The NAU8401 is a low power, high quality audio output system for portable applications. In addition to
precision 24-bit stereo DACs, this device integrates a broad range of additional functions to simplify
implementation of complete audio systems. The NAU8401 includes drivers for speaker, headphone, and stereo
line outputs, and integrates mixing of the DAC outputs with analog input signals.
Advanced on-chip digital signal processing includes a 5-band equalizer, a 3-D audio enhancer, and a digital
limiter/dynamic range compressor function for the playback path. The digital interface can operate as either a
master or a slave. Additionally, an internal fractional-N PLL is available to generate accurate audio sample rate
clocks for the DAC derived from any available system clock from 8MHz through 33MHz.
The NAU8401 operates with analog supply voltages from 2.5V to 3.6V, while the digital core can operate as low
as 1.7V to reduce power. The loudspeaker BTL output pair and two auxiliary line outputs can use a 5V supply to
increase output power capability, enabling the NAU8401 to drive 1 Watt into an external speaker. Internal
control registers enable flexible power conserving modes, shutting down sub-sections of the chip under software
control.
The NAU8401 is specified for operation from -40°C to +85°C.
AEC-Q100 & TS16949 compliant device is
available upon request.
emPowerAudio
™
Key Features
DAC: 94dB SNR and -84dB THD (“A” weighted)
Integrated BTL speaker driver: 1W into 8Ω
Integrated head-phone driver: 40mW into 16Ω
Integrated line inputs and line outputs
On-chip high resolution fractional-N PLL
Integrated DSP with specific functions:
5-band equalizer
3-D audio enhancement
Automatic level control
Audio level limiter/dynamic range compressor
Standard audio interfaces: PCM and I
2
S
Serial control interfaces with read/write capability
Supports audio sample rates from 8kHz to 48kHz
Applications
Personal Navigation Devices
Personal Media Players
Personal Navigation Devices
Portable Game Players
Portable TVs
Datasheet Rev 2.5
Page 1 of 69
March, 2014
NAU8401
NAU8401YG
LINPUT
RINPUT
Limiter/
Dynamic
Range
Compressor
LDAC
Headphones/
Line drivers
AUXOUT2
AUXOUT1
LHP
5-Band
Stereo
Equalizer
3D Audio
Effects
RDAC
Output
Mixer
RHP
BTL Speaker
Digital Audio Interface
Serial Control Interface
2-wire
SPI
LSPKOUT
RSPKOUT
GPIO
PLL
I
2
S
PCM
Pinout
LSPKOUT
25
25
27
27
29
29
28
28
n/c
n/c
GPIO2
26
26
32
32
31
31
30
30
VDDSPK
PRGREF
VDDA
VSSA
VREF
RHP
LHP
1
2
3
4
5
6
7
8
12
14
10
11
13
15
16
9
24
24
23
23
VSSSPK
RSPKOUT
AUXOUT2
AUXOUT1
RINPUT
LINPUT
MODE
SDIO
n/c
n/c
GPIO3
FS
BCLK
NAU8401YG
32-lead QFN
RoHS
22
22
21
21
20
20
19
19
18
18
17
17
n/c
CSB/GPIO1
VDDC
MCLK
DACIN
VDDB
VSSD
SCLK
Part Number
NAU8401YG
Dimension
5 x 5 mm
Package
32-QFN
Package
Material
Pb-Free
Datasheet Rev 2.5
Page 2 of 69
March, 2014
NAU8401
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Name
n/c
n/c
GPIO2
n/c
n/c
GPIO3
FS
BCLK
n/c
DACIN
MCLK
VSSD
VDDC
VDDB
CSB/GPIO1
SCLK
SDIO
MODE
LINPUT
RINPUT
AUXOUT1
AUXOUT2
RSPKOUT
VSSSPK
LSPKOUT
VDDSPK
VREF
VSSA
RHP
LHP
VDDA
PRGREF
GPAD
Type
Functionality
Not internally connected
Not internally connected
General purpose I/O. Can be used for jack detect.
Not internally connected
Not internally connected
General Purpose I/O. Can be used for jack detect. In 4-wire
mode, must be used as output to read register data.
Digital Audio DAC and ADC Frame Sync
Digital Audio Bit Clock
Not internally connected
Digital Audio DAC Data Input
Master Clock Input
Digital Ground
Digital Core Supply
Digital Buffer (Input/Output) Supply
3-Wire MPU Chip Select or General Purpose I/O
3-Wire MPU Clock Input / 2-Wire MPU Clock Input
3-Wire MPU Data Input / 2-Wire MPU Data I/O
Control Interface Mode Selection Pin
Left Analog Input
Right Analog Input
Headphone Ground / Mono Mixed Output / Line Output
Headphone Ground / Line Output
BTL Speaker Positive Output or Right high current output
Speaker Ground (ground pin for RSPKOUT, LSPKOUT,
AUXOUT2 and AUXTOUT1 output drivers)
BTL Speaker Negative Output or Left high current output
Speaker Supply (power supply pin for RSPKOUT,
LSPKOUT, AUXOUT2 and AUXTOUT1 output drivers)
Decoupling for Midrail Reference Voltage
Analog Ground
Headphone Positive Output / Line Output Right
Headphone Negative Output / Line Output Left
Analog Power Supply
Programmable buffered DC voltage output
Electrical and Thermal pad on underside of device
Digital Input
Digital Output
Digital I/O
Digital I/O
Digital Input
Digital Input
Supply
Supply
Supply
Digital I/O
Digital Input
Digital I/O
Digital Input
Analog Input
Analog Input
Analog Output
Analog Output
Analog Output
Supply
Analog Output
Supply
Reference
Supply
Analog Output
Analog Output
Supply
Analog Output
Bulk Ground Pad
Notes
1. The 32-QFN package includes a bulk ground connection pad on the underside of the device. This bulk ground should
be thermally tied to the PCB as much as possible, and electrically tied to the analog ground (VSSA, pin 28).
2. Unused analog input pins should be left as no-connection.
3. Unused digital input pins should be tied to ground.
4. Pins designated as "n/c" (Not Internally Connected) should be left as no-connection
Datasheet Rev 2.5
Page 3 of 69
March, 2014
NAU8401
n/c
1
2
n/c
4
n/c
5
n/c
9
n/c
LINPUT
19
VDDB
14
VDDC
13
VSSD
12
VDDA
31
VSSA
28
VDDSPK
26
Normal
-6dB
VSSSPK
24
PLL
LDAC
-
1.0X
+1.5X
AUXOUT1
21
RDAC
AUX1
MIXER
GPIO3
6
LDAC
Σ
LMAIN
MIXER
LMIX
Σ
-
1.0X
+1.5X
AUXOUT2
22
FS
7
BCLK
8
AUDIO
INTERFACE
(PCM/IIS)
Limiter
DACIN
10
5 Band EQ
3D
30
LHP
MCLK
RMAIN
MIXER
11
RDAC
CSB/GPIO1
15
Σ
RMIX
29
RHP
SCLK
16
CONTROL
LOGIC
&
REGISTERS
LMIX
LDAC
SDIO
17
Σ
-
1.0X
MODE
18
CONTROL
INTERFACE
(2-, 3- and 4-wire)
AUX2
MIXER
+1.5X
LSPKOUT
25
GPIO2
27
VDDA
R
R
27
Σ
Programmable
Voltage
32
20
-
1.0X
+1.5X
RSPKOUT
23
RMIX
RSPK
SUBMIXER
VREF
PRGREF
RINPUT
Figure 1: NAU8401 Block Diagram
Datasheet Rev 2.5
Page 4 of 69
March, 2014
NAU8401
Table of Contents
1
2
3
3.1
3.2
GENERAL DESCRIPTION .............................................................................................................................10
POWER SUPPLY .............................................................................................................................................12
3D Stereo Enhancement ............................................................................................................................18
DAC Output A-law and µ-law Expansion ...................................................................................................19
8-bit Word Length .......................................................................................................................................19
5
5.1
5.2
5.3
5.4
5.5
5.6
ANALOG OUTPUTS .......................................................................................................................................20
Main Mixers (LMAIN MIX and RMAIN MIX)................................................................................................20
Auxiliary Mixers (AUX1 MIXER and AUX2 MIXER) ....................................................................................21
Right Speaker Submixer ............................................................................................................................21
Headphone Outputs (LHP and RHP) .........................................................................................................22
Right-Justified Audio Data ..........................................................................................................................36
Left-Justified Audio Data ............................................................................................................................37
2
I S Audio Data ............................................................................................................................................37
PCM A Audio Data .....................................................................................................................................38
9
9.1
9.2
9.3
9.4
DIGITAL AUDIO INTERFACES ...................................................................................................................36
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