TS4994IQT [STMICROELECTRONICS]
1W Differential Input/Output Audio Power Amplifier with Selectable Standby; 1W差分输入/输出音频功率放大器，可选择待机
| 型号： | TS4994IQT |
| 厂家： | 
ST |
| 描述： | 1W Differential Input/Output Audio Power Amplifier with Selectable Standby |
| 文件： | 总31页 (文件大小：764K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TS4994
1W Differential Input/Output Audio Power Amplifier
with Selectable Standby
■
■
■
■
■
Differential inputs
Near zero pop & click
100dB PSRR @ 217Hz with grounded inputs
Operating from VCC = 2.5V to 5.5V
Pin Connections (top view)
TS4994IQT - DFN10
1W RAIL to RAIL output power @ Vcc=5V,
THD=1%, F=1kHz, with 8Ω load
90dB CMRR @ 217Hz
Ultra-low consumption in standby mode (10nA)
Selectable standby mode (active low or
active high
Ultra fast startup time: 15ms typ.
Available in DFN10 3x3, 0.5mm pitch &
MiniSO8
STBY
VIN -
1
2
3
4
5
10
9
VO+
VDD
N/C
GND
■
■
■
STBY MODE
VIN +
8
7
BYPASS
6
VO-
■
■
■
All lead-free packages
TS4994IST - MiniSO8
Description
STBY
VIN-
VO+
1
2
3
4
8
7
6
5
The TS4994 is an audio power amplifier capable
of delivering 1W of continuous RMS output power
into an 8Ω load @ 5V. Thanks to its differential
inputs, it exhibits outstanding noise immunity.
Vcc
VIN+
GND
BYPASS
VO-
An external standby mode control reduces the
supply current to less than 10nA. A STBY MODE
pin allows the standby pin to be active HIGH or
LOW (except in the MiniSO8 version). An internal
thermal shutdown protection is also provided,
making the device capable of sustaining short-
circuits.
Applications
■
■
■
■
■
■
Mobile phones (cellular / cordless)
Laptop / notebook computers
PDAs
The device is equipped with Common Mode
Feedback circuitry allowing outputs to be always
biased at Vcc/2 regardless of the input common
mode voltage.
Portable audio devices
The TS4994 has been designed for high quality
audio applications such as mobile phones and
requires few external components.
Order Codes
Part Number
TS4994IQT
Temperature Range
Package
Packaging
Marking
-40°C to +85°C
-40°C to +85°C
DFN10
Tape & Reel
Tape & Reel
K994
K994
TS4994IST
MiniSO8
April 2005
Revision 4
1/31
TS4994
Application Component Information
1 Application Component Information
Components
Functional Description
Supply Bypass capacitor which provides power supply filtering.
C
C
S
B
Bypass capacitor which provides half supply filtering.
Feedback resistor which sets the closed loop gain in conjunction with R
IN
R
FEED
A = Closed Loop Gain= R
/R .
V
FEED IN
R
C
Inverting input resistor which sets the closed loop gain in conjunction with R
.
FEED
IN
IN
Optional input capacitor making a high pass filter together with R . (fcl = 1 / (2 x Pi x R x C )
IN
IN
IN
Figure 1. Typical Application DFN10 Version
VCC
+
Cs
1u
Rfeed1
20k
9
GND
VCC
Diff. input -
Cin1
Rin1
2
Vin-
-
Vo+ 10
20k
220nF
Cin2
Rin2
Vo-
GND
Diff. Input +
4
5
Vin+
+
6
20k
+
220nF
8 Ohms
Bypass
Bias
Optional
Cb
1u
Standby
Mode
3
Stdby
1
TS4994IQ
GND
7
GND
Rfeed2
20k
GND
GND VCC GND VCC
Figure 2. Typical Application Mini-SO8 Version
VCC
+
Cs
1u
Rfeed1
20k
GND
7
VCC
Diff. input -
Cin1
Rin1
2
Vin-
-
Vo+ 8
20k
220nF
Cin2
Rin2
Vo-
5
GND
3
4
Vin+
+
20k
+
220nF
8 Ohms
Diff. Input +
Bypass
Bias
Optional
Cb
1u
Standby
GND
6
TS4994IS
Stdby
1
GND
Rfeed2
20k
GND
GNDVCC
2/31
Absolute Maximum Ratings
TS4994
2 Absolute Maximum Ratings
Table 1. Key parameters and their absolute maximum ratings
Symbol
Parameter
Value
Unit
1
VCC
6
V
V
Supply voltage
2
V
G
to VCC
i
Input Voltage
ND
T
Operating Free Air Temperature Range
Storage Temperature
-40 to + 85
-65 to +150
150
°C
°C
°C
oper
T
stg
T
Maximum Junction Temperature
j
3
R
Thermal Resistance Junction to Ambient
thja
120
215
°C/W
DFN10
Mini-SO8
Pd
Power Dissipation
internally limited
W
kV
V
ESD
ESD
Human Body Model
Machine Model
2
200
200
260
Latch-up Immunity
mA
°C
Lead Temperature (soldering, 10sec)
1) All voltages values are measured with respect to the ground pin.
2) The magnitude of input signal must never exceed V + 0.3V / G - 0.3V
CC
ND
3) The device is protected by a thermal shutdown active at 150°C
Table 2. Operating conditions
Symbol
Parameter
Value
Unit
V
Supply Voltage
2.5 to 5.5
V
CC
Standby Mode Voltage Input:
Standby Active LOW
V
V
=GND
V
V
V
SM
SM
Standby Active HIGH
=V
SM
CC
Standby Voltage Input:
Device ON (V =GND) or Device OFF (V =V
)
)
1.5 ≤ V
≤ V
CC
V
SM
SM
CC
CC
STB
STB
1
Device OFF (V =GND) or Device ON (V =V
SM
SM
G
≤ V
≤ 0.4
STB
ND
T
Thermal Shutdown Temperature
Load Resistor
150
°C
SD
R
≥ 8
Ω
L
Thermal Resistance Junction to Ambient
DFN10
Mini-SO8
2
R
80
190
°C/W
THJA
1) The minimum current consumption (I
range.
) is guaranteed when V
=GND or V
(i.e. supply rails) for the whole temperature
CC
STB
STANDBY
2) When mounted on a 4-layer PCB.
3/31
TS4994
Electrical Characteristics
= 25°C (unless otherwise
amb
3 Electrical Characteristics
Table 3. Electrical characteristics - V = +5V, GND = 0V, T
CC
specified)
Symbol
Parameter
Min.
Typ.
Max.
Unit
Supply Current
No input signal, no load
ICC
4
7
mA
Standby Current
No input signal, Vstdby = V = G , RL = 8Ω
ISTANDBY
10
1000
10
nA
SM
ND
No input signal, Vstdby = V = V , RL = 8Ω
SM
CC
Differential Output Offset Voltage
No input signal, RL = 8Ω
Voo
0.1
mV
V
Input Common Mode Voltage
CMRR ≤ -60dB
V
V
- 0.9
0.6
0.8
ICM
CC
Output Power
THD = 1% Max, F= 1kHz, RL = 8Ω
Po
1
W
%
Total Harmonic Distortion + Noise
Po = 850mW rms, Av = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
THD + N
0.5
1
Power Supply Rejection Ratio with Inputs Grounded
PSRR
F = 217Hz, R = 8Ω, Av = 1, C = 4.7µF, C =1µF
100
90
dB
dB
IG
in
b
Vripple = 200mV
PP
Common Mode Rejection Ratio
F = 217Hz, RL = 8Ω, Av = 1, C = 4.7µF, C =1µF
CMRR
in
b
Vic = 200mV
PP
Signal-to-Noise Ratio (A Weighted Filter, A = 2.5)
v
SNR
GBP
100
2
dB
(R = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz)
L
Gain Bandwidth Product
MHz
R = 8Ω
L
Output Voltage Noise, 20Hz ≤ F ≤ 20kHz, R = 8Ω
L
6
5.5
12
10.5
33
28
1.5
1
Unweighted, Av = 1
A weighted, Av = 1
Unweighted, Av = 2.5
A weighted, Av = 2.5
Unweighted, Av = 7.5
A weighted, Av = 7.5
Unweighted, Standby
A weighted, Standby
V
µV
RMS
N
2
Wake-Up Time
T
15
ms
WU
C =1µF
b
1) Dynamic measurements - 20*log(rms(Vout)/rms (Vripple)). Vripple is the super-imposed sinus signal relative to Vcc.
2) Transition time from standby mode to fully operational amplifier.
4/31
Electrical Characteristics
TS4994
Table 4. Electrical Characteristics: V = +3.3V (all electrical values are guaranteed with correlation
CC
measurements at 2.6V and 5V) GND = 0V, T
= 25°C (unless otherwise specified)
amb
Symbol
Parameter
Min.
Typ.
Max.
Unit
ICC
Supply Current No input signal, no load
3
7
mA
Standby Current
No input signal, Vstdby = V = G , RL = 8Ω
ISTANDBY
10
1000
10
nA
SM
ND
No input signal, Vstdby = V = V , RL = 8Ω
SM
CC
Differential Output Offset Voltage
No input signal, RL = 8Ω
Voo
0.1
mV
V
Input Common Mode Voltage
CMRR ≤ -60dB
V
V
- 0.9
0.6
ICM
CC
Output Power
THD = 1% Max, F= 1kHz, RL = 8Ω
Po
300
380
0.5
mW
%
Total Harmonic Distortion + Noise
Po = 300mW rms, Av = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
THD + N
1
Power Supply Rejection Ratio with Inputs Grounded
PSRR
F = 217Hz, R = 8Ω, Av = 1, C = 4.7µF, C =1µF
100
90
dB
dB
IG
in
b
Vripple = 200mV
PP
Common Mode Rejection Ratio
F = 217Hz, RL = 8Ω, Av = 1, C = 4.7µF, C =1µF
CMRR
in
b
Vic = 200mV
PP
Signal-to-Noise Ratio (A Weighted Filter, A = 2.5)
v
SNR
GBP
100
2
dB
(R = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz)
L
Gain Bandwidth Product
MHz
R = 8Ω
L
Output Voltage Noise, 20Hz ≤ F ≤ 20kHz, R = 8Ω
L
6
5.5
12
10.5
33
28
1.5
1
Unweighted, Av = 1
A weighted, Av = 1
Unweighted, Av = 2.5
A weighted, Av = 2.5
Unweighted, Av = 7.5
A weighted, Av = 7.5
Unweighted, Standby
A weighted, Standby
V
µV
RMS
N
2
Wake-Up Time
T
15
ms
WU
C =1µF
b
1) Dynamic measurements - 20*log(rms(Vout)/rms (Vripple)). Vripple is the super-imposed sinus signal relative to Vcc.
2) Transition time from standby mode to fully operational amplifier.
5/31
TS4994
Electrical Characteristics
Table 5. Electrical Characteristics - V = +2.6V, GND = 0V, T
= 25°C (unless otherwise specified)
CC
amb
Symbol
Parameter
Min.
Typ.
Max.
Unit
Supply Current
No input signal, no load
ICC
3
7
mA
Standby Current
No input signal, Vstdby = V = G , RL = 8Ω
ISTANDBY
10
1000
10
nA
SM
ND
No input signal, Vstdby = V = V , RL = 8Ω
SM
CC
Differential Output Offset Voltage
No input signal, RL = 8Ω
Voo
0.1
mV
V
V
-
Input Common Mode Voltage
CMRR ≤ -60dB
CC
V
0.6
ICM
0.9
Output Power
THD = 1% Max, F= 1kHz, RL = 8Ω
Po
200
250
0.5
mW
%
Total Harmonic Distortion + Noise
Po = 225mW rms, Av = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
THD + N
1
Power Supply Rejection Ratio with Inputs Grounded
PSRR
F = 217Hz, R = 8Ω, Av = 1, C = 4.7µF, C =1µF
100
90
dB
dB
IG
in
b
Vripple = 200mV
PP
Common Mode Rejection Ratio
F = 217Hz, RL = 8Ω, Av = 1, C = 4.7µF, C =1µF
CMRR
in
b
Vic = 200mV
PP
Signal-to-Noise Ratio (A Weighted Filter, A = 2.5)
v
SNR
GBP
100
2
dB
(R = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz)
L
Gain Bandwidth Product
MHz
R = 8Ω
L
Output Voltage Noise, 20Hz ≤ F ≤ 20kHz, R = 8Ω
L
6
5.5
12
10.5
33
28
1.5
1
Unweighted, Av = 1
A weighted, Av = 1
Unweighted, Av = 2.5
A weighted, Av = 2.5
Unweighted, Av = 7.5
A weighted, Av = 7.5
Unweighted, Standby
A weighted, Standby
V
µV
RMS
N
2
Wake-Up Time
T
15
ms
WU
C =1µF
b
1) Dynamic measurements - 20*log(rms(Vout)/rms (Vripple)). Vripple is the super-imposed sinus signal relative to Vcc.
2) Transition time from standby mode to fully operational amplifier.
6/31
Electrical Characteristics
TS4994
Figure 3. Current consumption vs. power
supply voltage
Figure 6. Current consumption vs. standby
voltage
4.0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
No load
Tamb=25°C
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Standby mode=0V
Standby mode=2.6V
Vcc = 2.6V
No load
Tamb=25°C
0
1
2
3
4
5
0.0
0.6
1.2
1.8
2.4
Power Supply Voltage (V)
Standby Voltage (V)
Figure 4. Current consumption vs. standby
voltage
Figure 7. Differential DC output voltage vs.
common mode input voltage
4.0
3.5
1000
Av = 1
Tamb = 25°C
100
10
Vcc=3.3V
Vcc=5V
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Standby mode=0V
Standby mode=5V
Vcc=2.5V
1
0.1
0.01
Vcc = 5V
No load
Tamb=25°C
0
1
2
3
4
5
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Standby Voltage (V)
Common Mode Input Voltage (V)
Figure 5. Current consumption vs. standby
voltage
Figure 8. Power dissipation vs. output power
3.5
3.0
0.6
RL=8
Ω
2.5
2.0
1.5
1.0
0.5
0.0
Standby mode=0V
Standby mode=3.3V
0.4
0.2
0.0
RL=16
Ω
Vcc = 3.3V
No load
Tamb=25°C
Vcc=5V
F=1kHz
THD+N<1%
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.6
1.2
1.8
2.4
3.0
Output Power (W)
Standby Voltage (V)
7/31
TS4994
Electrical Characteristics
Figure 9. Power dissipation vs. output power
Figure 12. Output power vs. power supply
voltage
0.3
1.50
Cb = 1µF
F = 1kHz
8Ω
1.25
1.00
0.75
0.50
0.25
0.00
BW < 125kHz
Tamb = 25°C
RL=8Ω
0.2
0.1
0.0
16
Ω
RL=16
Ω
Vcc=3.3V
F=1kHz
THD+N<1%
32Ω
0.0
0.1
0.2
0.3
0.4
2.5
3.0
3.5
4.0
4.5
5.0
Vcc (V)
Output Power (W)
Figure 10. Power dissipation vs. output power
Figure 13. Output power vs. load resistance
0.20
1.0
Vcc=2.6V
F=1kHz
THD+N=1%
Cb = 1 F
THD+N<1%
0.15
0.8
0.6
0.4
0.2
0.0
Vcc=5V
F = 1kHz
BW < 125kHz
Tamb = 25°C
Vcc=4.5V
RL=8Ω
Vcc=4V
0.10
0.05
0.00
RL=16
Ω
Vcc=3.5V
12
Vcc=3V
16
Vcc=2.5V
20
0.0
0.1
0.2
Output Power (W)
0.3
8
24
28
32
Load Resistance
Figure 11. Output power vs. power
supply voltage
Figure 14. Power derating curves
1.0
1.5
Cb = 1µF
F = 1kHz
8Ω
with 4 layers PCB
0.8
0.6
0.4
0.2
0.0
BW < 125kHz
Tamb = 25°C
1.0
0.5
0.0
16
Ω
AMR Value
50
32
Ω
0
25
75
100
125
2.5
3.0
3.5
4.0
4.5
5.0
Ambiant Temperature ( C)
Vcc (V)
8/31
Electrical Characteristics
TS4994
Figure 15. Power derating curves
Figure 18. Open Loop gain vs. frequency
0
0.6
60
40
20
0
Gain
Nominal Value
-40
-80
-120
-160
-200
0.4
Phase
AMR Value
0.2
Vcc = 2.6V
ZL = 8 + 500pF
-20
-40
Ω
Tamb = 25
°C
0.0
0.1
1
10
100
1000
10000
0
25
50
75
100
125
Ambiant Temperature ( C)
Frequency (kHz)
Figure 16. Open loop gain vs. frequency
Figure 19. Close loop gain vs. frequency
0
10
0
Phase
60
Gain
0
Gain
-40
-40
-80
-120
-160
-200
40
-80
-10
20
0
Phase
-120
-160
-200
-20
Vcc = 5V
Av = 1
-30
Vcc = 5V
ZL = 8 + 500pF
-20
Ω
ZL = 8
Ω + 500pF
Tamb = 25
°C
Tamb = 25
°C
-40
0.1
-40
0.1
1
10
100
1000
10000
1
10
100
1000
10000
Frequency (kHz)
Frequency (kHz)
Figure 17. Open loop gain vs. frequency
Figure 20. Close loop gain vs. frequency
0
10
0
Phase
60
Gain
0
Gain
-40
-80
-120
-160
-200
-40
-80
-120
-160
-200
40
-10
20
0
Phase
-20
Vcc = 3.3V
Av = 1
-30
Vcc = 3.3V
ZL = 8 + 500pF
-20
Ω
ZL = 8
Ω + 500pF
Tamb = 25
°C
Tamb = 25
°C
-40
0.1
-40
0.1
1
10
100
1000
10000
1
10
100
1000
10000
Frequency (kHz)
Frequency (kHz)
9/31
TS4994
Electrical Characteristics
Figure 21. Close loop gain vs. frequency
Figure 24. PSRR vs. frequency
10
0
0
-10
-20
-30
-40
Phase
Vcc = 2.6V
Vripple = 200mVpp
Inputs = Grounded
Gain
0
-40
-80
-120
-160
-200
Av = 1, Cin = 4.7
µF
RL
≥ 8Ω
-10
Cb=0.1µF
-50 Tamb = 25
°C
-60
-70
-80
-90
Cb=0.47µF
-20
Cb=1µF
Vcc = 2.6V
-30
-40
Av = 1
ZL = 8
-100
Ω
+ 500pF
Cb=0
-110
-120
Tamb = 25
°C
0.1
1
10
100
1000
10000
20
100
1000
Frequency (Hz)
10000 20k
Frequency (kHz)
Figure 22. PSRR vs. frequency
Figure 25. PSRR vs. frequency
0
0
-10
-20
-30
-40
-10
-20
-30
-40
Vcc = 5V
Vripple = 200mVpp
Inputs = Grounded
Vcc = 5V
Vripple = 200mVpp
Inputs = Grounded
Av = 1, Cin = 4.7
µF
Av = 2.5, Cin = 4.7
µF
RL
≥
8Ω
RL
≥ 8Ω
Cb=0.1µF
Cb=0.1µF
-50 Tamb = 25
°C
-50 Tamb = 25
°C
-60
-70
-80
-90
-60
-70
-80
-90
Cb=0.47
µF
Cb=0.47
µF
Cb=1µF
Cb=1µF
Cb=0
-100
-100
Cb=0
-110
-120
-110
-120
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
Figure 23. PSRR vs. frequency
Figure 26. PSRR vs. frequency
0
0
-10
-20
-30
-40
-10
-20
-30
-40
Vcc = 3.3V
Vripple = 200mVpp
Inputs = Grounded
Vcc = 3.3V
Vripple = 200mVpp
Inputs = Grounded
Av = 1, Cin = 4.7
µF
Av = 2.5, Cin = 4.7
µF
RL
≥
8Ω
RL
≥ 8Ω
Cb=0.1µF
Cb=0.1µF
-50 Tamb = 25
°C
-50 Tamb = 25
°C
-60
-70
-80
-90
-60
-70
-80
-90
Cb=0.47
µF
Cb=0.47
µF
Cb=1µF
Cb=1µF
Cb=0
-100
-100
Cb=0
-110
-120
-110
-120
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
10/31
Electrical Characteristics
TS4994
Figure 27. PSRR vs. frequency
Figure 30. PSRR vs. frequency
0
0
-10
-10
-20
-30
-40
Vcc = 2.6V
Vripple = 200mVpp
Inputs = Floating
Vcc = 2.6V
Vripple = 200mVpp
Inputs = Grounded
-20
-30
Rfeed = 20k
Ω
Av = 2.5, Cin = 4.7
RL
Tamb = 25
µF
-40
RL
≥ 8Ω
≥ 8Ω
Cb=0.1µF
Cb=0.1µF
-50
-50 Tamb = 25
°C
°C
-60
Cb=0.47
µF
-60
-70
-80
-90
Cb=0.47
µF
-70
Cb=1µF
Cb=1µF
-80
-90
Cb=0
-100
-110
-120
-100
Cb=0
-110
-120
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
Figure 28. PSRR vs. frequency
Figure 31. PSRR vs. common mode input
voltage
0
0
Vcc = 5V
Vripple = 200mVpp
Inputs Grounded
F = 217Hz
-10
-20
-30
-40
Vcc = 5V
Vripple = 200mVpp
Inputs = Floating
-20
Rfeed = 20k
Ω
Av = 1
-40
RL
≥ 8Ω
RL
≥ 8Ω
Cb=0.1µF
-50 Tamb = 25
°C
Cb=1
Cb=0.47
Cb=0.1
µF
Tamb = 25
°
C
µ
F
F
-60
-70
-80
-90
Cb=0.47
µF
-60
-80
µ
Cb=0
Cb=1µF
-100
Cb=0
-100
-110
-120
0
1
2
3
4
5
20
100
1000
Frequency (Hz)
10000 20k
Common Mode Input Voltage (V)
Figure 29. PSRR vs. frequency
Figure 32. PSRR vs. common mode input
voltage
0
Vcc = 3.3V
0
-20
-10
-20
-30
-40
Vcc = 3.3V
Vripple = 200mVpp
Inputs = Floating
Vripple = 200mVpp
Inputs Grounded
F = 217Hz
Rfeed = 20k
Ω
Av = 1
RL
≥ 8Ω
RL
≥ 8Ω
-40
Cb=1
Cb=0.47
Cb=0.1
µF
Cb=0.1µF
-50 Tamb = 25
°C
Tamb = 25
°
C
µ
F
F
-60
-70
-80
-90
Cb=0.47
µF
µ
-60
Cb=0
Cb=1µF
-80
-100
Cb=0
-100
-110
-120
0.0
0.6
1.2
1.8
2.4
3.0
20
100
1000
Frequency (Hz)
10000 20k
Common Mode Input Voltage (V)
11/31
TS4994
Electrical Characteristics
Figure 33. PSRR vs. common mode input
voltage
Figure 36. CMRR vs. frequency
0
-10
0
Vcc = 2.5V
Vripple = 200mVpp
Inputs Grounded
F = 217Hz
Vcc = 2.6V
Vic = 200mVpp
Av = 1, Cin = 470
-20
-20
µF
-30
RL
≥ 8Ω
Cb=1µF
Av = 1
-40
≥ 8Ω
-40
Tamb = 25
°C
Cb=0.47µF
RL
-50
Cb=0.1µF
Tamb = 25°C
-60
Cb=0
-60
-80
Cb=1
Cb=0.47
Cb=0.1
µF
-70
Cb=0
µ
F
-80
µF
-90
-100
-110
-120
-100
0.0
0.5
1.0
1.5
2.0
2.5
20
100
1000
Frequency (Hz)
10000 20k
10000 20k
10000 20k
Common Mode Input Voltage (V)
Figure 34. CMRR vs. frequency
Figure 37. CMRR vs. frequency
0
0
-10
Vcc = 5V
Vcc = 5V
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
Vic = 200mVpp
Av = 2.5, Cin = 470
-20 Vic = 200mVpp
µ
F
Av = 1, Cin = 470
RL
Tamb = 25
µF
-30
-40
RL
≥ 8Ω
≥ 8Ω
Cb=1µF
Tamb = 25
°C
°
C
Cb=0.47
µ
F
-50
Cb=1µF
Cb=0.1µF
-60
Cb=0.47
µ
F
Cb=0
-70
Cb=0.1µF
Cb=0
-80
-90
-100
-110
-120
20
20
100
1000
10000 20k
100
1000
Frequency (Hz)
Frequency (Hz)
Figure 35. PSRR vs. frequency
Figure 38. CMRR vs. frequency
0
0
-10
Vcc = 3.3V
Vic = 200mVpp
Av = 2.5, Cin = 470
Vcc = 3.3V
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-20 Vic = 200mVpp
µ
F
Av = 1, Cin = 470
RL
Tamb = 25
µF
-30
-40
RL
≥ 8Ω
≥ 8Ω
Cb=1µF
Tamb = 25
°C
°
C
Cb=0.47
µF
-50
Cb=1µF
Cb=0.1µF
-60
Cb=0.47
µF
Cb=0
-70
Cb=0.1µF
Cb=0
-80
-90
-100
-110
-120
20
20
100
1000
10000 20k
100
1000
Frequency (Hz)
Frequency (Hz)
12/31
Electrical Characteristics
TS4994
Figure 39. CMRR vs. frequency
Figure 42. THD+N vs. output power
10
0
RL = 8
F = 20Hz
Av = 1
Ω
Vcc = 2.6V
Vic = 200mVpp
Av = 2.5, Cin = 470
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
Vcc=2.6V
Vcc=3.3V
Vcc=5V
µ
F
1
0.1
Cb = 1
BW < 125kHz
Tamb = 25
µF
RL
≥ 8Ω
Tamb = 25
°C
°C
Cb=1
Cb=0.47
Cb=0.1
Cb=0
µF
µ
F
µF
0.01
1E-3
1E-3
0.01
0.1
1
20
100
1000
Frequency (Hz)
10000 20k
Output Power (W)
Figure 43. THD+N vs. output power
Figure 40. CMRR vs. common mode input
voltage
10
0
RL = 8
Ω
F = 20Hz
Av = 2.5
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Vcc=5V
1
0.1
-20
-40
Vcc=2.5V
Cb = 1
BW < 125kHz
Tamb = 25
µF
Vic = 200mVpp
F = 217Hz
°C
Av = 1, Cb = 1
RL
Tamb = 25
µF
-60
≥ 8Ω
°
C
0.01
1E-3
-80
-100
Vcc=5V
1E-3
0.01
0.1
1
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Output Power (W)
Common Mode Input Voltage (V)
Figure 44. THD+N vs. output power
Figure 41. CMRR vs. common mode input
voltage
10
RL = 8
F = 20Hz
Av = 7.5
Ω
0
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Vcc=5V
Cb = 1µF
BW < 125kHz
Tamb = 25
-20
-40
Vcc=2.5V
1
0.1
°
C
Vic = 200mVpp
F = 217Hz
Av = 1, Cb = 0
-60
RL
≥ 8Ω
Tamb = 25
°C
-80
0.01
-100
Vcc=5V
1E-3
0.01
0.1
1
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Output Power (W)
Common Mode Input Voltage (V)
13/31
TS4994
Electrical Characteristics
Figure 45. THD+N vs. output power
Figure 48. THD+N vs. output power
10
10
RL = 8
F = 1kHz
Ω
RL = 8
F = 20kHz
Ω
Av = 1
Cb = 1µF
BW < 125kHz
Tamb = 25
Av = 1
Cb = 1
BW < 125kHz
Tamb = 25°C
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
µF
1
0.1
1
°C
Vcc=5V
Vcc=5V
0.1
0.01
1E-3
0.01
0.1
1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
Figure 49. THD+N vs. output power
Figure 46. THD+N vs. output power
10
10
RL = 8
Ω
RL = 8
Ω
F = 20kHz
Av = 2.5
F = 1kHz
Av = 2.5
Cb = 1µF
BW < 125kHz
Tamb = 25
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Cb = 1µF
1
0.1
BW < 125kHz
Tamb = 25°C
1
°C
Vcc=5V
Vcc=5V
0.1
0.01
1E-3
0.01
0.1
1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
Figure 50. THD+N vs. output power
Figure 47. THD+N vs. output power
10
10
RL = 8
F = 20kHz
Av = 7.5
Ω
RL = 8
F = 1kHz
Av = 7.5
Cb = 1µF
BW < 125kHz
Tamb = 25
Ω
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Cb = 1
BW < 125kHz
Tamb = 25
µF
1
0.1
Vcc=5V
°C
°C
1
Vcc=5V
0.01
0.1
1E-3
0.01
0.1
1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
14/31
Electrical Characteristics
TS4994
Figure 51. THD+N vs. output power
Figure 54. THD+N vs. output power
10
10
RL = 16
F = 20Hz
Av = 1
Ω
RL = 16Ω
F = 1kHz
Av = 7.5
Cb = 1µF
BW < 125kHz
Tamb = 25
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
1
0.1
Cb = 1
BW < 125kHz
Tamb = 25
µF
1
0.1
°C
°C
Vcc=5V
Vcc=5V
0.01
0.01
1E-3
1E-3
0.01
0.1
1
1
1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
Figure 52. THD+N vs. output power
Figure 55. THD+N vs. output power
10
10
RL = 16
Ω
RL = 16Ω
F = 20kHz
Av = 1
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
F = 20Hz
Av = 7.5
Cb = 1
BW < 125kHz
Tamb = 25
1
0.1
µ
F
Cb = 1µF
BW < 125kHz
Tamb = 25
1
0.1
°
C
°C
Vcc=5V
Vcc=5V
0.01
1E-3
0.01
1E-3
1E-3
0.01
0.1
0.01
0.1
1
Output Power (W)
Output Power (W)
Figure 53. THD+N vs. output power
Figure 56. THD+N vs. output power
10
10
RL = 16
Ω
RL = 16Ω
F = 20kHz
Av = 7.5
Cb = 1
BW < 125kHz
Tamb = 25
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
F = 1kHz
Av = 1
Cb = 1
BW < 125kHz
Tamb = 25
1
0.1
µ
F
µF
°C
°C
Vcc=5V
Vcc=5V
1
0.01
1E-3
0.1
1E-3
1E-3
0.01
0.1
0.01
0.1
1
Output Power (W)
Output Power (W)
15/31
TS4994
Electrical Characteristics
Figure 57. THD+N vs. output power
Figure 60. THD+N vs. output power
10
10
RL = 16
Ω
RL = 8
Ω
Vcc = 2.6V
Vcc = 5V
Av = 1, Cb = 0
BW < 125kHz
Tamb = 25°C
Av = 1
Cb = 0
BW < 125kHz
Tamb = 25°C
1
F=20kHz
F=1kHz
F=20kHz
F=1kHz
1
0.1
0.1
F=20Hz
F=20Hz
0.01
0.01
1E-3
1E-3
1E-3
0.01
0.1
1
0.01
Output Power (W)
0.1
Output Power (W)
Figure 58. THD+N vs. output power
Figure 61. THD+N vs. frequency
10
10
RL = 8
Av = 1
Cb = 1
Bw < 125kHz
Tamb = 25
Ω
RL = 8
Vcc = 2.6V
Av = 1, Cb = 0
BW < 125kHz
Tamb = 25°C
Ω
µF
1
0.1
1
0.1
F=20kHz
Vcc=2.6V, Po=225mW
°C
F=1kHz
0.01
1E-3
0.01
1E-3
Vcc=5V, Po=850mW
F=20Hz
20
100
1000
Frequency (Hz)
10000 20k
1E-3
0.01
Output Power (W)
0.1
Figure 59. THD+N vs. output power
Figure 62. THD+N vs. frequency
10
10
RL = 8
Av = 1
Cb = 0
Bw < 125kHz
Tamb = 25
Ω
RL = 16
Vcc = 5V
Av = 1, Cb = 0
BW < 125kHz
Tamb = 25°C
Ω
1
0.1
1
0.1
F=20kHz
F=1kHz
Vcc=2.6V, Po=225mW
°C
F=20Hz
0.01
1E-3
0.01
1E-3
Vcc=5V, Po=850mW
20
100
1000
10000 20k
1E-3
0.01
0.1
1
Output Power (W)
Frequency (Hz)
16/31
Electrical Characteristics
TS4994
Figure 63. THD+N vs. frequency
Figure 66. THD+N vs. frequency
10
10
RL = 8
Av = 7.5
Cb = 1
Bw < 125kHz
Ω
RL = 16
Av = 7.5
Cb = 1µF
Bw < 125kHz
Tamb = 25
Ω
Vcc=2.6V, Po=155mW
µF
1
0.1
Vcc=2.6V, Po=225mW
1
0.1
Tamb = 25
°C
°C
0.01
1E-3
Vcc=5V, Po=850mW
Vcc=5V, Po=600mW
0.01
20
100
1000
10000 20k
20
100
1000
10000 20k
Frequency (Hz)
Frequency (Hz)
Figure 64. THD+N vs. frequency
Figure 67. SNR vs. power supply voltage with
unweighted filter
110
10
RL = 8
Av = 7.5
Cb = 0
Bw < 125kHz
Ω
RL=16
Ω
105
100
95
Vcc=2.6V, Po=225mW
1
0.1
Tamb = 25°C
RL=8Ω
90
Av = 2.5
Cb = 1
THD+N < 0.7%
µ
F
85
Vcc=5V, Po=850mW
Tamb = 25
°
C
80
0.01
2.5
3.0
3.5
4.0
4.5
5.0
20
100
1000
10000 20k
Frequency (Hz)
Power Supply Voltage (V)
Figure 65. THD+N vs. frequency
Figure 68. SNR vs. power supply voltage with
a weighted filter
10
RL = 16
Av = 1
Ω
110
RL=16
Ω
Cb = 1µF
1
0.1
105
100
95
Bw < 125kHz
Vcc=2.6V, Po=155mW
Tamb = 25
°C
RL=8Ω
0.01
1E-3
90
Av = 2.5
Cb = 1
THD+N < 0.7%
Vcc=5V, Po=600mW
µ
F
85
Tamb = 25
°
C
20
100
1000
10000 20k
80
Frequency (Hz)
2.5
3.0
3.5
4.0
4.5
5.0
Power Supply Voltage (V)
17/31
TS4994
Electrical Characteristics
Figure 69. Startup time vs. bypass capacitor
20
Tamb=25°C
Vcc=5V
15
10
5
Vcc=3.3V
Vcc=2.6V
0
0.0
0.4
0.8
1.2
1.6
2.0
Bypass Capacitor Cb ( F)
18/31
Application Information
TS4994
4 Application Information
4.1 Differential configuration principle
The TS4994 is a monolithic full-differential input/ output power amplifier. The TS4994 also includes a
common mode feedback loop that controls the output bias value to average it at Vcc/2 for any DC
common mode input voltage. This allows the device to always have a maximum output voltage swing,
and by consequence, maximize the output power. Moreover, as the load is connected differentially
compared to a single-ended topology, the output is four times higher for the same power supply voltage.
The advantages of a full-differential amplifier are:
Very high PSRR (Power Supply Rejection Ratio).
High common mode noise rejection.
Virtually zero pop without additional circuitry, giving an faster start-up time compared to conventional
single-ended input amplifiers.
Easier interfacing with differential output audio DAC.
No input coupling capacitors required thanks to common mode feedback loop.
In theory, the filtering of the internal bias by an external bypass capacitor is not necessary. But, to
reach maximal performances in all tolerance situations, it’s better to keep this option.
The main disadvantage is:
As the differential function is directly linked to external resistors mismatching, in order to reach
maximal performances of the amplifier paying particular attention to this mismatching is mandatory.
4.2 Gain in typical application schematic
Typical differential applications are shown on the figures on page 2.
In the flat region of the frequency-response curve (no C effect), the differential gain is expressed by the
in
relation:
VO+ − VO−
Diff.Input + −Diff.Input−
Rfeed
Rin
Avdiff
=
=
where R = R = R and R
= R
= R
.
feed2
in
in1
in2
feed
feed1
Note: For the rest of this chapter, Av will be called Av to simplify the expression.
diff
4.3 Common mode feedback loop limitations
As explained previously, the common mode feedback loop allows the output DC bias voltage to be
averaged at Vcc/2 for any DC common mode bias input voltage.
However, due to VICM limitation of the input stage (see Electrical Characteristics on page 4), the
common mode feedback loop can ensure its role only within a defined range. This range depends upon
the values of Vcc, R and R
(Av). To have a good estimation of the VICM value, we can apply this
in
feed
formula:
Vcc×Rin + 2× V ×Rfeed
IC
V
=
(V)
ICM
2×(Rin + Rfeed
)
with
Diff.
+Diff.Input−
2
Input+
V
=
(V)
IC
19/31
TS4994
Application Information
and the result of the calculation must be in the range:
0.6V ≤ V
≤ Vcc − 0.9V
IC
M
If the result of VICM calculation is not in the previous range, an input coupling capacitor must be used.
Example: With Vcc=2.5V, R =R =20k and V =2V, we found V =1.63V. This is higher than 2.5V-
in
feed
IC
ICM
0.9V=1.6V, so input coupling capacitors are required or you will have to change the V value.
IC
4.4 Low and high frequency response
In the low frequency region, C starts to have an effect. C forms, with R , a high-pass filter with a -3dB
in
in
in
cut-off frequency. F is in Hz.
CL
1
FCL
=
(Hz)
2× π×Rin ×Cin
In the high-frequency region, you can limit the bandwidth by adding a capacitor (C
) in parallel with
feed
R
. It forms a low-pass filter with a -3dB cut-off frequency. F is in Hz.
feed
CH
1
FCH
=
(Hz)
2× π×Rfeed ×Cfeed
While these bandwidth limitations are in theory attractive, in practice, because of low performance in
terms of capacitor precision (and by consequence in terms of mismatching), they deteriorate the values of
PSRR and CMRR.
We will discuss the influence of mismatching on PSRR and CMRR performance in more detail in the
following paragraphs.
Example: A typical application with input coupling and feedback capacitor with F =50Hz and
CL
F
=8kHz. We assume that the mismatching between R
and C
can be neglected. If we sweep
CH
in1,2
feed1,2
the frequency from DC to 20kHz we observe the following with respect to the PSRR value:
From DC to 200Hz, the C impedance decreases from infinite to a finite value and the C
in
feed
impedance is high enough to be neglected. Due to the tolerance of C
, we must introduce a
in1,2
mismatch factor (R x C ≠ R x C ) that will decrease the PSRR performance.
in1
in
in2
in2
From 200Hz to 5kHz, the C impedance is low enough to be neglected when compare to R and
in
in,
the C
impedance is high enough to be neglected as well. In this range, we can reach the PSRR
feed
performance of the TS4994 itself.
From 5kHz to 20kHz, the C impedance is low to be neglected when compared to R and the C
in
in,
feed
impedance decreases to a finite value. Due to tolerance of C
, we introduce a mismatching
feed1,2
factor (R
x C
≠ R
x C
) that will decrease the PSRR performance.
feed2
feed1
feed1
feed2
20/31
Application Information
TS4994
4.5 Calculating the influence of mismatching
On PSRR performance:
For this calculation, we consider that C and C
have no influence.
feed
in
We use the same kind of resistor (same tolerance) and ∆R is the tolerance value in %.
The following equation is valid for frequencies ranging from DC to about 1kHz. Above this frequency,
parasitic effects start to be significant and a literal equation is not possible to write.
The PSRR equation is (∆R in %):
⎡
⎢
⎣
⎤
⎥
⎦
∆R×100
(10000 − ∆R2)
PSRR ≤ 20×Log
(dB)
This equation doesn’t include the additional performance provided by bypass capacitor filtering. If a
bypass capacitor is added, it acts, together with the internal high output impedance bias, as a low-pass
filter, and the result is a quite important PSRR improvement with a relatively small bypass capacitor.
The complete PSRR equation (∆R in %, C in microFarad and F in Hz) is:
b
∆R × 100
----------------------------------------------------------------------------------------------------
PSRR ≤ 20 × log
(dB)
2
2
2
(10000 – ∆R ) × 1 + F × C × 22.2
b
Example: With ∆R=0.1% and C =0, the minimum PSRR would be -60dB. With a 100nF bypass
b
capacitor, at 100Hz the new PSRR would be -93dB.
This example is a worst case scenario, where each resistor has extreme tolerance and illustrates the fact
that with only a small bypass capacitor, the TS4994 produce high PSRR performance.
In addition, it’s important to note that this is a theoretical formula. As the TS4994 has self-generated
noise, you should consider that the highest practical PSRR reachable is about -110dB. It is therefore
unreasonable to target a -120dB PSRR.
The three following graphs show PSRR versus frequency and versus bypass capacitor C in worst-case
b
condition (∆R=0.1%).
Figure 70. PSRR vs. frequency worst case
condition
Figure 71. PSRR vs. frequency worst case
condition
0
-10
-20
-30
-40
-50
-60
-70
-80
0
-10
-20
-30
-40
-50
-60
-70
-80
Vcc = 5V, Vripple = 200mVpp
Av = 1, Cin = 4.7µF
Vcc = 3.3V, Vripple = 200mVpp
Av = 1, Cin = 4.7
µF
∆R/R = 0.1%, RL ≥ 8Ω
∆R/R = 0.1%, RL ≥ 8Ω
Tamb = 25°C, Inputs = Grounded
Cb=0
Tamb = 25°C, Inputs = Grounded
Cb=0
Cb=0.1µF
Cb=0.1µF
-90
-90
-100
-110
-120
-130
-140
-100
-110
-120
-130
-140
Cb=1µF
Cb=0.47µF
Cb=1µF
Cb=0.47µF
20
100
1000
10000 20k
20
100
1000
10000 20k
Frequency (Hz)
Frequency (Hz)
21/31
TS4994
Application Information
Figure 72. PSRR vs. frequency worst case condition
0
-10
-20
Vcc = 2.5V, Vripple = 200mVpp
Av = 1, Cin = 4.7
µF
-30
∆R/R = 0.1%, RL ≥ 8Ω
Tamb = 25°C, Inputs = Grounded
-40
Cb=0
-50
-60
-70
-80
Cb=0.1µF
-90
-100
-110
-120
-130
-140
Cb=1
µF
Cb=0.47µF
20
100
1000
10000 20k
Frequency (Hz)
The two following graphs show typical application of TS4994 with four 0.1% tolerances and a random
choice for them.
Figure 73. PSRR vs. frequency with random
choice condition
Figure 74. PSRR vs. frequency with random
choice condition
0
0
-10
-20
-30
-10
-20
-30
Vcc = 5V, Vripple = 200mVpp
Av = 1, Cin = 4.7
R/R 0.1%, RL
Tamb = 25 C, Inputs = Grounded
Vcc = 2.5V, Vripple = 200mVpp
Av = 1, Cin = 4.7
R/R 0.1%, RL
Tamb = 25 C, Inputs = Grounded
µ
≥
F
8
µF
≥ 8Ω
∆
≤
Ω
∆
≤
°
°
-40
-40
-50
-50
-60
-70
-60
-70
Cb=0
Cb=0
Cb=0.1µF
Cb=0.1µF
-80
-80
-90
-90
-100
-110
-120
-130
-140
-100
-110
-120
-130
-140
Cb=1
µF
Cb=0.47
µ
F
Cb=1
µF
Cb=0.47µF
20
20
100
1000
10000 20k
100
1000
10000 20k
Frequency (Hz)
Frequency (Hz)
CMRR performance
For this calculation, we consider there to be no influence of C and C
. C has no influence in the
b
in
feed
calculation of the CMRR.
We use the same kind of resistor (same tolerance) and ∆R is the tolerance value in %.
The following equation is valid for frequencies ranging from DC to about 1kHz. Above this frequency,
parasitic effects start to be significant and a literal equation is not possible to write.
The CMRR equation is (∆R in %):
⎡
⎢
⎣
⎤
⎥
⎦
∆R× 200
(10000 − ∆R2)
CMRR ≤ 20×Log
(dB)
Example: With ∆R=1%, the minimum CMRR would be -34dB.
With a DC Vic=2.5V, the DC differential output (Voo) which results is 50mV maximum. As this Voo is
across the load, for an 8Ω load the extra consumption would be 50mV/8=6.2mA.
22/31
Application Information
TS4994
With ∆R=1%, the minimum CMRR would be -53dB that give Voo=5.6mV and an maximum extra
consumption less than 700µA.
This example is of a worst case scenario where each resistor has extreme tolerance and illustrates the
fact that for CMRR, good matching is essential.
As with the PSRR, due to self-generated noise, the TS4994 CMRR limitation would be about -110dB.
Figures 75 and 76 show CMRR versus frequency and versus bypass capacitor C in worst-case condition
b
( R=0.1%).
∆
Figure 75. CMRR vs. frequency worst case
condition
Figure 76. CMRR vs. frequency worst case
condition
0
0
Vcc = 2.5V
Vic = 200mVpp
Av = 1, Cin = 470µF
Vcc = 5V
-10 Vic = 200mVpp
-10
-20
-30
-40
-50
-60
Av = 1, Cin = 470
R/R = 0.1%, RL
Tamb = 25
µF
≥ 8Ω
∆R/R = 0.1%, RL
≥ 8Ω
∆
-20
-30
-40
-50
-60
Tamb = 25
°C
°
C
Cb=1
Cb=0
µF
Cb=1
Cb=0
µF
20
100
1000
Frequency (Hz)
10000 20k
20
100
1000
Frequency (Hz)
10000 20k
Figures 77 and 78 show CMRR versus frequency for a typical application with four 0.1% tolerances and
a random choice for them.
Figure 77. CMRR vs. frequency with random
choice condition
Figure 78. CMRR vs. frequency with random
choice condition
0
0
Vcc = 2.5V
-10
Vcc = 5V
-10
Vic = 200mVpp
Vic = 200mVpp
-20 Av = 1, Cin = 470
R/R 0.1%, RL
Tamb = 25
µF
≥ 8Ω
-20 Av = 1, Cin = 470
R/R 0.1%, RL
Tamb = 25
µF
≥ 8Ω
∆
≤
∆
≤
-30
-40
-50
-60
-70
-80
-90
-30
-40
-50
-60
-70
-80
-90
°C
°C
Cb=1
Cb=0
µF
Cb=1
Cb=0
µF
20
100
1000
Frequency (Hz)
10000 20k
20
100
1000
Frequency (Hz)
10000 20k
23/31
TS4994
Application Information
4.6 Power dissipation and efficiency
Assumptions:
Load voltage and current are sinusoidal (V and I
)
out
out
Supply voltage is a pure DC source (V )
cc
Regarding the load we have:
V
= VPEAK sinωt (V)
out
and
V
out
I
= ------------- (A)
out
RL
and
2
VPEAK
2RL
P
= ---------------------- ( W )
out
Therefore, the average current delivered by the supply voltage is:
VPEAK
πRL
ICC
= 2------------------- (A)
AVG
The power delivered by the supply voltage is:
P
= Vcc Icc
(W)
AVG
supply
Then, the power dissipated by each amplifier is
= P - P (W)
P
diss
supply
out
2 2V
CC
-----------------------
P
=
P
–P
out out
diss
π R
L
and the maximum value is obtained when:
∂Pdiss
--------------------- = 0
∂P
out
and its value is:
2Vcc2
π2RL
Pdissmax =
(W)
Note: This maximum value is only dependent on power supply voltage and load values.
The efficiency is the ratio between the output power and the power supply
P
πVPEAK
out
η = -------------------- =-----------------------
P
4VCC
supply
The maximum theoretical value is reached when Vpeak = Vcc, so
π
---- = 78.5%
4
24/31
Application Information
TS4994
The maximum die temperature allowable for the TS4994 is 125°C. However, in case of overheating, a
thermal shutdown set to 150°C, puts the TS4994 in standby until the temperature of the die is reduced by
about 5°C.
To calculate the maximum ambient temperature T
Power supply Voltage value, Vcc
Load resistor value, RL
allowable, we need to know:
AMB
The package type, RTH
JA
2
Example: Vcc=5V, RL=8Ω, RTH Flip-Chip=100°C/W (100mm copper heatsink).
JA
We calculate P
With
= 633mW.
dissmax
TAMB = 125°C −RTHJA ×P
(°C)
diss
T
= 125-100x0.633=61.7°C
AMB
4.7 Decoupling of the circuit
Two capacitors are needed to correctly bypass the TS4994. A power supply bypass capacitor C and a
S
bias voltage bypass capacitor C .
B
C has particular influence on the THD+N in the high frequency region (above 7kHz) and an indirect
S
influence on power supply disturbances. With a value for C of 1µF, you can expect similar THD+N
S
performances to those shown in the datasheet.
In the high frequency region, if C is lower than 1µF, it increases THD+N and disturbances on the power
S
supply rail are less filtered.
On the other hand, if C is higher than 1µF, those disturbances on the power supply rail are more filtered.
S
C has an influence on THD+N at lower frequencies, but its function is critical to the final result of PSRR
b
(with input grounded and in the lower frequency region).
4.8 Wake-up Time: T
WU
When the standby is released to put the device ON, the bypass capacitor C will not be charged
b
immediately. As C is directly linked to the bias of the amplifier, the bias will not work properly until the C
b
b
voltage is correct. The time to reach this voltage is called the wake-up time or T
and is specified in the
WU
tables found in Electrical Characteristics on page 4, with C =1µF. During the wake-up time phase, the
b
TS4994 gain is close to zero. After the wake-up time period, the gain is released and set to its nominal
value.
If C has a value other than 1µF, please refer to the graph in Figure 69 on page 18 to establish the wake-
b
up time value.
4.9 Shutdown time
When the standby command is set, the time required to put the two output stages in high impedance and
the internal circuitry in shutdown mode is a few microseconds.
Note: In shutdown mode, Bypass pin and Vin+, Vin- pins are short-circuited to ground by internal switches. This allows
a quick discharge of C and C capacitors.
b
in
25/31
TS4994
Application Information
4.10 Pop performance
In theory, due to a fully differential structure, the pop performance of the TS4994 should be perfect.
However, due to R , R , and C mismatching, some noise could remain at startup. In TS4994 we
in
feed
in
included a pop reduction circuitry reach the pop that is theoretical with mismatched components. With this
circuitry, the TS4994 is close to zero pop for all common applications possible.
In addition, when the TS4994 is set in standby, due to the high impedance output stage configuration in
this mode, no pop is possible.
4.11 Single ended input configuration
It’s possible to use the TS4994 in a single-ended input configuration. However, input coupling capacitors
areneeded in this configuration. The schematic in Figure 79 shows this configuration using the miniSO8
version of the TS4994 as example.
Figure 79. Single ended input typical application
VCC
+
Cs
1u
Rfeed1
20k
GND
7
VCC
Ve
Cin1
Rin1
2
Vin-
-
Vo+
Vo-
8
5
20k
220nF
Cin2
Rin2
3
4
Vin+
+
20k
+
GND
220nF
8 Ohms
Bypass
Bias
Optional
Cb
1u
Standby
GND
6
TS4994IS
Stdby
1
GND
Rfeed2
20k
GND
GND VCC
The components calculations remain the same except for the gain. The new formula is:
VO+ − VO− Rfeed
AvSE
=
=
Ve
Rin
26/31
Application Information
4.12 Demoboard
TS4994
A demoboard for the TS4994 is available, however it is designed only for the TS4994 in the DFN10
package. However, we can guarantee that all electrical parameters are similar except for the power
dissipation.
For more information about this demoboard, please refer to Application Note AN2013.
Figure 80. Demoboard schematic
Cn8
Vcc
+
C4
1uF/6V
C5
100nF/10V
GND
R2
GND
GND
22k/1%
R4
22k/1%
Cn3
9
J1
VCC
Cn1
C1
R1
Cn5
2
Vin-
-
Vo+ 10
Vo-
Pos. Input
Neg. Input
22k/1%
100nF/10V
100nF/10V R3
22k/1%
GND
GND
4
5
Vin+
+
6
C2
Bypass
Bias
+
Cn2
J2
C3
1uF/6V
Standby
GND
7
Cn4
Mode
3
Stdby
1
TS4994DFN10
GND
Cn6
Cn7
Vcc
Vcc
1
1
GND
J4
2
3
2
3
J3
GND
GND
Figure 81. Components location
Figure 82. Top layer
27/31
TS4994
Application Information
Figure 83. Bottom layer
28/31
Package Mechanical Data
TS4994
5 Package Mechanical Data
5.1 MiniSO8 package
29/31
TS4994
Package Mechanical Data
5.2 DFN10 package
Dimensions in millimeters unless otherwise indicated.
3.0
10
3.0
0.35
0.8
1
0.25
0.5
* The Exposed Pad is connected to the Ground
30/31
Revision History
TS4994
6 Revision History
Date
Revision
Description of Changes
01 Sept. 2003
01 Oct. 2004
01 Jan. 2005
17 Mar. 2005
1
First Release
Curves updated in the document
2
3
Update Mechanical Data on Flip-Chip Package
Remove datas on Flip-Chip Package
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics
All other names are the property of their respective owners
© 2005 STMicroelectronics - All rights reserved
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31/31
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