STMICROELECTRONICS TS4902IST

TS4902
300mW at 3.3V SUPPLY AUDIO POWER AMPLIFIER
WITH STANDBY MODE ACTIVE LOW
■ OPERATING FROM VCC = 2.2V to 5.5V
■ 0.7W OUTPUT POWER @ Vcc=5V, THD=1%,
PIN CONNECTIONS (top view)
f=1kHz, with an 8Ω load
■ 0.3W OUTPUT POWER @ Vcc=3.3V,
THD=1%, f=1kHz, with an 8Ω load
■ ULTRA LOW CONSUMPTION IN STANDBY
MODE (10nA)
■ 77dB PSRR @ 217Hz from 5V to 2.2V
■ ULTRA LOW POP & CLICK
■ ULTRA LOW DISTORTION (0.1%)
■ UNITY GAIN STABLE
■ AVAILABLE IN MiniSO8 & SO8
TS4902IS-TS4902IST - MiniSO8
Standby
1
8
VOUT2
Bypass
2
7
GND
VIN+
3
6
VCC
VIN-
4
5
VOUT1
DESCRIPTION
The TS4902 is an audio power amplifier designed
to provide the best price to power ratio while preserving high audio quality.
Available in MiniSO8 & SO8 package, it is capable
of delivering up to 0.7W of continuous RMS ouput
power into an 8Ω load @ 5V.
TS4902 is also exhibiting an outstanding 0.1%
distortion level (THD) from a 5V supply for a Pout
of 200mW RMS.
TS4902ID-TS4902IDT - SO8
Standby
1
8
VOUT2
Bypass
2
7
GND
VIN+
3
6
VCC
VIN-
4
5
VOUT1
An externally controlled standby mode reduces
the supply current to less than 10nA. It also includes an internal thermal shutdown protection.
The unity-gain stable amplifier can be configured
by external gain setting resistors.
APPLICATIONS
■ Mobile Phones (Cellular / Cordless)
■ PDAs
■ Portable Audio Devices
TYPICAL APPLICATION SCHEMATIC
Cfeed
Rfeed
VCC
Cs
6
Audio
Input
Rin
4
Vin-
-
3
Vin+
+
V
C
Vout 1
Cin
ORDER CODE
Part Number
TS4902IST
TS4902ID
Temperature
Range
-40, +85°C
5
RL
8 Ohms
Package
-
VCC
ST
AV = -1
D
•
•
2
Bypass
1
Standby Bias
Rstb
GND
Cb
Vout 2
8
+
TS4902
7
S = MiniSO Package (MiniSO) is only available in Tape & Reel (ST)
D = Small Outline Package (SO) - also available in Tape & Reel (DT)
January 2002
1/19
TS4902
ABSOLUTE MAXIMUM RATINGS
Symbol
VCC
Vi
Parameter
Supply voltage
Input Voltage
1)
2)
Unit
6
V
GND to VCC
V
°C
Toper
Operating Free Air Temperature Range
-40 to + 85
Tstg
Storage Temperature
Tj
Rthja
Pd
-65 to +150
°C
Maximum Junction Temperature
150
°C
Thermal Resistance Junction to Ambient 3)
SO8
MiniSO8
175
215
Power Dissipation 4)
ESD
Human Body Model
ESD
Machine Model
Latch-up Latch-up Immunity
Lead Temperature (soldering, 10sec)
1.
2.
3.
4.
Value
°C/W
See the power derating
curves Fig 20.
2
200
Class A
250
kV
V
Value
Unit
2.2 to 5.5
V
°C
All voltages values are measured with respect to the ground pin.
The magnitude of input signal must never exceed VCC + 0.3V / G ND - 0.3V
Device is protected in case of over temperature by a thermal shutdown active @ 150°C.
Exceeding the power derating curves during a long period, will cause abnormal operation.
OPERATING CONDITIONS
Symbol
Parameter
VCC
Supply Voltage
VICM
Common Mode Input Voltage Range
GND to VCC - 1.5V
V
VSTB
Standby Voltage Input :
Device ON
Device OFF
1.5 ≤ VSTB ≤ VCC
GND ≤ VSTB ≤ 0.5
V
4 - 32
Ω
RL
Rthja
Load Resistor
Thermal Resistance Junction to Ambient 1)
SO8
MiniSO8
1. This thermal resistance can be reduced with a suitable PCB layout (see Power Derating Curves)
2/19
°C/W
150
190
TS4902
ELECTRICAL CHARACTERISTICS
VCC = +5V, GND = 0V, Tamb = 25°C (unless otherwise specified)
Symbol
Typ.
Max.
Unit
Supply Current
No input signal, no load
6
8
mA
Standby Current 1)
No input signal, Vstdby = GND, RL = 8Ω
10
1000
nA
Voo
Output Offset Voltage
No input signal, RL = 8Ω
5
20
mV
Po
Output Power
THD = 1% Max, f = 1kHz, RL = 8Ω
0.7
W
Total Harmonic Distortion + Noise
Po = 250mW rms, Gv = 2, 20Hz < f < 20kHz, RL = 8Ω
0.15
%
Power Supply Rejection Ratio 2)
f = 217Hz, RL = 8Ω, RFeed = 22KΩ, Vripple = 200mV rms
77
dB
ΦM
Phase Margin at Unity Gain
RL = 8Ω, CL = 500pF
70
Degrees
GM
Gain Margin
RL = 8Ω, CL = 500pF
20
dB
GBP
Gain Bandwidth Product
RL = 8Ω
2
MHz
ICC
ISTANDBY
THD + N
PSRR
Parameter
Min.
1. Standby mode is actived when Vstdby is tied to GND
2. Dynamic measurements - 20*log(rms(Vout)/rms(Vripple)). Vripple is the surimposed sinus signal to Vcc @ f = 217Hz
VCC = +3.3V, GND = 0V, Tamb = 25°C (unless otherwise specified)3)
Symbol
Typ.
Max.
Unit
Supply Current
No input signal, no load
5.5
8
mA
Standby Current 1)
No input signal, Vstdby = GND, RL = 8Ω
10
1000
nA
Voo
Output Offset Voltage
No input signal, RL = 8Ω
5
20
mV
Po
Output Power
THD = 1% Max, f = 1kHz, RL = 8Ω
300
mW
Total Harmonic Distortion + Noise
Po = 250mW rms, Gv = 2, 20Hz < f < 20kHz, RL = 8Ω
0.15
%
Power Supply Rejection Ratio 2)
f = 217Hz, RL = 8Ω, RFeed = 22KΩ, Vripple = 200mV rms
77
dB
ΦM
Phase Margin at Unity Gain
RL = 8Ω, CL = 500pF
70
Degrees
GM
Gain Margin
RL = 8Ω, CL = 500pF
20
dB
GBP
Gain Bandwidth Product
RL = 8Ω
2
MHz
ICC
ISTANDBY
THD + N
PSRR
Parameter
Min.
1. Standby mode is actived when Vstdby is tied to GND
2. Dynamic measurements - 20*log(rms(Vout)/rms(Vripple)). Vripple is the surimposed sinus signal to Vcc @ f = 217Hz
3. All electrical values are made by correlation between 2.6V and 5V measurements
3/19
TS4902
ELECTRICAL CHARACTERISTICS
VCC = 2.6V, GND = 0V, Tamb = 25°C (unless otherwise specified)
Symbol
Typ.
Max.
Unit
Supply Current
No input signal, no load
5.5
8
mA
Standby Current 1)
No input signal, Vstdby = GND, RL = 8Ω
10
1000
nA
Voo
Output Offset Voltage
No input signal, RL = 8Ω
5
20
mV
Po
Output Power
THD = 1% Max, f = 1kHz, RL = 8Ω
180
mW
Total Harmonic Distortion + Noise
Po = 200mW rms, Gv = 2, 20Hz < f < 20kHz, RL = 8Ω
0.15
%
Power Supply Rejection Ratio 2)
f = 217Hz, RL = 8Ω, RFeed = 22KΩ, Vripple = 200mV rms
77
dB
ΦM
Phase Margin at Unity Gain
RL = 8Ω, CL = 500pF
70
Degrees
GM
Gain Margin
RL = 8Ω, CL = 500pF
20
dB
GBP
Gain Bandwidth Product
RL = 8Ω
2
MHz
ICC
ISTANDBY
THD + N
PSRR
Parameter
Min.
1. Standby mode is actived when Vstdby is tied to GND
2. Dynamic measurements - 20*log(rms(Vout)/rms(Vripple)). Vripple is the surimposed sinus signal to Vcc @ f = 217Hz
Components
Functional Description
Rin
Inverting input resistor which sets the closed loop gain in conjunction with Rfeed. This resistor also
forms a high pass filter with Cin (fc = 1 / (2 x Pi x Rin x Cin))
Cin
Input coupling capacitor which blocks the DC voltage at the amplifier input terminal
Rfeed
Feed back resistor which sets the closed loop gain in conjunction with Rin
Cs
Supply Bypass capacitor which provides power supply filtering
Cb
Bypass pin capacitor which provides half supply filtering
Cfeed
Rstb
Gv
Low pass filter capacitor allowing to cut the high frequency
(low pass filter cut-off frequency 1 / (2 x Pi x Rfeed x Cfeed))
Pull-up resistor which fixes the right supply level on the standby pin
Closed loop gain in BTL configuration = 2 x (Rfeed / Rin)
REMARKS
1. All measurements, except PSRR measurements, are made with a supply bypass capacitor Cs = 100µF.
2. The standby response time is about 1µs.
4/19
TS4902
Fig. 1 : Open Loop Frequency Response
Fig. 2 : Open Loop Frequency Response
0
40
Phase (Deg)
-120
-140
0
Vcc = 5V
ZL = 8Ω + 560pF
Tamb = 25°C
-100
20
-120
-140
0
-180
-20
-200
1
10
100
1000
10000
-200
-220
-40
0.3
1
10
Frequency (kHz)
Fig. 3 : Open Loop Frequency Response
Gain
60
Vcc = 33V
RL = 8Ω
Tamb = 25°C
-140
-160
Gain (dB)
-120
0
Gain
-60
-100
20
-220
0
60
-40
Phase (Deg)
Gain (dB)
Phase
10000
80
-20
-80
40
100
1000
Frequency (kHz)
Fig. 4 : Open Loop Frequency Response
0
80
-60
-160
-180
-40
0.3
-40
-80
Phase
-160
-20
-20
Vcc = 3.3V
ZL = 8Ω + 560pF
Tamb = 25°C
Phase
10
100
1000
Frequency (kHz)
10000
-140
-160
-180
-200
-20
-220
-240
-40
0.3
Fig. 5 : Open Loop Frequency Response
Gain
60
Vcc = 2.6V
RL = 8Ω
Tamb = 25°C
60
-40
-60
-120
-140
-160
0
10000
Vcc = 2.6V
ZL = 8Ω + 560pF
Tamb = 25°C
Phase
-200
1
10
100
1000
Frequency (kHz)
10000
-240
-40
-60
-120
-140
-160
0
-180
-200
-20
-220
-220
-40
0.3
-20
-100
20
-180
-20
-240
-80
40
Gain (dB)
-100
20
100
1000
Frequency (kHz)
0
Gain
Phase (Deg)
Gain (dB)
Phase
10
80
-20
-80
40
1
Fig. 6 : Open Loop Frequency Response
0
80
-60
-120
-220
1
-40
-100
20
0
-200
-40
0.3
-20
-80
40
-180
-20
Phase (Deg)
-60
-100
20
Gain
-40
-80
Phase
Gain (dB)
60
Phase (Deg)
40
0
-20
Phase (Deg)
Vcc = 5V
RL = 8Ω
Tamb = 25°C
Gain
Gain (dB)
60
-40
0.3
1
10
100
1000
Frequency (kHz)
10000
-240
5/19
TS4902
Phase
60
100
-100
80
-120
60
Gain (dB)
Gain
-140
40
-160
20
0
-20
-40
0.3
-180
1
10
100
-40
0.3
-80
80
-100
Phase
Gain (dB)
Gain
-140
40
-160
20
-180
0
-40
0.3
6/19
-200
Vcc = 2.6V
CL = 560pF
Tamb = 25°C
1
10
-220
100
1000
Frequency (kHz)
10000
-240
Phase (Deg)
-120
60
-20
-180
-220
Fig. 9 : Open Loop Frequency Response
-140
-160
-20
10000
-120
20
-200
100
1000
Frequency (kHz)
-100
Phase
40
0
Vcc = 5V
CL = 560pF
Tamb = 25°C
-80
Gain
Gain (dB)
80
-80
Phase (Deg)
100
Fig. 8 : Open Loop Frequency Response
-200
Vcc = 3.3V
CL = 560pF
Tamb = 25°C
1
10
-220
100
1000
Frequency (kHz)
10000
-240
Phase (Deg)
Fig. 7 : Open Loop Frequency Response
TS4902
Fig. 10 : Power Supply Rejection Ratio (PSRR)
vs Power supply
Fig. 11 : Power Supply Rejection Ratio (PSRR)
vs Feedback Capacitor
-30
-50
-60
-20
-30
PSRR (dB)
PSRR (dB)
-40
-10
Vripple = 200mVrms
Rfeed = 22kΩ
Input = floating
RL = 8Ω
Tamb = 25°C
Vcc = 5V to 2.2V
Cb = 1µF & 0.1µF
-40
Vcc = 5 to 2.2V
Cb = 1µF & 0.1µF
Rfeed = 22kΩ
Vripple = 200mVrms
Input = floating
RL = 8Ω
Tamb = 25°C
Cfeed=0
Cfeed=150pF
Cfeed=330pF
-50
-60
-70
-70
Cfeed=680pF
-80
10
100
1000
10000
Frequency (Hz)
100000
Fig. 12 : Power Supply Rejection Ratio (PSRR)
vs Bypass Capacitor
-80
10
-10
Cb=10µF
PSRR (dB)
-30
Vcc = 5 to 2.2V
Rfeed = 22k
Rin = 22k, Cin = 1µF
Rg = 100Ω, RL = 8Ω
Tamb = 25°C
-40
Cin=1µF
Cb=47µF
-50
100000
Vcc = 5 to 2.2V
Rfeed = 22k, Rin = 22k
Cb = 1µF
Rg = 100Ω, RL = 8Ω
Tamb = 25°C
Cin=330nF
-20
PSRR (dB)
-20
1000
10000
Frequency (Hz)
Fig. 13 : Power Supply Rejection Ratio (PSRR)
vs Input Capacitor
-10
Cb=1µF
100
Cin=220nF
-30
-40
Cin=100nF
-60
-50
Cin=22nF
-70
Cb=100µF
-80
10
100
1000
10000
100000
-60
10
100
1000
10000
100000
Frequency (Hz)
Frequency (Hz)
Fig. 14 : Power Supply Rejection Ratio (PSRR)
vs Feedback Resistor
-10
-20
PSRR (dB)
-30
-40
Vcc = 5 to 2.2V
Cb = 1µF & 0.1µF
Vripple = 200mVrms
Input = floating
RL = 8Ω
Tamb = 25°C
Rfeed=110kΩ
Rfeed=47kΩ
-50
-60
Rfeed=22kΩ
-70
-80
10
Rfeed=10kΩ
100
1000
10000
Frequency (Hz)
100000
7/19
TS4902
Fig. 15 : Pout @ THD + N = 1% vs Supply
Voltage vs RL
Fig. 16 : Pout @ THD + N = 10% vs Supply
Voltage vs RL
1.2
0.8
Gv = 2 & 10
Cb = 1µF
F = 1kHz
BW < 125kHz
Tamb = 25°C
Output power @ 10% THD + N (W)
Output power @ 1% THD + N (W)
1.0
8Ω
4Ω
0.6
16 Ω
0.4
0.2
32 Ω
0.0
2.5
3.0
3.5
4.0
4.5
Gv = 2 & 10
Cb = 1µF
F = 1kHz
BW < 125kHz
Tamb = 25°C
1.0
0.8
4Ω
8Ω
16 Ω
0.6
0.4
0.2
32 Ω
0.0
2.5
5.0
3.0
3.5
Vcc (V)
Fig. 17 : Power Dissipation vs Pout
Vcc=3.3V
f=1kHz
THD+N<1%
0.5
RL=4Ω
Power Dissipation (W)
Power Dissipation (W)
5.0
0.6
Vcc=5V
f=1kHz
THD+N<1%
1.0
0.8
0.6
RL=8Ω
0.4
0.2
0.4
RL=4Ω
0.4
0.3
0.2
RL=8Ω
0.1
RL=16Ω
0.2
0.0
0.0
4.5
Fig. 18 : Power Dissipation vs Pout
1.4
1.2
4.0
Vcc (V)
RL=16Ω
0.6
0.8
0.0
0.0
1.0
0.2
Output Power (W)
0.4
0.6
Output Power (W)
Fig. 19 : Power Dissipation vs Pout
Fig. 20 : Power Derating Curves
0.40
0.30
RL=4Ω
0.25
0.20
0.15
RL=8Ω
0.10
MiniSO8 on
demoboard
0.8
0.6
0.4
MiniSO8
SO8
RL=16Ω
0.0
0.1
0.2
Output Power (W)
8/19
1.0
0.2
0.05
0.00
0.0
SO8 on
demoboard
1.2
Vcc=2.6V
f=1kHz
THD+N<1%
Power Dissipation (W)
Power Dissipation (W)
0.35
0.3
0
25
50
75
100
Ambiant Temperature (°C)
125
150
TS4902
Fig. 21 : Output Power vs Load Resistance
Fig. 22 : Output Power vs Load Resistance
1.0
Output power (W)
0.8
Vcc=5V
0.6
Vcc=4.5V
Vcc=4V
0.4
1.2
1.0
Output Power (W)
THD+N=1%
Gv = 2 & 10
Cb = 1µF
F = 1kHz
BW < 125kHz
Tamb = 25°C
THD+N=10%
Gv = 2 & 10
Cb = 1µF
F = 1kHz
BW < 125kHz
Tamb = 25°C
Vcc=5V
0.8
Vcc=4.5V
0.6
Vcc=4V
0.4
0.2
0.2
Vcc=3.5V
Vcc=3.5V
Vcc=3V
0.0
8
Vcc=2.5V
0.0
16
24
32
Fig. 23 : Clipping Voltage vs Supply Voltage
Vcc=2.5V
16
24
32
Fig. 24 : Frequency response vs Cin & Cfeed
10
Tamb = 25°C
0.9
5
0.8
4Ω High Side
0
4Ω Low Side
0.7
Gain (dB)
Dropout Voltage (V)
8
Load Resistance (ohm)
Load Resistance (ohm)
1.0
Vcc=3V
0.6
0.5
8Ω High Side
8Ω Low Side
0.4
-10
-20
0.2
2.5
3.0
3.5
4.0
4.5
5.0
Supply Voltage (V)
Cfeed = 680pF
-5
-15
0.3
Cfeed = 330pF
-25
10
Cin = 470nF
Cfeed = 2.2nF
Cin = 22nF
Cin = 82nF
Rin = Rfeed = 22kΩ
Tamb = 25°C
100
1000
Frequency (Hz)
10000
Fig. 25 : Noise Floor
Output Noise Voltage ( V)
100
80
60
Vcc = 2.5V to 5V
Rin = Rfeed = 22kΩ
Cb = Cin = 1µF
Input Grounded
BW < 22kHz
Tamb = 25°C
40
VOUT1 + VOUT2
Standby = ON
20
0
20
100
1000
Frequency (Hz)
10000
9/19
TS4902
Fig. 26 : THD + N vs Output Power
Fig. 27 : THD + N vs Output Power
10
RL = 4Ω, Vcc = 5V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz, Tamb = 25°C
Rl = 4Ω
Vcc = 5V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
THD + N (%)
10
1
20kHz
20kHz
1
20Hz
20Hz, 1kHz
0.1
1E-3
1kHz
0.01
0.1
Output Power (W)
0.1
1E-3
1
Fig. 28 : THD + N vs Output Power
1
Fig. 29 : THD + N vs Output Power
10
10
RL = 4Ω, Vcc = 3.3V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
THD + N (%)
0.01
0.1
Output Power (W)
1
RL = 4Ω, Vcc = 3.3V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
20kHz
1
20kHz
0.1
20Hz
1kHz
20Hz, 1kHz
0.1
1E-3
0.01
0.1
Output Power (W)
1
Fig. 30 : THD + N vs Output Power
0.01
0.1
Output Power (W)
1
Fig. 31 : THD + N vs Output Power
10
RL = 4Ω, Vcc = 2.6V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
THD + N (%)
10
1E-3
1
RL = 4Ω, Vcc = 2.6V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
1
20kHz
20kHz
20Hz
0.1
1kHz
20Hz, 1kHz
0.1
1E-3
10/19
0.01
Output Power (W)
0.1
1E-3
0.01
Output Power (W)
0.1
TS4902
Fig. 32 : THD + N vs Output Power
Fig. 33 : THD + N vs Output Power
10
10
20Hz, 1kHz
THD + N (%)
THD + N (%)
RL = 8Ω
Vcc = 5V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
1 Tamb = 25°C
20kHz
0.1
RL = 8Ω
Vcc = 5V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
1
20Hz
20kHz
0.1
1kHz
1E-3
0.01
0.1
Output Power (W)
1
1E-3
Fig. 34 : THD + N vs Output Power
1
Fig. 35 : THD + N vs Output Power
10
10
RL = 8Ω, Vcc = 3.3V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
THD + N (%)
0.01
0.1
Output Power (W)
1
RL = 8Ω, Vcc = 3.3V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
1
20kHz
20Hz
20kHz
20Hz, 1kHz
0.1
0.1
1kHz
1E-3
0.01
0.1
Output Power (W)
1
Fig. 36 : THD + N vs Output Power
0.01
0.1
Output Power (W)
1
Fig. 37 : THD + N vs Output Power
10
RL = 8Ω, Vcc = 2.6V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
THD + N (%)
10
1E-3
1
20Hz, 1kHz
1
20Hz
20kHz
20kHz
0.1
1E-3
RL = 8Ω, Vcc = 2.6V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
0.1
0.01
Output Power (W)
0.1
1E-3
1kHz
0.01
Output Power (W)
0.1
11/19
TS4902
Fig. 38 : THD + N vs Output Power
Fig. 39 : THD + N vs Output Power
10
10
THD + N (%)
1
20kHz
RL = 16Ω, Vcc = 5V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
1
THD + N (%)
RL = 16Ω, Vcc = 5V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
20kHz
0.1
0.1
1kHz
20Hz, 1kHz
0.01
1E-3
0.01
0.1
Output Power (W)
1
0.01
1E-3
0.01
0.1
Output Power (W)
10
10
THD + N (%)
RL = 16Ω, Vcc = 3.3V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
1
20kHz
RL = 16Ω
Vcc = 3.3V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
1
20kHz
0.1
0.1
1kHz
20Hz
20Hz, 1kHz
0.01
1E-3
0.01
Output Power (W)
0.01
1E-3
0.1
RL = 16Ω
Vcc = 2.6V
Gv = 2
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
THD + N (%)
0.1
10
10
20kHz
1
RL = 16Ω
Vcc = 2.6V
Gv = 10
Cb = Cin = 1µF
BW < 125kHz
Tamb = 25°C
20Hz
20Hz, 1kHz
0.01
1E-3
20kHz
0.1
0.1
12/19
0.01
Output Power (W)
Fig. 43 : THD + N vs Output Power
Fig. 42 : THD + N vs Output Power
1
1
Fig. 41 : THD + N vs Output Power
Fig. 40 : THD + N vs Output Power
THD + N (%)
20Hz
0.01
Output Power (W)
1kHz
0.1
0.01
1E-3
0.01
Output Power (W)
0.1
TS4902
Fig. 44 : Signal to Noise Ratio vs Power Supply
with Unweighted Filter (20Hz to 20kHz)
Fig. 45 : Signal to Noise Ratio Vs Power Supply
with Unweighted Filter (20Hz to 20kHz)
100
90
90
RL=16Ω
80
RL=4Ω
RL=8Ω
SNR (dB)
SNR (dB)
80
70
Gv = 2
Cb = Cin = 1µF
THD+N < 0.4%
Tamb = 25°C
60
50
2.5
3.0
3.5
4.0
4.5
RL=8Ω
70
RL=4Ω
RL=16Ω
Gv = 10
Cb = Cin = 1µF
THD+N < 0.7%
Tamb = 25°C
60
50
2.5
5.0
3.0
3.5
4.0
4.5
5.0
Vcc (V)
Vcc (V)
Fig. 46 : Signal to Noise Ratio vs Power Supply
with Weighted Filter type A
Fig. 47 : Signal to Noise Ratio vs Power Supply
with Weighted Filter Type A
110
90
100
80
RL=4Ω
RL=8Ω
90
SNR (dB)
SNR (dB)
RL=16Ω
80
Gv = 2
Cb = Cin = 1µF
THD+N < 0.4%
Tamb = 25°C
70
60
2.5
3.0
3.5
4.0
4.5
RL=8Ω
70
RL=4Ω
RL=16Ω
Gv = 10
Cb = Cin = 1µF
THD+N < 0.7%
Tamb = 25°C
60
50
2.5
5.0
3.0
3.5
Fig. 48 : Current Consumption vs Power
Supply Voltage
4.5
5.0
Fig. 49 : Current Consumption vs Standby
Voltage @ Vcc = 5V
7
7
Vstandby = Vcc
Tamb = 25°C
6
6
5
5
Icc (mA)
Icc (mA)
4.0
Vcc (V)
Vcc (V)
4
3
4
3
2
2
1
1
0
0
0.0
0
1
2
3
Vcc (V)
4
5
Vcc = 5V
Tamb = 25°C
0.5
1.0
1.5
2.0
2.5 3.0 3.5
Vstandby (V)
4.0
4.5
5.0
13/19
TS4902
Fig. 50 : Current Consumption vs Standby
Voltage @ Vcc = 3.3V
Fig. 51 : Current Consumption vs Standby
Voltage @ Vcc = 2.6V
6
6
5
5
4
Icc (mA)
Icc (mA)
4
3
2
2
1
0
0.0
14/19
3
Vcc = 3.3V
Tamb = 25°C
0.5
1.0
1.5
2.0
Vstandby (V)
2.5
3.0
1
0
0.0
Vcc = 2.6V
Tamb = 25°C
0.5
1.0
1.5
Vstandby (V)
2.0
2.5
TS4902
■ BTL Configuration Principle
The TS4902 is a monolithic power amplifier with a
BTL (Bridge Tied Load) output configuration. BTL
means that each end of the load is connected to
two single ended output amplifiers. Thus, we have:
Single ended output 1 = Vout1 = Vout (V)
Single ended output 2 = Vout2 = -Vout (V)
In high frequency region, you can limit the
bandwidth by adding a capacitor (Cfeed) in
parallel with Rfeed. Its form a low pass filter with a
-3dB cut off frequency
1
F C H = ----------------------------------------------- ( Hz )
2π Rfe ed Cfeed
■ Power dissipation and efficiency
Hypothesis :
And Vout1 - Vout2 = 2Vout (V)
The output power is :
Pout =
( 2 Vout RMS ) 2
(W )
RL
For the same power supply voltage, the output
power in BTL configuration is four times higher
than the output power in single ended
configuration.
• Voltage and current in the load are sinusoidal
(Vout and Iout)
• Supply voltage is a pure DC source (Vcc)
Regarding the load we have :
V O UT = V PEAK sin ωt (V)
and
V OU T
I OU T = ----------------- (A)
RL
■ Gain In Typical Application Schematic
(cf. page 1)
In flat region (no effect of Cin), the output voltage
of the first stage is :
R fe ed
Vout1 = – Vin -------------------- (V)
Rin
For the second stage : Vout2 = -Vout1 (V)
The differential output voltage is
Rfee d
Vout2 – Vo ut1 = 2Vin -------------------- (V)
Rin
The differential gain named gain (Gv) for more
convenient usage is :
Vout2 – Vou t1
Rfee d
G v = --------------------------------------- = 2 -------------------Vin
Rin
Remark : Vout2 is in phase with Vin and Vout1 is
180 phased with Vin. It means that the positive
terminal of the loudspeaker should be connected
to Vout2 and the negative to Vout1.
■ Low and high frequency response
In low frequency region, the effect of Cin starts.
Cin with Rin forms a high pass filter with a -3dB cut
off frequency
1
F C L = -------------------------------- ( Hz )
2 π R in Cin
and
VPEAK 2
P O U T = ---------------------- (W)
2 RL
Then, the average current delivered by the supply
voltage is:
I CC
AVG
VPEAK
= 2 -------------------- (A)
πR L
The power delivered by the supply voltage is
Psupply = Vcc IccAVG (W)
Then, the power dissipated by the amplifier is
Pdiss = Psupply - Pout (W)
2 2 Vcc
P di ss = ---------------------- P OU T – P O UT (W)
π RL
and the maximum value is obtained when
∂Pdiss
---------------------- = 0
∂P OU T
and its value is:
Pdiss max =
2 Vcc 2
π2RL
(W)
Remark : This maximum value is only depending
on power supply voltage and load values.
15/19
TS4902
The efficiency is the ratio between the output
power and the power supply
P O UT
πV P E A K
η = ------------------------ = ----------------------Psup ply
4V C C
The maximum theoretical value is reached when
Vpeak = Vcc, so
π
----- = 78.5%
4
■ Decoupling of the circuit
Two capacitors are needed to bypass properly the
TS4902, a power supply bypass capacitor Cs and
a bias voltage bypass capacitor Cb.
Cs has especially an influence on the THD+N in
high frequency (above 7kHz) and indirectly on the
power supply disturbances.
With 100µF, you can expect similar THD+N
performances like shown in the datasheet.
If Cs is lower than 100µF, in high frequency
increases, THD+N and disturbances on the power
supply rail are less filtered.
To the contrary, if Cs is higher than 100µF, those
disturbances on the power supply rail are more
filtered.
Cb has an influence on THD+N in lower frequency,
but its function is critical on the final result of PSRR
with input grounded in lower frequency.
If Cb is lower than 1µF, THD+N increase in lower
frequency (see THD+N vs frequency curves) and
the PSRR worsens up
If Cb is higher than 1µF, the benefit on THD+N in
lower frequency is small but the benefit on PSRR
is substantial (see PSRR vs. Cb curve : fig.12).
Note that Cin has a non-negligible effect on PSRR
in lower frequency. Lower is its value, higher is the
PSRR (see fig. 13).
■ Pop and Click performance
Pop and Click performance is intimately linked
with the size of the input capacitor Cin and the bias
voltage bypass capacitor Cb.
Size of Cin is due to the lower cut-off frequency
and PSRR value requested. Size of Cb is due to
THD+N and PSRR requested always in lower
frequency.
16/19
Moreover, Cb determines the speed that the
amplifier turns ON. The slower the speed is, the
softer the turn ON noise is.
The charge time of Cb is directly proportional to
the internal generator resistance 50kΩ.
Then, the charge time constant for Cb is
τb = 50kΩxCb (s)
As Cb is directly connected to the non-inverting
input (pin 2 & 3) and if we want to minimize, in
amplitude and duration, the output spike on Vout1
(pin 5), Cin must be charged faster than Cb. The
charge time constant of Cin is
τin = (Rin+Rfeed)xCin (s)
Thus we have the relation
τin << τb (s)
The respect of this relation permits to minimize the
pop and click noise.
Remark : Minimize Cin and Cb has a benefit on
pop and click phenomena but also on cost and
size of the application.
Example : your target for the -3dB cut off
frequency is 100 Hz. With Rin=Rfeed=22 kΩ,
Cin=72nF (in fact 82nF or 100nF).
With Cb=1µF, if you choose the one of the latest
two values of Cin, the pop and click phenomena at
power supply ON or standby function ON/OFF will
be very small
50 kΩx1µF >> 44kΩx100nF (50ms >> 4.4ms).
Increasing Cin value increases the pop and click
phenomena to an unpleasant sound at power
supply ON and standby function ON/OFF.
Why Cs is not important in pop and click
consideration ?
Hypothesis :
• Cs = 100µF
• Supply voltage = 5V
• Supply voltage internal resistor = 0.1Ω
• Supply current of the amplifier Icc = 6mA
At power ON of the supply, the supply capacitor is
charged through the internal power supply
resistor. So, to reach 5V you need about five to ten
times the charging time constant of Cs (τs =
0.1xCs (s)).
Then, this time equal 50µs to 100µs << τb in the
majority of application.
TS4902
At power OFF of the supply, Cs is discharged by a
constant current Icc. The discharge time from 5V
to 0V of Cs is
5Cs
t D i s ch C s = -------------- = 83 ms
Icc
■ Remark on PSRR measurement conditions
What is the PSRR ?
The PSRR is the Power Supply Rejection Ratio.
Now, we must consider the discharge time of Cb.
At power OFF or standby ON, Cb is discharged by
a 100kΩ resistor. So the discharge time is about
τb Disch ≈ 3xCbx100kΩ (s).
In the majority of application, Cb=1µF, then
τbDisch≈300ms >> tdischCs.
It's a kind of SVR in a determined frequency range.
The PSRR of a device is the ratio between the
power supply disturbance and the result on the
output. We can say that the PSRR is the ability of
a device to minimize the impact of power supply
disturbances to the output.
■ How to use the PSRR curves (page 7)
How do we measure the PSRR ?
We have finished a design and we have chosen
the components values :
Fig. B : PSRR measurement schematic
• Rin=Rfeed=22kΩ, Cin=100nF, Cb=1µF
The process to obtain the final curve (Cb=100µF,
Cin=100nF, Rin=Rfeed=22kΩ) is a simple transfer
point by point on each frequency of the curve on
fig. 13 to the curve on fig. 12.
The measurement result is shown on figure A.
6
Vcc
Vripple
Vcc
Rin
4
Vin-
3
Vin+
-
Vout1 5
Vs-
+
Cin
RL
Rg
100 Ohms
2
Bypass
1
Standby
Av=-1
+
Cb
Vout2
8
Vs+
Bias
GND
Now, on fig. 13, we can see the PSRR (input
grounded) vs frequency curves. At 217Hz we have
a PSRR value of -36dB.
In fact, we want a value of about -70dB. So, we
need a gain of +34dB !
Now, on fig. 12 we can see the effect of Cb on the
PSRR (input grounded) vs. frequency. With
Cb=100µF, we can reach the -70dB value.
Rfeed
TS4902
7
■ Measurement process:
Fig. A : PSRR changes with Cb
• Fix the DC voltage supply (Vcc)
PSRR (dB)
-40
• Fix the AC sinusoidal ripple voltage (Vripple)
Vcc = 5, 3.3 & 2.6V
Rfeed = 22k, Rin = 22k
Rg = 100Ω, RL = 8Ω
Tamb = 25°C
-30
Cin=100nF
Cb=1µF
• No bypass capacitor Cs is used
The PSRR value for each frequency is :
-50
-60
PSRR ( d B ) = 20 x Log 10
Cin=100nF
Cb=100µF
Remark : The measurement of the RMS voltage is
-70
10
R ms ( V r i p pl e )
--------------------------------------------Rms ( Vs + - Vs - )
100
1000
Frequency (Hz)
10000
100000
not a selective RMS measurement but a full range
(2 Hz to 125 kHz) RMS measurement. This means
we have: the effective RMS signal + the noise.
17/19
TS4902
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO)
s
b1
b
a1
A
a2
C
c1
a3
L
E
e3
D
M
5
F
8
1
4
Millimeters
Inches
Dim.
Min.
A
a1
a2
a3
b
b1
C
c1
D
E
e
e3
F
L
M
S
18/19
Typ.
Max.
0.65
0.35
0.19
0.25
1.75
0.25
1.65
0.85
0.48
0.25
0.5
4.8
5.8
5.0
6.2
0.1
Min.
Typ.
Max.
0.026
0.014
0.007
0.010
0.069
0.010
0.065
0.033
0.019
0.010
0.020
0.189
0.228
0.197
0.244
0.004
45° (typ.)
1.27
3.81
3.8
0.4
0.050
0.150
4.0
1.27
0.6
0.150
0.016
8° (max.)
0.157
0.050
0.024
TS4902
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (miniSO)
k
0,25mm
.010inch
GAGEPLANE
C
SEATING
PLANE
E1
L1
L
c
A
E
A2
A1
4
8
1
e
C
ccc
b
D
5
PIN1IDENTIFICA TION
Dim.
Millimeters
Min.
A
A1
A2
b
c
D
E
E1
e
L
L1
k
ccc
0.050
0.780
0.250
0.130
2.900
4.750
2.900
0.400
0d
Typ.
0.100
0.860
0.330
0.180
3.000
4.900
3.000
0.650
0.550
0.950
3d
Inches
Max.
Min.
1.100
0.150
0.940
0.400
0.230
3.100
5.050
3.100
0.002
0.031
0.010
0.005
0.114
0.187
0.114
0.700
0.016
6d
0.100
0d
Typ.
0.004
0.034
0.013
0.007
0.118
0.193
0.118
0.026
0.022
0.037
3d
Max.
0.043
0.006
0.037
0.016
0.009
0.122
0.199
0.122
0.028
6d
0.004
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.
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19/19