TS4994IJT [STMICROELECTRONICS]
暂无描述;TS4994
1W differential input/output audio power amplifier
with selectable standby
Features
Pin connections (top view)
■ Differential inputs
■ Near-zero pop & click
TS4994IQT - DFN10
■ 100dB PSRR @ 217Hz with grounded inputs
■ Operating range from VCC = 2.5V to 5.5V
STBY
VIN -
1
2
3
4
5
10
9
VO+
■ 1W rail-to-rail output power @ VCC = 5V,
THD = 1%, F = 1kHz, with 8Ωload
VDD
N/C
GND
STBY MODE
VIN +
8
■ 90dB CMRR @ 217Hz
7
■ Ultra-low consumption in standby mode (10nA)
BYPASS
6
VO-
■ Selectable standby mode (active low or active
high)
TS4994IST - MiniSO-8
■ Ultra fast startup time: 15ms typ.
■ Available in DFN10 3x3 (0.5mm pitch) &
STBY
VIN-
VO+
1
2
3
4
8
7
6
5
MiniSO-8
Vcc
■ All lead-free packages
VIN+
GND
BYPASS
VO-
Description
biased at V /2 regardless of the input common
mode voltage.
CC
The TS4994 is an audio power amplifier capable
of delivering 1W of continuous RMS output power
into an 8Ωload @ 5V. Due to its differential inputs,
it exhibits outstanding noise immunity.
The TS4994 is designed for high quality audio
applications such as mobile phones and requires
few external components.
An external standby mode control reduces the
supply current to less than 10nA. An STBY
MODE pin allows the standby to be active HIGH
or LOW (except in the MiniSO-8 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
■ Portable audio devices
Order codes
Part number
TS4994IQT
Temperature range
Package
Packing
Marking
DFN10
K994
K994
-40°C to +85°C
Tape & reel
TS4994IST
MiniSO-8
December 2006
Rev 6
1/35
www.st.com
35
Contents
TS4994
Contents
1
2
3
4
Application component information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
Differential configuration principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Gain in typical application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Common mode feedback loop limitations . . . . . . . . . . . . . . . . . . . . . . . . . 21
Low and high frequency response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Calculating the influence of mismatching on PSRR performance . . . . . . 23
CMRR performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power dissipation and efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Decoupling of the circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Wake-up time: tWU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.10 Shutdown time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.11 Pop performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.12 Single-ended input configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.13 Demoboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5
6
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.1
5.2
DFN10 package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
MiniSO-8 package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2/35
TS4994
Application component information
1
Application component information
Components
Functional description
Cs
Cb
Supply bypass capacitor that provides power supply filtering.
Bypass capacitor that provides half supply filtering.
Feedback resistor that sets the closed loop gain in conjunction with Rin
AV = closed loop gain = Rfeed/Rin.
Rfeed
Rin
Inverting input resistor that sets the closed loop gain in conjunction with Rfeed
.
Optional input capacitor making a high pass filter together with Rin.
(FCL = 1/(2πRinCin).
Cin
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-
6
GND
Diff. Input +
4
5
Vin+
+
20k
+
220nF
8 Ohms
Bypass
Bias
Optional
Cb
1u
Standby
GND
7
Mode
3
Stdby
1
TS4994IQ
GND
Rfeed2
20k
GND
GND VCC GND VCC
3/35
Application component information
TS4994
Figure 2.
Typical application, MiniSO-8 version
VCC
+
Cs
1u
Rfeed1
20k
7
GND
VCC
Diff. input -
Cin1
Rin1
2
Vin-
-
Vo+ 8
20k
220nF
Cin2
Rin2
Vo-
5
GND
Diff. Input +
3
4
Vin+
+
20k
+
220nF
8 Ohms
Bypass
Bias
Optional
Cb
1u
Standby
GND
6
TS4994IS
Stdby
1
GND
Rfeed2
20k
GND
GND VCC
4/35
TS4994
Absolute maximum ratings and operating conditions
2
Absolute maximum ratings and operating conditions
Table 1.
Symbol
Absolute maximum ratings
Parameter
Value
Unit
VCC
Vi
Supply voltage (1)
Input voltage (2)
6
V
V
GND to VCC
-40 to + 85
-65 to +150
150
Toper
Tstg
Tj
Operating free air temperature range
Storage temperature
°C
°C
°C
Maximum junction temperature
Thermal resistance junction to ambient (3)
Rthja
°C/W
DFN10
MiniSO-8
120
215
Pdiss
ESD
Power dissipation
internally limited
W
kV
V
Human body model
Machine model
2
200
200
260
Latch-up immunity
mA
°C
Lead temperature (soldering, 10sec)
1. All voltage values are measured with respect to the ground pin.
2. The magnitude of the input signal must never exceed VCC + 0.3V / GND - 0.3V.
3. The device is protected by a thermal shutdown active at 150°C.
Table 2.
Symbol
Operating conditions
Parameter
Value
Unit
VCC
Supply voltage
2.5 to 5.5
V
Standby mode voltage input:
VSM
V
V
Standby active LOW
Standby active HIGH
VSM=GND
VSM=VCC
Standby voltage input:
VSTBY
Device ON (VSM = GND) or device OFF (VSM = VCC
Device OFF (VSM = GND) or device ON (VSM = VCC
)
)
1.5 ≤ VSTBY ≤ VCC
GND ≤ VSTBY≤ 0.4 (1)
TSD
RL
Thermal shutdown temperature
Load resistor
150
°C
≥ 8
Ω
Thermal resistance junction to ambient
DFN10 (2)
MiniSO-8
80
190
Rthja
°C/W
1. The minimum current consumption (ISTBY) is guaranteed when VSTBY = GND or VCC (i.e. supply rails) for the whole
temperature range.
2. When mounted on a 4-layer PCB.
5/35
Electrical characteristics
TS4994
3
Electrical characteristics
Table 3.
Electrical characteristics for V = +5V, GND = 0V, T
= 25°C (unless otherwise
CC
amb
specified)
Symbol
Parameter
Min.
Typ.
Max.
Unit
Supply current
No input signal, no load
ICC
4
7
mA
Standby current
ISTBY
No input signal, VSTBY = VSM = GND, RL = 8Ω
No input signal, VSTBY = VSM = VCC, RL = 8Ω
10
1000
nA
Differential output offset voltage
No input signal, RL = 8Ω
Voo
VICM
0.1
10
mV
V
Input common mode voltage
CMRR ≤ -60dB
0.6
0.8
VCC - 0.9
Output power
THD = 1% Max, F= 1kHz, RL = 8Ω
Pout
1
W
%
Total harmonic distortion + noise
Pout = 850mW rms, AV = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
THD + N
0.5
Power supply rejection ratio with inputs grounded(1)
PSRRIG F = 217Hz, R = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF
100
90
dB
dB
Vripple = 200mVPP
Common mode rejection ratio
CMRR
F = 217Hz, RL = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF
Vic = 200mVPP
Signal-to-noise ratio (A-weighted filter, AV = 2.5)
RL = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz
SNR
GBP
100
2
dB
Gain bandwidth product
RL = 8Ω
MHz
Output voltage noise, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
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
6
5.5
12
10.5
33
28
1.5
1
VN
μVRMS
Wake-up time(2)
Cb =1μF
tWU
15
ms
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.
.
6/35
TS4994
Table 4.
Electrical characteristics
Electrical characteristics for V = +3.3V (all electrical values are guaranteed with
CC
correlation measurements at 2.6V and 5V), GND = 0V, T
specified)
= 25°C (unless otherwise
amb
Symbol
Parameter
Min.
Typ.
Max.
Unit
ICC
Supply current no input signal, no load
3
7
mA
Standby current
ISTBY
No input signal, VSTBY = VSM = GND, RL = 8Ω
No input signal, VSTBY = VSM = VCC, RL = 8Ω
10
1000
nA
Differential output offset voltage
No input signal, RL = 8Ω
Voo
VICM
0.1
10
mV
V
Input common mode voltage
CMRR ≤ -60dB
0.6
VCC - 0.9
Output power
THD = 1% max, F= 1kHz, RL = 8Ω
Pout
300
380
0.5
mW
%
Total harmonic distortion + noise
Pout = 300mW rms, AV = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
THD + N
Power supply rejection ratio with inputs grounded(1)
PSRRIG F = 217Hz, R = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF
100
90
dB
dB
Vripple = 200mVPP
Common mode rejection ratio
CMRR
F = 217Hz, RL = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF
Vic = 200mVPP
Signal-to-noise ratio (A-weighted filter, AV = 2.5)
RL = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz
SNR
GBP
100
2
dB
Gain bandwidth product
RL = 8Ω
MHz
Output voltage noise, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
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
6
5.5
12
10.5
33
28
1.5
1
VN
μVRMS
Wake-up time(2)
Cb =1μF
tWU
15
ms
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.
.
7/35
Electrical characteristics
TS4994
Table 5.
Electrical characteristics for V = +2.6V, GND = 0V, T
= 25°C (unless otherwise
CC
amb
specified)
Symbol
Parameter
Min.
Typ.
Max.
Unit
Supply current
No input signal, no load
ICC
3
7
mA
Standby current
ISTBY
No input signal, VSTBY = VSM = GND, RL = 8Ω
No input signal, VSTBY = VSM = VCC, RL = 8Ω
10
1000
nA
Differential output offset voltage
No input signal, RL = 8Ω
Voo
VICM
0.1
10
mV
V
Input common mode voltage
CMRR ≤-60dB
0.6
V
CC- 0.9
Output power
THD = 1% max, F= 1kHz, RL = 8Ω
Pout
200
250
0.5
mW
%
Total harmonic distortion + noise
Pout = 225mW rms, AV = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
THD + N
Power supply rejection ratio with inputs grounded(1)
PSRRIG F = 217Hz, R = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF
100
90
dB
dB
Vripple = 200mVPP
Common mode rejection ratio
CMRR
F = 217Hz, RL = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF
Vic = 200mVPP
Signal-to-noise ratio (A-weighted filter, AV = 2.5)
RL = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz
SNR
GBP
100
2
dB
Gain bandwidth product
RL = 8Ω
MHz
Output voltage noise, 20Hz ≤ F ≤ 20kHz, RL = 8Ω
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
6
5.5
12
10.5
33
28
1.5
1
VN
μVRMS
Wake-up time(2)
Cb =1μF
tWU
15
ms
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.
.
8/35
TS4994
Electrical characteristics
Figure 3.
Current consumption vs. power
supply voltage
Figure 4.
Current consumption vs. standby
voltage
4.0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
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=5V
Vcc = 5V
No load
Tamb=25°C
0.0
0
0
1
2
3
4
5
1
2
3
4
5
Power Supply Voltage (V)
Standby Voltage (V)
Figure 5.
Current consumption vs. power
supply voltage
Figure 6.
Current consumption vs. standby
voltage
3.5
3.0
2.5
2.0
1.5
1.0
0.5
3.0
2.5
2.0
1.5
1.0
0.5
Standby mode=0V
Standby mode=0V
Standby mode=2.6V
Standby mode=3.3V
Vcc = 3.3V
No load
Vcc = 2.6V
No load
Tamb=25°C
Tamb=25°C
0.0
0.0
0.0
0.0
0.6
1.2
1.8
2.4
3.0
0.6
1.2
1.8
2.4
Standby Voltage (V)
Standby Voltage (V)
Figure 7.
Differential DC output voltage vs.
common mode input voltage
Figure 8.
Power dissipation vs. output power
1000
Av = 1
Tamb = 25
0.6
0.4
0.2
°C
100
10
Vcc=3.3V
Vcc=5V
RL=8Ω
Vcc=2.5V
1
RL=16
Ω
0.1
Vcc=5V
F=1kHz
THD+N<1%
0.0
0.0
0.01
0.2
0.4
0.6
0.8
1.0
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)
9/35
Electrical characteristics
TS4994
Figure 9.
Power dissipation vs. output power Figure 10. Power dissipation vs. output power
0.20
0.15
0.10
0.05
0.00
0.3
Vcc=2.6V
F=1kHz
THD+N<1%
RL=8
Ω
0.2
0.1
RL=8Ω
RL=16
Ω
RL=16
Ω
Vcc=3.3V
F=1kHz
THD+N<1%
0.0
0.0
0.0
0.1
0.2
Output Power (W)
0.3
0.1
0.2
0.3
0.4
Output Power (W)
Figure 11. Output power vs. power supply
voltage
Figure 12. Output power vs. power supply
voltage
1.0
1.50
Cb = 1μF
F = 1kHz
BW < 125kHz
Tamb = 25°C
Cb = 1μF
F = 1kHz
BW < 125kHz
Tamb = 25°C
8
Ω
8
Ω
1.25
1.00
0.75
0.50
0.25
0.00
0.8
0.6
0.4
0.2
0.0
16
Ω
16
Ω
32Ω
32
Ω
2.5
3.0
3.5
4.0
4.5
5.0
2.5
3.0
3.5
4.0
4.5
5.0
Vcc (V)
Vcc (V)
Figure 13. Output power vs. load resistance
Figure 14. Power derating curves
1.0
1.5
THD+N=1%
Cb = 1 F
F = 1kHz
with 4 layers PCB
0.8
0.6
0.4
0.2
0.0
Vcc=5V
BW < 125kHz
Tamb = 25°C
Vcc=4.5V
1.0
0.5
0.0
Vcc=4V
AMR Value
Vcc=3.5V
12
Vcc=3V
16
Vcc=2.5V
20
0
25
50
75
100
125
8
24
28
32
Ambiant Temperature ( C)
Load Resistance
10/35
TS4994
Electrical characteristics
Figure 15. Power derating curves
Figure 16. Open loop gain vs. frequency
0.6
0
60
40
20
0
Nominal Value
Gain
-40
-80
-120
-160
-200
0.4
Phase
AMR Value
0.2
Vcc = 5V
ZL = 8 + 500pF
-20
Ω
Tamb = 25
°C
-40
0.1
0.0
1
10
100
1000
10000
0
25
50
75
100
125
Frequency (kHz)
Ambiant Temperature ( C)
Figure 17. Open loop gain vs. frequency
Figure 18. Open loop gain vs. frequency
0
0
60
60
40
20
0
Gain
Gain
-40
-40
40
-80
-80
20
Phase
Phase
-120
-160
-200
-120
-160
-200
0
Vcc = 2.6V
ZL = 8 + 500pF
Vcc = 3.3V
-20
-20
Ω
ZL = 8
Tamb = 25
Ω + 500pF
Tamb = 25
°C
°C
-40
0.1
-40
0.1
1
10
100
1000
10000
1
10
100
1000
10000
Frequency (kHz)
Frequency (kHz)
Figure 19. Closed loop gain vs. frequency
Figure 20. Closed loop gain vs. frequency
10
0
0
10
0
0
Phase
Phase
Gain
Gain
-40
-80
-120
-160
-200
-40
-80
-120
-160
-200
-10
-20
-30
-40
-10
-20
-30
-40
Vcc = 5V
Av = 1
ZL = 8
Vcc = 3.3V
Av = 1
ZL = 8Ω + 500pF
Ω
+ 500pF
Tamb = 25
°C
Tamb = 25
°C
0.1
1
10
100
1000
10000
0.1
1
10
100
1000
10000
Frequency (kHz)
Frequency (kHz)
11/35
Electrical characteristics
TS4994
Figure 21. Closed loop gain vs. frequency
Figure 22. PSRR vs. frequency
0
10
0
0
Phase
-10
-20
Vcc = 5V
Vripple = 200mVpp
Inputs = Grounded
Gain
-40
-80
-120
-160
-200
-30
Av = 1, Cin = 4.7
RL
Tamb = 25
μF
-40
≥ 8Ω
-10
-20
-30
-40
Cb=0.1μF
-50
°C
-60
Cb=0.47μF
-70
Cb=1μF
-80
Vcc = 2.6V
Av = 1
ZL = 8
-90
-100
-110
-120
Ω + 500pF
Cb=0
Tamb = 25
°C
0.1
1
10
100
1000
10000
20
100
1000
Frequency (Hz)
10000 20k
Frequency (kHz)
Figure 23. PSRR vs. frequency
Figure 24. PSRR vs. frequency
0
0
-10
-20
-30
-40
Vcc = 2.6V
Vripple = 200mVpp
Inputs = Grounded
-10
-20
-30
-40
Vcc = 3.3V
Vripple = 200mVpp
Inputs = Grounded
Av = 1, Cin = 4.7
μF
Av = 1, 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
-100
-100
Cb=0
Cb=0
-110
-120
-110
-120
20
100
1000
Frequency (Hz)
10000 20k
20
100
1000
Frequency (Hz)
10000 20k
Figure 25. PSRR vs. frequency
Figure 26. PSRR vs. frequency
0
0
-10
-20
-30
-40
-10
-20
-30
-40
Vcc = 5V
Vripple = 200mVpp
Inputs = Grounded
Vcc = 3.3V
Vripple = 200mVpp
Inputs = Grounded
Av = 2.5, 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
Cb=0.47
μF
-60
-70
-80
-90
Cb=0.47
μF
Cb=1μF
Cb=1μF
Cb=0
Cb=0
-100
-100
-110
-120
-110
-120
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
12/35
TS4994
Electrical characteristics
Figure 27. PSRR vs. frequency
Figure 28. PSRR vs. frequency
0
0
-10
-20
-30
-40
-10
Vcc = 5V
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 29. PSRR vs. frequency
Figure 30. PSRR vs. frequency
0
0
-10
-20
-30
-40
-10
-20
-30
-40
Vcc = 3.3V
Vripple = 200mVpp
Inputs = Floating
Vcc = 2.6V
Vripple = 200mVpp
Inputs = Floating
Rfeed = 20k
Ω
Rfeed = 20k
Ω
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
-100
-100
Cb=0
Cb=0
-110
-120
-110
-120
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
Figure 31. PSRR vs. common mode input
voltage
Figure 32. PSRR vs. common mode input
voltage
0
Vcc = 3.3V
0
-20
Vcc = 5V
Vripple = 200mVpp
Inputs Grounded
F = 217Hz
Vripple = 200mVpp
Inputs Grounded
F = 217Hz
-20
Av = 1
Av = 1
-40
RL
≥ 8Ω
-40
RL
≥ 8Ω
Cb=1
Cb=0.47
Cb=0.1
μF
Cb=1
Cb=0.47
Cb=0.1
μF
Tamb = 25
°
C
Tamb = 25
°
C
μ
F
F
μ
F
F
-60
-80
μ
-60
μ
Cb=0
Cb=0
-80
-100
-100
0.0
0.6
1.2
1.8
2.4
3.0
0
1
2
3
4
5
Common Mode Input Voltage (V)
Common Mode Input Voltage (V)
13/35
Electrical characteristics
TS4994
Figure 33. PSRR vs. common mode input
voltage
Figure 34. CMRR vs. frequency
0
0
Vcc = 2.5V
Vripple = 200mVpp
Inputs Grounded
F = 217Hz
-10
Vcc = 5V
Vic = 200mVpp
Av = 1, Cin = 470μF
-20
-30
-20
RL
Tamb = 25
≥ 8Ω
Cb=1
Cb=0.47
Cb=0.1
Cb=0
μF
Av = 1
-40
≥ 8Ω
-40
°C
μ
F
RL
-50
μF
Tamb = 25°C
-60
-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 35. CMRR vs. frequency
Figure 36. CMRR vs. frequency
0
0
-10
-10
-20
Vcc = 2.6V
Vic = 200mVpp
Av = 1, Cin = 470
Vcc = 3.3V
Vic = 200mVpp
Av = 1, Cin = 470μF
-20
-30
μF
-30
RL
≥ 8Ω
RL
≥ 8Ω
Cb=1μF
Cb=1μF
-40
-40
Tamb = 25
°C
Tamb = 25
°
C
Cb=0.47
μ
F
F
Cb=0.47μF
Cb=0.1
Cb=0
-50
-50
Cb=0.1
μ
μF
-60
-60
Cb=0
-70
-70
-80
-80
-90
-90
-100
-110
-120
-100
-110
-120
20
20
100
1000
10000 20k
100
1000
Frequency (Hz)
Frequency (Hz)
Figure 37. CMRR vs. frequency
Figure 38. CMRR vs. frequency
0
0
Vcc = 5V
Vic = 200mVpp
Av = 2.5, Cin = 470
Vcc = 3.3V
Vic = 200mVpp
Av = 2.5, Cin = 470μF
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
μF
RL
≥
8Ω
RL
≥ 8Ω
Tamb = 25
°
C
Tamb = 25°C
Cb=1
μF
Cb=1μF
Cb=0.47
μ
F
Cb=0.47μF
Cb=0.1μF
Cb=0.1μF
Cb=0
Cb=0
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
14/35
TS4994
Electrical characteristics
Figure 39. CMRR vs. frequency
Figure 40. CMRR vs. common mode input
voltage
0
0
Vcc = 2.6V
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
Vcc=3.3V
Vic = 200mVpp
Av = 2.5, Cin = 470
-20
-40
Vcc=2.5V
μ
F
RL
≥ 8Ω
Tamb = 25
°C
Vic = 200mVpp
F = 217Hz
Cb=1
Cb=0.47
Cb=0.1
Cb=0
μF
Av = 1, Cb = 1
RL
Tamb = 25
μF
μ
F
-60
≥ 8Ω
μF
°
C
-80
-100
Vcc=5V
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
20
100
1000
Frequency (Hz)
10000 20k
Common Mode Input Voltage (V)
Figure 41. CMRR vs. common mode input
voltage
Figure 42. THD+N vs. output power
10
0
RL = 8
F = 20Hz
Av = 1
Ω
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Vcc=5V
-20
-40
Vcc=2.5V
1
0.1
Cb = 1
BW < 125kHz
Tamb = 25
μF
Vic = 200mVpp
F = 217Hz
Av = 1, Cb = 0
°C
-60
RL
≥ 8Ω
Tamb = 25
°C
-80
0.01
1E-3
-100
Vcc=5V
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
1E-3
0.01
0.1
1
Common Mode Input Voltage (V)
Output Power (W)
Figure 43. THD+N vs. output power
Figure 44. THD+N vs. output power
10
10
RL = 8
Ω
RL = 8
Ω
F = 20Hz
Av = 7.5
Cb = 1μF
BW < 125kHz
F = 20Hz
Av = 2.5
Vcc=2.6V
Vcc=3.3V
Vcc=5V
Vcc=2.6V
Vcc=3.3V
Vcc=5V
1
0.1
Cb = 1
BW < 125kHz
Tamb = 25
μF
1
0.1
Tamb = 25
°C
°C
0.01
0.01
1E-3
1E-3
0.01
0.1
1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
15/35
Electrical characteristics
TS4994
Figure 45. THD+N vs. output power
Figure 46. THD+N vs. output power
10
10
RL = 8
Ω
RL = 8Ω
F = 1kHz
Av = 1
F = 1kHz
Av = 2.5
Cb = 1μF
BW < 125kHz
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Cb = 1μF
1
0.1
1
0.1
BW < 125kHz
Tamb = 25
°C
Tamb = 25
°C
Vcc=5V
Vcc=5V
0.01
0.01
1E-3
0.01
0.1
1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
Figure 47. THD+N vs. output power
Figure 48. THD+N vs. output power
10
10
RL = 8
F = 1kHz
Av = 7.5
Ω
RL = 8Ω
F = 20kHz
Av = 1
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Cb = 1
μ
F
Cb = 1μF
1
0.1
BW < 125kHz
Tamb = 25
BW < 125kHz
Tamb = 25°C
Vcc=5V
1
°
C
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 50. THD+N vs. output power
10
10
RL = 8
Ω
RL = 8Ω
F = 20kHz
F = 20kHz
Av = 2.5
Av = 7.5
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
Cb = 1μF
Cb = 1
BW < 125kHz
Tamb = 25
μF
BW < 125kHz
Tamb = 25
1
°C
°C
1
Vcc=5V
Vcc=5V
0.1
0.1
1E-3
1E-3
0.01
0.1
1
0.01
0.1
1
Output Power (W)
Output Power (W)
16/35
TS4994
Electrical characteristics
Figure 51. THD+N vs. output power
Figure 52. THD+N vs. output power
10
10
RL = 16
F = 20Hz
Av = 1
Ω
RL = 16Ω
F = 20Hz
Av = 7.5
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
1
0.1
1
Cb = 1
BW < 125kHz
Tamb = 25
μF
Cb = 1
BW < 125kHz
Tamb = 25
μF
°C
°C
Vcc=5V
Vcc=5V
0.1
0.01
0.01
1E-3
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 53. THD+N vs. output power
Figure 54. THD+N vs. output power
10
10
RL = 16
F = 1kHz
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
1E-3
0.01
1E-3
0.01
0.1
1E-3
0.01
0.1
1
Output Power (W)
Output Power (W)
Figure 55. THD+N vs. output power
Figure 56. THD+N vs. output power
10
10
RL = 16
Ω
RL = 16Ω
F = 20kHz
Av = 7.5
Vcc=2.6V
Vcc=3.3V
Vcc=2.6V
Vcc=3.3V
F = 20kHz
Av = 1
Cb = 1μF
Cb = 1
BW < 125kHz
Tamb = 25
μF
1
0.1
BW < 125kHz
Tamb = 25
°C
°C
Vcc=5V
Vcc=5V
1
0.01
1E-3
0.1
1E-3
0.01
0.1
0.01
0.1
1
Output Power (W)
Output Power (W)
17/35
Electrical characteristics
TS4994
Figure 57. THD+N vs. output power
Figure 58. THD+N vs. output power
10
10
RL = 8
Vcc = 2.6V
Av = 1, Cb = 0
BW < 125kHz
Tamb = 25°C
Ω
RL = 8
Vcc = 5V
Av = 1
Cb = 0
BW < 125kHz
Ω
1
0.1
F=20kHz
F=1kHz
F=20kHz
1
0.1
Tamb = 25°C
F=1kHz
F=20Hz
0.01
0.01
F=20Hz
1E-3
1E-3
1E-3
0.01
0.1
1
0.01
Output Power (W)
0.1
Output Power (W)
Figure 59. THD+N vs. output power
Figure 60. THD+N vs. output power
10
10
RL = 16
Ω
RL = 16Ω
Vcc = 5V
Vcc = 2.6V
Av = 1, Cb = 0
BW < 125kHz
Av = 1, Cb = 0
BW < 125kHz
Tamb = 25°C
1
0.1
1
0.1
F=20kHz
F=1kHz
F=20kHz
F=1kHz
Tamb = 25
°C
F=20Hz
F=20Hz
0.01
1E-3
0.01
1E-3
1E-3
0.01
0.1
1
1E-3
0.01
Output Power (W)
0.1
Output Power (W)
Figure 61. THD+N vs. frequency
Figure 62. THD+N vs. frequency
10
10
RL = 8
Av = 1
Cb = 1
Bw < 125kHz
Tamb = 25
Ω
RL = 8
Av = 1
Cb = 0
Bw < 125kHz
Tamb = 25
Ω
μF
1
0.1
1
0.1
Vcc=2.6V, Po=225mW
Vcc=2.6V, Po=225mW
°C
°C
0.01
1E-3
0.01
1E-3
Vcc=5V, Po=850mW
Vcc=5V, Po=850mW
20
100
1000
10000 20k
20
100
1000
Frequency (Hz)
10000 20k
Frequency (Hz)
18/35
TS4994
Electrical characteristics
Figure 63. THD+N vs. frequency
Figure 64. THD+N vs. frequency
10
10
RL = 8
Av = 7.5
Cb = 1
Bw < 125kHz
Ω
RL = 8Ω
Av = 7.5
Cb = 0
Bw < 125kHz
μF
Vcc=2.6V, Po=225mW
Vcc=2.6V, Po=225mW
1
0.1
1
Tamb = 25
°C
Tamb = 25°C
0.1
0.01
Vcc=5V, Po=850mW
Vcc=5V, Po=850mW
0.01
20
100
1000
10000 20k
20
100
1000
10000 20k
Frequency (Hz)
Frequency (Hz)
Figure 65. THD+N vs. frequency
Figure 66. THD+N vs. frequency
10
10
RL = 16
Av = 1
Ω
RL = 16
Av = 7.5
Cb = 1μF
Bw < 125kHz
Tamb = 25
Ω
Vcc=2.6V, Po=155mW
Cb = 1μF
1
0.1
1
0.1
Bw < 125kHz
Tamb = 25
Vcc=2.6V, Po=155mW
°C
°C
0.01
1E-3
0.01
1E-3
Vcc=5V, Po=600mW
Vcc=5V, Po=600mW
20
100
1000
10000 20k
20
100
1000
10000 20k
Frequency (Hz)
Frequency (Hz)
Figure 67. SNR vs. power supply voltage with Figure 68. SNR vs. power supply voltage with
unweighted filter A-weighted filter
110
105
100
95
110
105
100
95
RL=16
Ω
RL=16
Ω
RL=8Ω
RL=8Ω
90
90
Av = 2.5
Cb = 1
THD+N < 0.7%
Tamb = 25
Av = 2.5
Cb = 1μF
THD+N < 0.7%
μ
F
85
85
°
C
Tamb = 25
°C
80
80
2.5
3.0
3.5
4.0
4.5
5.0
2.5
3.0
3.5
4.0
4.5
5.0
Power Supply Voltage (V)
Power Supply Voltage (V)
19/35
Electrical characteristics
TS4994
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)
20/35
TS4994
Application information
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
V
/2 for any DC common mode input voltage. This allows the device to always have a
CC
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 a faster start-up time compared
with conventional single-ended input amplifiers.
●
●
●
Easier interfacing with differential output audio DAC.
No input coupling capacitors required due to common mode feedback loop.
In theory, the filtering of the internal bias by an external bypass capacitor is not
necessary. But, to reach maximum performance in all tolerance situations, it is better to
keep this option.
The main disadvantage is:
●
As the differential function is directly linked to the mismatch between external resistors,
paying particular attention to this mismatch is mandatory in order to get the best
performance from the amplifier.
4.2
Gain in typical application schematic
Typical differential applications are shown in Figure 1 and Figure 2 on page 4.
In the flat region of the frequency-response curve (no C effect), the differential gain is
in
expressed by the relation:
V
O+ – VO
Rfeed
Rin
AV = ------------------------------------------------------ = --------------
diff
Diffinput+ – Diffinput-
where R = R = R and R
= R
= R
.
in
in1
in2
feed
feed1
feed2
Note:
For the rest of this section, Av will be called A to simplify the expression.
diff V
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 V /2 for any DC common mode bias input voltage.
CC
However, due to V
limitation of the input stage (see Table 3 on page 6), the common
ICM
mode feedback loop can play its role only within a defined range. This range depends upon
21/35
Application information
TS4994
the values of V , R and R
(AV). To have a good estimation of the V value, use the
ICM
CC
in
feed
following formula:
VCC × Rin + 2 × Vic × Rfeed
-------------------------------------------------------------------------
VICM
=
(V)
2 × (Rin + Rfeed
)
with
Diffinput+ + Diffinput-
------------------------------------------------------
2
Vic
=
(V)
The result of the calculation must be in the range:
0.6V ≤VICM≤ VCC – 0.9V
If the result of the V
used.
calculation is not in this range, an input coupling capacitor must be
ICM
Example: With V =2.5V, R = R
= 20k and V = 2V, we find V
= 1.63V. This is
ICM
CC
in
feed
ic
higher than 2.5V - 0.9V = 1.6V, so input coupling capacitors are required. Alternatively, you
can 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
in
in
in
with a -3dB 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
feed
parallel with 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.
The influence of mismatching on PSRR and CMRR performance is discussed in more detail
in the following sections.
Example: A typical application with input coupling and feedback capacitor with F = 50Hz
CL
and F = 8kHz. We assume that the mismatching between R
and C
can be
CH
in1,2
feed1,2
neglected. If we sweep 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
in
C
impedance is high enough to be neglected. Due to the tolerance of C
, we
feed
in1,2
22/35
TS4994
Application information
must introduce a mismatch factor (R x C ≠ R x C ) that will decrease the PSRR
in1
in
in2
in2
performance.
●
●
From 200Hz to 5kHz, the C impedance is low enough to be neglected when
in
compared with R and the C
impedance is high enough to be neglected as well. In
in,
feed
this range, we can reach the PSRR performance of the TS4994 itself.
From 5kHz to 20kHz, the C impedance is low to be neglected when compared to R
in
in,
and the C
impedance decreases to a finite value. Due to tolerance of C
, we
feed
feed1,2
introduce a mismatching factor (R
PSRR performance.
x C
≠ R
x C
) that will decrease the
feed1
feed1
feed2
feed2
4.5
Calculating the influence of mismatching on PSRR
performance
For calculating PSRR performance, we consider that C and C
have no influence.
feed
in
We use the same kind of resistor (same tolerance) and ΔR is the tolerance value in %.
The following PSRR equation is valid for frequencies ranging from DC to about 1kHz.
The PSRR equation is (ΔR in %):
⎡
⎢
⎣
⎤
⎥
⎦
ΔR×100
(10000 − ΔR2)
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 (ΔR in %, C in microFarad and F in Hz) is:
b
ΔR × 100
--------------------------------------------------------------------------------------------------------
PSRR ≤20 × log
(dB)
2
2
2
(1000 – ΔR ) × 1 + F × C × 22.2
b
Example: With ΔR = 0.1% and C = 0, the minimum PSRR would be -60dB. With a 100nF
b
bypass capacitor, at 100Hz the new PSRR would be -93dB.
This example is a worst case scenario, where each resistor has extreme tolerance. It
illustrates the fact that with only a small bypass capacitor, the TS4994 provides high PSRR
performance.
Note also that this is a theoretical formula. Because 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.
23/35
Application information
TS4994
The three following graphs show PSRR versus frequency and versus bypass capacitor C in
b
worst-case conditions (ΔR = 0.1%).
Figure 70. PSRR vs. frequency (worst case
Figure 71. PSRR vs. frequency (worst case
conditions)
conditions)
0
-10
-20
0
-10
-20
Vcc = 5V, Vripple = 200mVpp
Av = 1, Cin = 4.7μF
Vcc = 3.3V, Vripple = 200mVpp
Av = 1, Cin = 4.7μF
-30
-30
-40
ΔR/R = 0.1%, RL ≥ 8Ω
ΔR/R = 0.1%, RL ≥ 8Ω
-40
Tamb = 25°C, Inputs = Grounded
Tamb = 25°C, Inputs = Grounded
Cb=0
Cb=0
-50
-50
-60
-60
-70
-70
Cb=0.1μF
Cb=0.1μF
-80
-80
-90
-90
-100
-110
-120
-130
-140
-100
-110
-120
-130
-140
Cb=1
μF
Cb=0.47μF
Cb=1
μF
Cb=0.47μF
20
100
1000
Frequency (Hz)
10000 20k
20
100
1000
Frequency (Hz)
10000 20k
Figure 72. PSRR vs. frequency (worst case
conditions)
0
-10
-20
Vcc = 2.5V, Vripple = 200mVpp
Av = 1, Cin = 4.7
μF
-30
ΔR/R = 0.1%, RL ≥ 8Ω
Tamb = 25°C, Inputs = Grounded
-40
Cb=0
-50
-60
-70
Cb=0.1μF
-80
-90
-100
-110
-120
-130
-140
Cb=1
μF
Cb=0.47μF
20
100
1000
10000 20k
Frequency (Hz)
24/35
TS4994
Application information
The two following graphs show typical applications of the TS4994 with a random selection of
four ΔR/R values with a 0.1% tolerance.
Figure 73. PSRR vs. frequency with random
choice condition
Figure 74. PSRR vs. frequency with random
choice condition
0
0
-10
-20
-10
-20
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
Δ
≤
Ω
Δ
≤
-30
-30
°
°
-40
-40
-50
-50
-60
-60
Cb=0
Cb=0
Cb=0.1μF
Cb=0.1μF
-70
-70
-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)
4.6
CMRR performance
For calculating CMRR performance, we consider that C and C
have no influence. C
b
in
feed
has no influence in the calculation of the CMRR.
We use the same kind of resistor (same tolerance) and ΔR is the tolerance value in %.
The following CMRR equation is valid for frequencies ranging from DC to about 1kHz.
The CMRR equation is (ΔR in %):
⎡
⎢
⎣
⎤
⎥
⎦
ΔR × 200
(10000 − ΔR2 )
CMRR ≤ 20 × Log
(dB)
Example: With ΔR = 1%, the minimum CMRR is -34dB.
This example is a worst case scenario where each resistor has extreme tolerance. Ut
illustrates the fact that for CMRR, good matching is essential.
As with the PSRR, due to self-generated noise, the TS4994 CMRR limitation is about
-110dB.
Figure 75 and Figure 76 show CMRR versus frequency and versus bypass capacitor C in
b
worst-case conditions (ΔR=0.1%).
25/35
Application information
TS4994
Figure 75. CMR vs. frequency (worst case
conditions)
Figure 76. CMR vs. frequency (worst case
conditions)
0
0
-10
-20
-30
-40
-50
-60
Vcc = 2.5V
Vic = 200mVpp
Av = 1, Cin = 470μF
Vcc = 5V
Vic = 200mVpp
Av = 1, Cin = 470μF
-10
-20
-30
-40
-50
-60
ΔR/R = 0.1%, RL
≥ 8Ω
ΔR/R = 0.1%, RL
≥ 8Ω
Tamb = 25
°C
Tamb = 25
°
C
Cb=1
Cb=0
μF
Cb=1μF
Cb=0
20
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
Figure 77 and Figure 78 show CMRR versus frequency for a typical application with a
random selection of four ΔR/R values with a 0.1% tolerance.
Figure 77. CMR vs. frequency with random
choice condition
Figure 78. CMR vs. frequency with random
choice condition
0
0
Vcc = 5V
-10
Vcc = 2.5V
-10
Vic = 200mVpp
Vic = 200mVpp
-20 Av = 1, Cin = 470
R/R 0.1%, RL
Tamb = 25
μ
≥
F
8
-20 Av = 1, Cin = 470
R/R 0.1%, RL
Tamb = 25
μF
≥ 8Ω
Δ
≤
Ω
Δ
≤
-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
20
100
1000
Frequency (Hz)
10000 20k
100
1000
Frequency (Hz)
10000 20k
4.7
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
The output voltage is:
Vout = V
sinωt (V)
peak
and
Vout
------------
Iout
=
(A)
RL
26/35
TS4994
Application information
and
2
Vpeak
--------------------
(W)
Pout
=
2RL
Therefore, the average current delivered by the supply voltage is:
Equation 1
Vpeak
----------------
(A)
ICC
= 2
AVG
The power delivered by the supply voltage is:
Psupply = VCC ⋅ ICC
πRL
(W)
AVG
Therefore, the power dissipated by each amplifier is:
Pdiss = Psupply – Pout (W)
Equation 2
2 2VCC
----------------------
Pout–Pout
Pdiss
=
π RL
and the maximum value is obtained when:
∂Pdiss
----------------- = 0
∂Pout
and its value is:
Equation 3
2Vcc2
π2RL
Pdissmax =
(W)
Note:
This maximum value is only dependent on the power supply voltage and load values.
The efficiency is the ratio between the output power and the power supply:
Equation 4
Pout
πVpeak
4VCC
------------------ --------------------
η=
=
Psupply
The maximum theoretical value is reached when V
= V , so:
CC
PEAK
π
----
η=
= 78.5%
4
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.
27/35
Application information
TS4994
To calculate the maximum ambient temperature T
allowable, you need to know:
amb
●
●
●
The value of the power supply voltage, V
CC
The value of the load resistor, R
L
The R
value for the package type
thja
Example: V = 5V, R = 8Ω, R = 80°C/W
thja
CC
L
Using the power dissipation formula given above in Equation 3 this gives a result of:
= 633mW
P
dissmax
T
is calculated as follows:
amb
Equation 5
T
amb= 125° C – RTJHA × Pdissmax
Therefore, the maximum allowable value for T is:
amb
T
= 125-80x0.633=74°C
amb
4.8
Decoupling of the circuit
Two capacitors are needed to correctly bypass the TS4994. A power supply bypass
capacitor C and a bias voltage bypass capacitor Cb.
s
C has particular influence on the THD+N in the high frequency region (above 7kHz) and an
s
indirect influence on power supply disturbances. With a value for C of 1µF, you can expect
s
similar THD+N performance to that shown in the datasheet.
In the high frequency region, if C is lower than 1µF, it increases THD+N, and disturbances
s
on the power supply rail are less filtered.
On the other hand, if C is higher than 1µF, the disturbances on the power supply rail are
s
more filtered.
C has an influence on THD+N at lower frequencies, but its function is critical to the final
b
result of PSRR (with input grounded and in the lower frequency region).
4.9
Wake-up time: tWU
When the standby is released to put the device ON, the bypass capacitor C is not charged
b
immediately. As C is directly linked to the bias of the amplifier, the bias will not work
b
properly until the C voltage is correct. The time to reach this voltage is called the wake-up
b
time or t
and is specified in Table 3 on page 6, with C =1µF. During the wake-up time, the
WU
b
TS4994 gain is close to zero. After the wake-up time, the gain is released and set to its
nominal value.
If C has a value other than 1µF, refer to the graph in Figure 69 on page 20 to establish the
b
wake-up time.
28/35
TS4994
Application information
4.10
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, the Bypass pin and Vin+, Vin- pins are short-circuited to ground by
internal switches. This allows a quick discharge of the C and C capacitors.
b
in
4.11
Pop performance
Due to its fully differential structure, the pop performance of the TS4994 is close to perfect.
However, due to mismatching between internal resistors R , R , and external input
in
feed
capacitors C , some noise might remain at startup. To eliminate the effect of mismatched
in
components, the TS4994 includes pop reduction circuitry. With this circuitry, the TS4994 is
close to zero pop for all possible common applications.
In addition, when the TS4994 is in standby mode, due to the high impedance output stage in
this configuration, no pop is heard.
4.12
Single-ended input configuration
It is possible to use the TS4994 in a single-ended input configuration. However, input
coupling capacitors are needed in this configuration. The schematic in Figure 79 shows this
configuration using the MiniSO-8 version of the TS4994 as an example.
Figure 79. Single-ended input typical application
VCC
+
Cs
1u
Rfeed1
20k
7
GND
VCC
Ve
Cin1
Rin1
2
Vin-
-
Vo+
Vo-
8
5
20k
220nF
Cin2
Rin2
3
4
Vin+
+
20k
+
220nF
8 Ohms
GND
Bypass
Bias
Optional
Cb
1u
Standby
GND
6
TS4994IS
Stdby
1
GND
Rfeed2
20k
GND
GND VCC
29/35
Application information
TS4994
The component calculations remain the same, except for the gain. In single-ended input
configuration, the formula is:
VO+ − VO− Rfeed
AvSE
=
=
Ve
Rin
4.13
Demoboard
A demoboard for the TS4994 is available. It is designed for the TS4994 in the DFN10
package. However, we can guarantee that all electrical parameters except the power
dissipation are similar for all packages.
For more information about this demoboard, refer to Application Note AN2013.
30/35
TS4994
Package mechanical data
5
Package mechanical data
In order to meet environmental requirements, STMicroelectronics offers these devices in
®
ECOPACK packages. These packages have a Lead-free second level interconnect. The
category of second level interconnect is marked on the package and on the inner box label,
in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics
trademark. ECOPACK specifications are available at: www.st.com.
31/35
Package mechanical data
TS4994
5.1
DFN10 package
Dimensions
Ref.
Millimeters
Typ.
Mils
Typ.
Min.
Max.
Min.
Max.
A
A1
A2
A3
b
0.80
0.90
0.02
0.70
0.20
0.23
3.00
2.26
3.00
1.64
0.50
0.4
1.00
0.05
31.5
35.4
0.8
39.4
2.0
25.6
7.9
0.18
2.21
1.49
0.3
0.30
2.31
1.74
0.5
7.1
9.1
11.8
91.0
68.5
19.7
D
118.1
89.0
118.1
64.6
19.7
15.7
D2
E
87.0
58.7
11.8
E2
e
L
32/35
TS4994
Package mechanical data
5.2
MiniSO-8 package
Dimensions
Ref.
Millimeters
Typ.
Inches
Min.
Max.
Min.
Typ.
Max.
A
1.1
0.043
0.006
0.037
0.016
0.009
0.122
0.199
0.122
A1
A2
b
0.05
0.78
0.25
0.13
2.90
4.75
2.90
0.10
0.86
0.33
0.18
3.00
4.90
3.00
0.65
0.15
0.94
0.40
0.23
3.10
5.05
3.10
0.002
0.031
0.010
0.005
0.114
0.187
0.114
0.004
0.034
0.013
0.007
0.118
0.193
0.118
0.026
c
D
E
E1
e
K
0°
6°
0°
6°
L
0.40
0.55
0.70
0.10
0.016
0.022
0.028
0.04
L1
33/35
Revision history
TS4994
6
Revision history
Date
Revision
Changes
1-Sep-2003
1-Oct-2004
2-Jan-2005
2-Apr-2005
15-Nov- 2005
12-Dec-2006
1
2
4
4
5
6
Initial release.
Curves updated in the document.
Update mechanical data on flip-chip package.
Remove data on flip-chip package.
Mechanical data updated on DFN10 package.
Removed demo board views. Format update.
34/35
TS4994
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35/35
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