Mono Configuration of the
TPA005D02 ClassĆD Audio
Power Amplifier
Application
Report
July 1999
Mixed Signal Products
SLOA028
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Contents
Design Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
List of Figures
1 TPA005D02 Class-D EVM Schematic Diagram for Mono Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Mono Configuration of the TPA005D02 Class-D Audio Power Amplifier
iii
iv
SLOA028
Mono Configuration of the TPA005D02 Class-D Audio Power
Amplifier
Edward A. Thomas
ABSTRACT
Class-D Audio Power Amplifiers (APAs) are becoming an extremely popular choice for
audio solutions in battery-powered applications. The increased efficiency and reduction
in heat dissipation of a Class-D APA versus that of a Class-AB APA allows the battery life
on an application to be extended. The TPA005D02 is monolithic stereo Class-D APA
offered from Texas Instruments. This document discusses how to configure the
TPA005D02 to be used in a mono configuration. The actual specifications of the
TPA005D02 can be found in the published Texas Instruments data sheet (literature
#SLOS227A).
Design Problem
Many battery-powered applications would like to take advantage of the increased
efficiency of the TPA005D02 APA but do not need stereo output. This document
will show the specific application circuit in a mono configuration. The use of this
device in the mono configuration saves board space, cost, and supply current
when compared with the same device used in a stereo configuration.
Solution
The use of the TPA005D02 APA in the mono configuration eliminates the need
for many of the surrounding components required to operate the device in the
stereo configuration. The schematic for the TPA005D02 APA is in the
TPA005D02 Evaluation Module User’s Guide (literature #SLOU032A). The
modifications needed to be made to the evaluation board for the mono
configuration of the TPA005D02 are shown in the schematic shown in Figure 1.
The TPA005D02 APA integrated circuit consists of two separate amplifiers inside
the device, one for the right channel and one for the left channel. To operate in
the mono configuration, only one of the two amplifiers inside the TPA005D02 will
be used. The TPA005D02 has two pins (LCOMP and RCOMP) that can be used
to shut down power to the respective amplifier. Tying the respective xCOMP to
GND will stop the bridge from switching and will save quiescent power of the
device. In this document, the left amplifier will be shut down to allow operation of
the device in the mono configuration. In order to shut down the left amplifier,
LCOMP (pin 43) and input pins LINP (pin 5) and LINN (pin 4), will be tied directly
to GND (see Figure 1). The operation of this device in the mono configuration
eliminates ten external components when compared with use of this device in the
stereo configuration. The capacitors on the inputs of the unused amplifier and on
the xCOMP will be eliminated from use in the mono configuration. The two
inductors and three capacitors on the output of the unused amplifier will also be
eliminated.
1
The VDD power supply pin sets for both amplifiers in the TPA005D02 must be
connected even though one amplifier (left in this example) is shut down. No power
will be pulled by the unused amplifier. The VDD supply pin sets are connected
through a guard ring internally, the device can be destroyed if only one supply pin
set is connected. The unused amplifier (see Figure 1) will not pull large current
transients through the power pins, therefore the 1 µF bypass capacitor (C13) on
the LPVDD (pin 16) can be replaced with a 0.1 µF ceramic capacitor (shown). The
bypass capacitors C15 (220 µF) and C11 (10 µF) on the unused channel may be
removed. The output pins LOUTP (10, 11) and LOUTN (14, 15), for the unused
amplifier, will be left floating.
The MUTE and FAULT features of the TPA005D02 will operate normally in this
mono configuration. The two detectable fault conditions are the charge pump
under-voltage lock-out condition and the thermal fault condition. More details on
the functionality of these features can be found in the product’s data sheet.
VDD
VDD
R1
20 KΩ
VDD
1
MUTE
S2
2
3
Mute
5
4
6
7
C2
RIN+
C3
RIN–
1 µF 44
1 µF
C4
45
470 pF 43
17
19
30
C5
470 pF 48
47
46
20
C19
C21
0.047 µF
1 µF
22
28
26
23
24
25
C20
0.047 µF
SHUTDOWN LPVDD
LPVDD
MUTE
AGND
LINP
VDD
LINN
PVDD
RPVDD
LCOMP
RPVDD
AGND
RINP
PVDD
FAULT0
RINN
FAULT1
RCOMP
LOUTP
NC
LOUTP
NC
PGND
NC
PGND
COSC
LOUTN
AGND
LOUTN
AGND
ROUTP
AGND
ROUTP
VCP
PGND
LSBIAS
PGND
CP4
ROUTN
CP3
ROUTN
CP2
NC
CP1
NC
V2P5
PowerPAD
PGND
C13
0.1µF
9
+
C16
U1
TPA005D02
R5
100 KΩ
1 µF
R4
100 KΩ
C12
Shutdown
S1
1 µF
R3
20 KΩ
D1
3.9 V
VDD
C14
R2
1 KΩ
220 µF
Q1
2N3906
GND
C10
GND
C1
1 µF
10 µF
VDD
16
8
C9
1 µF
21
C17
1 µF
40
33
VDD
32
R6
D2
42
R7
D3
41
1 KΩ
1 KΩ
10
11
12
13
14
15
39
38
37
L1
15 µH
ROUT+
C24
0.22 µF
C22
1 µF
36
35
34
L2
15 µH
C26
0.22 µF
ROUT–
18
31
29
27
C18
1 µF
Figure 1. TPA005D02 Class-D EVM Schematic Diagram for Mono Configuration
2
Conclusion
The Class-D APA is an effective, highly efficient, audio solution for many
battery-powered applications. A comparison of class D amplifier versus linear
amplifier supply current is included in the TPA005D02 datasheet. The results at
normal listening levels show the linear amplifier to have three times the current
draw of the class D device. This comparison is important in showing the selection
of the type of audio amplifier used in a battery-powered system can extend
battery life by three times, if a class-D amplifier is used. Offering flexibility in the
way to configure the TPA005D02 allows both mono and stereo configurations the
advantage of this increased efficiency in battery-powered systems. This allows
use of this device in many different applications that could benefit from Texas
Instruments, Class-D technology.
Mono Configuration of the TPA005D02 Class-D Audio Power Amplifier
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