NXP Semiconductors UM10340-5 User manual

UM10340_5
TFA9879 digital input mono Class-D amplifier demo PCB
Rev. 05 — 30 aug. 2011 User manual
Document information
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Keywords Class-D amplifier, Digital input, High efficiency, Filter free
Abstract This User Manual describes the TFA9879 digital input mono Class-D
demonstration PCB based on NXP Semiconductors’ TFA9879 filter-free
mono BTL Class-D audio amplifier device. The TFA9879 device is
intended for portable applications that support a digital output, which is
less sensitive to external RF fields. The low power consumption will
increase the battery life and an excellent audio performance with high
PSRR is achieved by the integrated feedback loop.
Furthermore the device is very robust due to the integrated protections
like OCP, OTP and several input protections.
The demonstration PCB is designed to operate from a single supply with
a wide supply voltage range of 2.5V…5.5V delivering an output power up
to 1.6WRMS in 8 Ω BTL or 2.7WRMS 4 Ω BTL. The application PCB area for
the TFA9879 is very small because only three external components are
required. The demo board is EMC compliant and contains 15kV ESD
protections at the speaker output.

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
<DOC ID>
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 2 of 20
Con
tact information
For additional information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: sales[email protected]
Revision history
Rev Date Description
1 20090227 Initial version
2 20090806 Main PCB updated to revision 2 and WLCSP translation PCB replaced by HVQFN24
translation PCB
3 20090911 Translation PCB updated to revision 3 for TFA9879 (N1B2/N1C) engineering samples
4 20091210 Main PCB and translation PCB updated to revision R3 for the final TFA8979 (N1C)
samples
5 20110830 Main PCB Revision 4

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 3 of 20
1. Introduction
This User Manual describes the TFA9879 digital input mono Class-D amplifier
demonstration PCB based on NXP Semiconductors’ TFA9879HN device. Extension “HN”
is referring to the HVQFN24 package dedicated for reflow soldering.
The TFA9879 demonstration PCB is designed in such a way that it is easy to operate the
TFA9879 device for demonstration purposes and for validation. Therefore the
demonstration PCB facilitates the following circuitry (see Figure 1):
•TFA9879 Class-D amplifier requires only three external components that are
stuffed at a translation PCB.
•Analog to digital converter (ADC + clock generator, I2S format, fs = 48kHz) to
drive the speaker via the Class-D amplifier with analog signals.
•3.3V buck boost converter (DCDC) for the ADC and I2C pull-up voltage.
•1.8V linear regulator for the digital core of the TFA9879.
•External 15kV ESD protection at amplifier output.
Figure 1: Block diagram demonstration PCB
Demonstration PCB
Speaker
TFA9879
OUTA
Class-D
Class-D
Volume control
5-band parametric EQ
DRC
Bass-treble control
High-pass filter
Power limiter
PWM
modulator
PLL
I2C
control
interface
Interface
I2S input 1
I2S input 2
I2C control input
Protections
OCP
OTP
Mono speaker driver
Digital processor
Digital
audio
receiver
MUX
Input
protections
OFP
UFP
IBP
VDDP VDDD
Supply 2.5V...5.5V
Feedback
loop
Feedback
loop OUTB
C
STABA
STABA
1.8V
Address select
A/D converter
3.3V
Analog input
Class-D amplifier
1.8V linear
regulator
3.3V buck boost
converter
12.29 MHz
Left
ADC
SYSCLK
Right
LRCK1
SCK1
SDI1
3.3V
VP
SDA
S1
1.8V
1.8V
LRCK2
SCK2
SDI2
S3
S4
S2
Shutdown
DCDC
Shutdown
LDO
Shutdown
ADC
GNDPGNDD
GND
S5
SCL
ADSEL1
ADSEL2

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 4 of 20
The necessary information is given for a quick start-up of the demonstration PCB (see
paragraph 2). Paragraph 3 shows the results of the audio characterization and the
schematic, BOM and layout is provided in paragraph 4, 5 and 6.
The TFA9879 device has the following functions / features:
General
•Wide supply voltage range 2.5V…5.5V
•Two digital inputs (I2S and PCM/IOM2 formats, 1.8V and 3.3V tolerant) which
are less sensitive to external RF fields
•Internal Phase-Locked Loop (PLL) requiring no system clock
•High efficiency of 92% and low power consumption
•Closed loop amplifier resulting in excellent audio performance:
•PSRR = -76 dB
•S/N = -95dB (A-weighted)
•THD+N = 0.015% at 100mW
RMS
•High power capability:
•2.7 W
RMS
in 4ΩBTL at 5V
•1.6 W
RMS
in 8ΩBTL at 5V
•Protections including diagnostic via I2C
•I2S and PCM/IOM2 input protections
•Under Frequency Protection (UFP)
•Over Frequency Protection (OFP)
•Invalid Bit clock Protection (IBP)
•Over Current Protection (OCP)
•Over Temperature Protection (OTP)
•HVQFN24 package
DSP
•Volume control (-70dB to +24dB)
•5-band parametric equalizer
•Dynamic Range Compression
•Bass-treble control (-18dB to +18dB)
•High-pass filter
•Power limiter (0dB to –124dB)
•Zero crossing detect

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 5 of 20
2. Setup demonstration PCB
2.1 Hardware setup
Figure 2 is showing the hardware setup of the TFA9879 mono demonstration PCB with
screw terminals for connecting the power supply (X3) and the speaker cables (X7).
The speaker can be driven by the Class-D amplifier with:
•A digital audio signal via the headers X4 (I2S input 1) or X5 (I2S input 2);
•An analog stereo audio signal via the RCA Jacks X14 and X11 (I2S input 2).
Remark: Default the ADC is connected to the I2S input 2 of the TFA9879 via R35, R36
and R37 (10R, see schematic in paragraph 4). These 10R resistors must be removed
from the PCB when driving I2S via X5.
The USM interface (USB to I2C converter) including the 4-wire flat cable, which are
provided with the board, should be connected between demonstration PCB (connector
X9) and USM interface. The USB port should be connected to the PC.
Important remark: First install the GUI software (see paragraph 2.2.1), which includes the
USB driver, before connecting the USM interface to the PC.
+ OUT - Supply I2C input
Right Left
Analog Class
-D input
S3
X7 X3
X14 X11
S2
S4
S1
X4 X5
X9
Digital
Class-
D input
I2S input 1
I2S input 2
S5
3
Figure 2: Setup demonstration PCB Figure 3: USM interface
Table 1. Input/output connector assignment
REF
TYPE
Pin
Lab
el
Description
X3
Terminal block, screw
1
GND
Ground
2
V
P
Positive supply input (2.5V…5.5V)
X4
Header, double row
1, 2, 9, 10
Not connected
3
SDI1
Data input 1

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 6 of 20
REF
TYPE
Pin
Lab
el
Description
4, 6, 8
GND
Ground
5
LRCK1
Word clock input 1
7
SCK1
Bit clock input 1
X5
Header, double row
1, 2, 9, 10
Not connected
3
SDI2
Data input 2
4, 6, 8
GND
Ground
5
LRCK2
Word clock input 2
7
SCK2
Bit clock input 2
X7
Terminal block, screw
1
OUTB
PWM output B (negative output)
2
OUTA
PWM output A (positive output)
X9
Stocko header
1
SCL
Serial clock input
2
GND
Ground
3
3.3V
3.3V supply output
4
SDA
Serial data I/O
X11
RCA Jack
1
Left
Left analog input to drive Class
-
D amplifier
2
GND
Ground
X14
RCA Jack
1
Right
Right analog input to drive Class
-
D am
plifier
2
GND
Ground
2.1.1 PCB switch settings
PCB switch S1 and S5 are incorporated to select between the I2C addresses.
I2C address select
S5
S1
address
0 0 D8
0 1 DA
1 0 DC
1 1 DE
S2, S3 and S4 are incorporated to power-down respectively the 1.8V LDO, the DCDC
converter and the ADC converter if required. The LDO and the DCDC converter must be
turned on to operate the TFA9879. The ADC might be turned off when not used.
2.1.2 Digital input formats
Below digital formats are supported by the TFA9879 device:
I2S formats (fs = 8kHz to 96kHz)
•Philips standard I2S
•Japanese I2S MSB-justified
•Sony I2S LSB-justified
PCM/IOM2 formats (fs = 8kHz)
•Long frame sync
•Short frame sync

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 7 of 20
L
E
R
DC
2.1.3 Speaker dummy load
The TFA9879 is a filter-free Class-D amplifier that will directly drive the loudspeaker. For
realistic measurement at a filter-free Class-D amplifier a dummy load, consisting out of a
resistor (R
DC
) in series with an inductor (L
E
), should replace the loudspeaker. The resistor
represents the loudspeaker dc resistance and the inductor (L
E
) represents the
loudspeaker coil.
Figure 4: Simplified loudspeaker model
Measurement at the demonstration PCB are performed with resistor of R
DC
= 8Ω, L
E
=
44µH or R
DC
= 4Ω, L
E
= 20µH. But inductor values between respectively 15µH and 60µH
are suitable (saturation current >1.5A) for measurements as well.

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 8 of 20
2.2 Software setup (GUI)
The TFA9879 is controlled via I2C. The Graphic User Interface (GUI) software (including
USM drivers), which are supplied by the demonstration PCB, enable easy control of the
I2C registers in the TFA9879.
Important remark: First install the GUI software, which includes the USM drivers, before
connecting the USM interface to the PC.
2.2.1 Installing software
Follow below steps for a proper installation of the I2C GUI and USM drivers:
1. Run the installation file (TFA9879_4_2_0.exe or higher) on a Windows XP operating
system (or higher) and follow the installation procedure. The GUI will start
automatically after installation.
2. Exit the I2C GUI program.
3. Connect the USM interface to the PC.
4. Windows will automatically detect the USM interface and a hardware wizard helps to
install the software. Select the option “install the software automatically”. Furthermore
a warning about Windows Logo testing might appear. Click on “Continue Anyway”
and installation of the USM interface will be finalized.
5. Connect the I2C cable to the demonstration PCB and turn-on the power supply. S2
and S3 at the demonstration PCB should be in the “ON” position. Start-up the I2C
GUI program:
6. Select from the menu respectively I2C Config Detect and wait until “USM”
appears in the interface box. Close this window.
Figure 6: I2C menu
Figure 5: Warning

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 9 of 20
7. Select a device address (D8, DA, DC or DE) from the GUI (top right side).
The installation of I2C GUI is finalized and the indicator of the I2C communication
should be green.
Figure 7: GUI communication
If the indication is still red the following should be checked:
•An equal device address should be selected (D8, DA, DC or DE) in GUI and
demonstration PCB (S1/S5)
•Connection of the USM interface
•S2 and S3 should be in the “ON” position
2.3 Settings to play audio
The following settings are required to play audio via the analog RCA-jack inputs.
Hardware settings:
•Turn on ADC, S4 in “ON” position (S2 and S3 also in “ON” position)
•Apply Left and Right audio signal to the RCA-jack inputs (X11, X14)

NXP Semiconductors
UM10340_5
TFA9879 demonstration PCB
© NXP B.V. 2011. All rights reserved.
User manual Rev. 05 — 30 aug. 2011 10 of 20
GUI settings:
•Select Powerup
•Select input 2
•Select Operating Mode “On”
•Increase volume (for example to 0dB)
Figure 8: GUI settings to play audio