TS4909
Dual mode low power 150mW stereo headphone amplifier
with capacitor-less and single-ended outputs
Features
■
DFN10 (3x3)
No output coupling capacitors necessary
■
Pop-and-click noise reduction circuitry
■
Operating from V
CC
= 2.2V to 5.5V
■
■
■
■
■
■
■
■
■
Standby mode active low
Output power:
– 158mW @5V, into 16Ω with 1% THD+N
max (1kHz)
– 52mW @3.0V into 16Ω with 1% THD+N
max (1kHz)
Ultra low current consumption: 2.0mA typ.@3V
Ultra low standby consumption: 10nA typ.
High signal-to-noise ratio: 105 dB typ.@5V
High crosstalk immunity: 110dB (F=1kHz) for
single-ended outputs
PSRR: 72dB (F=1kHz), inputs grounded, for
phantom ground outputs
Low t
WU
: 50ms in PHG mode, 100ms in SE mode
Available in lead-free DFN10 3x3mm
Pin connections (top view)
Vin1
Stdby
SE/PHG
Bypass
Vin2
1
2
3
4
5
10
9
8
7
6
Vdd
Vout1
Vout3
Vout2
Gnd
Functional block diagram
Vdd
SE/PHG
Vin1
Vout1
Applications
■
Stdby
Bypass
BIAS
Vout3
Headphone amplifier
■
Mobile phone
■
PDA, portable audio player
Vin2
Vout2
Gnd
Description
The TS4909 is a stereo audio amplifier designed
to drive headphones in portable applications.
The integrated phantom ground is a circuit
topology that eliminates the heavy output coupling
capacitors. This is of primary importance in
portable applications where space constraints are
very high. A single-ended configuration is also
available, offering even lower power consumption
because the phantom ground can be switched off.
Pop-and-click noise during switch-on and switch-
off phases is eliminated by integrated circuitry.
Specially designed for applications requiring low
power supplies, the TS4909 is capable of
delivering 31mW of continuous average power
into a 32Ω load with less than 1% THD+N from a
3V power supply.
Featuring an active low standby mode, the
TS4909 reduces the supply current to only 10nA
(typ.). The TS4909 is unity gain stable and can be
configured by external gain-setting resistors.
September 2007
Rev 8
1/32
www.st.com
32
Contents
TS4909
Contents
1
2
3
4
Typical application schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 4
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1
4.2
4.3
4.4
General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Frequency response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Gain using the typical application schematics . . . . . . . . . . . . . . . . . . . . . 23
Power dissipation and efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.4.1
4.4.2
4.4.3
Single-ended configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Phantom ground configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.5
4.6
4.7
4.8
Decoupling of the circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Wake-up time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Pop performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5
6
7
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2/32
TS4909
Typical application schematics
1
Typical application schematics
Figure 1.
Typical applications for the TS4909
Rfeed1
20k
Vcc
Cs
1µF
SE/PHG
Phantom ground configuration
Vin1
Cin1
330nF
20k
Rin1
Vout1
Standby
Vout3
Cb
1µF
Vin2
330nF
Cin2
20k
Rin2
Gnd
Vout2
BIAS
20k
Rfeed2
Rfeed1
20k
Vcc
Cs
1µF
SE/PHG
Single-ended configuration
Vin1
Cin1
330nF
20k
Rin1
Vout1
Cout1
Standby
Vout3
Cb
1µF
BIAS
Vin2
330nF
Cin2
Cout2
20k
Rin2
Gnd
Vout2
20k
Rfeed2
Table 1.
Component
R
in1,2
C
in1,2
R
feed1,2
C
b
C
s
Application component information
Functional description
Inverting input resistor that sets the closed loop gain in conjunction with R
feed
. This
resistor also forms a high pass filter with C
in
(f
c
= 1 / (2 x Pi x R
in
x C
in
)).
Input coupling capacitor that blocks the DC voltage at the amplifier’s input terminal.
Feedback resistor that sets the closed loop gain in conjunction with R
in
.
A
V
= closed loop gain = -R
feed
/R
in
.
Half supply bypass capacitor.
Supply bypass capacitor that provides power supply filtering.
3/32
Absolute maximum ratings and operating conditions
TS4909
2
Absolute maximum ratings and operating conditions
Table 2.
Symbol
V
CC
V
i
T
stg
T
j
R
thja
P
diss
ESD
ESD
Latch-up
Supply voltage
(1)
Input voltage
Storage temperature
Maximum junction temperature
Thermal resistance junction to ambient DFN10
Power dissipation
(2)
DFN10
Human body model (pin to pin)
Machine model
220pF - 240pF (pin to pin)
Latch-up immunity (all pins)
Lead temperature (soldering, 10 sec)
Output current
1. All voltage values are measured with respect to the ground pin.
2. P
d
is calculated with T
amb
= 25°C, T
junction
= 150°C.
3. Caution: this device is not protected in the event of abnormal operating conditions, such as for example,
short-circuiting between any one output pin and ground, between any one output pin and V
CC
, and
between individual output pins.
Absolute maximum ratings
Parameter
Value
6
-0.3V to V
CC
+0.3V
-65 to +150
150
120
1.79
2
200
200
260
170
(3)
Unit
V
V
°C
°C
°C/W
W
kV
V
mA
°C
mA
Table 3.
Symbol
V
CC
R
L
T
oper
C
L
Operating conditions
Parameter
Supply voltage
Load resistor
Operating free air temperature range
Load capacitor
R
L
= 16 to 100Ω
R
L
> 100Ω
Standby voltage input
TS4909 in STANDBY
TS4909 in active state
Single-ended or phantom ground configuration
voltage Input
TS4909 outputs in single-ended configuration
TS4909 outputs in phantom ground configuration
Thermal resistance junction to ambient DFN10
(2)
Value
2.2 to 5.5
≥
16
-40 to + 85
400
100
GND
≤
V
STBY
≤
0.4
(1)
1.35V
≤
V
STBY
≤
V
CC
Unit
V
Ω
°C
pF
V
STBY
V
V
SE/PHG
V
SE/PHG
=V
CC
V
SE/PHG
=0
41
V
R
thja
°C/W
1. The minimum current consumption (I
STBY
) is guaranteed at ground for the whole temperature range.
2. When mounted on a 4-layer PCB.
4/32
TS4909
Electrical characteristics
3
Table 4.
Symbol
I
CC
I
STBY
Electrical characteristics
Electrical characteristics at V
CC
= +5V with GND = 0V and T
amb
= 25°C
(unless otherwise specified)
Parameter
Supply current
Standby
current
Test conditions
No input signal, no load, single-ended
No input signal, no load, phantom ground
No input signal, R
L
=32Ω
single-ended
single-ended
phantom ground
phantom ground
60
95
60
95
Min.
Typ. Max. Unit
2.1
3.1
10
88
158
85
150
0.3
0.3
0.3
0.3
3.2
4.8
1000
mA
nA
P
out
THD+N = 1% max, F = 1kHz, R
L
= 32Ω,
THD+N = 1% max, F = 1kHz, R
L
= 16Ω,
Output power
THD+N = 1% max, F = 1kHz, R
L
= 32Ω,
THD+N = 1% max, F = 1kHz, R
L
= 16Ω,
Total
harmonic
distortion +
noise
(A
v
=-1)
R
L
= 32Ω,
R
L
= 16Ω,
R
L
= 32Ω,
R
L
= 16Ω,
mW
THD+N
P
out
= 60mW, 20Hz
≤
F
≤
20kHz, single-ended
P
out
= 90mW, 20Hz
≤
F
≤
20kHz, single-ended
P
out
= 60mW, 20Hz
≤
F
≤
20kHz, phantom ground
P
out
= 90mW, 20Hz
≤
F
≤
20kHz, phantom ground
%
PSRR
,
Inputs grounded
(1)
, A
v
= -1, R
L
>=16Ω C
b
=1μF, F = 217Hz,
Power supply V
ripple
= 200mVpp
rejection ratio
Single-ended output referenced to phantom ground
Single-ended output referenced to ground
Max output
current
THD +N
≤
1%, R
L
= 16Ω connected between out and V
CC
/2
66
61
72
67
140
0.14
4.75
0.25
4.55
0.47
0.69
dB
I
out
mA
V
O
V
OL
: R
L
= 32Ω
V
OH
: R
L
= 32Ω
Output swing
V
OL
: R
L
= 16Ω
V
OH
: R
L
= 16Ω
Signal-to-
noise ratio
A-weighted, A
v
=-1, R
L
= 32Ω, THD +N < 0.4%,
20Hz
≤
F
≤
20kHz
Single-ended
Phantom ground
R
L
= 32Ω, A
v
=-1, phantom ground
F = 1kHz
F = 20Hz to 20kHz
R
L
= 32Ω, A
v
=-1, single-ended
F = 1kHz
F = 20Hz to 20kHz
Phantom ground configuration, floating inputs, R
feed
=22KΩ
Phantom ground configuration
Single-ended configuration
4.39
4.17
V
SNR
104
105
-73
-68
-110
-90
5
50
100
20
80
160
dB
Cross-
talk
Channel
separation
dB
V
OO
t
WU
Output offset
voltage
Wake-up time
mV
ms
1. Guaranteed by design and evaluation.
5/32
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