Texas Instruments TPA3251 User manual

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TPA3251 Evaluation Module
User's Guide
SLAU751–November 2017
TPA3251 Evaluation Module
This user's guide describes the characteristics, operation, and use of the TPA3251 evaluation module
(EVM). A complete printed-circuit board (PCB) description, schematic diagram, and bill of materials are
also included.
Figure 1. TPA3251 Evaluation Module
Contents
1 Quick Start (BTL Mode)..................................................................................................... 3
2 Setup By Mode............................................................................................................... 5
3 Hardware Configuration ................................................................................................... 10
4 EVM Design Documents ................................................................................................. 14
List of Figures
1 TPA3251 Evaluation Module............................................................................................... 1
2 EVM Board (Top Side)...................................................................................................... 3
3 EVM Board (Bottom Side).................................................................................................. 3
4 AIB Input: THD+N vs Frequency .......................................................................................... 5
5 AIB Input: THD+N vs Power ............................................................................................... 5
6 Molex™ Input: THD+N vs Frequency .................................................................................... 5
7 Molex Input: THD+N vs Power ............................................................................................ 5
8 RCA Input: THD+N vs Frequency ........................................................................................ 5
9 RCA Input: THD+N vs Power ............................................................................................. 5

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10 AIB Input: THD+N vs Frequency .......................................................................................... 7
11 AIB Input: THD+N vs Power ............................................................................................... 7
12 Molex Input: THD+N vs Frequency ....................................................................................... 8
13 Molex Input: THD+N vs Power ............................................................................................ 8
14 RCA Input: THD+N vs Frequency ........................................................................................ 8
15 RCA Input: THD+N vs Power ............................................................................................. 8
16 AIB Input: THD+N vs Frequency .......................................................................................... 9
17 AIB Input: THD+N vs Power ............................................................................................... 9
18 Molex Input: THD+N vs Frequency ..................................................................................... 10
19 Molex Input: THD+N vs Power .......................................................................................... 10
20 RCA Input: THD+N vs Frequency ....................................................................................... 10
21 RCA Input THD+N vs Power ............................................................................................. 10
22 EVM Power Tree........................................................................................................... 13
23 BTL LC Frequency Response ........................................................................................... 13
24 SE LC Frequency Response ............................................................................................. 13
25 TPA3251 EVM Top Composite Assembly .............................................................................. 14
26 TPA3251 EVM Bottom Composite Assembly .......................................................................... 15
27 TPA3251EVM Board Dimensions........................................................................................ 16
28 TPA3251EVM Schematic 1............................................................................................... 17
29 TPA3251EVM Schematic 2............................................................................................... 18
30 TPA3251EVM Schematic 3............................................................................................... 18
List of Tables
1 Jumper Configurations (BTL Mode)....................................................................................... 4
2 Mode Selection Pins ........................................................................................................ 5
3 Jumper Configurations (2.1 BTL Mode) .................................................................................. 6
4 Jumper Configuration (PBTL Mode) ...................................................................................... 7
5 Jumper Configuration (SE Mode).......................................................................................... 9
6 Fault and Clip Overtemperature Status ................................................................................. 10
7 Frequency Adjust Master Mode Selection .............................................................................. 11
8 Overcurrent Protection Selection......................................................................................... 11
9 AIB Connector (J28) Pinout............................................................................................... 12
10 TPA3251EVM Bill of Materials ........................................................................................... 19
Trademarks
PurePath is a trademark of Texas Instruments.
CoilCraft is a trademark of Coilcraft, Incorporated.
Molex is a trademark of Molex, LLC.
All other trademarks are the property of their respective owners.

www.ti.com Quick Start (BTL Mode)
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1 Quick Start (BTL Mode)
This section describes the necessary hardware, connections, configuration, and steps to quick start the
EVM into bridge-tied load (BTL) mode with stereo audio playing out of two speakers.
1.1 Required Hardware
The EVM requires the following hardware:
• TPA3251EVM (AMPS030-001) power supply 18-V to 36-V DC, 15 A
• Two 2-Ωto 8-Ω, 100-W speakers or resistor loads
• Four speaker or banana cables
• RCA input cables
• Analog output audio source
1.2 Connections and Board Configuration
Figure 2 and Figure 3 show both sides of the EVM board.
Figure 2. EVM Board (Top Side) Figure 3. EVM Board (Bottom Side)
The steps for making the connections are as follows:
1. Set S1 to the RESET position.
2. Set the power supply to 36 V (18-V to 38-V range) and current to 10 A (5-A to 14-A range).
3. Connect the power supply to the TPA3251EVM positive terminal to PVDD (J1-RED) and negative
terminal to GND (J1-BLACK).
4. Connect the positive side of the left channel load to the TPA3251EVM OUTA (J9-RED) terminal.
5. Connect the negative side of the left channel load to the TPA3251EVM OUTB (J9-BLACK) terminal.
6. Connect the positive side of the right channel load to the TPA3251EVM OUTC (J2-RED) terminal.
7. Connect the negative side of the right channel load to the TPA3251EVM OUTD (J2-BLACK) terminal.
8. Be careful not to mix up PVDD, OUTA, and OUTC because the colors are the same (RED).
9. Input configuration:
a. Single-ended (SE) inputs: Set J4 and J19 to SE and set J26, J27, J34, and J35 to RCA.
a. Connect the RCA male jack to the female RCA jack input A/AB (J3-RED).
b. Connect the RCA male jack to the female RCA jack input C/CD (J18-WHITE) .
b. Differential inputs: Set J4 and J19 to DIFF and set J26, J27, J34, and J35 to RCA
a. Connect the positive RCA male jack to the female RCA jack input A/AB (J3-RED) and connect
the negative RCA male jack to the female RCA jack input B (J14-BLACK).

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b. Connect the positive RCA male jack to the female RCA jack input C/CD (J18-RED) and
connect the negative RCA male jack to the female RCA jack input D (J15-BLACK).
c. Analog-Input Board (AIB) input: Set J26, J27, J34, and J35 to AIB.
10. Power up the power supply after correctly making all the connections. The 3.3-V and 12-V LEDs
(GREEN) then illuminate.
11. Set S1 to the NORMAL position.
12. The CLIP_OTW (ORANGE) and FAULT (RED) LEDs must be off if the audio source is off.
Table 1 lists the jumper configurations in BTL mode.
Table 1. Jumper Configurations (BTL Mode)
Jumper Setting Configuration for BTL
J29 IN PVDD to 15-V BUCK
J32 IN 12-V LDO to 12-V TERM
J33 IN 3.3-V LDO to 3.3-V TERM
J36 IN 12-V LDO to GVDD
J16 3 to 4 MASTER MODE 600kHz
J22 IN OUTA CAP SHUNT
J23 IN OUTB CAP SHUNT
J24 IN OUTC CAP SHUNT
J25 IN OUTD CAP SHUNT
J5 2 to 3 M1-L
J6 2 to 3 M2-L
J7 OUT PBTL SELECT INC
J8 OUT PBTL SELECT IND
J4 1 to 2 INA/B SE INPUT
J19 1 to 2 INC/D SE INPUT
J26 1 to 2 INC-SEL RCA
J27 1 to 2 IND-SEL RCA
J34 1 to 2 INA-SEL RCA
J35 1 to 2 INB-SEL RCA
J21 OUT C_START

Frequency (Hz)
THD+N (%)
0.0001
0.001
0.01
0.1
1
10
20 200 2000 20000
D013
1 W
20 W
75 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100 200
0.001
0.01
0.1
1
10
D004
Frequency (Hz)
THD+N (%)
0.0001
0.001
0.01
0.1
1
10
20 200 2000 20000
D010D010
1 W
20 W
75 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100 200
0.001
0.01
0.1
1
10
D001
www.ti.com Setup By Mode
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2 Setup By Mode
The user can configure the TPA3251EVM for four different output operations. The 2.0 BTL configuration is
the default set up of the TPA3251EVM as described in Section 1.2. The remaining three configurations
are 2.1 BTL plus two SE outputs, 0.1 PBTL output, and 4.0 SE outputs.
Table 2. Mode Selection Pins
Mode Pins Input Mode Output Configuration Description
M2 M1
0 0 2N + 1 2 x BTL Stereo BTL output configuration
0 1 2N-1N + 1 1 x BTL + 2 × SE 2.1 BTL + SE mode
1 0 2N + 1 1 × PBTL Parallel BTL configuration; connect INPUT_C
2.1 BTL Mode (Two-Speaker Output)
This mode is the same as described in Section 1.
2.1.1 Performance Data (BTL Mode)
All measurements are taken at an audio frequency = 1 kHz, PVDD_X = 36 V, RL = 4 Ω, fS = 600 kHz,
ROC = 22 kΩ, Output filter: L = 7 μH, C = 0.68 µF, with AES17 + AUX-0025 measurement filters.
Figure 4. AIB Input: THD+N vs Frequency Figure 5. AIB Input: THD+N vs Power
Figure 6. Molex™ Input: THD+N vs Frequency Figure 7. Molex Input: THD+N vs Power

Frequency (Hz)
THD+N (%)
0.0001
0.001
0.01
0.1
1
10
20 200 2000 20000
D016
1 W
20 W
75 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100 200
0.001
0.01
0.1
1
10
D007
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Figure 8. RCA Input: THD+N vs Frequency Figure 9. RCA Input: THD+N vs Power
2.2 BTL MODE (Three-Speaker Output)
OUTC and OUTD are the SE output channels and OUTA and OUTB are the BTL channels for 2.1
operations. OUTC and OUTD can only be in DIFF input mode.
1. Set J6 to L and J5 to H.
2. Remove jumpers J24 and J25.
3. Connect the positive side of the left channel load to OUTC (J2- RED) terminal and the negative side of
the left channel load to the GND (J20) terminal.
4. Connect the positive side of the right channel load to OUTD (J2-BLACK) terminal and the negative
side of the right channel load to the GND (J20) terminal.
5. Connect the positive terminal to OUTA (J9-RED) and the negative terminal to OUTB (J9-BLACK).
6. Set the J19 jumper position to DIFF.
7. Input configuration:
a. SE inputs: Connect the RCA male jack to the female RCA jack input A/AB (J3-RED) and set the J4
jumper positions to SE. Set J26, J27, J34, and J35 to RCA.
b. Differential inputs: Connect the positive RCA male jack to the female RCA jack input A/AB (J3-
RED) and connect the negative RCA male jack to the female RCA jack input B (J14-BLACK) and
set the J4 jumper positions to DIFF. Set J26, J27, J34, and J35 to RCA.
c. AIB inputs: Set J26, J27, J34, and J35 to AIB.
Table 3. Jumper Configurations (2.1 BTL Mode)
Jumper Setting Comment
J29 IN PVDD to 15-V BUCK
J32 IN 12-V LDO to 12-V TERM
J33 IN 3.3-V LDO to 3.3-V TERM
J36 IN 12-V LDO to GVDD
J16 3 to 4 MASTER MODE 600kHz
J22 IN OUTA CAP SHUNT
J23 IN OUTB CAP SHUNT
J24 OUT OUTC CAP SHUNT
J25 OUT OUTD CAP SHUNT
J5 1 to 2 M1 – H
J6 2 to 3 M2 – L
J7 OUT PBTL SELECT INC
2.3 PBTL Mode (One-Speaker Output)
This mode uses all four half bridges for a mono output, allowing for the maximum power output from the
device across one load.

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2.3.1 Connections and Board Configuration
1. Set J6 to H and J5 to L.
2. Connect the positive side of the load to OUTA (J9-RED) and OUTC (J2-RED) terminals (OUTA and
OUTC shorted).
3. Connect the negative side of the load to OUTB (J9-BLACK) and OUTD (J2-BLACK) terminals (OUTB
and OUTD shorted).
4. Install PBTL jumpers J7 and J8 (pulls input C and input D to GND).
5. Input configuration:
a. SE inputs: Connect the RCA male jack to the female RCA jack input A/AB (J3-RED) and set the J4
jumper positions to SE. Set J26, J27, J34, and J35 to RCA.
b. Differential inputs: Connect the positive RCA male jack to the female RCA jack input A/AB (J3-
RED) and connect the negative RCA male jack to the female RCA jack input B (J14-BLACK). Set
the J4 jumper position to DIFF, and set J26, J27, J34, and J35 to RCA.
c. AIB input: Set J26, J27, J34, and J35 to AIB.
(1) INA and INB are the inputs for PBTL, and INC and IND are grounded
for PBTL operation.
Table 4. Jumper Configuration (PBTL Mode)
Jumper Setting Comment(1)
J29 IN PVDD to 15-V BUCK
J32 IN 12-V LDO to 12-V TERM
J33 IN 3.3-V LDO to 3.3-V TERM
J36 IN 12-V LDO to GVDD
J16 3 to 4 MASTER MODE 600kHz
J22 IN OUTA CAP SHUNT
J23 IN OUTB CAP SHUNT
J24 IN OUTC CAP SHUNT
J25 IN OUTD CAP SHUNT
J5 2 to 3 M1 – L
J6 1 to 2 M2 – H
J7 IN PBTL SELECT INC – GND
J8 IN PBTL SELECT IND – GND
J4 1 to 2 INA/B SE INPUT
J19 1 to 2 INC/D SE INPUT
J26 1 to 2 INC-SEL RCA
J27 1 to 2 IND-SEL RCA
J34 1 to 2 INA-SEL RCA
J35 1 to 2 INB-SEL RCA
J21 OUT C_START
2.3.2 Performance Data (PBTL Mode)
All measurements are taken at an audio frequency = 1 kHz, PVDD_X = 36 V, RL = 4 Ω, fS = 600 kHz,
ROC = 22 kΩ, Output filter: L = 7μH, C = 0.68 µF, with AES17 + AUX-0025 measurement filters.

Frequency (Hz)
THD+N (%)
0.0001
0.001
0.01
0.1
1
10
20 200 2000 20000
D017
1 W
50 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100 200
0.001
0.01
0.1
1
10
D008
Frequency (%)
THD+N (%)
0.0001
0.001
0.01
0.1
1
10
20 200 2000 20000
D014
1 W
50 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100 200
0.001
0.01
0.1
1
10
D005
Frequency (Hz)
THD+N (%)
0.0001
0.001
0.01
0.1
1
10
20 200 2000 20000
D011
1 W
50 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100 200
0.001
0.01
0.1
1
10
D002D002
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Figure 10. AIB Input: THD+N vs Frequency Figure 11. AIB Input: THD+N vs Power
Figure 12. Molex Input: THD+N vs Frequency Figure 13. Molex Input: THD+N vs Power
Figure 14. RCA Input: THD+N vs Frequency Figure 15. RCA Input: THD+N vs Power
2.4 SE Mode (Four-Speaker Output)
1. Set J6 to H and J5 to H.
2. Remove jumpers J22, J23, J24, and J25.
3. Connect the positive side of the load to the OUTA (J9-RED) terminal and the negative side of the load
to the GND (J11) terminal.
4. Connect the positive side of the load to the OUTB (J9-BLACK) terminal and the negative side of the
load to the GND (J11) terminal.
5. Connect the positive side of the load to the OUTC (J2-RED) terminal and the negative side of the load
to the GND (J20) terminal.
6. Connect the positive side of the load to the OUTD (J2-BLACK) terminal and the negative side of the
load to the GND (J20) terminal.
7. Set both J4 and J19 jumpers position to DIFF.
8. Input configuration:
a. Differential inputs: Set J26, J27, J34, and J35 to RCA.
i. Connect the male RCA jack to the female RCA jack input A/AB (J3-RED) for the OUTA
speaker.

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ii. Connect the male RCA jack to the female RCA jack input B (J14-BLACK) for the OUTB
speaker.
iii. Connect the male RCA jack to the female RCA jack input C/CD (J18-WHITE) for the OUTC
speaker.
iv. Connect the male RCA jack to the female RCA jack input D (J15-BLUE) for the OUTD
speaker.
b. AIB input: Set J26, J27, J34, and J35 to AIB.
Table 5. Jumper Configuration (SE Mode)
Jumper Setting Comment
J29 IN PVDD to 15-V BUCK
J32 IN 12-V LDO to 12-V TERM
J33 IN 3.3-V LDO to 3.3-V TERM
J36 IN 12-V LDO to GVDD
J16 3 to 4 MASTER MODE 600kHz
J22 OUT OUTA CAP SHUNT
J23 OUT OUTB CAP SHUNT
J24 OUT OUTC CAP SHUNT
J25 OUT OUTD CAP SHUNT
J5 1 to 2 M1 – H
J6 1 to 2 M2 – H
J7 OUT PBTL SELECT INC
J8 OUT PBTL SELECT IND
J4 2 to 3 INA/B DIFF INPUT
J19 2 to 3 INC/D DIFF INPUT
J26 1 to 2 INC-SEL RCA
J27 1 to 2 IND-SEL RCA
J34 1 to 2 INA-SEL RCA
J35 1 to 2 INB-SEL RCA
J21 IN C_START
NOTE: The performance of the TPA3251EVM/TPA3251D2DDV is dependent on the power supply.
Design the power supply with margins that can deliver the required power. Some low-
frequency applications can require additional bulk capacitance. Replacing the bulk capacitors
on the TPA3251EVM with 3300 µF or more capacitance can be necessary depending on the
power supply used.
2.4.1 Performance Data (SE Mode)
All measurements are taken at audio frequency = 1 kHz, PVDD_X = 36 V, RL = 4 Ω, fS = 600 kHz, ROC
= 22 kΩ, Output filter: L = 7 μH, C = 0.68 µF, with AES17 + AUX-0025 measurement filters.

Frequency (Hz)
THD+N (%)
0.001
0.01
0.1
1
10
50
20 200 2000 20000
D018
1 W
10 W
30 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100
0.001
0.01
0.1
1
10
D009
Frequency (Hz)
THD+N (%)
0.001
0.01
0.1
1
10
50
20 200 2000 20000
D015
1 W
10 W
30 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100
0.001
0.01
0.1
1
10
D006D006
Frequency (Hz)
THD+N (%)
0.001
0.01
0.1
1
10
50
20 200 2000 20000
D012
1 W
10 W
30 W
Power (W)
THD+N (%)
0.01 0.1 1 10 100
0.001
0.01
0.1
1
10
D003
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Figure 16. AIB Input: THD+N vs Frequency Figure 17. AIB Input: THD+N vs Power
Figure 18. Molex Input: THD+N vs Frequency Figure 19. Molex Input: THD+N vs Power
Figure 20. RCA Input: THD+N vs Frequency Figure 21. RCA Input THD+N vs Power
3 Hardware Configuration
3.1 Indicator Overview (OTW_CLIP and FAULT)
The TPA3251EVM is equipped with LED indicators that illuminate when the FAULT or CLIP_OTW pin (or
both) goes low. See Table 6 and TPA3251 175-W Stereo, 350-W Mono PurePath™ Ultra-HD Analog-
Input Class-D Amplifier for more details on which events trigger the pins to go low.
Table 6. Fault and Clip Overtemperature Status
FAULT OTW_CLIP Description
0 0 Overtemperature (OTE), overload (OLP), or undervoltage (UVP) junction temperature higher than
125°C (overtemperature warning)
0 0 OLP or UVP; junction temperature higher than 125°C (overtemperature warning)
0 1 OLP or UVP; junction temperature lower than 125°C
1 0 Junction temperature higher than 125°C (overtemperature warning)
1 1 Junction temperature lower than 125°C and no OLP or UVP faults (normal operation)