Texas Instruments TPA3123D2 User manual

User's Guide
TPA3123D2 2.1 AUDIO POWER AMPLIFIER DEMO BOARD
Contents
Introduction2
Introduction .............................................................................................................2
Operation................................................................................................................3
TPA3123D2 2.1 Demo EVM Schematic.............................................................................4
TPA3123D2 2.1 Demo EVM PCB Layers……………………………………………………………………….. 5
TPA3123D2 2.1 Demo Evaluation Module Parts List..............................................................9
List of Tables
TPA3123D2 2.1 Demo EVM Specifications..........................................................................2
Gain Settings.............................................................................................................3
TPA3123D2 2.1 Demo EVM Bill of Materials........................................................................10
List of Figures
TPA3122D2 2.1 Audio Power Amplifier EVM Top View……………………………………………………………2
TPA3122D2 2.1 Audio Power Amplifier EVM Bottom View.............................................................................3
TPA3122D2 2.1 EVM Schematic.....................................................................................................................4
TPA3122D2 2.1 EVM Top Side Layout............................................................................................................5
TPA3122D2 2.1 EVM Bottom Side Layout…………………………………………………………………………..5
Frequency Response (Stereo Output)………………………………………………………………………………..6
THD +N Ratio vs. Frequency (Stereo Output)……………………………………………………………………….6
THD +N Ratio vs. Power (Stereo Output)…………………………………………………………………………….7
Frequency Response (Subwoofer Output)…………………………………………………………………………...8
THD +N Ratio vs. Frequency (Subwoofer Output)…………………………………………………………………..8
THD +N Ratio vs. Power (Subwoofer Output)………………………………………………………………………..9

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INTRODUCTION:
The TPA3123D2 2.1 Demo evaluation module consists of two 25-W, class-D, TPA3123D2 audio
power amplifiers complete with a small number of external components mounted on a circuit
board that are used to directly drive speakers with external analog audio source as the input.
One TPA3123D2 is configured as a stereo amplifier driving the treble speakers and another
TPA3123D2 is configured as a mono amplifier driving the subwoofer speaker.
TABLE1:TPA3123D2 2.1 Demo EVM’s Specifications
Value UNIT
VCC 10 to 30 V
ICC 4 A
Stereo PO Continuous output power: 4Ohms;Vcc
=24V ;THD+N% =10
18 W
Mono PO Continuous output power: 8Ohms;Vcc
=24V ;THD+N% =10
40 W
ZLMinimum load impedance (stereo) 3.2 Ohms
ZLMinimum load impedance (Mono) 6.4 Ohms
Figure 1. TPA3123D2 2.1 DEMO BOARD Audio Power Amplifier EVM (Top View)
Music In
p
ut from CD
24V supply
4ohms Right Speaker
4ohms Left Speaker
8Ohms Sub Woofer

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Figure 2. TPA3123D2 2.1 DEMO BOARD Audio Power Amplifier EVM (Bottom View)
2. OPERATION
2.1 Quick Start List for Stand-Alone Operation
Follow these steps to use the TPA3123D2 2.1 Demo EVM stand-alone or when connecting it into existing
circuits or equipment. Connections to the EVM module can be made by inserting stripped wire, or using
banana plugs for the power supply and output connections. The inputs accept standard RCA plugs.
2.1.1 Power Supply
1. Ensure that all external power sources are set to OFF.
2. Connect an external regulated power supply adjusted from 10 V to 30 V to the module VCC (J10) and
GND (J9) banana jacks taking care to observe marked polarity.
2.1.2 Evaluation Module Preparations
INPUTS AND OUTPUTS:
1. Connect an audio source to the input jacks, J1 and J2.
2. Connect a speaker across -ROUT (J6) and +ROUT (J5). Connect another speaker across LOUT (J3)
and -LOUT (J4) (Note: Make sure the speakers are of 4 Ohms Each)
3. Connect a Subwoofer across –SUBWOOF OUT (J7) and +SUBWOOF OUT (J8). (Note: Make sure the
subwoofer is of 8 Ohms)
4. Install both gain jumpers GAIN0 (J1) and GAIN1 (J2). This sets the gain of the amplifier to the lowest
Level, 20 dB.
Note: ON means Jumpers ON
OFF means Jumpers OFF TABLE 2: GAIN SETTINGS
Gain1 Gain0 Amplifier Gain (dB)
ON ON 20
ON OFF 26
OFF ON 32
OFF OFF 36

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CONTROL INPUTS:
SHUTDOWN: This terminal is active LOW. A LOW on the device terminal (<0.8 V) shuts down the amplifier; a HIGH (>2
V) on the device terminal places the amplifier in the active state. Holding down Switch S1 places the amplifier in the
SHUTDOWN state. Releasing S1 returns the amplifier to the active state. This terminal is VCC compliant. There is also a
switch S3 for the Subwoofer output which puts the Subwoofer in the shutdown mode when it is hold down.
MUTE: This terminal is active HIGH. A HIGH (>2 V) on this terminal will immediately terminate audio Playback through
the speakers; a LOW (<0.8 V) enables the device. The outputs remain switching with fifty percent duty cycle. SW2 on the
EVM controls the state of the MUTE terminal. Holding down switch S2 places the amplifier (1) in the MUTE state.
Releasing S2 returns the amplifier (1) to the active state meant for the stereo speaker output. This terminal is VCC
compliant. Holding down switch S4 places the amplifier (2) in the MUTE state. Releasing S4 returns the amplifier (2) to
the active state which is meant for the Subwoofer output.
GAIN0/GAIN1: Together, these terminals determine the gain of the amplifiers (one pair for the stereo speaker output
and one pair for the Subwoofer output) on the EVM. See Table 1. Installing a Jumper in JP1 or JP2 sets the respective
terminal to GND. Removing the jumper sets the respective terminals to VCC. Removing jumpers increases the gain while
installing jumpers decreases the gain. Logic levels are TTL compatible. These terminals are VCC compliant.
2.1.3 POWER UP
Verify correct voltage and input polarity, and turn the external power supplies ON.
The EVM should begin operation.
1. Adjust the input signal.(If giving input from the AP then adjust the input V rms in the analog generator window still it
gives a THD of 10% ) to get reasonable output)
2. Adjust the control inputs to the desired settings.
3. Adjust the amplifier gain by installing/removing the gain jumpers, JP1 and JP2 for the stereo output and jumpers JP4
and JP3.
SCHEMATIC:

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Figure 4:TPA3123D2 2.1 TOP SIDE LAYOUT
Figure 5:TPA3123D2 2.1 BOTTOM SIDE LAYOUT

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TPA3123D2 2.1EVM Performance
STEREO PERFORMANCE
Figure 6: Frequency Response
Frequency Response Stereo Output TPA3123D2 2.1
gainvsFreqstereo output.at2
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Red Solid 1 Anlr.Level A Left
1 3 Cyan Solid 1 Anlr.Level B Left
1 4 Green Solid 1 Anlr.Level B Left
VCC = 24VRLOAD =4 Ohms (Both the channels)
+0
+40
+5
+10
+15
+20
+25
+30
+35
d
B
m
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Figure 7: THD vs. Frequency
THDvs. Freq. Stereo Output TPA3123D2
THDvsFreqstereo output.at2
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Red Solid 1 Anlr.THD+N Ratio Left Pout=5W
1 2 Cyan Solid 1 Anlr.THD+N Ratio Left Pout=5W
2 1 Magenta Solid 1 Anlr.THD+N Ratio Left Pout=1W
2 2 Green Solid 1 Anlr.THD+N Ratio Left Pout=1W
3 1 Blue Solid 1 Anlr.THD+N Ratio Left Pout=10W
3 2 Yellow Solid 1 Anlr.THD+N Ratio Left Pout=10W
VCC = 24VRLOAD =4 Ohms (Both the channels)
0.01
10
0.02
0.05
0.1
0.2
0.5
1
2
5
%
600 20k700 800 900 1k 2k 3k 4k 5k 6k 7k 8k 9k 10k
Hz

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Figure 8: THD vs. Power
THD vs Po StereoOutput TPA3123D2 2.1
THD_POWER Stereoutput.at2
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Cyan Solid 1 Anlr.THD+N Ratio Left Freq. =1KHz
1 3 Yellow Solid 1 Anlr.THD+N Ratio Left Freq. =1KHz
2 1 Green Solid 1 Anlr.THD+N Ratio Left Freq. =10KHz
2 3 Red Solid 1 Anlr.THD+N Ratio Left Freq. =10KHz
VCC =24VRLOAD =4 Ohms (Both the channels)
0.01
20
0.02
0.05
0.1
0.2
0.5
1
2
5
10
%
200m 20500m 1 2 5 10
W

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SUBWOOFER PERFORMANCE
Figure 9: Frequency Response
Frequency Response Sub W oofer TPA3123D2 2.1
gainVs.Freq.SUBWOOF.at2
ColorSweep Trace Line Style Thick Data Axis Com m ent
1 1 Red Solid 2 Anlr.Level A Left
VDD=24V RLOAD=8 OH MS Sub-W oofer Perform ance
-0
+40
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+24
+26
+28
+30
+32
+34
+36
+38
d
B
m
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Figure 10: THD vs. Frequency
THD vs. Freq. subwoofer TPA3123D2 2.1
THD_Freq SUBWOOF.at2
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Yellow Solid 1 Anlr.THD+N Ratio Left Pout=1W
2 1 Red Solid 1 Anlr.THD+NRatio Left Pout=10W
3 1 Magenta Solid 1 Anlr.THD+NRatio Left
VCC =24VRLOAD =8 Ohms (Sub-woofer)
0.01
10
0.02
0.05
0.1
0.2
0.5
1
2
5
%
20 50030 40 50 60 70 80 90 100 200 300 400
Hz
RRRRRR

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Figure 11: THD vs. Power
THD_POWER SUBWOOF.at2
ColorSweep Trace Line Style Thick Data Axis Comment
1 1 Magenta Solid 2 Anlr.THD+N Ratio Left Freq. - 100Hz
2 1 Blue Solid 2 Anlr.THD+N Ratio Left Freq. - 200Hz
VDD=24VRLOAD=8 OHMS Sub-Woofer Performance
0.01
10
0.02
0.05
0.1
0.2
0.5
1
2
5
%
300m 50500m 1 2 5 10 20
W

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TABLE 3:TPA3123D2 2.1 EVM BOM (Bill of materials)

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Contd…

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