Preliminary Datasheet
LPA4732
215mW TrueCapFree Stereo Headphone Amplifier
General Description
Features
The LPA4732 stereo headphone amplifiers are
2.5V to 5.5V Single-Supply Operation
designed for portable equipment where board space is
No Bulky DC-Blocking Capacitors Required
at a premium. The LPA4732 deliver up to 215mW per
No Degradation of Low-Frequency Response Due
to Output Capacitors
Differential Inputs for Enhanced Noise
Cancellation
194mW into 32Ω Load from 5V Power Supply at
THD+N = 0.1% (TYP, per Channel)
anticlick-and-pop circuitry suppresses audible clicks
Low 0.003% THD+N
and pops on startup and shutdown. A low-power
High PSRR (-78dB at 217Hz)
shutdown mode reduces the supply current to 0.1µA.
Short-Circuit and Thermal-Overload Protection
The LPA4732 operates from a single 2.5V to 5.5V
Integrated Click-and-Pop Suppression
supply, consumes only 5mA supply current, and is
Low Quiescent Current (3mA at VDD = 5V)
specified over the extended -40 ℃
Enable Control
Under-Voltage Lockout Function
-40℃ to +85℃ Operating Temperature Range
Available in a Space-Saving 16-Pin TQFN
(3mm✕ 3mm✕ 0.8mm) Package
channel into a 16Ω load or 194mW into a 32Ω load
and have low 0.003% THD+N. An 78dB at 217Hz
power-supply rejection ratio (PSRR) allows these
devices to operate from noisy digital supplies without
an
additional
linear
regulator.
Comprehensive
to +85 ℃
temperature range. The devices are available in tiny
16-pin TQFN (3mm✕ 3mm✕0.8mm) packages.
Order Information
LPA4732 □ □ □
F: Pb-Free
Package Type
QV:TQFN-16
Marking Information
Device
Marking
Package
Shipping
LPA4732
LPS
TQFN-16
3K/REEL
XXX
Applications
LPA4732
MP3 Players
Smart/Cellular Phones
PDAs
Portable Audio
Notebook and Desktop PCs
Flat-Panel Monitors
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Preliminary Datasheet
LPA4732
Functional Pin Description
INL-
1
INL+
2
OUTL
SGND
PVDD
EN
15
14
13
Pin Configurations
16
Package Type
12
HPVDD
11
CAP+
TQFN-16
CAP-
8
9
HPVSS
4
7
INR-
NC
PGND
6
10
NC
3
5
INR+
OUTR
TQFN
Figure 1. The P i n C o n f i g u r a t i o n s
Pin Description
PIN
NAME
1
INL-
Inverting left input for differential signals.
2
INL+
Non-inverting left input for differential signals.
3
INR+
Inverting right input for differential signals.
4
INR-
Non-inverting right input for differential signals.
5
OUTR
6,7
NC
8
HPVSS
9
CAP-
Charge pump negative flying cap.
10
PGND
Power Ground.
11
CAP+
Charge pump positive flying cap.
12
HPVDD
13
EN
14
PVDD
Power VDD.
15
SGND
Amplifier reference voltage.
16
OUTL
Left headphone amplifier output. Connect to left terminal of headphone jack.
-
EP
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DESCRIPTION
Right headphone amplifier output. Connect to right terminal of headphone jack.
No connection.
Charge pump output and negative power supply for output amplifiers; connect 1uF capacitor to GND.
Positive power supply for headphone amplifiers. Charge pump positive half VDD output.
Amplifier enable. Connect to logic low to shutdown; connect to logic high to activate.
Exposed Paddle. Electrically connect to PGND or leave unconnected.
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Preliminary Datasheet
LPA4732
Typical Application Circuit
Figure 2. Typical Differential Input Application Circuit
Figure 3. Typical Single-Ended Input Application Circuit
Absolute Maximum Ratings
These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time
periods may affect device reliability. All voltages are with respect to ground.
Supply Voltage (PVDD) ……………………………………………………………………………………………………………..…… 6.0V
Input Voltage (INR+, INR-, INL+, INL-)........................................................................................ HPVSS-0.3V to HPVDD+0.3V
Control Interface Voltage……………......................................................................................................... -0.3V to PVDD+0.3V
Junction Temperature ................................................................................................................................................... +150℃
Storage Temperature Range ........................................................................................................................... -65℃ to +150℃
Lead Temperature (Soldering, 10s) .............................................................................................................................. +260℃
ESD Susceptibility HBM ................................................................................................................................................ 2000V
HBM (Output pins to Supply and Ground pins) ……………………………………………………………………………………. 2000V
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Preliminary Datasheet
LPA4732
Recommended Operating Conditions
Supply Voltage Range ………………………………………………………………………………………………………….. 2.5V to 5.5V
Operating Temperature Range ........................................................................................................................... -40℃ to +85℃
Electrical Characteristics
TA=25°C, PVDD=3.6V, RL=16Ω (unless otherwise noted)
Parameter
Symbol
Condition
Min
Typ
Max
Units
5.5
V
GENERAL
Supply Voltage Range
PVDD
2.5
Quiescent Supply Current
IQ
EN=PVDD, No load
Shutdown Supply Current
ISD
EN=0V, PVDD=2.5V to 5.5V
EN Input Logic High
VIH
EN Input Logic Low
VIL
EN to Full Operation Time
tSON
3
0.1
mA
1
1
μA
V
0.6
1.6
V
ms
AMPLIFIERS
Output Offset Voltage
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Output Power
Vos
CMRR
PSRR
POUT
Between OUTL(OUTR) and GND, input
0.2
AC-coupled to ground.
Input referred, LPA4732, TA = +25°C
-70
-86
DC, VDD = 2.5V to 5.5V, input referred
-80
-90
f = 217Hz, 100mVP-P ripple, input referred
-80
f = 10kHz, 100mVP-P ripple, input referred
-60
RL = 16Ω, THD+N = 1%, TA = +25°C
115
RL = 32Ω, THD+N = 1%, TA = +25°C
105
Output Impedance in Shutdown
Total Harmonic Distortion Plus
Noise
Signal-to-Noise Ratio
10
THD+N
SNR
RL = 16Ω, POUT = 55mW, f = 1kHz
0.008
RL = 32Ω, POUT = 125mW, f = 1kHz
0.007
RL = 32Ω, POUT = 20mW, f = 22Hz to 22kHz
2
mV
dB
dB
mW
kΩ
%
100
dB
7
µVRMS
200
pF
500
kHz
80
dB
Thermal Shutdown Threshold
145
℃
Thermal Shutdown Hysteresis
5
℃
Noise
Vn
22Hz to 22kHz bandwidth, input AC
Capacitive Drive
CL
No sustained oscillation
Charge-Pump Oscillator
Crosstalk
Note
Note
Note
Note
47
fOSC
RL = 32Ω, VIN = 200mVP-P, f = 10kHz, AV = 1
1: All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design.
2: Gain for the LPA4732 is adjustable.
3: The amplifier inputs are AC-coupled to ground through CIN_.
4: Measurement bandwidth is 22Hz to 22kHz.
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Preliminary Datasheet
LPA4732
Typical Operating Characteristic
Audio Precision
06/30/17 17:42:54
10
5
2
1
0.5
%
0.2
0.1
0.05
0.02
0.01
0.005
0.002
0.001
3m
5m
10m
20m
50m
100m
200m 300m
W
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
4
5
1
1
1
1
1
Cyan
Green
Yellow
Red
Magenta
Solid
Solid
Solid
Solid
Solid
3
3
3
3
3
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Left
Left
Left
Left
Left
3.0V,16ohm
3.3V,16ohm
3.7V,16ohm
4.2V,16ohm
5.0V,16ohm
Figure 4. THD+N VS Output Power，Freq=1kHz，RL=16Ω
Audio Precision
06/30/17 16:45:34
10
5
2
1
0.5
0.2
%
0.1
0.05
0.02
0.01
0.005
0.002
0.001
3m
5m
10m
50m
20m
100m
300m
W
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
4
5
1
1
1
1
1
Cyan
Green
Yellow
Red
Magenta
Solid
Solid
Solid
Solid
Solid
3
3
3
3
3
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Left
Left
Left
Left
Left
3.0V,32ohm
3.3V,32ohm
3.7V,32ohm
4.2V,32ohm
5.0V,32ohm
Figure 5. THD+N VS Output Power，Freq=1kHz，RL=32Ω
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Preliminary Datasheet
Audio Precision
LPA4732
07/14/17 10:49:53
1
0.5
0.2
0.1
0.05
%
0.02
0.01
0.005
0.002
0.001
0.0006
20
50
100
200
500
1k
2k
5k
10k
20k
Hz
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Cyan
Green
Yellow
Solid
Solid
Solid
3
3
3
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Left
Left
Left
PVDD=3V,RL=16ohm,PO=5mW
PVDD=3V,RL=16ohm,PO=20mW
PVDD=3V,RL=16ohm,PO=40mW
Figure 6. THD VS Frequency, PVDD=SVDD=3V，RL=16Ω
Audio Precision
07/14/17 10:43:45
1
0.5
0.2
0.1
0.05
%
0.02
0.01
0.005
0.002
0.001
0.0006
20
50
100
200
500
1k
2k
5k
10k
20k
Hz
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Cyan
Green
Yellow
Solid
Solid
Solid
3
3
3
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Left
Left
Left
PVDD=5V,RL=16ohm,PO=5mW
PVDD=5V,RL=16ohm,PO=20mW
PVDD=5V,RL=16ohm,PO=80mW
Figure 7. THD VS Frequency, PVDD=SVDD=5V，RL=16Ω
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Preliminary Datasheet
Audio Precision
LPA4732
07/14/17 10:18:59
1
0.5
0.2
0.1
0.05
%
0.02
0.01
0.005
0.002
0.001
0.0006
20
50
100
200
500
1k
2k
5k
10k
20k
Hz
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Cyan
Green
Yellow
Solid
Solid
Solid
3
3
3
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Left
Left
Left
3V,32ohm,5mW
3V,32ohm,20mW
3V,32ohm,40mW
Figure 8. THD VS Frequency, PVDD=SVDD=3V，RL=32Ω
Audio Precision
07/14/17 10:09:32
1
0.5
0.2
0.1
0.05
%
0.02
0.01
0.005
0.002
0.001
0.0006
20
50
100
200
500
1k
2k
5k
10k
20k
Hz
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
3
1
1
1
Cyan
Green
Yellow
Solid
Solid
Solid
3
3
3
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Analyzer.THD+N Ratio A
Left
Left
Left
5V,32ohm,5mW
5V,32ohm,20mW
5V,32ohm,80mW
Figure 9. THD VS Frequency, PVDD=SVDD=5V，RL=32Ω
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Preliminary Datasheet
Audio Precision
LPA4732
07/14/17 10:25:25
+12
+11
+10
+9
+8
d
B
V
+7
+6
+5
+4
+3
+2
+1
+0
20
50
100
200
500
1k
2k
5k
10k
20k
Hz
Sweep
Trace
Color
Line Style
Thick
Data
Axis
Comment
1
2
1
1
Cyan
Green
Solid
Solid
3
3
Analyzer.Level A
Analyzer.Level A
Left
Left
PVDD=5V,RL=32ohm,THD=1%
PVDD=5V,RL=32ohm,THD=0.1%
Figure 10. Output Amplitude VS Frequency，PVDD=SVDD=5V，RL=32Ω
Application Information
Maximum Gain
Input Coupling Capacitors
The LPA4732 has two internal amplifier stages. The
Input coupling capacitors block any DC bias from the
first stage's gain is externally configurable, while the
audio source and ensure maximum dynamic range.
second stage's is internally fixed. The closed-loop gain
Input coupling capacitors also minimize LPA4732
of the first stage is set by selecting the ratio of Rf to
turn-on pop to an inaudible level.
Ri while the second stage's gain is fixed at 2x.The
The input capacitors are in series with LPA4732
output of amplifier 1 serves as the input to amplifier 2,
internal input resistors, creating a high-pass filter. The
thus the two amplifiers produce signals identical in
following Equation calculates the high-pass filter
magnitude,
corner frequency.
but
different
in
phase
by
180°.
Consequently, the differential gain for the IC is
AV=20*log [2*Rf/(Ri+10)]
Rf= 10 k Ω±10%
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f=
1
2πR IN CIN
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Preliminary Datasheet
LPA4732
Charge Pump Flying Capacitor, HPVDD Capacitor
deactivate the LPA4732; set to 1.0 V or higher to
and HPVSS Capacitor
activate.
The LPA4732 uses a built-in charge pump to generate
Layout Recommendations
a positive and negative voltage supply for the
headphone amplifiers. The charge pump flying
capacitor connects between CAP+ and CAP-. It
transfers charge to generate the positive and negative
supply voltage. The HPVDD capacitor or HPVSS
capacitor must be at least equal in or larger than value
to the flying capacitor to allow maximum charge
transfer. Use low equivalent-series-resistance (ESR)
ceramic capacitors (X5R material or better is required
for best performance) to maximize charge pump
efficiency. Typical values are 1uF for the HPVDD,
Exposed PAD On LPA4732
Solder the exposed metal pad on the LPA4732 TQFN
package to the landing pad on the PCB. Connect the
landing pad to ground or leave it electrically
unconnected(floating). Do not connect the landing pad
to PVDD or to any other power supply voltage. If the
pad is grounded, it must be connected to the same
ground as the PGND pin 9. Soldering the thermal pad
is required for mechanical reliability and enhances
thermal conductivity of the package.
GND Connections
HPVSS and flying capacitors.
The SGND pin is an input reference and must be
Power Supply Decoupling Capacitors
connected to the headphone ground connector pin.
The LPA4732 TureCapFree headphone amplifier
This ensures no turn-on pop and minimizes output
requires adequate power supply decoupling to ensure
offset voltage. Do not connect more than±0.3 V to
that output noise and total harmonic distortion (THD)
SGND.
remain low. Use good low equivalent-series-resistance
(ESR) ceramic capacitors (X5R material or better is
required for best performance). Place a 2.2uF
PGND is a power ground. Connect supply decoupling
capacitors for PVDD, HPVDD, and HPVSS to PGND.
capacitor within 5 mm of the PVDD pin. Reducing the
distance between the decoupling capacitor and PVDD
minimizes
parasitic
inductance
and
resistance,
improving LPA4732 supply rejection performance. Use
0402 or smaller size capacitors if possible.
Power Supply Sequencing
Use input coupling capacitors to ensure inaudible
turn-on pop. Activate the LPA4732 after all audio
sources have been activated and their output voltages
have settled. On power-down , deactiate the LPA4732
before deactivating the audio input source. The EN pin
controls device shutdown: Set to 0.6 V or lower to
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Preliminary Datasheet
LPA4732
Packaging Information
TQFN-16
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