NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Table of Contents
1.1
1.2
Description .................................................................................................................................................. 2
Pin Descriptions .......................................................................................................................................... 3
Operating Characteristics ............................................................................................................................ 5
1.3
1.4
Absolute Maximum Ratings ......................................................................................................................... 6
1.5
Recommended Operating Conditions ......................................................................................................... 6
1.6
Special Feature Description ........................................................................................................................ 7
1.7
Device Protection .......................................................................................................................................16
1.7.1
Thermal Overload Protection ..............................................................................................................16
1.7.2
Short Circuit Protection .......................................................................................................................16
1.7.3
Supply under Voltage Protection .........................................................................................................16
1.8
Max Power Limiting feature ........................................................................................................................16
1.8.1
Power limiting VDD independent configuration ...................................................................................17
1.8.2
Power limiting VDD dependent configuration ......................................................................................17
1.8.3
ATTACK TIME, HOLD TIME, AND RELEASE TIME...........................................................................17
1.8.4
Attach time Plot ...................................................................................................................................18
1.8.5
Hold & Release plots ...........................................................................................................................18
1.9
Power up and Power down Control ............................................................................................................18
1.10
Application diagram ....................................................................................................................................19
1.10.1
Single ended input configuration .........................................................................................................19
1.10.2
Differential input configuration .............................................................................................................19
1.11
Component selection ..................................................................................................................................19
1.11.1
Coupling Capacitors ............................................................................................................................19
1.11.2
Bypass Capacitors ..............................................................................................................................20
1.12
Layout considerations ................................................................................................................................20
1.13
Class D without filter ...................................................................................................................................20
1.14
Class D with filter ........................................................................................................................................20
1.14.1
Ferrite Bead filter .................................................................................................................................21
1.14.2
LC filter ................................................................................................................................................21
1.15
NAU8214 EMI performance .......................................................................................................................22
Package Dimensions ...............................................................................................................................................23
1.16
20 Pin QFN Package ..................................................................................................................................23
1.17
8 pin SOP package ...................................................................................................................................24
Ordering Information ...............................................................................................................................................25
1.18
Nuvoton Part Number Description ..............................................................................................................25
NAU8214 Data Sheet Rev1.6
Page 1 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.1
Description
The NAU8214 is a mono high efficiency filter-free Class-D audio amplifier with variable gain amplifier, which is
capable of driving a 4Ω load with up to 2.9W output power. This device provides chip enable pin with extremely low
standby current and fast start-up time of 4ms.The NAU8214 is ideal for the portable applications of battery drive, low
quiescent current (i.e. 1.7mA at 3.6V), Max power limiting function for a given load and superior EMI performance. It
has the ability to configure the inputs in either single-ended or differential mode.
NAU8214 is available in SOP-8 package.
Key Features
Low Quiescent Current:
1.4mA at 3.6V
2.7mA at 5V
Powerful Mono Class-D Amplifier:
1.48 W (4Ω @ 3.6V, 10% THD+N)
1.2 W (4Ω @ 3.6V, 1% THD+N)
0.87 W (8Ω @ 3.6V, 10% THD+N)
0.71 W (8Ω @ 3.6V, 1% THD+N)
2.9W (4Ω @ 5V, 10% THD+N)
2.3W (4Ω @ 5V, 1% THD+N)
1.7W (8Ω @ 5V, 10% THD+N)
1.38W (8Ω @ 5V, 1% THD+N)
Low Output Noise: 56 µVRMS (A –Weighted @3.6V)
82dB PSRR @217Hz
Low Current Shutdown Mode
Click-and Pop Suppression
Max Power limiting feature
Applications
Smartphones
Tablet PCs
Personal Navigation Devices
Rugged hand held computer and two-way radios
VIN
Class D
Modulator
ALC
VIP
R
PLMT
NAU8214
Click / Pop
Suppression
Output
Driver
Current / Thermal
Protection
VDD
VSS
EN
NAU8214 Block Diagram
NAU8214 Data Sheet Rev1.6
Page 2 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Pin Descriptions
EN
1
8
VOUTN
PLMT
2
7
GND
VIP
3
6
VDD
VIN
4
5
VOUTP
NAU8214SG
Package
Package Material
NAU8214SG
4mm x 5mm
SOP-8
Green
Part Number
Dimension
Package
Package Material
NAU8214YG
4mm x 4mm
QFN-20
Green
1
NC
2
16
17
18
19
20
NAU8214 Data Sheet Rev1.6
VOUTP
NC
Dimension
VSS(output
stage GND
VDD(output
stage PWR
Part Number
NC
NAU8214
MQFN 20-Pin
15
OUTLN
14
NC
13
GND
5
11
IPL
Page 3 of 25
INL
PLM
10
NC
9
NC
8
12
7
4
VIP
NC
6
3
NC
EN
NC
1.2
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Pin #
Name
Type
Functionality
1
2
3
4
5
6
7
8
EN
PLMT
VIP
VIN
VOUTP
VDD
VSS
VOUTN
Digital Input
Power Limiting
Analog Input
Analog Input
Analog Output
Supply
Supply
Analog Output
Chip Enable (High = Power Up; Low = Power Down)
Power Limiting Threshold
Positive Differential Input
Negative Differential Input
Positive BTL Output
Power Supply
High Current Ground
Negative BTL Output
Table 1 NAU8214 Pin description
NAU8214 Data Sheet Rev1.6
Page 4 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.3
Operating Characteristics
Conditions: EN = VDD = 5V, VSS = 0V, Av = 18dB, ZL = ∞, Bandwidth = 20Hz to 22kHz, T A = 25 °C
Parameter
Symbol
Comments/Conditions
Min
Typ
Max
Units
Power Delivered
Output Power
Pout
Parameter
Chip Enable (EN)
Voltage Enable High
Voltage Enable Low
Input Leakage Current
Thermal and Current Protection
Thermal Shutdown Temperature
ZL = 4Ω + 33µH
THD + N = 10%
ZL = 4Ω + 33µH
THD + N = 1%
ZL = 8Ω + 68µH
THD + N = 10%
ZL = 8Ω + 68µH
THD + N = 1%
Symbol
VEN_H
VEN_L
VDD = 5.0V
VDD = 3.6V
VDD = 5.0V
VDD = 3.6V
VDD = 5.0V
VDD = 3.6V
VDD = 5.0V
VDD = 3.6V
Comments/Conditions
VDD = 2.5V to 5.5V
VDD = 2.5V to 5.5V
2.9
1.48
2.3
1.2
1.7
0.87
1.38
0.71
Min
0.1
Parameter
ILIMIT
RIN
REN
Symbol
AV = 18dB
Comments/Conditions
Max
1.3
Thermal Shutdown Hysteresis
Limiting Current
Single Ended Input Resistance
Resistance (EN pin to GND)
Typ
W
Min
0.35
2.0
Units
V
V
µA
150
°C
20
°C
2.0
10
300
A
kΩ
kΩ
Typ
Max
Units
Normal Operation
Quiescent Current Consumption
IQUI
Shut Down Current
Oscillator Frequency
Efficiency
Start Up Time
Output Offset Voltage
Common Mode Rejection Ratio
IOFF
fOSC
η
Tstart
VOS
CMRR
Power Supply Rejection Ratio
PSRR
Noise Performance
NAU8214 Data Sheet Rev1.6
VDD = 3.6V
VDD = 5V
EN = 0
1.4
2.7
0.5
300
91
4
±1
60
92
82
mA
mA
µA
kHz
%
ms
mV
dB
dB
dB
VRIPPLE = 0.2Vpp@1kHz
80
dB
VRIPPLE =
0.2Vpp@10kHz
60
dB
VDD = 3.6V (A-weighted)
56
µVRMS
SOP-8 (ZL=8Ω)
fIN = 1KHz
DC PSRR
AC PSRR
VRIPPLE = 0.2Vpp
@217Hz
Page 5 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Parameter
1.4
Symbol
Comments/Conditions
Min
Typ
Max
Units
Absolute Maximum Ratings
Parameter
Symbol
Condition
Min
Max
Units
DC Power Supply
VDD
VDD-VSS
-0.30
+6.00
V
Analog Input Voltage
AVIN
VIN-VSS
-0.3
VDD+0.3
V
Digital Input Voltage
DVIN
DVIN-VSS
-0.3
VDD+0.3
V
3.2
Ω
Minimum Load Resistance
RL
Continuous Power Dissipation
PO
WCSP,
T=25°C
530
mW
Continuous Power Dissipation
PO
WCSP,
T=85°C
275
mW
Storage temperature range
Tst
+150
°C
-55
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may
adversely influence product reliability and result in failures not covered by warranty.
1.5
Recommended Operating Conditions
Parameter
DC Power Supply
High-level input
voltage(EN pin)
Low-level input
voltage(EN pin)
Operating Temperature
NAU8214 Data Sheet Rev1.6
Symbol
Condition
Min
Typical
Max
Units
VDD
VDD-VSS
2.50
5.00
5.50
V
VIH
1.30
V
VIL
TA
-40
Page 6 of 25
+25
0.35
V
+85
°C
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Audio Precision NAU8214 THD+N vs.Output Power into 8 Ω + 66 μ 04/07/14 14:05:49
H, Gain = 18 dB
TYPICAL PERFORMANCE CHARACTERISTICS
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100u 200u
500u
1m
2m
5m
10m
20m
50m 100m 200m
500m
1
2
5
10
OUTPUT POWER (W)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
Comment
Audio Precision NAU8214 THD+N vs.Output Power into 4 Ω + 33 μ 04/07/14 13:54:18
A-A THD+N % vs Output Levl_8ohm.at27
H, Gain = 18 dB
THD + N vs. Output Power into 8 Ω + 66 μH, Gain = 18 dB
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
100u 200u
500u
1m
2m
5m
10m
20m
50m 100m 200m
500m
1
2
5
10
OUTPUT POWER (W)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
S2C.Anlr.THD+N Ratio
S2C.Anlr.THD+N Ratio
S2C.Anlr.THD+N Ratio
Left
Left
Left
VDD 2.5V
VDD 3.6V
VDD 5V
A-A THD+N % vs Output Levl.at27
THD + N vs. Output Power into 4 Ω + 33 μH, Gain = 18 dB
NAU8214 Data Sheet Rev1.6
Page 7 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Audio Precision
THD + N vs. Frequency, VDD = 5V,
Rl=8ohm+66uH, Gain = 18dB
04/07/14 14:16:47
100
50
20
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k 100k
Frequency (Hz)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
OUTPUT POWER 0.25W
OUTPUT POWER 0.5W
OUTPUT POWER 1W
Audio Precision
THD + N vs. Frequency, VDD = 5V,
04/07/14 14:24:04
A-A THD+N % vs Frequency_8ohm.at27
Rl=4ohm+33uH, Gain = 18dB
THD + N vs. Frequency, VDD = 5 V, RL = 8 Ω + 66 μH, Gain = 18 dB
100
50
20
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k 100k
Frequency (Hz)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
OUTPUT POWER 0.5W
OUTPUT POWER 1W
OUTPUT POWER 2W
A-A THD+N % vs Frequency_4ohm.at27
THD + N vs. Frequency, VDD = 5 V, RL = 4 Ω + 33 μH, Gain = 18 dB
NAU8214 Data Sheet Rev1.6
Page 8 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Audio Precision
THD + N vs. Frequency, VDD = 3.6V,
Rl=8ohm+66uH, Gain = 18dB
04/07/14 14:43:34
100
50
20
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k 100k
Frequency (Hz)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
OUTPUT POWER 0.125W
OUTPUT POWER 0.25W
OUTPUT POWER 0.5W
Audio Precision
THD + N vs. Frequency, VDD = 3.6V,
04/07/14 14:29:03
A-A THD+N % vs Frequency_8ohm.at27
Rl=4ohm+33uH, Gain = 18dB
THD + N vs. Frequency, VDD = 3.6 V, RL = 8 Ω + 66 μH, Gain = 18 dB
100
50
20
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k 100k
Frequency (Hz)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
OUTPUT POWER 0.25W
OUTPUT POWER 0.5W
OUTPUT POWER 1W
A-A THD+N % vs Frequency_4ohm.at27
THD + N vs. Frequency, VDD = 3.6 V, RL = 4 Ω + 33 μH, Gain = 18 dB
NAU8214 Data Sheet Rev1.6
Page 9 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Audio Precision
THD + N vs. Frequency, VDD = 2.5V,
Rl=8ohm+66uH, Gain = 18dB
04/07/14 14:39:21
100
50
20
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k 100k
Frequency (Hz)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
OUTPUT POWER 0.0625W
OUTPUT POWER 0.125W
OUTPUT POWER 0.25W
Audio Precision
THD + N vs. Frequency, VDD = 2.5V,
04/07/14 14:33:12
A-A THD+N % vs Frequency_8ohm.at27
Rl=4ohm+33uH, Gain = 18dB
THD + N vs. Frequency, VDD = 2.5 V, RL = 8 Ω + 66 μH, Gain = 18 dB
100
50
20
10
5
T
H
D
+
N
(
%
)
2
1
0.5
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
10
20
50
100
200
500
1k
2k
5k
10k
20k
50k 100k
Frequency (Hz)
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Blue
Green
Red
Solid
Solid
Solid
3
3
3
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Anlr.THD+N Ratio
Left
Left
Left
OUTPUT POWER 0.125W
OUTPUT POWER 0.25W
OUTPUT POWER 0.5W
A-A THD+N % vs Frequency_4ohm.at27
THD + N vs. Frequency, VDD = 2.5 V, RL = 4 Ω + 33 μH, Gain = 18 dB
NAU8214 Data Sheet Rev1.6
Page 10 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Supply Current vs. Supply Voltage
4
SUPPLY CURRENT (mA)
3.5
3
2.5
NO LOAD
2
RL = 4ohm+33uH
1.5
RL = 8ohm+66uH
1
0.5
SUPPLY VOLTAGE( V )
0
2.5
3
3.5
4
4.5
5
5.5
Maximum Output Power vs Supply
Voltage , RL=8Ω+33uH, Gain = 18dB
2
1.8
OUTPUT POWER (W)
1.6
1.4
1.2
1%
1
10%
0.8
0.6
0.4
0.2
SUPPLY VOLTAGE (V)
0
2.5
NAU8214 Data Sheet Rev1.6
3
3.5
Page 11 of 25
4
4.5
5
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Maximum Output Power vs Supply
Voltage , RL=4Ω+33uH, Gain = 18dB
3.5
OUTPUT POWER (W)
3
2.5
2
1%
1.5
10%
1
0.5
SUPPLY VOLTAGE (V)
0
2.5
3
3.5
4
4.5
5
Maximum Output Power vs Supply
Voltage , RL=3Ω+33uH, Gain = 18dB
4
OUTPUT POWER (W)
3.5
3
2.5
1%
2
10%
1.5
1
0.5
SUPPLY VOLTAGE (V)
0
2.5
NAU8214 Data Sheet Rev1.6
3
3.5
Page 12 of 25
4
4.5
5
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Efficiency vs. Output Power into 8ohm + 66uH
100.00
90.00
80.00
EFFICIENCY (%)
70.00
60.00
VDD 2.5V
50.00
VDD 3.6V
40.00
VDD 5V
30.00
20.00
10.00
OUTPUT POWER
(W)
0.00
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
Efficiency vs. Output Power into 4ohm + 33uH
100.00
90.00
80.00
EFFICIENCY (%)
70.00
60.00
VDD 2.5V
50.00
VDD 3.6V
40.00
VDD 5V
30.00
20.00
10.00
OUTPUT POWER
(W)
0.00
0
0.2 0.4 0.6 0.8
NAU8214 Data Sheet Rev1.6
1
1.2 1.4 1.6 1.8
Page 13 of 25
2
2.2 2.4 2.6 2.8
3
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Supply Current vs. Output Power into 8ohm+66uH
450.0000
400.0000
SUPPLY CURRENT (mA)
350.0000
300.0000
250.0000
VDD 2.5V
VDD 3.6V
200.0000
VDD 5V
150.0000
100.0000
50.0000
OUTPUT POWER (W)
0.0000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
Supply Current vs. Output Power into 4ohm +
33uH
800.00
SUPPLY CURRENT (mA)
700.00
600.00
500.00
VDD 2.5V
400.00
VDD 3.6V
300.00
VDD 5V
200.00
100.00
OUTPUT POWER
(W)
0.00
0
0.2 0.4 0.6 0.8
NAU8214 Data Sheet Rev1.6
1
1.2 1.4 1.6 1.8
Page 14 of 25
2
2.2 2.4 2.6 2.8
3
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
ALC release waveform , VDD 5V Input 0dBV / 3kHz sine Output LC Load 4ohm+30uH
Start up time 4ms , VDD 5V Input 0dBV / 1kHz sine Output LC Load 4ohm+30uH
NAU8214 Data Sheet Rev1.6
Page 15 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.6
Special Feature Description
The NAU8214 offers excellent quantity performance as high efficiency, high output power and low quiescent current. It
also provides the following special features.
1.7
Device Protection
The NAU8214 includes device protection for three operating scenarios. They are
1.
2.
3.
Thermal Overload
Short circuit
Supply under voltage
1.7.1
Thermal Overload Protection
When the device internal junction temperature reaches 150°C, the NAU8214 will disable the output drivers. When the
device cools down and a safe operating temperature of 130°C has been reached for at least about 100ms, the output
drivers will be enabled again.
1.7.2
Short Circuit Protection
If a short circuit is detected on any of the pull-up or pull-down devices on the output drivers for at least 16.7µs, the
output drivers will be disabled for 100ms. The output drivers will then are enabled again and check for the short circuit.
If the short circuit is still present, the output drivers are disabled after 16.7µs. This cycle will continue until the short
circuit is removed. The short circuit threshold is 2.0A at 3.6V.
1.7.3
Supply under Voltage Protection
If the supply voltage drops under 2.1V, the output drivers will be disabled while the NAU8214 control circuitry still
operates. This will avoid the battery supply to drag down too low before the host processor can safely shut down the
devices on the system. If the supply drops further below 1.6 V the internal power on reset is activated and puts the entire
device in power down state.
1.8
Max Power Limiting feature
The NAU8214 has a unique feature that limits the Maximum output power delivered to the load. This Max power limit
is set by using external resistor connected to the dedicated pin PLMT. Once the threshold is set, the NAU8214 will not
allow the voltage output more than the set value irrespective of the power supply voltage variations. Because of this
output voltage control, the NAU8214 is able to achieve Power limit function for any given load. There are two methods
to set the maximum output amplitude threshold (Vout) during the limiting mode. The following equations show the Max
output voltage limit in terms of external resistor (RLMT). In equation 1, RLMT is tied to GND, which sets (Vout) as
VDD independent, unlike equations two where Vout is proportional to (VDD-1.2V). The maximum peak voltage (Vout)
is VDD dependent with offset voltage 1.2V in equation 2.
1.
Vout =
2.
Vout =
V with RLMT tied to ground
V with RLMT tied to supply voltage
The maximum output power is calculated from the following eq.
Pout =
(
√
)
Where R is the Load resistance (Speaker Resistance)
If the supply voltage is lower than the pre-set Max Vout voltage, then the output signal will clip to the supply voltage
rather than being limited by the power limiter.
NAU8214 Data Sheet Rev1.6
Page 16 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.8.1
Power limiting VDD independent configuration
VIN
0.1uF
Output
Driver
Class D
Modulator
ALC
VIP
0.1uF
VDD
NAU8214
Click / Pop
Suppression
RLMT
PLMT
10uF
0.1uF
VSS
VDD
1.8.2
Current / Thermal
Protection
EN
Power limiting VDD dependent configuration
VIN
0.1uF
Class D
Modulator
ALC
VIP
Output
Driver
0.1uF
VDD
VDD
NAU8214
Click / Pop
Suppression
PLMT
10uF
0.1uF
VSS
RLMT
VDD
1.8.3
Current / Thermal
Protection
EN
ATTACK TIME, HOLD TIME, AND RELEASE TIME
When the input to the NAU8214 exceeds a preset threshold, MPL reduces amplifier gain rapidly until its output settles to
a target level. This gain level is maintained for a certain period. If the input does not exceed the threshold again, MPL
increases the gain gradually. The attack time is the time taken to reduce the gain from maximum to minimum. The hold
time is the time to sustain the reduced gain. The release time is the time taken to increase the gain from minimum to
maximum. See below plots for these times.
NAU8214 Data Sheet Rev1.6
Page 17 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.8.4
Attach time Plot
1.8.5
Hold & Release plots
1.9
Power up and Power down Control
When the supply voltage ramps up, the internal power on reset, circuit is triggered. At this time, all internal circuits will
be set to power down state. The device can be enabled by setting the EN pin high. Upon setting the EN pin high, the
device will go through an internal power up sequence in order to minimize ‘pops’ on the speaker output. The complete
power up sequence will take about 4ms. The device will power down in about 30µs, when the EN pin is set low.
It is important to keep the input signal at zero amplitude or enable the mute condition in order to minimize the ‘pops’
when the EN pin is toggled.
NAU8214 Data Sheet Rev1.6
Page 18 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.10 Application diagram
1.10.1 Single ended input configuration
VIN
0.1uF
Class D
Modulator
ALC
VIP
Output
Driver
0.1uF
R
PLMT
Click / Pop
Suppression
NAU8214
Current / Thermal
Protection
VDD
10uF
0.1uF
VSS
VDD
EN
1.10.2 Differential input configuration
VIN
0.1uF
Class D
Modulator
ALC
VIP
Output
Driver
0.1uF
R
PLMT
Click / Pop
Suppression
NAU8214
Current / Thermal
Protection
VDD
10uF
0.1uF
VSS
VDD
EN
1.11 Component selection
1.11.1 Coupling Capacitors
An ac coupling capacitor (Cin) is used to block the dc content from the input source. The input resistance of the amplifier
(Rin) together with the Cin will act as a high pass filter. So depending on the required cut off frequency the Cin can be
calculated by using the following formula
NAU8214 Data Sheet Rev1.6
Page 19 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Where
is the desired cut off frequency of the High pass filter.
Input
Cin
Amplifier
Output
Rin(Input
Resistance)
1.11.2 Bypass Capacitors
Bypass capacitors are required to remove the ac ripple on the VDD pins. The value of these capacitors depends on the
length of the VDD trace. In most cases, 10µF and 0.1µF are enough to get the good performance.
1.12 Layout considerations
Good PCB layout and grounding techniques are essential to get the good audio performance. It is better to use low
resistance traces as these devices are driving low impedance loads. The resistance of the traces has a significant effect on
the output power delivered to the load. In order to dissipate more heat, use wide traces for the power and ground lines.
1.13 Class D without filter
The NAU8214 is designed for use without any filter on the output line. That means the outputs can be directly connected
to the speaker in the simplest configuration. This type of filter less design is suitable for portable applications where the
speaker is very close to the amplifier. In other words, this is preferable in applications where the length of the traces
between the speaker and amplifier is short. The following diagram shows this simple configuration.
VOUTP
VOUTN
NAU8214 outputs connected to speaker without filter circuit
1.14 Class D with filter
NAU8214 Data Sheet Rev1.6
Page 20 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
In some applications, short trace lengths are not possible because of speaker size limitations and other layout reasons. In
these applications, the long traces will cause EMI issues. There are two types of filter circuits available to reduce the
EMI effects. These are ferrite bead and LC filters.
1.14.1 Ferrite Bead filter
The ferrite bead filters are used to reduce the high frequency emissions. The typical circuit diagram is shown in the
figure.
Ferrite Bead
VOUTP
1nF
Ferrite Bead
VOUTN
1 nF
NAU8214 outputs connected to speaker with Ferrite Bead filter
The characteristic of ferrite bead is such that it offers higher impedance at high frequencies. For better EMI performance
select ferrite bead which offers highest impedance at high frequencies, so that it will attenuate the signals at higher
frequencies. Usually the ferrite beads have low impedance in the audio range, so it will act as a pass through filter in the
audio frequency range.
1.14.2 LC filter
The LC filter is used to suppress the low frequency emissions. The following diagram shows the NAU8214 outputs
connected to the speaker with LC filter circuit. R L is the resistance of the speaker coil.
L
OUTLP
RL
C
OUTLN
C
L
NAU8214 outputs connected to speaker with LC filter
NAU8214 Data Sheet Rev1.6
Page 21 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Ls
Input
Output
R
Cs
Standard Low pass LCR filter
The following are the equations for the critically damped (ζ = 0.707) standard low pass LCR filter
√
is the cutoff frequency
√
The L and C values for differential configuration can be calculated by duplicating the single ended configuration values
and substituting RL = 2R.
1.15 NAU8214 EMI performance
The NAU8214 includes a spread spectrum oscillator for reduced EMI. The PWM oscillator frequency typically sweeps
in a range of 300 kHz +/- 15 kHz in order to spread the energy of the PWM pulses over a larger frequency band. In
addition, slew rate control on the output drivers allows the application of ‘filter less’ loads, while suppressing EMI at
high frequencies.
NAU8214 Data Sheet Rev1.6
Page 22 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Package Dimensions
1.16 20 Pin QFN Package
TOP VIEW
15
BOTTOM VIEW
11
16
11
10
10
6
6
15
16
20
20
1
NAU8214 Data Sheet Rev1.6
5
5
Page 23 of 25
1
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
1.17 8 pin SOP package
8
5
E
4
1
Control demensions are in milmeters .
E
NAU8214 Data Sheet Rev1.6
Page 24 of 25
April 22, 2015
NAU8214 2.9W Mono Filter-Free Class-D Audio Amplifier
Ordering Information
1.18 Nuvoton Part Number Description
NAU8214XG
Package Material:
G
=
Green Package
Package Type:
S
=
8-pin SOP Package
Y
=
20-pin QFN Package
Version History
VERSION
DATE
PAGE
DESCRIPTION
Rev1.0
May, 2013
NA
Preliminary Revision
Rev 1.1
May, 2013
5
Rev1.2
November 2013
6-7
Rev1.3
December 2013
2 and
12
Added new package information
Rev 1.4
August 28,2014
13
Added QFN20 Package info
Rev1.5
October 27, 2014
7-15
Added Performance graphs.
Rev 1.6
April 22, 2015
13-25
Corrected the ordering number for SOP 8 package.
Populated the Power limiting table with resistance and Vout
values.
Added attack time, hold time, and release time plots PLM
Table 2 Version History
Important Notice
Nuvoton products are not designed, intended, authorized or warranted for use as components in systems or equipment
intended for surgical implantation, atomic energy control instruments, airplane or spaceship instruments, transportation
instruments, traffic signal instruments, combustion control instruments, or for other applications intended to support or
sustain life. Furthermore, Nuvoton products are not intended for applications wherein failure of Nuvoton products could
result or lead to a situation wherein personal injury, death or severe property or environmental damage could occur.
Nuvoton customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify Nuvoton for any damages resulting from such improper use or sales.
NAU8214 Data Sheet Rev1.6
Page 25 of 25
April 22, 2015
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