Texas Instruments TAS6421-Q1 EVM User manual

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User's Guide
SLOU415–April 2019
TAS6421-Q1 Evaluation Module
This manual describes the operations of the TAS6421-Q1. The TAS6421-Q1 is a stand-alone EVM. The
PurePath™ Control Console 3 GUI (PPC3) is used to initialize and operate the EVM. The main topics of
this document are:
• Hardware implementation and descriptions
• Software implementation and descriptions
• TAS6421-Q1 EVM operations (hardware and software)
Required equipment and accessories:
1. TAS6421-Q1 EVM
2. USB A male to micro B male cable
3. Power Supply Unit (PSU) up to 26.4 V, > 6 A capable, if J12 is removed and 12 V is provided.
If J12 is in, limit the input voltage to 18 V.
4. 1 resistive load or speaker load
5. 2 pair of wires stripped both ends
6. 2-mm slotted screwdriver
7. Optical audio source (optional)
8. Optical SPDIF cable (optional)
9. Desktop or laptop PC with Microsoft®Windows®7 or Windows®10 operating system
Contents
1 Hardware Overview.......................................................................................................... 2
2 Hardware Overview.......................................................................................................... 3
3 Software Overview........................................................................................................... 3
4 Board Layouts, Bill of Materials, and Schematic....................................................................... 20
List of Tables
1 TAS6421-Q1 EVM Bill of Materials ...................................................................................... 26
Trademarks
PurePath is a trademark of Texas Instruments.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
All other trademarks are the property of their respective owners.

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1 Hardware Overview
1.1 TAS6421-Q1E1 Evaluation Module Description
The TAS6421-Q1 EVM is a stand-alone EVM. It has single power supply input, USB control via PurePath
Control Console 3 (PPC3) and two digital (I2S) audio input options. See the EVM block diagram in
Figure 1.
Figure 1. TAS6421-Q1 EVM

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2 Hardware Overview
2.1 TAS6421-Q1 Evaluation Module Functions
• The EVM only needs single supply to operate
• The VBAT can be separated for PVDD operation higher than 18 V
• Two audio sources can be selected readily
1. If USB is selected, Windows Media Player can be used to stream audio.
2. If optical is selected, an optical source such as DVD player can be used to stream audio.
3. If external digital audio source such as those from Audio Precision, jumpers can be removed and
I2S signals can be inserted at the jumper headers..
• There are four switches
1. SPDIF power switch turns on and off optical to I2S converter.
2. Standby switch puts the device on or out of standby.
3. Mute switch stops or starts PWM modulation.
4. The XMOS USB controller can be enabled or disabled. Used for EMC testing.
• USB connection also uses as a controller via I2C. The Pure Path Console 3 is the User Interface
sending I2C commands to the device. PPC3 is discussed in a later section.
3 Software Overview
3.1 PurePath™ Console 3 (PPC3) Access and Description
The PPC3 is a server-based tool. Access can be requested on
http://www.ti.com/tool/PUREPATHCONSOLE.
Once approval is given, go to www.ti.com/mysecuresoftware to download the software. After login, the
user will see this web page with a similar list of software products available for download.

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Figure 2. PPC3 Download Window

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Run the installation program. Also download the PPC3 User Manual (SLOU408) for further instructions.
The following window is displayed when first running PPC3.
Figure 3. PPC3 Window
When the window in Figure 3 is displayed, click on “sign in” to see TAS6421 EVM application. All of the
apps shown below may not be displayed for the user.

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Click on TAS6421 App box to download TAS6421 application. Installation window pops up, then click
“Install”.
TAS6421 EVM box appears in “Installed EVM Apps” section, see Figure 4. Click on TAS6421 box to
launch TAS6421 App.
Figure 4. Available Apps Window

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3.2 PurePath™ Console 3 – TAS6421-Q1 EVM Home Window
When the TAS6421 EVM PPC3 is launched, the Home Window is shown. If the EVM is powered on and
the USB is connected to the PC, the Home Window displays “Connect” box in the bottom right hand
corner. If the EVM is not powered on or the USB is not connected, only “TAS6421-Q1 EVM – Offline” is
displayed. There are three windows available with the TAS6421-Q1 EVM PPC3: Home Window, Register
Map Window and Device Monitor and Control Window.
Figure 5. TAS6421-Q1 EVM Home Window

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3.3 PurePath™ Console 3 – TAS6421-Q1 EVM Register Map Window
When click on Register Map Box on the Home Window, the Register Map Window is displayed. The
Register Map indicates the current setting of all the registers in TAS6421-Q1.
Figure 6. TAS6421-Q1 EVM Register Map Window

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3.4 PurePath™ Console 3 – TAS6421-Q1 EVM Monitor and Control Window
When click on Device Monitor and Control Box on the Home Window, the Device Monitor and Control
Window is displayed. The Register Map indicates the current setting of all the registers in TAS6421-Q1.
Figure 7. TAS6421-Q1 EVM Device Monitor and Control Window

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3.5 TAS6421-Q1 EVM Start Up
This section describes the TAS6421-Q1 start-up procedure. Have the equipment and accessories listed
on the first page of this document available.
3.5.1 TAS6421-Q1 EVM Setup
Hardware and software connections:
• Desk top or laptop PC running Windows 7. Open PPC3 GUI.
• Connect 14.4 VDC PSU to TAS6421-Q1 EVM
• Connect speaker or resistive load to TAS6421-Q1 EVM
• Connect USB micro cable from PC to the EVM
• Set the switches (SPDIF, STANDBY, MUTE, XMOS Enable) to up positions
• Turn on the PSU
• Audio source: This can be a DVD player with optical SPDIF cable or Windows Media Player from PC
• At this point, 3.3 V LED, USB-LOCK LED and SPDIF-LOCK LED (if optical SPDIF is used) are on.
• If the SPDIF LED is not on, the default I2S input is the USB audio source.
• On the PPC3 window, launch TAS6421-Q1 EVM application
• The audio can be streamed now to the speakers. Go to the GUI and click on “Device Monitor &
Control” box. Click on play button located on the top right of the window.
• The following sections describe in detail the register settings of TAS6421-Q1.
Figure 8. TAS6421-Q1 EVM Connections

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3.5.2 TAS6421-Q1 Settings on Device Monitor and Control Window
The TAS6421-Q1 Register Map window is for reference. Most of the register settings are done on the
Device Monitor and Control window
Click on “CONNECT” button on the bottom left corner of the TAS6421-Q1 EVM application window, see
Figure 9. The LED next to the TAS6421-Q1 EVM changes from gray to green and the “CONNECT” button
changes to “DISCONNECT” button.
Click on the TAS6421-Q1 Device Monitor and Control box. The following window is displayed.
Figure 9. Device Monitor and Control Window
This window has 6 major sections: global control section, channel control section, other control section,
faults and warnings section, AC load diagnostics section and DC load diagnostics section.
3.5.2.1 Global Control Section
The Mute Pin button is the GPIO pin controlling the mute function of the device.
The Wakeup button is the GPIO pin controlling the standby function of the device.
The Reset button is software reset. This places the device back in default settings.
Figure 10. Global Control Section

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3.5.2.2 Channel Control Section
The one channel as the following selections: Hi-z, Mute, Unmute, Volume, Line-out mode and Speaker
mode.
The drop down menu allows user to select either Hi-z, Mute or Unmute state
The volume slide controls the digital gain of the channel.
The default setting for the channel is speaker mode. If line-out is used, select Line Output button.
Figure 11. Channel Control Section
3.5.2.3 Miscellaneous Control Section
There are miscellaneous settings that are available on the GUI for easy access.
The over-current has two levels. The lower level is 1. The default is level 2. When running at lower output
current, OC level can be set to 1. I2S and TDM are automatically detected. Use the pull down menu from
“Input Format” box to manually select the audio format.
If sampling frequency is greater than 48 kHz, select 96 kHz from the “Input FS” pull down.
Over-temperature warning can be programmable, use the pull down menu to choose the OTW
temperature. The default setting is 120°C.
The output switching frequency (FSW) or Pulse Width Modulation frequency (PWM) is set at 2.1 MHz. The
pull-down menu on the PWM FRQ box is used to choose a lower FSW. LC value should be adjusted
when FSW is changed.
There are four gain settings in TAS6421-Q1: low, normal, high and maximum. The default setting is high.
However, the recommended setting is normal for lower noise performance for driving speakers at
14.4 VDC. The gain setting is selectable via the drop down menu in the ”Gain” box.
The volume slew rate is measured with sampling frequency. The default setting is 1 period of sampling
frequency (FSYNC or FS). This rate is selectable from 1 to 8 sampling periods with the drop down menu
under “Vol Rate” box.

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Figure 12. Other Control Section
3.5.2.4 Faults and Warnings Section
The top right buttons on this box serve as controlling and monitoring faults.
Clip enable route the clip detection bit to the warning pin. This is displayed as yellow LED on the EVM.
Thermal enable route the over-temperature warning bit to the warning pin. This is display as the same
yellow LED on the EVM.
Clear button clears all the faults and warnings.
Read button manually read the faults and warnings.
Figure 13. Faults and Warnings Section

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3.5.2.5 AC Load Diagnostics Section
AC load diagnostics report speaker impedance and phase.
Select the correct output impedance and click start. Follow the pop up instructions to complete the load
diagnostics run.
NOTE: THE AC LOAD DIAGNOSTICS IS DISABLED AT THIS TIME
Make sure to set the digital input to 0 dBFS (100% full-scale). If the sine wave is provided
from the USB audio, turn the audio media volume and PC sound card volume to maximum.
Click on the “flip” icon located on the top right of the AC load diagnostics box to see the results.
Figure 14. AC Load Diagnostics Section
3.5.2.6 DC Load Diagnostics Section
The DC load diagnostics report if a short to power, short to ground, short to load or open is present.
Select the impedance of the load from 0.5 to 5 Ω. Click start and then click the “flip” on the top right of the
box to view results.
If the channel is selected as a line-out, click on “LO ENA LD” to enable line-out load diagnostics.
“Retry” box is used when DC load diagnostics are run more than one time.
DC load diagnostics can be aborted by click on the “Abort LD” box.

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Figure 15. DC Load Diagnostics Section

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3.5.3 TAS6421-Q1 Settings on Register Map Window
The register map can be sorted either alphabetically or numerically (register number).
Figure 16. Register Map Window

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When a register is selected, the hex value along with the individual bit value is displayed. The name and
description for each bit are shown to the right in the "Fields" box.
Figure 17. Register Map Window - Expanding
Double click on any bit, the bit changes state. This state is executed at the end of the click.

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3.5.4 I2C Window
The PPC3 has an I2C monitor and also configuration program options.
When this window is first open, the round button is green. To record I2C commands, click on this button
and it turns red. The recording can be saved for later used by clicking the save icon.
The I2C commands can also be copied to clip board by clicking the icon next to trash bin icon.
Figure 18. I2C Window – I2C Logging

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A set of I2C commands can be loaded and executed from this window. On the top right corner, click on
“I/O” button to display the above window. Write I2C commands here or open an existing *.cfg file then
click “Execute” button on the bottom left corner. The I2C commands are sent to the device when the
“Execute” button is pressed.
Figure 19. I2C Window – Sending I2C Commands

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4 Board Layouts, Bill of Materials, and Schematic
4.1 TAS6421-Q1 EVM Layouts
Figure 20. TAS6421-Q1 EVM Top