STMICROELECTRONICS TS4900IDT

TS4900
300mW at 3.3V SUPPLY AUDIO POWER AMPLIFIER
WITH STANDBY MODE ACTIVE HIGH
■ OPERATING FROM VCC = 2.5V to 5.5V
■ 0.7W OUTPUT POWER @ Vcc=5V, THD=1%,
PIN CONNECTIONS (top view)
f=1kHz, with an 8 Ω load
■ 0.3W OUTPUT POWER @ Vcc=3.3V,
THD=1%, f=1kHz, with an 8 Ω load
■ ULTRA LOW CONSUMPTION IN STANDBY
MODE (10nA)
■ 75dB PSRR @ 217Hz from 5V to 2.6V
■ ULTRA LOW POP & CLICK
■ ULTRA LOW DISTORTION (0.1%)
■ UNITY GAIN STABLE
■ AVAILABLE IN MiniSO8 & SO8
TS4900IST - MiniSO8
Standby
1
8
VOUT2
Bypass
2
7
GND
VIN+
3
6
VCC
VIN-
4
5
VOUT1
DESCRIPTION
The TS4900 is an audio power amplifier designed
to provide the best price to power ratio while preserving high audio quality.
TS4900ID-TS4900IDT - SO8
Available in MiniSO8 & SO8 package, it is capable
of delivering up to 0.7W of continuous RMS ouput
power into an 8Ω load @ 5V.
TS4900 is also exhibiting an outstanding 0.1%
distortion level (THD) from a 5V supply for a Pout
of 200mW RMS.
Standby
1
8
VOUT2
Bypass
2
7
GND
VIN+
3
6
VCC
VIN-
4
5
VOUT1
An externally controlled standby mode control 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.
TYPICAL APPLICATION SCHEMATIC
APPLICATIONS
■ Mobile Phones (Cellular / Cordless)
■ PDAs
■ Portable Audio Devices
ORDER CODE
Part Number
TS4900IS
TS4900ID
Temperature
Range
-40, +85°C
Package
S
D
•
•
S = MiniSO Package (MiniSO) only available in Tape & Reel (ST)
D = Small Outline Package (SO) - also available in Tape & Reel (DT)
January 2002
1/19
TS4900
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
°C/W
Internally Limited4)
2
200
Class A
250
Power Dissipation
ESD
Human Body Model
ESD
Machine Model
Latch-up Latch-up Immunity
Lead Temperature (soldering, 10sec)
1.
2.
3.
4.
Value
kV
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
VSTB
Standby Voltage Input :
Device ON
Device OFF
RL
Rthja
Load Resistor
Thermal Resistance Junction to Ambient
SO8
MiniSO8
Unit
2.5 to 5.5
V
GND to VCC - 1.5V
V
GND ≤ VSTB ≤ 0.5V
VCC - 0.5V ≤ VSTB ≤ VCC
V
4 - 32
Ω
1)
1. This thermal resistance can be reduced with a suitable PCB layout (see Power Derating Curves)
2/19
Value
°C/W
150
190
TS4900
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 = Vcc, 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 Ratio2)
f = 217Hz, RL = 8Ω, RFeed = 22KΩ, Vripple = 200mV rms
75
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 Vcc
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 = Vcc, 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 Ratio2)
f = 217Hz, RL = 8Ω, RFeed = 22KΩ, Vripple = 200mV rms
75
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 Vcc
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
TS4900
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 = Vcc, 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 Ratio2)
f = 217Hz, RL = 8Ω, RFeed = 22KΩ, Vripple = 200mV rms
75
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 Vcc
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
TS4900
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
TS4900
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
TS4900
Fig. 10 : Power Supply Rejection Ratio (PSRR)
vs Power supply
Fig. 11 : Power Supply Rejection Ratio (PSRR)
vs Feedback Capacitor
-10
-30
Vripple = 200mVrms
Rfeed = 22Ω
Input = floating
RL = 8Ω
Tamb = 25°C
-50
-20
-30
PSRR (dB)
PSRR (dB)
-40
Vcc = 5V, 3.3V & 2.6V
Cb = 1µF & 0.1µF
-60
-40
Vcc = 5, 3.3 & 2.6V
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
-80
10
100
1000
10000
Frequency (Hz)
-80
10
100000
Fig. 12 : Power Supply Rejection Ratio (PSRR)
vs Bypass Capacitor
-10
Cb=10µF
PSRR (dB)
-30
-40
Cb=47µF
-50
Cin=1µF
Cin=220nF
-30
100000
Vcc = 5, 3.3 & 2.6V
Rfeed = 22kΩ, Rin = 22k
Cb = 1µF
Rg = 100Ω, RL = 8Ω
Tamb = 25°C
-40
-60
Cin=100nF
-50
-70
1000
10000
Frequency (Hz)
Cin=330nF
-20
PSRR (dB)
-20
Vcc = 5, 3.3 & 2.6V
Rfeed = 22k
Rin = 22k, Cin = 1µF
Rg = 100Ω, RL = 8Ω
Tamb = 25°C
100
Fig. 13 : Power Supply Rejection Ratio (PSRR)
vs Input Capacitor
-10
Cb=1µF
Cfeed=680pF
Cin=22nF
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, 3.3 & 2.6V
Cb = 1µF & 0.1µF
Vripple = 200mVrms
Input = floating
RL = 8Ω
Tamb = 25°C
Rfeed=110kΩ
Rfeed=47kΩ
-50
-60
Rfeed=22kΩ
-70
Rfeed=10kΩ
-80
10
100
1000
10000
Frequency (Hz)
100000
7/19
TS4900
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 = 25οC
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
1.0
0.8
Gv = 2 & 10
Cb = 1µF
F = 1kHz
BW < 125kHz
Tamb = 25°C
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
RL=4Ω
Power Dissipation (W)
Power Dissipation (W)
0.5
0.8
0.6
RL=8Ω
0.4
0.2
0.4
0.8
1.0
Power Dissipation (W)
Vcc=2.6V
f=1kHz
THD+N<1%
RL=4Ω
0.25
0.20
0.15
RL=8Ω
0.10
RL=16Ω
0.1
0.2
Output Power (W)
8/19
0.2
RL=8Ω
0.0
0.0
0.2
0.4
Fig. 20 : Power Derating Curves
0.40
0.00
0.0
0.3
Output Power (W)
Fig. 19 : Power Dissipation vs Pout
0.05
RL=4Ω
0.4
RL=16Ω
0.6
Output Power (W)
0.30
Vcc=3.3V
f=1kHz
THD+N<1%
0.1
RL=16Ω
0.2
0.35
5.0
0.6
Vcc=5V
f=1kHz
THD+N<1%
1.0
0.0
0.0
4.5
Fig. 18 : Power Dissipation vs Pout
1.4
1.2
4.0
Vcc (V)
0.3
0.6
TS4900
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 ( )
Load Resistance ( )
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
TS4900
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
TS4900
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
TS4900
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
TS4900
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
80
RL=4Ω
RL=8Ω
80
SNR (dB)
SNR (dB)
RL=16Ω
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
5.0
7
Vstandby = 0V
Tamb = 25°C
6
Vcc = 5V
Tamb = 25°C
6
5
Icc (mA)
5
Icc (mA)
4.5
Fig. 49 : Current Consumption vs Standby
Voltage @ Vcc = 5V
7
4
3
4
3
2
2
1
1
0
4.0
Vcc (V)
Vcc (V)
0
1
2
3
Vcc (V)
4
5
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Vstandby (V)
13/19
TS4900
Fig. 50 : Current Consumption vs Standby
Voltage @ Vcc = 3.3V
Fig. 51 : Current Consumption vs Standby
Voltage @ Vcc = 2.6V
6
6
Vcc = 3.3V
Tamb = 25°C
5
4
Icc (mA)
Icc (mA)
4
3
2
1
1
0.5
1.0
1.5
2.0
Vstandby (V)
14/19
3
2
0
0.0
Vcc = 2.6V
Tamb = 25°C
5
2.5
3.0
0
0.0
0.5
1.0
1.5
Vstandby (V)
2.0
2.5
TS4900
■ BTL Configuration Principle
The TS4900 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)
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.
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 :
• 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
and
VPEAK 2
P O U T = ---------------------- (W)
2 RL
Then, the average current delivered by the supply
voltage is:
For the second stage : Vout2 = -Vout1 (V)
I CC
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
In high frequency region, you can limit the
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.
The efficiency is the ratio between the output
15/19
TS4900
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
TS4900, 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.
TS4900
5Cs
t D i s ch C s = -------------- = 83 ms
Icc
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.
■ How to use the PSRR curves (page 7)
We have finished a design and we have chosen
the components values :
■ Remark on PSRR measurement conditions
What is the PSRR ?
The PSRR is the Power Supply Rejection Ratio.
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 do we measure the PSRR ?
Fig. B : PSRR measurement schematic
Rfeed
6
Vripple
Vcc
At power OFF of the supply, Cs is discharged by a
constant current Icc. The discharge time from 5V
to 0V of Cs is
Vcc
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.
Rin
4
Vin-
3
Vin+
-
Vout1 5
Cin
RL
Rg
100 Ohms
2
Bypass
1
Standby
Av=-1
+
Vout2
Fig. A : PSRR changes with Cb
8
Vs+
Bias
TS4900
Cb
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.
Vs-
+
GND
• Rin=Rfeed=22kΩ, Cin=100nF, Cb=1µF
■ Measurement process:
• Fix the DC voltage supply (Vcc)
• Fix the AC sinusoidal ripple voltage (Vripple)
• No bypass capacitor Cs is used
The PSRR value for each frequency is :
PSRR ( d B ) = 20 x Log 10
Vcc = 5, 3.3 & 2.6V
Rfeed = 22k, Rin = 22k
Rg = 100Ω, RL = 8Ω
Tamb = 25°C
-30
PSRR (dB)
-40
Cin=100nF
Cb=1µF
Remark : The measurement of the RMS voltage is
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.
-50
-60
R ms ( V r i p pl e )
--------------------------------------------Rms ( Vs + - Vs - )
Cin=100nF
Cb=100µF
-70
10
100
1000
10000
100000
Frequency (Hz)
17/19
TS4900
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
TS4900
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
ccc C
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
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consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
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19/19