buf)
Bus free time between stop and start condition
1.3
μs
tSU2
Setup time, SCL to start condition
0.6
μs
th2
Hold time, start condition to SCL
0.6
μs
tSU3
Setup time, SCL to stop condition
0.6
μs
6
No wait states
TYP
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tw(L)
tw(H)
SCL
th1
t su1
SDA
Figure 1. SCL and SDA Timing
SCL
t(buf)
th2
tsu2
tsu3
Start Condition
Stop Condition
SDA
Figure 2. Start and Stop Conditions Timing
7.8 Typical Characteristics
with C(DECOUPLE) = 1 μF, CI = 1 µF. All THD + N graphs are taken with outputs out of phase (unless otherwise noted).
9
8
100
RL = 8 W + 33 µH
EN = VDD
90
IDD − Supply Current − mA
IDD − Quiescent Supply Current − mA
10
7
6
5
4
3
2
1
0
2.5
RL = 8 W + 33 mH
SWS = 1
80
70
60
50
40
30
20
En = 0 V
10
3.0
3.5
4.0
4.5
VDD − Supply Voltage − V
5.0
5.5
0
2.5
3.5
4.0
4.5
5.0
5.5
VDD − Supply Voltage − V
G001
Figure 3. Quiescent Supply Current vs Supply Voltage
3.0
G002
Figure 4. Supply Current vs Supply Voltage in Shutdown
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Typical Characteristics (continued)
20
20
10
10
Output Level − dBV
Output Level − dBV
with C(DECOUPLE) = 1 μF, CI = 1 µF. All THD + N graphs are taken with outputs out of phase (unless otherwise noted).
0
−10
Limiter
Limiter
Limiter
Limiter
Limiter
Limiter
Limiter
Limiter
Limiter
−20
−30
RL = 8 W + 33 mH
VDD = 5 V
Fixed Gain = Max Gain = 30 dB
Compression Ratio = 1:1
−40
−50
−40
−30
−20
−10
Level
Level
Level
Level
Level
Level
Level
Level
Level
= −6.5
= −4.5
= −2.5
= −0.5
= 1.5
= 3.5
= 5.5
= 7.5
=9
0
0
−10
−30
−50
−70
10
G003
−10
−30
Fixed Gain = −27
Fixed Gain = −24
Fixed Gain = −21
Fixed Gain = −18
−40
−50
−70
−50
−30
Fixed Gain = −15
Fixed Gain = −12
Fixed Gain = −9
Fixed Gain = −6
Fixed Gain = −3
Fixed Gain = 0
Fixed Gain = 3
Fixed Gain = 6
−10
−20
−30
0
−20
−30
Compression
Compression
Compression
Compression
−50
−30
Ratio = 1:1
Ratio = 2:1
Ratio = 4:1
Ratio = 8:1
−10
10
Input Level − dBV
8
−10
10
Input Level − dBV
G006
0
−10
Gain = 6 dB
RL = 8 W + 33 mH
−20
−30
−40
VDD = 2.5 V
−50
−60
VDD = 3.6 V
−70
VDD = 5 V
−80
20
100
1k
f − Frequency − Hz
G007
Figure 9. Output Level vs Input Level
−30
Fixed Gain = −12
Fixed Gain = −9
Fixed Gain = −6
Fixed Gain = −3
Fixed Gain = 0
Fixed Gain = 3
Figure 8. Output Level vs Input Level With 8:1
Compression
−10
−50
−70
−50
G005
Limiter Level = 9 dBV
RL = 8 W + 33 mH
VDD = 5 V
Fixed Gain = 0 dB
Max Gain = 30 dB
−40
Fixed Gain = −27
Fixed Gain = −24
Fixed Gain = −21
Fixed Gain = −18
Fixed Gain = −15
−50
−70
KSVR − Supply Ripple Rejection Ratio − dB
Output Level − dBV
10
G004
−10
Figure 7. Output Level vs Input Level With 4:1
Compression
20
10
0
−40
10
Input Level − dBV
−10
Limiter Level = 9 dBV
RL = 8 W + 33 mH
VDD = 5 V
Max Gain = 30 dB
10
Output Level − dBV
Output Level − dBV
20
0
−30
Figure 6. Output Level vs Input Level With 2:1
Compression
Limiter Level = 9 dBV
RL = 8 W + 33 mH
VDD = 5 V
Max Gain = 30 dB
−20
−50
Input Level − dBV
Figure 5. Output Level vs Input Level With Limiter Enabled
10
Fixed Gain = −12
Fixed Gain = −9
Fixed Gain = −6
Fixed Gain = −3
Fixed Gain = 0
Fixed Gain = 3
Fixed Gain = 6
Fixed Gain = 9
Fixed Gain = 12
−20
−40
Input Level − dBV
20
Limiter Level = 9 dBV
RL = 8 W + 33 mH
VDD = 5 V
Max Gain = 30 dB
10k
20k
G014
Figure 10. Supply Ripple Rejection Ratio vs Frequency
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Typical Characteristics (continued)
10
Gain = 6 dB
RL = 8 W + 33 mH
VDD = 3.6 V
1
PO = 0.5 W
PO = 0.25 W
0.1
0.01
PO = 0.05 W
0.001
20
100
10k
1k
f − Frequency − Hz
20k
THD+N − Total Harmonic Distortion + Noise − %
THD+N − Total Harmonic Distortion + Noise − %
with C(DECOUPLE) = 1 μF, CI = 1 µF. All THD + N graphs are taken with outputs out of phase (unless otherwise noted).
0.1
PO = 0.5 W
PO = 0.1 W
0.01
PO = 1 W
0.001
20
100
1k
10k
f − Frequency − Hz
20k
VDD = 3.6 V
VDD = 5 V
0.1
0.01
0.01
0.1
PO − Output Power − W
PO = 0.1 W
0.01
PO = 0.5 W
0.001
20
100
1
3
20k
G010
10
Gain = 6 dB
RL = 4 W + 33 mH
VDD = 5 V
1
PO = 2 W
PO = 1 W
0.1
0.01
PO = 0.2 W
0.001
20
100
1k
10k
20k
G011
Figure 14. Total Harmonic Distortion + Noise vs Frequency
100
10
Gain = 6 dB
RL = 4 W + 33 mH
f = 1 kHz
VDD = 3.6 V
VDD = 5 V
1
0.1
0.01
0.01
0.1
1
PO − Output Power − W
G012
Figure 15. Total Harmonic Distortion + Noise vs Output
Power
10k
1k
f − Frequency − Hz
THD+N − Total Harmonic Distortion + Noise − %
THD+N − Total Harmonic Distortion + Noise − %
Gain = 6 dB
RL = 8 W + 33 mH
f = 1 kHz
1
0.1
G009
100
PO = 1 W
Figure 12. Total Harmonic Distortion + Noise vs Frequency
Figure 13. Total Harmonic Distortion + Noise vs Frequency
10
1
f − Frequency − Hz
THD+N − Total Harmonic Distortion + Noise − %
THD+N − Total Harmonic Distortion + Noise − %
10
1
Gain = 6 dB
RL = 4 W + 33 mH
VDD = 3.6 V
G008
Figure 11. Total Harmonic Distortion + Noise vs Frequency
Gain = 6 dB
RL = 8 W + 33 mH
VDD = 5 V
10
5
G013
Figure 16. Total Harmonic Distortion + Noise vs Output
Power
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Typical Characteristics (continued)
with C(DECOUPLE) = 1 μF, CI = 1 µF. All THD + N graphs are taken with outputs out of phase (unless otherwise noted).
100
100
90
90
80
70
VDD = 2.5 V
VDD = 5 V
VDD = 3.6 V
h − Efficiency − %
h − Efficiency − %
80
60
50
40
30
Gain = 6 dB
RL = 8 W + 33 mH
f = 1 kHz
20
10
0
0.0
0.5
1.0
1.5
70
60
50
40
30
Gain = 6 dB
RL = 4 Ω + 33 µH
f = 1 kHz
20
10
0
0.0
2.0
PO − Output Power − W
0.5
G015
2.0
2.5
3.0
3.5
4.0
G018
0.50
Gain = 6 dB
RL = 8 W + 33 mH
f = 1 kHz
0.12
0.10
Gain = 6 dB
RL = 4 W + 33 mH
f = 1 kHz
0.45
PD − Power Dissipation − W
PD − Power Dissipation − W
1.5
Figure 18. Efficiency vs Output Power
0.14
VDD = 3.6 V
0.08
VDD = 2.5 V
VDD = 5 V
0.06
0.04
0.02
0.40
0.35
VDD = 3.6 V
0.30
VDD = 5 V
VDD = 2.5 V
0.25
0.20
0.15
0.10
0.05
0.00
0.0
0.5
1.0
1.5
0.00
0.0
2.0
PO − Output Power − W
2.5
3.0
3.5
4.0
G019
VDD = 5 V
0.7
VDD = 5 V
VDD = 3.6 V
0.30
VDD = 2.5 V
0.20
0.15
0.10
VDD = 3.6 V
0.6
0.5
VDD = 2.5 V
0.4
0.3
0.2
Gain = 6 dB
RL = 4 W + 33 mH
f = 1 kHz
0.1
0.05
0.00
0.0
2.0
0.8
Gain = 6 dB
RL = 8 W + 33 mH
f = 1 kHz
0.35
0.25
1.5
Figure 20. Power Dissipation vs Output Power
IDD − Supply Current − A
0.40
1.0
PO − Output Power − W
0.50
0.45
0.5
G016
Figure 19. Power Dissipation vs Output Power
IDD − Supply Current − A
1.0
PO − Output Power − W
Figure 17. Efficiency vs Output Power
0.5
1.0
1.5
2.0
PO − Output Power − W
0.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
PO − Output Power − W
G017
Figure 21. Supply Current vs Output Power
10
VDD = 5 V
VDD = 3.6 V
VDD = 2.5 V
4.0
G020
Figure 22. Supply Current vs Output Power
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Typical Characteristics (continued)
with C(DECOUPLE) = 1 μF, CI = 1 µF. All THD + N graphs are taken with outputs out of phase (unless otherwise noted).
4.0
Gain = 6 dB
RL = 8 W + 33 mH
f = 1 kHz
2.0
1.5
Gain = 6 dB
RL = 4 W + 33 mH
f = 1 kHz
3.5
PO − Output Power − W
PO − Output Power − W
2.5
THD = 10%
1.0
THD = 1%
0.5
3.0
2.5
THD = 10%
2.0
1.5
THD = 1%
1.0
0.5
0.0
2.5
3.0
3.5
4.0
4.5
5.0
0.0
2.5
5.5
VDD − Supply Voltage − V
G021
4.0
4.5
5.0
5.5
G022
Figure 24. Output Power vs Supply Voltage
10
10
VDD = 5.0 V
Fixed Gain = 6 dB, CR = 1:1
VIN = 707 mVRMS @ 1kHz
RL = 8 Ω + 33 µH
8
TPA2028D1 OUTP−OUTM
TPA2018D1 OUTP−OUTM
SCL − Speaker Enable
VDD = 5.0 V
Fixed Gain = 6 dB, CR = 1:1
VIN = 707 mVRMS @ 1kHz
RL = 8 Ω + 33 µH
8
TPA2028D1 OUTP−OUTM
TPA2018D1 OUTP−OUTM
SCL − Speaker Enable
6
V − Voltage − V
6
V − Voltage − V
3.5
VDD − Supply Voltage − V
Figure 23. Output Power vs Supply Voltage
4
2
4
2
0
0
−2
−2
−4
−4
0
5m
10m
t − Time − s
15m
20m
0
1
2
3
4
5
t − Time − s
Figure 25. Shutdown Gain Ramp Comparison
Figure 26. Startup Gain Ramp Comparison
1
140
0.5
ZI – Input Impedance – kW
Output
0.75
V – Voltage– V
3.0
SWS Disable
0.25
0
-0.25
-0.5
-0.75
-1
0
1m 2m 3m 4m 5m 6m 7m 8m
t – Time – s
Figure 27. Startup Time
9m 10m
120
100
80
60
40
20
0
0
4
8
12
16
20
24
28
32
Gain – dB
G024
Figure 28. Nominal Input Impedance - Per Leg
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8 Parameter Measurement Information
All parameters are measured according to the conditions described in the Specifications section.
TPA2028D1
CI
+
Measurement
Output
–
IN+
OUT+
Load
CI
IN–
VDD
+
OUT–
30 kHz
Low-Pass
Filter
+
Measurement
Input
–
GND
1 mF
VDD
–
(1)
All measurements were taken with a 1-μF CI (unless otherwise noted.)
(2)
A 33-μH inductor was placed in series with the load resistor to emulate a small speaker for efficiency measurements.
(3)
The 30-kHz low-pass filter is required, even if the analyzer has an internal low-pass filter. An RC low-pass filter (1 kΩ
4.7 nF) is used on each output for the data sheet graphs.
Figure 29. Test Set-Up for Typical Characteristics Graphs
12
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9 Detailed Description
9.1 Overview
The TPA2028D1 device is a mono, filter-free Class-D audio power amplifier with volume control, dynamic range
compression (DRC) and automatic gain control (AGC). The DRC/AGC function is programmable via a digital I2C
interface.
The gain can be selected from -28 dB to +30 dB in 1-dB steps. The device is able to do hardware and software
shutdown and also provides thermal and short-circuit protection.
9.2 Functional Block Diagram
SDA
2
I C Interface
Bias and
References
SCL
PVDD
2
I C Interface
and Control
EN
IC Enable
CIN
OUT +
IN -
Differential
Input
IN +
Volume
Control
Class - D
Modulator
Power
Stage
OUT -
1 mF
PGND
AGC
Reference
AGC
9.3 Feature Description
9.3.1 Automatic Gain Control
The Automatic Gain Control (AGC) feature provides continuous automatic gain adjustment to the amplifier
through an internal PGA. This feature enhances the perceived audio loudness and at the same time prevents
speaker damage from occurring (Limiter function).
The AGC function attempts to maintain the audio signal gain as selected by the user through the Fixed Gain,
Limiter Level, and Compression Ratio variables. Other advanced features included are Maximum Gain and Noise
Gate Threshold. Table 1 describes the function of each variable in the AGC function.
Table 1. TPA2028D1 AGC Variable Descriptions
VARIABLE
DESCRIPTION
Maximum Gain
The gain at the lower end of the compression region.
Fixed Gain
The normal gain of the device when the AGC is inactive.
The fixed gain is also the initial gain when the device comes out of shutdown mode or when the AGC is
disabled.
Limiter Level
The value that sets the maximum allowed output amplitude.
Compression Ratio
The relation between input and output voltage.
Noise Gate Threshold
Below this value, the AGC holds the gain to prevent breathing effects.
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Feature Description (continued)
Table 1. TPA2028D1 AGC Variable Descriptions (continued)
VARIABLE
DESCRIPTION
Attack Time
The minimum time between two gain decrements.
Release Time
The minimum time between two gain increments.
Hold Time
The time it takes for the very first gain increment after the input signal amplitude decreases.
The AGC works by detecting the audio input envelope. The gain changes depending on the amplitude, the limiter
level, the compression ratio, and the attack and release time. The gain changes constantly as the audio signal
increases and/or decreases to create the compression effect. The gain step size for the AGC is 0.5 dB. If the
audio signal has near-constant amplitude, the gain does not change. Figure 30 shows how the AGC works.
INPUT SIGNAL
Limiter threshold
Limiter threshold
B
C
D
E
A
GAIN
OUTPUT SIGNAL
Limiter threshold
Release Time
Hold Time
Attack Time
Limiter threshold
A.
Gain decreases with no delay; attack time is reset. Release time and hold time are reset.
B.
Signal amplitude above limiter level, but gain cannot change because attack time is not over.
C.
Attack time ends; gain is allowed to decrease from this point forward by one step. Gain decreases because the
amplitude remains above limiter threshold. All times are reset
D.
Gain increases after release time finishes and signal amplitude remains below desired level. All times are reset after
the gain increase.
E.
Gain increases after release time is finished again because signal amplitude remains below desired level. All times
are reset after the gain increase.
Figure 30. Input and Output Audio Signal Versus Time
Since the number of gain steps is limited the compression region is limited as well. The following figure shows
how the gain changes versus the input signal amplitude in the compression region.
14
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Gain - dB
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VIN - dBV
Figure 31. Input Signal Voltage Versus Gain
Thus the AGC performs a mapping of the input signal versus the output signal amplitude. This mapping can be
modified according to the variables from Table 1.
The following graphs and explanations show the effect of each variable to the AGC independently and which
considerations should be taken when choosing values.
Fixed Gain: The fixed gain determines the initial gain of the AGC. Set the gain using the following variables:
• Set the fixed gain to be equal to the gain when the AGC is disabled.
• Set the fixed gain to maximize SNR.
• Set the fixed gain such that it will not overdrive the speaker.
Increasing
Fixed Gain
G
xe
d
Decreasing
Fixed Gain
1:
1
Fi
VOUT - dBV
ai
n
=
3
Fi
xe
dB
d
G
ai
n
=
6
dB
Figure 32 shows how the fixed gain influences the input signal amplitude versus the output signal amplitude state
diagram. The dotted 1:1 line is displayed for reference. The 1:1 line means that for a 1dB increase in the input
signal, the output increases by 1dB.
VIN - dBV
Figure 32. Output Signal Versus Input Signal State Diagram Showing Different Fixed Gain Configurations
If the Compression function is enabled, the Fixed Gain is adjustable from –28dB to 30dB. If the Compression
function is disabled, the Fixed gain is adjustable from 0dB to 30dB.
Limiter Level: The Limiter level sets the maximum amplitude allowed at the output of the amplifier. The limiter
should be set with the following constraints in mind:
• Below or at the maximum power rating of the speaker
• Below the minimum supply voltage in order to avoid clipping
Figure 33 shows how the limiter level influences the input signal amplitude versus the output signal amplitude
state diagram.
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Limiter Level= 630mW
Limiter Level= 500mW
VOUT - dBV
Limiter Level = 400 mW
Increasing
Limiter
Level
Decreasing
Limiter
Level
VIN - dBV
Figure 33. Output Signal Versus Input Signal State Diagram Showing Different Limiter Level
Configurations
The limiter level and the fixed gain influence each other. If the fixed gain is set high, the AGC has a large limiter
range. The fixed gain is set low, the AGC has a short limiter range. Figure 34 illustrates the two examples:
Small
Fixed
Gain
1:
1
VOUT - dBV
Large Fixed Gain
VIN - dBV
Figure 34. Output Signal Versus Input Signal State Diagram Showing Same Limiter Level Configurations
With Different Fixed Gain Configurations
Compression Ratio: The compression ratio sets the relation between input and output signal outside the limiter
level region. The compression ratio compresses the dynamic range of the audio. For example if the audio source
has a dynamic range of 60dB and compression ratio of 2:1 is selected, then the output has a dynamic range of
30dB. Most small form factor speakers have small dynamic range. Compression ratio allows audio with large
dynamic range to fit into a speaker with small dynamic range.
The compression ratio also increases the loudness of the audio without increasing the peak voltage. The higher
the compression ratio, the louder the perceived audio.
For example:
• A compression ratio of 4:1 is selected (meaning that a 4dB change in the input signal results in a 1dB signal
change at the output)
• A fixed gain of 0dB is selected and the maximum audio level is at 0dBV.
When the input signal decreases to –32dBV, the amplifier increases the gain to 24dB in order to achieve an
output of –8dBV. The output signal amplitude equation is:
Output signal amplitude =
16
Input signal initial amplitude - |Current input signal amplitude|
Compression ratio
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In this example:
-8dBV =
0dBV - | - 32 dBV|
4
(2)
The gain change equation is:
æ
ö
1
Gain change = ç 1 ÷ × Input signal change
Compression ratio ø
è
(3)
1ö
æ
24 dB = ç 1 - ÷ × 32
4ø
è
(4)
Consider the following when setting the compression ratio:
• Dynamic range of the speaker
• Fixed gain level
• Limiter Level
• Audio Loudness versus Output Dynamic Range.
Figure 35 shows different settings for dynamic range and different fixed gain selected but no limiter level.
Rotation
Point@
higher gain
8 :1
4 :1
Increasing
Fixed Gain
1
2:
VOUT - dBV
1
Rotation
Point@
lower gain
:1
8 :1
Decreasing
4 :1
2:
1
1
:1
VIN - dBV
Figure 35. Output Signal Versus Input Signal State Diagram Showing Different Compression Ratio
Configurations With Different Fixed Gain Configurations
The rotation point is always at Vin = 10dBV. The rotation point is not located at the intersection of the limiter
region and the compression region. By changing the fixed gain the rotation point will move in the y-axis direction
only, as shown in the previous graph.
Interaction between compression ratio and limiter range: The compression ratio can be limited by the limiter
range. Note that the limiter range is selected by the limiter level and the fixed gain.
For a setting with large limiter range, the amount of gain steps in the AGC remaining to perform compression are
limited. Figure 36 shows two examples, where the fixed gain was changed.
1. Small limiter range yielding a large compression region (small fixed gain).
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2. Large limiter range yielding a small compression region (large fixed gain).
Small
Compression
Region
Large Limiter
Range
Rotation
Point @
higher gain
Large
Compression
Region
1:
1
VOUT - dBV
Rotation
Point @
lower gain
Small Limiter
Range
VIN - dBV
Figure 36. Output Signal Versus Input Signal State Diagram Showing the Effects of the Limiter Range to
the Compression Region
Input Signal
Amplitude - Vrms
Noise Gate Threshold: The noise gate threshold prevents the AGC from changing the gain when there is no
audio at the input of the amplifier. The noise gate threshold stops gain changes until the input signal is above the
noise gate threshold. Select the noise gate threshold to be above the noise but below the minimum audio at the
input of the amplifier signal. A filter is needed between delta-sigma CODEC/DAC and TPA2028D1 for
effectiveness of the noise gate function. The filter eliminates the out-of-band noise from delta-sigma modulation
and keeps the CODEC/DAC output noise lower than the noise gate threshold.
No
Audio
Noise Gate Threshold
time
Gain - dB
Gain does not change
in this region
time
Figure 37. Time Diagram Showing the Relationship Between Input Signal Amplitude, Noise Gate
Threshold and Gain Versus Time
Maximum Gain: This variable limits the number of gain steps in the AGC. This feature is useful in order to
accomplish a more advanced output signal versus input signal transfer characteristic.
For example, to prevent the gain from going above a certain value, reduce the maximum gain.
However, this variable will affect the limiter range and the compression region. If the maximum gain is
decreased, the limiter range and/or compression region is reduced. Figure 38 illustrates the effects.
18
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1:
1
VOUT - dBV
Max Gain Max Gain
= 30dB
= 22dB
VIN - dBV
Figure 38. Output Signal Versus Input Signal State Diagram Showing Different Maximum Gains
A particular application requiring maximum gain of 22dB, for example. Thus, set the maximum gain at 22dB. The
amplifier gain will never have a gain higher than 22dB; however, this will reduce the limiter range.
Attack, Release, and Hold time:
• The attack time is the minimum time between gain decreases.
• The release time is the minimum time between gain increases.
• The hold time is the minimum time between a gain decrease (attack) and a gain increase (release). The hold
time can be deactivated. Hold time is only valid if greater than release time.
Successive gain decreases are never faster than the attack time. Successive gain increases are never faster
than the release time.
All time variables (attack, release and hold) start counting after each gain change performed by the AGC. The
AGC is allowed to decrease the gain (attack) only after the attack time finishes. The AGC is allowed to increase
the gain (release) only after the release time finishes counting. However, if the preceding gain change was an
attack (gain increase) and the hold time is enabled and longer than the release time, then the gain is only
increased after the hold time.
The hold time is only enabled after a gain decrease (attack). The hold time replaces the release time after a gain
decrease (attack). If the gain needs to be increased further, then the release time is used. The release time is
used instead of the hold time if the hold time is disabled.
The attack time should be at least 100 times shorter than the release and hold time. The hold time should be the
same or greater than the release time. It is important to select reasonable values for those variables in order to
prevent the gain from changing too often or too slow.
Figure 39 illustrates the relationship between the three time variables.
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Input Signal
Amplitue (Vrms)
Gain dB
Time end
Attack time
Time reset
Release time
Hold timer not used after
first gain increase
Hold time
time
Figure 39. Time Diagram Showing the Relation Between the Attack, Release, and Hold Time Versus Input
Signal Amplitude and Gain
Figure 40 shows a state diagram of the input signal amplitude versus the output signal amplitude and a summary
of how the variables from table 1 described in the preceding pages affect them.
Fixed
Gain
Rotation
Point
8:1
¥:1
1:
1
4:1
2:1
nR
sio
1
:1
A
tta
R
c
el
k
ea
Ti
se
m
e
Ti
m
e
Noise Gate Threshold
VOUT - dBV
r es
mp
Co
Limiter
Level
ion
eg
Maximum
Gain
VIN - dBV
10 dBV
Figure 40. Output Signal Versus Input Signal State Diagram
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9.3.2 Operation With DACs and CODECs
In using Class-D amplifiers with CODECs and DACs, sometimes there is an increase in the output noise floor
from the audio amplifier. This occurs when output frequencies of the CODEC/DAC mix with the Class-D
switching frequency and create sum/difference components in the audio band. The noise increase can be solved
by placing an RC low-pass filter between the CODEC/DAC and audio amplifier. The filter reduces high
frequencies that cause the problem and allows proper performance.
TPA2028D1 includes an integrated low-pass filter for this purpose. It is still possible that Class-D output noise will
be affected in extreme cases. In such a case, the RC filter may still be needed.
9.3.3 Filter Free Operation and Ferrite Bead Filters
A ferrite bead filter can often be used if the design is failing radiated emissions without an LC filter and the
frequency sensitive circuit is greater than 1 MHz. This filter functions well for circuits that just have to pass FCC
and CE because FCC and CE only test radiated emissions greater than 30 MHz. When choosing a ferrite bead,
choose one with high impedance at high frequencies, and low impedance at low frequencies. In addition, select a
ferrite bead with adequate current rating to prevent distortion of the output signal.
Use an LC output filter if there are low frequency (< 1 MHz) EMI sensitive circuits and/or there are long leads
from amplifier to speaker. Figure 41 shows typical ferrite bead and LC output filters.
Ferrite
Chip Bead
OUTP
1 nF
Ferrite
Chip Bead
OUTN
1 nF
Figure 41. Typical Ferrite Bead Filter (Chip Bead Example: TDK: MPZ1608S221A)
Figure 42. EMC Performance Under FCC Class-B
Figure 42 shows the EMC performance of TPA2028D1 under FCC Class-B. The test circuit configuration is
shown in Figure 41. The worst-case quasi peak margin is 29.8 dB at 30.5 MHz.
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Table 2. Measurement Condition for TPA2028D1 EMC Test
PARAMETER
VALUE
UNIT
4.2
V
VDD
Supply voltage
AV
Gain
6
dB
fAUD
Input signal frequency
1
kHz
VI
Input signal amplitude
1
VRMS
VO
Output signal amplitude
2
VRMS
RL
Load impedance
Output cable length
8
Ω
100
mm
Spacer
9.3.4 General I2C Operation
The I2C bus employs two signals, SDA (data) and SCL (clock), to communicate between integrated circuits in a
system. The bus transfers data serially one bit at a time. The address and data 8-bit bytes are transferred most
significant bit (MSB) first. In addition, each byte transferred on the bus is acknowledged by the receiving device
with an acknowledge bit. Each transfer operation begins with the master device driving a start condition on the
bus and ends with the master device driving a stop condition on the bus. The bus uses transitions on the data
terminal (SDA) while the clock is at logic high to indicate start and stop conditions. A high-to-low transition on
SDA indicates a start and a low-to-high transition indicates a stop. Normal data-bit transitions must occur within
the low time of the clock period. Figure 43 shows a typical sequence. The master generates the 7-bit slave
address and the read/write (R/W) bit to open communication with another device, and then waits for an
acknowledge condition. The TPA2028D1 holds SDA low during the acknowledge clock period to indicate
acknowledgment. When this acknowledgment occurs, the master transmits the next byte of the sequence. Each
device is addressed by a unique 7-bit slave address plus R/W bit (1 byte). All compatible devices share the same
signals via a bidirectional bus using a wired-AND connection.
An external pull-up resistor must be used for the SDA and SCL signals to set the logic high level for the bus.
8- Bit Data for
Register (N)
8- Bit Data for
Register (N+1)
Figure 43. Typical I2C Sequence
There is no limit on the number of bytes that can be transmitted between start and stop conditions. When the last
word transfers, the master generates a stop condition to release the bus. A generic data transfer sequence is
shown in Figure 43.
9.3.4.1 Single- and Multiple-Byte Transfers
The serial control interface supports both single-byte and multi-byte read/write operations for all registers.
During multiple-byte read operations, the TPA2028D1 responds with data, one byte at a time, starting at the
register assigned, as long as the master device continues to respond with acknowledgments.
The TPA2028D1 supports sequential I2C addressing. For write transactions, if a register is issued followed by
data for that register and all the remaining registers that follow, a sequential I2C write transaction has occurred.
For I2C sequential write transactions, the register issued then serves as the starting point, and the amount of
data subsequently transmitted, before a stop or start is transmitted, determines the number of registers written.
22
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9.3.4.2 Single-Byte Write
As Figure 44 shows, a single-byte data write transfer begins with the master device transmitting a start condition
followed by the I2C device address and the read/write bit. The read/write bit determines the direction of the data
transfer. For a write data transfer, the read/write bit must be set to '0'. After receiving the correct I2C device
address and the read/write bit, the TPA2028D1 responds with an acknowledge bit. Next, the master transmits the
register byte corresponding to the TPA2028D1 internal memory address being accessed. After receiving the
register byte, the TPA2028D1 again responds with an acknowledge bit. Next, the master device transmits the
data byte to be written to the memory address being accessed. After receiving the register byte, the TPA2028D1
again responds with an acknowledge bit. Finally, the master device transmits a stop condition to complete the
single-byte data write transfer.
Start
Condition
Acknowledge
A6
A5
A4
A3
A2
A1
A0
Acknowledge
R/W ACK A7
A6
A5
I2C Device Address and
Read/Write Bit
A4
A3
A2
A1
Acknowledge
A0 ACK D7
D6
Register
D5
D4
D3
D2
D1
D0 ACK
Stop
Condition
Data Byte
Figure 44. Single-Byte Write Transfer
9.3.4.3 Multiple-Byte Write and Incremental Multiple-Byte Write
A multiple-byte data write transfer is identical to a single-byte data write transfer except that multiple data bytes
are transmitted by the master device to the TPA2028D1 as shown in Figure 45. After receiving each data byte,
the TPA2028D1 responds with an acknowledge bit.
Register
Figure 45. Multiple-Byte Write Transfer
9.3.4.4 Single-Byte Read
As Figure 46 shows, a single-byte data read transfer begins with the master device transmitting a start condition
followed by the I2C device address and the read/write bit. For the data read transfer, both a write followed by a
read are actually executed. Initially, a write is executed to transfer the address byte of the internal memory
address to be read. As a result, the read/write bit is set to a '0'.
After receiving the TPA2028D1 address and the read/write bit, the TPA2028D1 responds with an acknowledge
bit. The master then sends the internal memory address byte, after which the TPA2028D1 issues an
acknowledge bit. The master device transmits another start condition followed by the TPA2028D1 address and
the read/write bit again. This time the read/write bit is set to '1', indicating a read transfer. Next, the TPA2028D1
transmits the data byte from the memory address being read. After receiving the data byte, the master device
transmits a not-acknowledge followed by a stop condition to complete the single-byte data read transfer.
Repeat Start
Condition
Start
Condition
Acknowledge
A6
A5
A1
A0 R/W ACK A7
I2C Device Address and
Read/Write Bit
Acknowledge
A6
A5
A4
Register
A0 ACK
Not
Acknowledge
Acknowledge
A6
A5
A1
A0 R/W ACK D7
I2C Device Address and
Read/Write Bit
D6
D1
Data Byte
D0 ACK
Stop
Condition
Figure 46. Single-Byte Read Transfer
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9.3.4.5 Multiple-Byte Read
A multiple-byte data read transfer is identical to a single-byte data read transfer except that multiple data bytes
are transmitted by the TPA2028D1 to the master device as shown in Figure 47. With the exception of the last
data byte, the master device responds with an acknowledge bit after receiving each data byte.
Repeat Start
Condition
Start
Condition
Acknowledge
A6
A0 R/W ACK A7
I2C Device Address and
Read/Write Bit
Acknowledge
A6
A5
Acknowledge
A0 ACK
A6
A0 R/W ACK D7
I2C Device Address and
Read/Write Bit
Register
Acknowledge
D0
ACK D7
First Data Byte
Acknowledge
Not
Acknowledge
D0 ACK D7
D0 ACK
Other Data Bytes
Last Data Byte
Stop
Condition
Figure 47. Multiple-Byte Read Transfer
9.4 Device Functional Modes
9.4.1 Enable/Disable Amplifier
The amplifier is enabled by pulling EN high and disabled by pulling EN low.
It is necessary to wait 10ms after EN is pulled high and before the first I2C transaction. It is also required to wait
1ms after the last I2C transaction completes before pulling EN low otherwise it is not guaranteed that the I2C
transaction was successful.
If the amplifier is disabled by pulling EN low, it is required to wait at least 5ms before re-enabling the amplifier by
pulling EN high again.
EN
min. 5ms
SCL
min. 10ms
min. 1ms
Figure 48. Enable/Disable Amplifier
9.4.2 TPA2028D1 AGC and Start-Up Operation
The TPA2028D1 is controlled by the I2C interface. The correct start-up sequence is:
1. Apply the supply voltage to the PVDD pin.
2. Apply a voltage above VIH to the EN pin. The TPA2028D1 powers up the I2C interface and the control logic.
I2C registers are reset to default value. By default, the device is in active mode (SWS = 0). After 5 ms the
amplifier will enable the class-D output stage and become fully operational.
NOTE
Do not interrupt the start-up sequence after changing EN from VIL to VIH.
Do not interrupt the start-up sequence after changing SWS from 1 to 0.
9.4.2.1 AGC Startup Condition
The amplifier gain at start-up depends on the following conditions:
1. Start-up from hardware reset (EN from 0 to 1): The amplifier starts up immediately at default fixed gain. AGC
starts controlling gain once the input audio signal exceeds noise gate threshold.
2. Start-up from software shutdown (SWS from 1 to 0): The amplifier starts up immediately at the latest fixed
24
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Device Functional Modes (continued)
gain during software shutdown, regardless the attack/ release time. For example:
– Audio is playing at fixed gain 6dB
– Devices goes to software shutdown (SWS = 1)
– Set fixed gain from 6 dB to 12 dB
– Remove software shutdown (SWS = 0)
– Amplifier starts up immediately at 12 dB
3. During audio playback with AGC on, gain changes according to attack/ release time. For example:
– Audio is playing at fixed gain 6 dB and 1:1 compression ratio
– Set fixed gain from 6 dB to 12 dB, at release time 500 ms / 6 dB
– Amplifier will take 500 ms to ramp from 6 dB to 12 dB
4. When EN = 0 and SWS = 0, the amplifier is set at fixed gain. The amplifier starts up at fixed gain when EN
transitions from 0 to 1.
The default conditions of TPA2028D1 allows audio playback without I2C control. Refer to Table 5 for entire
default conditions.
There are several options to disable the amplifier:
• Write EN = 0 to the register (0x01, 6). This write disables the amplifier, but leaves all other circuits operating.
• Write SWS = 1 to the register (0x01, 5). This action disables most of the amplifier functions.
• Apply VIL to EN. This action shuts down all the circuits and has very low quiescent current consumption. This
action resets the register to its default values.
NOTE
Do not interrupt the shutdown sequence after changing EN from VIH to VIL.
Do not interrupt the shutdown sequence after changing SWS from 0 to 1.
9.4.3 Short Circuit Auto-Recovery
When a short circuit event happens, the TPA2028D1 goes to low duty cycle mode and tries to reactivate itself
every 110 µs. This auto-recovery will continue until the short circuit event stops. This feature can protect the
device without affecting the device's long term reliability. FAULT bit (register 1, bit 3) still requires a write to clear.
9.5 Programming
9.5.1 TPA2028D1 AGC Recommended Settings
Table 3. Recommended AGC Settings for Different Types of Audio Source (VDD = 3.6 V)
AUDIO
SOURCE
COMPRESSION
RATIO
ATTACK TIME
(ms/6 dB)
RELEASE TIME
(ms/6 dB)
HOLD TIME
(ms)
FIXED GAIN
(dB)
LIMITER LEVEL
(dBV)
Pop Music
4:1
1.28 to 3.84
986 to 1640
137
6
7.5
Classical
2:1
2.56
1150
137
6
8
Jazz
2:1
5.12 to 10.2
3288
—
6
8
Rap / Hip Hop
4:1
1.28 to 3.84
1640
—
6
7.5
Rock
2:1
3.84
4110
—
6
8
Voice / News
4:1
2.56
1640
—
6
8.5
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9.6 Register Maps
Table 4. TPA2028D1 Register Map
Register
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
1
1
EN
SWS
0
FAULT
Thermal
1
NG_EN
2
0
0
ATK_time [5]
ATK_time [4]
ATK_time [3]
ATK_time [2]
ATK_time [1]
ATK_time [0]
3
0
0
REL_time [5]
REL_time [4]
REL_time [3]
REL_time [2]
REL_time [1]
REL_time [0]
4
0
0
Hold_time [5]
Hold_time [4]
Hold_time [3]
Hold_time [2]
Hold_time [1]
Hold_time [0]
5
0
0
FixedGain [5]
FixedGain [4]
FixedGain [3]
FixedGain [2]
FixedGain [1]
FixedGain [0]
6
Output
Limiter
Disable
NoiseGate
Threshold
[1]
NoiseGate
Threshold [2]
Output Limiter
Level [4]
Output Limiter
Level [3]
Output Limiter
Level [2]
Output Limiter
Level [1]
Output Limiter
Level [0]
7
Max Gain
[3]
Max Gain
[2]
Max Gain [1]
Max Gain [0]
0
0
Compression
Ratio [1]
Compression
Ratio [0]
The default register map values are given in Table 5.
Table 5. TPA2028D1 Default Register Values Table
Register
0x01
0x02
0x03
0x04
0x05
0x06
0x07
Default
C3h
05h
0Bh
00h
06h
3Ah
C2h
Any register above address 0x08 is reserved for testing and should not be written to because it may change the
function of the device. If read, these bits may assume any value.
Some of the default values can be reprogrammed through the I2C interface and written to the EEPROM. This
function is useful to speed up the turn-on time of the device and minimizes the number of I2C writes. If this is
required, contact your local TI representative.
The TPA2028D1 I2C address is 0xB0 (binary 10110000) for writing and 0xB1 (binary 10110001) for reading. If a
different I2C address is required, please contact your local TI representative. See the General I2C operation
section for more detail.
The following tables show the details of the registers, the default values, and the values that can be programmed
through the I2C interface.
26
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Table 6. IC Function Control (Address: 1)
2
REGISTER
ADDRESS
01 (01H) – IC
Function Control
I C BIT
LABEL
DEFAULT
DESCRIPTION
7
Unused
1
6
EN
1 (enabled)
Enables amplifier
5
SWS
0 (enabled)
Shutdown IC when bit = 1
4
Unused
0
3
FAULT
0
Changes to a 1 when there is a short at the output. Reset by writing a 0
2
Thermal
0
Changes to a 1 when die temperature is above 150°C
1
Unused
1
0
NG_EN
1 (enabled)
Enables Noise Gate function
EN:
Enable bit for the audio amplifier channel. Amplifier is active when bit is high. This function is
gated by thermal and returns once the IC is below the threshold temperature
SWS:
Software shutdown control. The device is in software shutdown when the bit is '1' (control, bias
and oscillator are inactive). When the bit is '0' the control, bias and oscillator are enabled.
Fault:
This bit indicates that an over-current event has occurred on the channel with a '1'. This bit is
cleared by writing a '0' to it.
Thermal:
This bit indicates a thermal shutdown that was initiated by the hardware with a '1'. This bit is
deglitched and latched, and can be cleared by writing a '0' to it.
NG_EN:
Enable bit for the Noise Gate function. This function is enabled when this bit is high. This
function can only be enabled when the Compression ratio is not 1:1.
Table 7. AGC Attack Control (Address: 2)
REGISTER
ADDRESS
02 (02H) –
AGC Attack
Control
I2C BIT
LABEL
DEFAULT
7:6
Unused
00
5:0
ATK_time
000101
(6.4 ms/6 dB)
DESCRIPTION
AGC Attack time (gain ramp down)
Per Step
Per 6 dB
000001
0.1067 ms
1.28 ms
90% Range
5.76 ms
000010
0.2134 ms
2.56 ms
11.52 ms
000011
0.3201 ms
3.84 ms
17.19 ms
000100
0.4268 ms
5.12 ms
23.04 ms
(time increases by 0.1067 ms with every step)
111111
ATK_time
6.722 ms
80.66 ms
362.99 ms
These bits set the attack time for the AGC function. The attack time is the minimum time
between gain decreases.
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Table 8. AGC Release Control (Address: 3)
REGISTER
ADDRESS
I2C BIT
03 (03H) – AGC
Release
Control
7:6
Unused
00
5:0
REL_time
001011
(1.81 sec/6 dB)
LABEL
DEFAULT
DESCRIPTION
AGC Release time (gain ramp down)
Per Step
Per 6 dB
90% Range
000001
0.0137 s
0.1644 s
0.7398 s
000010
0.0274 s
0.3288 s
1.4796 s
000011
0.0411 s
0.4932 s
2.2194 s
000100
0.0548 s
0.6576 s
2.9592 s
(time increases by 0.0137 s with every step)
111111
REL_time
0.8631 s
10.36 s
46.6 s
These bits set the release time for the AGC function. The release time is the minimum time
between gain increases.
Table 9. AGC Hold Time Control (Address: 4)
REGISTER
ADDRESS
04 (04H) –
AGC Hold
Time Control
I2C BIT
LABEL
DEFAULT
7:6
Unused
00
5:0
Hold_time
000000 (Disabled)
DESCRIPTION
AGC Hold time
Per Step
000000
Hold Time
Disable
000001
0.0137 s
000010
0.0274 s
000011
0.0411 s
000100
0.0548 s
(time increases by 0.0137 s with every
step)
111111
Hold_time
28
0.8631 s
These bits set the hold time for the AGC function. The hold time is the minimum time between
a gain decrease (attack) and a gain increase (release). The hold time can be deactivated.
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Table 10. AGC Fixed Gain Control (Address: 5)
REGISTER
ADDRESS
05 (05H) –
AGC Fixed
Gain Control
I2C BIT
LABEL
DEFAULT
7:6
Unused
00
5:0
Fixed Gain
00110 (6dB)
DESCRIPTION
Sets the fixed gain of the amplifier: two's complement
Gain
100100
–28 dB
100101
–27 dB
100110
–26 dB
(gain increases by 1 dB with every step)
111101
–3 dB
111110
–2 dB
111111
–1 dB
000000
0 dB
000001
1 dB
000010
2 dB
000011
3 dB
(gain increases by 1dB with every step)
Fixed Gain
011100
28 dB
011101
29 dB
011110
30 dB
These bits are used to select the fixed gain of the amplifier. If the Compression is enabled,
fixed gain is adjustable from –28dB to 30dB. If the Compression is disabled, fixed gain is
adjustable from 0dB to 30dB.
Table 11. AGC Control (Address: 6)
REGISTER
ADDRESS
06 (06H) –
AGC Control
I2C BIT
7
6:5
4:0
LABEL
DEFAULT
DESCRIPTION
Output Limiter
Disable
0 (enable)
Disables the output limiter function. Can only be disabled when the AGC compression
ratio is 1:1 (off)
NoiseGate
Threshold
01 (4 mVrms)
Select the threshold of the noise gate
Output Limiter
Level
Threshold
11010 (6.5dBV)
00
1 mVrms
01
4 mVrms
10
10 mVrms
11
20 mVrms
Output Power (Wrms)
Peak Output Voltage
(Vp)
dBV
00000
0.03
0.67
–6.5
00001
0.03
0.71
–6
00010
0.04
0.75
–5.5
Selects the output limiter level
(Limiter level increases by 0.5dB with every step)
11101
0.79
3.55
8
11110
0.88
3.76
8.5
11111
0.99
3.99
9
Output Limiter
Disable
This bit disables the output limiter function when set to 1. Can only be disabled when
the AGC compression ratio is 1:1
NoiseGate Threshold
These bits set the threshold level of the noise gate. NoiseGate Threshold is only
functional when the compression ratio is not 1:1
Output Limiter Level
These bits select the output limiter level. Output Power numbers are for 8Ω load.
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Table 12. AGC Control (Address: 7)
REGISTER
ADDRESS
07 (07H) –
AGC Control
I2C BIT
7:4
LABEL
Max Gain
DEFAULT
1100 (30 dB)
DESCRIPTION
Selects the maximum gain the AGC can achieve
Gain
0000
18 dB
0001
19 dB
0010
20 dB
(gain increases by 1 dB with every step)
1100
3:2
UNUSED
00
1:0
Compression
Ratio
10 (4:1)
30 dB
Selects the compression ratio of the AGC
Ratio
00
1:1 (off)
01
2:1
10
4:1
11
8:1
Compression Ratio These bits select the compression ratio. Output Limiter is enabled by default when the
compression ratio is not 1:1.
Max Gain
30
These bits select the maximum gain of the amplifier. In order to maximize the use of the
AGC, set the Max Gain to 30dB
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10 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
10.1 Application Information
These typical connection diagrams highlight the required external components and system level connections for
proper operation of the device. Each of these configurations can be realized using the Evaluation Modules
(EVMs) for the device. These flexible modules allow full evaluation of the device in the most common modes of
operation. Any design variation can be supported by TI through schematic and layout reviews. Visit e2e.ti.com for
design assistance and join the audio amplifier discussion forum for additional information.
10.2 Typical Application
Battery
Cs
SCL
I2C Interface
PVDD
SDA
OUT+
OUT-
EN
Cin
Differential
Input
ININ+
Cin
TPA2028D1
PGND
Figure 49. TPA2028D1 Application Schematic
10.2.1 Design Requirements
For this design example, use the parameters listed in Table 13.
Table 13. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Power supply
5V
Supply current
2-A Maximum
Audio input voltage
0.5 V to VDD - 0.5 V
Speaker impedance
8Ω
10.2.2 Detailed Design Procedure
10.2.2.1 Decoupling Capacitor CS
The TPA2028D1 is a high-performance Class-D audio amplifier that requires adequate power supply decoupling
to ensure the efficiency is high and total harmonic distortion (THD) is low. For higher frequency transients,
spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) 1-μF ceramic capacitor
(typically) placed as close as possible to the device PVDD lead works best. Placing this decoupling capacitor
close to the TPA2028D1 is important for the efficiency of the Class-D amplifier, because any resistance or
inductance in the trace between the device and the capacitor can cause a loss in efficiency. For filtering lowerfrequency noise signals, a 4.7 μF or greater capacitor placed near the audio power amplifier would also help, but
it is not required in most applications because of the high PSRR of this device.
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10.2.2.2 Input Capacitors CI)
TPA2028D1 requires input capacitors to ensure low output offset and low pop.
The input capacitors and input resistors form a high-pass filter with the corner frequency, fC, determined in
Equation 5.
fC =
1
(2p ´ RI ´ CI )
(5)
The value of the input capacitor is important to consider as it directly affects the bass (low frequency)
performance of the circuit. Speakers in wireless phones cannot usually respond well to low frequencies, so the
corner frequency can be set to block low frequencies in this application. Not using input capacitors can increase
output offset. Equation 6 is used to solve for the input coupling capacitance. If the corner frequency is within the
audio band, the capacitors should have a tolerance of ±10% or better, because any mismatch in capacitance
causes an impedance mismatch at the corner frequency and below.
CI =
1
(2p ´ RI ´ fC )
(6)
10.2.3 Application Curves
For application curves, see the figures listed in Table 14.
Table 14. Table of Graphs
DESCRIPTION
32
FIGURE NUMBER
Output Level vs Input Level
Figure 9
Output Power vs Supply Voltage
Figure 23
Output Power vs Supply Voltage
Figure 24
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11 Power Supply Recommendations
The TPA2028D1 is designed to operate from an input voltage supply range between 2.5-V and 5.5-V. Therefore
the output voltage range of the power supply should be within this range and well regulated. The current
capability of upper power should not exceed the maximum current limit of the power switch.
11.1 Power Supply Decoupling Capacitors
The TPA2028D1 requires adequate power supply decoupling to ensure a high efficiency operation with low total
harmonic distortion (THD). Place a low equivalent-series-resistance (ESR) ceramic capacitor, typically 0.1 µF,
within 2 mm of the PVDD pin. This choice of capacitor and placement helps with higher frequency transients,
spikes, or digital hash on the line. In addition to the 0.1 μF ceramic capacitor, is recommended to place a 2.2 µF
to 10 µF capacitor on the VDD supply trace. This larger capacitor acts as a charge reservoir, providing energy
faster than the board supply, thus helping to prevent any droop in the supply voltage.
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12 Layout
12.1 Layout Guidelines
12.1.1 Component Placement
Place all the external components very close to the TPA2028D1. Placing the decoupling capacitor, CS, close to
the TPA2028D1 is important for the efficiency of the Class-D amplifier. Any resistance or inductance in the trace
between the device and the capacitor can cause a loss in efficiency.
12.1.2 Trace Width
Recommended trace width at the solder balls is 75 μm to 100 μm to prevent solder wicking onto wider PCB
traces. For high current pins (PVDD (L, R), PGND, and audio output pins) of the TPA2028D1, use 100-μm trace
widths at the solder balls and at least 500-μm PCB traces to ensure proper performance and output power for
the device. For the remaining signals of the TPA2028D1, use 75-μm to 100-μm trace widths at the solder balls.
The audio input pins (IN+ and IN–) must run side-by-side to maximize common-mode noise cancellation
12.1.3 Pad Size
In making the pad size for the DSBGA balls, TI recommends that the layout use non solder mask defined
(NSMD) land. With this method, the solder mask opening is made larger than the desired land area, and the
opening size is defined by the copper pad width. Figure 50 and Table 15 shows the appropriate diameters for a
DSBGA layout. The TPA2028D1 evaluation module (EVM) layout is shown in the next section as a layout
example.
Copper
Trace Width
Solder Mask
Opening
Solder Mask
Thickness
Solder
Pad Width
Copper Trace
Thickness
Figure 50. Land Pattern Dimensions
Table 15. Land Pattern Dimensions (1)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
34
SOLDER PAD
DEFINITIONS
COPPER PAD
SOLDER MASK (5)
OPENING
COPPER
THICKNESS
Non solder mask
defined (NSMD)
275 μm
(+0.0, –25 μm)
375 μm
(+0.0, –25 μm)
1 oz max (32 μm)
(2) (3) (4)
STENCIL (6)
(7)
OPENING
275 μm × 275 μm Sq. (rounded
corners)
STENCIL
THICKNESS
125 μm thick
Circuit traces from NSMD defined PWB lands should be 75 μm to 100 μm wide in the exposed area inside the solder mask opening.
Wider trace widths reduce device stand off and impact reliability.
Best reliability results are achieved when the PWB laminate glass transition temperature is above the operating the range of the
intended application.
Recommend solder paste is Type 3 or Type 4.
For a PWB using a Ni/Au surface finish, the gold thickness should be less 0.5 mm to avoid a reduction in thermal fatigue performance.
Solder mask thickness should be less than 20 μm on top of the copper circuit pattern
Best solder stencil performance is achieved using laser cut stencils with electro polishing. Use of chemically etched stencils results in
inferior solder paste volume control.
Trace routing away from DSBGA device should be balanced in X and Y directions to avoid unintentional component movement due to
solder wetting forces.
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12.2 Layout Example
Decoupling capacitor
placed as close as
possible to the device
Input Capacitors
placed as close as
possible to the device
0.1µF
IN -
OUT -
IN+
C3
C2
C1
B3
B2
B1
A3
A2
a
A1
OUT +
EN
TPA2028D1
SDA
SCL
Top Layer Ground Plane
Top Layer Traces
Pad to Top Layer Ground Plane
Via to Power Supply
Via to Bottom Layer Ground Plane
Figure 51. TPA2028D1 Layout Example
12.3 Efficiency and Thermal Considerations
The maximum ambient temperature depends on the heat-sinking ability of the PCB system. The derating factor
for the packages are shown in the dissipation rating table. Converting this to θJA for the DSBGA package:
105°C/W
(7)
Given θJA of 105°C/W, the maximum allowable junction temperature of 150°C, and the maximum internal
dissipation of 0.4 W for 3 W output power, 4-Ω load, 5-V supply, from Figure 17, the maximum ambient
temperature can be calculated with the following equation.
TA Max = TJMax - θJA PDMAX = 150 - 105 (0.4) = 108°C
(8)
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Efficiency and Thermal Considerations (continued)
Equation 8 shows that the calculated maximum ambient temperature is 108°C at maximum power dissipation
with a 5-V supply and 4-Ω a load. The TPA2028D1 is designed with thermal protection that turns the device off
when the junction temperature surpasses 150°C to prevent damage to the IC. Also, using speakers more
resistive than 8-Ω dramatically increases the thermal performance by reducing the output current and increasing
the efficiency of the amplifier.
36
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13 Device and Documentation Support
13.1 Device Support
13.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
13.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
13.3 Trademarks
Nano-Free, SmartGain, E2E are trademarks of Texas Instruments.
I2C is a trademark of NXP Semiconductors.
All other trademarks are the property of their respective owners.
13.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
13.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
14 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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Copyright © 2010–2015, Texas Instruments Incorporated
Product Folder Links: TPA2028D1
37
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
HPA00910YZFR
ACTIVE
DSBGA
YZF
9
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
NSU
TPA2028D1YZFR
ACTIVE
DSBGA
YZF
9
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
NSU
TPA2028D1YZFT
ACTIVE
DSBGA
YZF
9
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
NSU
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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