TS4998
2 x 1W differential input stereo audio amplifier
Features
■
■
■
■
■
■
■
■
■
QFN16 4x4mm
Operating range from V
CC
= 2.7V to 5.5V
1W output power per channel @ V
CC
=5V,
THD+N=1%, R
L
=8Ω
Ultra low standby consumption: 10nA typ.
80dB PSRR @ 217Hz with grounded inputs
High SNR: 106dB(A) typ.
Fast startup time: 45ms typ.
Pop&click-free circuit
Dedicated standby pin per channel
Lead-free QFN16 4x4mm package
Pin connections (top view)
Applications
■
■
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Cellular mobile phones
Notebook and PDA computers
LCD monitors and TVs
Portable audio devices
Description
bs
O
The TS4998 is designed for top-class stereo
audio applications. Thanks to its compact and
power-dissipation efficient QFN16 package with
exposed pad, it suits a variety of applications.
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With a BTL configuration, this audio power
amplifier is capable of delivering 1W per channel
of continuous RMS output power into an 8Ω load
@ 5V.
Each output channel (left and right), also has its
own external controlled standby mode pin to
reduce the supply current to less than 10nA per
channel. The device also features an internal
thermal shutdown protection.
The gain of each channel can be configured by
external gain setting resistors.
December 2007
Rev 1
1/33
www.st.com
33
Contents
TS4998
Contents
1
2
3
4
Typical application schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Differential configuration principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Gain in typical application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Common mode feedback loop limitations . . . . . . . . . . . . . . . . . . . . . . . . . 21
Low frequency response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Power dissipation and efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Footprint recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Decoupling of the circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Standby control and wake-up time t
WU
Shutdown time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Pop performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Single-ended input configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5
6
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QFN16 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
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Notes on PSRR measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7
2/33
TS4998
Typical application schematics
1
Typical application schematics
Figure 1
shows a typical application for the TS4998 with a gain of +6dB set by the input
resistors.
Figure 1.
Typical application schematics
VCC
Cs
1uF
13
Optional
Diff. input L-
P1
330nF
25k
1
Cin2
P2
2
Diff. input L+
330nF
25k
Rin2
Cin1
Rin1
U1
TS4998
Vcc
LIN-
-
LEFT
LOUT-
LIN+
Diff. input R-
P3
Cin3
Rin3
4
RIN-
330nF
25k
3
RIN+
RIGHT
Cin4
P4
Diff. input R+
330nF
Rin4
25k
bs
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Table 1.
External component descriptions
Functional description
Input resistors that set the closed loop gain in conjunction with a fixed internal
feedback resistor (Gain = R
feed
/R
IN
, where R
feed
= 50kΩ).
Input coupling capacitors that block the DC voltage at the amplifier input
terminal. Thanks to common mode feedback, these input capacitors are
optional. However, if they are added, they form with R
IN
a 1st order high pass
filter with -3dB cut-off frequency (f
cut-off
= 1 / (2 x
π
x R
IN
x C
IN
)).
Supply bypass capacitors that provides power supply filtering.
Bypass pin capacitor that provides half supply filtering.
Components
R
IN
C
IN
C
S
C
B
STBYR Control
STBYL Control
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GND
GND
STBYR
STBYL
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6
8
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+
-
+
STBY
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11
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Left Speaker
LOUT+
8 Ohms
ROUT-
Right Speaker
ROUT+
8 Ohms
Bypass
BIAS
7
TS4998 - QFN16
3/33
Absolute maximum ratings
TS4998
2
Absolute maximum ratings
Table 2.
Symbol
V
CC
V
in
T
oper
T
stg
T
j
R
thja
P
d
ESD
ESD
Supply voltage
(1)
Input voltage
(2)
Operating free air temperature range
Storage temperature
Maximum junction temperature
Thermal resistance junction to ambient
Power dissipation
Human body model
(3)
Digital pins STBYL, STBYR
Machine model
Latch-up immunity
Absolute maximum ratings
Parameter
Value
6
GND to V
CC
-40 to + 85
-65 to +150
150
120
Internally limited
Unit
V
V
°C
°C
1. All voltage values are measured with respect to the ground pin.
2. The magnitude of the input signal must never exceed V
CC
+ 0.3V / GND - 0.3V.
3. All voltage values are measured from each pin with respect to supplies.
Table 3.
Symbol
V
CC
V
ICM
V
STBY
Operating conditions
Supply voltage
Common mode input voltage range
Standby voltage input:
Device ON
Device OFF
Load resistor
b
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R
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TSD
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Parameter
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t(
°C/W
kV
V
mA
°C
200
200
Value
2.7 to 5.5
GND to V
CC
- 1V
1.3
≤
V
STBY
≤
V
CC
GND
≤
V
STBY
≤0.4
≥
4
≥
1
150
45
85
Unit
V
V
V
Ω
MΩ
°C
°C/W
R
OUT
/GND Output resistor to GND (V
STBY
= GND)
Thermal shutdown temperature
Thermal resistance junction to ambient
QFN16
(1)
QFN16
(2)
When mounted on a 4-layer PCB with vias.
When mounted on a 2-layer PCB with vias.
4/33
TS4998
Electrical characteristics
3
Table 4.
Symbol
I
CC
I
STBY
V
oo
P
o
THD + N
Electrical characteristics
V
CC
= +5V, GND = 0V, T
amb
= 25°C (unless otherwise specified)
Parameter
Supply current
No input signal, no load, left and right channel active
Standby current
(1)
No input signal, V
STBYL
= GND, V
STBYR
= GND, R
L
= 8Ω
Output offset voltage
No input signal, R
L
= 8Ω
Output power
THD = 1% max, F = 1kHz, R
L
= 8Ω
Total harmonic distortion + noise
P
o
= 700mW
rms
, G = 6dB, R
L
= 8Ω, 20Hz
≤
F
≤
20kHz
Power supply rejection ratio
(2)
, inputs grounded
R
L
= 8Ω, G = 6dB, C
b
= 1µF, V
ripple
= 200mV
pp
F = 217Hz
F = 1kHz
Common mode rejection ratio
(3)
R
L
= 8Ω, G = 6dB, C
b
= 1µF, V
incm
= 200mV
pp
F = 217Hz
F = 1kHz
SNR
800
Min.
Typ.
7.4
10
1
1000
0.5
Max.
9.6
2000
35
Unit
mA
nA
mV
PSRR
CMRR
Signal-to-noise ratio
A-weighted, G = 6dB, C
b
= 1µF, R
L
= 8Ω
(THD + N
≤
0.5%, 20Hz < F < 20kHz)
,
Channel separation, R
L
= 8Ω G = 6dB
F = 1kHz
F = 20Hz to 20kHz
Crosstalk
V
N
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Output voltage noise, F = 20Hz to 20kHz, R
L
= 8Ω, G=6dB
C
b
= 1µF
Unweighted
A-weighted
40
k
Ω
---------------
-
R
IN
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75
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mW
%
dB
dB
108
dB
105
80
dB
15
10
50
k
Ω
---------------
-
R
IN
µVrms
Gain
t
WU
Gain value (R
IN
in kΩ)
Wake-up time (C
b
= 1µF)
Standby time (C
b
= 1µF)
Phase margin at unity gain
,
R
L
= 8Ω C
L
= 500pF
,
Gain margin, R
L
= 8Ω C
L
= 500pF
Gain bandwidth product, R
L
= 8Ω
60
k
Ω
---------------
-
R
IN
V/V
ms
µs
Degrees
dB
MHz
46
10
65
15
1.5
t
STBY
GM
GBP
1. Standby mode is active when V
STBY
is tied to GND.
2. Dynamic measurements - 20*log(rms(V
out
)/rms(V
ripple
)). V
ripple
is the sinusoidal signal superimposed upon V
CC
.
3. Dynamic measurements - 20*log(rms(V
out
)/rms(V
incm
)).
5/33
Microchip MCU
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