1/28
■OPERATING FROM VCC = 2.5V to 5.5V
■1W RAIL TO RAIL OUTPUT POWER @
Vcc=5V, THD=1%, f=1kHz, with 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
DESCRIPTION
The TS4871 (MiniSO8 & SO8) is an Audio Power
Amplifier capable of delivering 1W of continuous
RMS Ouput Power into 8Ωload @ 5V.
This Audio Amplifier is exhibiting 0.1% distortion
level (THD) from a 5V supply for a Pout = 250mW
RMS. An external standby mode control reduces
the supply current to less than 10nA. An internal
thermal shutdown protection is also provided.
The TS4871 has been designed for high quality
audio applications such as mobile phones and to
minimize the number of external components.
The unity-gain stable amplifier can be configured
by external gain setting resistors.
APPLICATIONS
■Mobile Phones (Cellular / Cordless)
■Laptop / Notebook Computers
■PDAs
■Portable Audio Devices
ORDER CODE
S=MiniSO Package (MiniSO) - also available in Tape & Reel (ST)
D=Small Outline Package (SO) - also available in Tape & Reel (DT)
PIN CONNECTIONS (Top View)
Part Number Temperature
Range Package
SD
TS4871IS -40, +85°C•
TS4871ID •
Standby
Bypass
V+
IN
VIN-
V2OUT
GND
VCC
VOUT1
1
2
3
4
8
7
6
5
Rin
Cin
Rstb
Cb
Rfeed
4
3
2
1
5
8
Vin-
Vin+
-
+
-
+
Bypass
Standby Bias
6
Vout1
Vout2
Av=-1
TS4871
RL
8 Ohms
Vcc
GND
Audio
Input
Vcc
Vcc
Cfeed
Cs
7
TYPICAL APPLICATION SCHEMATIC
TS4871IS-TS4871IST - MiniSO8
TS4871ID-TS4871IDT - SO8
Standby
Bypass
V+
IN
VIN-
V2OUT
GND
VCC
VOUT1
1
2
3
4
8
7
6
5
TS4871
OUTPUT RAIL TO TAIL 1W AUDIO POWER AMPLIFIER
WITH STANDBY MODE
November 2001
TS4871
2/28
ABSOLUTE MAXIMUM RATINGS
OPERATING CONDITIONS
Symbol Parameter Value Unit
VCC Supply voltage 1) 6V
V
i
Input Voltage 2) GND toVCC V
Toper Operating Free Air Temperature Range -40 to + 85 °C
Tstg Storage Temperature -65 to +150 °C
TjMaximum Junction Temperature 150 °C
Rthja Thermal Resistance Junction to Ambient 3)
SO8
MiniSO8 175
215
°C/W
Pd Power Dissipation Internally Limited4)
ESD Human Body Model 2 kV
ESD Machine Model 200 V
Latch-up Latch-up Immunity Class A
Lead Temperature (soldering, 10sec) 260 °C
1. All voltages values are measured with respect to the ground pin.
2. The magnitude of input signal must never exceed VCC +0.3V/G
ND - 0.3V
3. Device is protected in case of over temperature by a thermal shutdown active @ 150°C.
4. Exceeding the power derating curves during a long period, involves abnormal operating condition.
Symbol Parameter Value Unit
VCC Supply Voltage 2.5 to 5.5 V
VICM Common Mode Input Voltage Range GND to VCC - 1.5V V
VSTB Standby Voltage Input :
Device ON
Device OFF GND ≤VSTB ≤0.5V
VCC - 0.5V ≤VSTB ≤VCC V
RLLoad Resistor 4 - 32 Ω
Rthja Thermal Resistance Junction to Ambient 1)
SO8
MiniSO8 150
190
°C/W
1. This thermal resistance can be reduced with a suitable PCB layout (see Power Derating Curves Fig. 20)
TS4871
3/28
ELECTRICAL CHARACTERISTICS
VCC =+5V, GND = 0V,T
amb =25°C (unless otherwise specified)
VCC =+3.3V, GND = 0V,T
amb =25°C (unless otherwise specified)3)
Symbol Parameter Min. Typ. Max. Unit
ICC Supply Current
No input signal, no load 68mA
I
STANDBY Standby Current 1)
No input signal, Vstdby = Vcc, RL = 8Ω
1. Standby mode is actived when Vstdby is tied to Vcc
10 1000 nA
Voo Output OffsetVoltage
No input signal, RL = 8Ω520mV
Po Output Power
THD = 1% Max, f = 1kHz, RL = 8Ω1W
THD + N Total Harmonic Distortion + Noise
Po = 250mW rms, Gv = 2, 20Hz < f < 20kHz, RL = 8Ω0.15 %
PSRR Power Supply Rejection Ratio2)
f = 217Hz, RL = 8
Ω,
RFeed = 22K
Ω,
Vripple = 200mV rms
2. Dynamic measurements - 20*log(rms(Vout)/rms(Vripple)). Vripple is the surimposed sinus signal to Vcc @ f = 217Hz
75 dB
ΦMPhase Margin at Unity Gain
RL=8Ω,C
L= 500pF 70 Degrees
GM Gain Margin
RL=8Ω,C
L= 500pF 20 dB
GBP Gain Bandwidth Product
RL=8Ω2MHz
Symbol Parameter Min. Typ. Max. Unit
ICC Supply Current
No input signal, no load 5.5 8 mA
ISTANDBY Standby Current 1)
No input signal, Vstdby = Vcc, RL = 8Ω
1. Standby mode is actived when Vstdby is tied to Vcc
10 1000 nA
Voo Output OffsetVoltage
No input signal, RL = 8Ω520mV
Po Output Power
THD = 1% Max, f = 1kHz, RL = 8Ω450 mW
THD + N Total Harmonic Distortion + Noise
Po = 250mW rms, Gv = 2, 20Hz < f < 20kHz, RL = 8Ω0.15 %
PSRR Power Supply Rejection Ratio2)
f = 217Hz, RL = 8
Ω,
RFeed = 22K
Ω,
Vripple = 200mV rms
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
75 dB
ΦMPhase Margin at Unity Gain
RL=8Ω,C
L= 500pF 70 Degrees
GM Gain Margin
RL=8Ω,C
L= 500pF 20 dB
GBP Gain Bandwidth Product
RL=8Ω2MHz
TS4871
4/28
ELECTRICAL CHARACTERISTICS
VCC =2.6V, GND = 0V,T
amb =25°C (unless otherwise specified)
REMARKS
1. All measurements, except PSRR measurements, are made with a supply bypass capacitor Cs = 100µF.
2. External resistors are not needed for having better stabilitywhen supply @Vcc downto 3V. By the way,
the quiescent current remains the same.
3. The standby response time is about 1µs.
Symbol Parameter Min. Typ. Max. Unit
ICC Supply Current
No input signal, no load 5.5 8 mA
ISTANDBY Standby Current 1)
No input signal, Vstdby = Vcc, RL = 8Ω
1. Standby mode is actived when Vstdby is tied to Vcc
10 1000 nA
Voo Output OffsetVoltage
No input signal, RL = 8Ω520mV
Po Output Power
THD = 1% Max, f = 1kHz, RL = 8Ω260 mW
THD + N Total Harmonic Distortion + Noise
Po = 200mW rms, Gv = 2, 20Hz < f < 20kHz, RL = 8Ω0.15 %
PSRR Power Supply Rejection Ratio2)
f = 217Hz, RL = 8
Ω,
RFeed = 22K
Ω,
Vripple = 200mV rms
2. Dynamic measurements - 20*log(rms(Vout)/rms(Vripple)). Vripple is the surimposed sinus signal to Vcc @ f = 217Hz
75 dB
ΦMPhase Margin at Unity Gain
RL=8Ω,C
L= 500pF 70 Degrees
GM Gain Margin
RL=8Ω,C
L= 500pF 20 dB
GBP Gain Bandwidth Product
RL=8Ω2MHz
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 Low pass filter capacitor allowing to cut the high frequency
(low pass filter cut-off frequency 1 / (2 x Pi x Rfeed x Cfeed))
Rstb Pull-up resistor which fixes the right supply level on the standby pin
Gv Closed loop gain in BTL configuration = 2 x (Rfeed / Rin)
TS4871
5/28
Fig. 1 : Open Loop Frequency Response
Fig. 3 : Open Loop Frequency Response
Fig. 5 : Open Loop Frequency Response
Fig. 2 : Open Loop Frequency Response
Fig. 4 : Open Loop Frequency Response
Fig. 6 : Open Loop Frequency Response
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
-220
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Gain (dB)
Frequency (kHz)
Vcc = 5V
RL = 8Ω
Tamb =
25
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
-240
-220
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Gain (dB)
Frequency (kHz)
Vcc = 3.3V
RL = 8Ω
Tamb = 2
5
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
-240
-220
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Gain (dB)
Frequency (kHz)
Vcc = 2.6V
RL =8Ω
Tamb =
25
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
-220
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Gain (dB)
Frequency (kHz)
Vcc = 5V
ZL = 8Ω+ 560pF
Tamb =
25
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
-240
-220
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Gain (dB)
Frequency (kHz)
Vcc = 3.3V
ZL = 8Ω+ 560pF
Tamb =
25
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
-240
-220
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
Gain (dB)
Frequency (kHz)
Vcc = 2.6V
ZL = 8Ω+ 560pF
Tamb =
25
C
Gain
Phase
Phase (Deg)
TS4871
6/28
Fig. 7 : Open Loop Frequency Response
Fig. 9 : Open Loop Frequency Response
Fig. 8 : Open Loop Frequency Response
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
100
-220
-200
-180
-160
-140
-120
-100
-80
Gain (dB)
Frequency (kHz)
Vcc = 5V
CL = 560pF
Tamb =
25
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
100
-240
-220
-200
-180
-160
-140
-120
-100
-80
Gain (dB)
Frequency (kHz)
Vcc = 2.6V
CL = 560pF
Tamb =
25
C
Gain
Phase
Phase (Deg)
0.3 1 10 100 1000 10000
-40
-20
0
20
40
60
80
100
-240
-220
-200
-180
-160
-140
-120
-100
-80
Gain (dB)
Frequency (kHz)
Vcc = 3.3V
CL = 560pF
Tamb = 2
5
C
Gain
Phase
Phase (Deg)
TS4871
7/28
Fig. 10 : Power Supply Rejection Ratio (PSRR)
vs Power supply
Fig. 12 : Power Supply Rejection Ratio (PSRR)
vs Bypass Capacitor
Fig. 14 : Power Supply Rejection Ratio (PSRR)
vs Feedback Resistor
Fig. 11 : Power Supply RejectionRatio (PSRR)
vs Feedback Capacitor
Fig. 13 : Power Supply RejectionRatio (PSRR)
vs Input Capacitor
10 100 1000 10000 100000
−80
−70
−60
−50
−40
−30
Vcc = 5V, 3.3V & 2.6V
Cb = 1µF& 0.1µF
Vripple = 200mVrms
Rfeed = 22kΩ
Input = floating
RL = 8Ω
Tamb = 25°C
PSRR (dB)
Frequency(Hz)
10 100 1000 10000 100000
−80
−70
−60
−50
−40
−30
−20
−10
Cb=100µF
Cb = 1µF
Cb = 10µF
Cb = 100µF
Cb = 47µF
Cb=47µF
Cb=10µF
Cb=1µFVcc = 5, 3.3 & 2.6V
Rfeed = 22k
Rin = 22k, Cin = 1µF
Rg = 100Ω,RL=8Ω
Tamb = 25°C
PSRR (dB)
Frequency (Hz)
10 100 1000 10000 100000
−80
−70
−60
−50
−40
−30
−20
−10
Rfeed=10kΩ
Rfeed=22kΩ
Rfeed=47kΩ
Rfeed=110kΩ
Vcc= 5, 3.3& 2.6V
Cb = 1µF & 0.1µF
Vripple= 200mVrms
Input = floating
RL = 8Ω
Tamb = 25°C
PSRR (dB)
Frequency (Hz)
10 100 1000 10000 100000
−80
−70
−60
−50
−40
−30
−20
−10
Cfeed=680pF
Cfeed=330pF
Cfeed=150pF
Cfeed=0
Vcc = 5, 3.3 & 2.6V
Cb = 1µF & 0.1µF
Rfeed = 22kΩ
Vripple = 200mVrms
Input = floating
RL = 8Ω
Tamb = 25°C
PSRR (dB)
Frequency(Hz)
10 100 1000 10000 100000
−60
−50
−40
−30
−20
−10
Cin=22nF
Cin=100nF
Cin=220nF
Cin=330nF
Cin=1µFVcc = 5, 3.3 & 2.6V
Rfeed = 22k, Rin= 22k
Cb = 1µF
Rg = 100Ω,RL=8Ω
Tamb =25°C
PSRR (dB)
Frequency (Hz)
TS4871
8/28
Fig. 15 : Pout @ THD + N = 1% vs Supply
Voltage vs RL
Fig. 17 : Power Dissipation vs Pout
Fig. 19 : Power Dissipation vs Pout
Fig. 16 : Pout @ THD + N = 10% vs Supply
Voltage vs RL
Fig. 18 : Power Dissipation vs Pout
Fig. 20 : Power Derating Curves
2.5 3.0 3.5 4.0 4.5 5.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 Gv = 2 & 10
Cb = 1 F
F = 1kHz
BW< 125kHz
Tamb=
25
C
32 Ω
16 Ω
4Ω
6Ω
8Ω
Output power @ 1% THD + N (W)
Vcc (V)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 Vcc=5V
F=1kHz
THD+N<1%
RL=16Ω
RL=8Ω
RL=4Ω
Power Dissipation (W)
Output Power (W)
0.0 0.1 0.2 0.3 0.4
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40 Vcc=2.6V
F=1kHz
THD+N<1%
RL=16Ω
RL=8Ω
RL=4Ω
Power Dissipation (W)
Output Power (W)
2.5 3.0 3.5 4.0 4.5 5.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4 Gv = 2 & 10
Cb = 1 F
F = 1kHz
BW< 125kHz
Tamb=
25
C
32Ω
16 Ω
4Ω
6Ω
8Ω
Output power @ 1% THD + N (W)
Vcc (V)
0.0 0.2 0.4 0.6 0.8
0.0
0.1
0.2
0.3
0.4
0.5
0.6 Vcc=3.3V
F=1kHz
THD+N<1% RL=4Ω
RL=8Ω
RL=16Ω
Power Dissipation (W)
Output Power (W)
0 25 50 75 100 125 150
0.0
0.2
0.4
0.6
0.8
1.0
1.2
MiniSO8 SO8
MiniSO8on
demoboard
SO8 on
demoboard
Power Dissipation (W)
Ambiant Temperature (°C)
TS4871
9/28
Fig. 21 : THD + N vs Output Power
Fig. 23 : THD + N vs Output Power
Fig. 25 : THD + N vs Output Power
Fig. 22 : THD + N vs Output Power
Fig. 24 : THD + N vs Output Power
Fig. 26 : THD + N vs Output Power
1E-3 0.01 0.1 1
0.1
1
10 Rl = 4Ω
Vcc = 5V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 4Ω, Vcc = 3.3V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.1
1
10 RL = 4Ω, Vcc = 2.6V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power(W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 4Ω, Vcc = 5V
Gv = 10
Cb = Cin = 1 F
BW < 125kHz, Tamb = 25 C
20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 4Ω, Vcc = 3.3V
Gv = 10
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C 20kHz
20Hz 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.1
1
10 RL = 4Ω, Vcc = 2.6V
Gv = 10
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
TS4871
10/28
Fig. 27 : THD + N vs Output Power
Fig. 29 : THD + N vs Output Power
Fig. 31 : THD + N vs Output Power
Fig. 28 : THD + N vs Output Power
Fig. 30 : THD + N vs Output Power
Fig. 32 : THD + N vs Output Power
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω
Vcc = 5V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω, Vcc = 3.3V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.1
1
10
RL = 8Ω, Vcc = 2.6V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power(W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω
Vcc = 5V
Gv = 10
Cb = Cin = 1 F
BW <125kHz
Tamb = 25 C
20kHz20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω, Vcc = 3.3V
Gv = 10
Cb = Cin = 1 F
BW <125kHz
Tamb = 25 C
20kHz20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.1
1
10
RL = 8Ω, Vcc = 2.6V
Gv = 10
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
TS4871
11/28
Fig. 33 : THD + N vs Output Power
Fig. 35 : THD + N vs Output Power
Fig. 37 : THD + N vs Output Power
Fig. 34 : THD + N vs Output Power
Fig. 36 : THD + N vs Output Power
Fig. 38 : THD + N vs Output Power
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω
Vcc = 5V
Gv = 2
Cb = 0.1 F, Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz 20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω, Vcc = 3.3V
Gv = 2
Cb = 0.1 F, Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.1
1
10 RL = 8Ω, Vcc = 2.6V
Gv = 2
Cb = 0.1 F, Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz
1kHz
THD + N (%)
Output Power(W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω, Vcc = 5V, Gv = 10
Cb = 0.1 F, Cin = 1 F
BW < 125kHz, Tamb = 25 C
20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.1
1
10 RL = 8Ω, Vcc = 3.3V, Gv = 10
Cb = 0.1 F, Cin = 1 F
BW < 1 25kHz, Tamb = 25 C
20kHz 20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.1
1
10 RL = 8Ω, Vcc = 2.6V, Gv = 10
Cb = 0.1 F, Cin = 1 F
BW < 125kHz, Tamb = 25 C
20kHz 20Hz
1kHz
THD + N (%)
Output Power (W)
TS4871
12/28
Fig. 39 : THD + N vs Output Power
Fig. 41 : THD + N vs Output Power
Fig. 43 : THD + N vs Output Power
Fig. 40 : THD + N vs Output Power
Fig. 42 : THD + N vs Output Power
Fig. 44 : THD + N vs Output Power
1E-3 0.01 0.1 1
0.01
0.1
1
10 RL = 16Ω, Vcc = 5V
Gv = 2
Cb = Cin = 1 F
BW <125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.01
0.1
1
10
RL = 16Ω, Vcc = 3.3V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.01
0.1
1
10
RL = 16Ω
Vcc = 2.6V
Gv = 2
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C
20kHz
20Hz, 1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1 1
0.01
0.1
1
10 RL = 16Ω, Vcc = 5V
Gv = 10
Cb = Cin = 1 F
BW <125kHz
Tamb = 25 C
20kHz
20Hz1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.01
0.1
1
10
RL = 16Ω
Vcc = 3.3V
Gv = 10
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C 20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
1E-3 0.01 0.1
0.01
0.1
1
10
RL = 16Ω
Vcc = 2.6V
Gv = 10
Cb = Cin = 1 F
BW < 125kHz
Tamb = 25 C 20kHz
20Hz
1kHz
THD + N (%)
Output Power (W)
TS4871
13/28
Fig. 45 : THD + N vs Frequency
Fig. 47 : THD + N vs Frequency
Fig. 49 : THD + N vs Frequency
Fig. 46 : THD + N vs Frequency
Fig. 48 : THD + N vs Frequency
Fig. 50 : THD + N vs Frequency
20 100 1000 10000
0.1
1
Pout = 600mW
Pout = 1.2W
RL =4Ω, Vcc = 5V
Gv =2
Cb =1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Pout = 270mW
Pout = 540mW
RL =4Ω, Vcc = 3.3V
Gv =2
Cb =1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Pout = 120mW
Pout = 240mW
RL =4Ω, Vcc = 2.6V
Gv =2
Cb =1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.01
0.1
1
Pout = 600mW
Pout = 1.2W
RL = 4Ω, Vcc = 5V
Gv = 10
Cb = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Pout = 270mW
Pout = 540mW
RL = 4Ω, Vcc = 3.3V
Gv = 10
Cb = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Pout = 240 & 120mW
RL = 4Ω, Vcc = 2.6V
Gv = 10
Cb = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
TS4871
14/28
Fig. 51 : THD + N vs Frequency
Fig. 53 : THD + N vs Frequency
Fig. 55 : THD + N vs Frequency
Fig. 52 : THD + N vs Frequency
Fig. 54 : THD + N vs Frequency
Fig. 56 : THD + N vs Frequency
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω
Vcc = 5V
Gv = 2
Pout = 900mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 5V
Gv = 10
Pout = 900mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 3.3V
Gv = 2
Pout = 400mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω
Vcc = 5V
Gv = 2
Pout =450mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 5V
Gv = 10
Pout =450mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 3.3V
Gv = 2
Pout = 200mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
TS4871
15/28
Fig. 57 : THD + N vs Frequency
Fig. 59 : THD + N vs Frequency
Fig. 61 : THD + N vs Frequency
Fig. 58 : THD + N vs Frequency
Fig. 60 : THD + N vs Frequency
Fig. 62 : THD + N vs Frequency
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 3.3V
Gv = 10
Pout = 400mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency(Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 2.6V
Gv = 2
Pout = 220mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 2.6V
Gv = 10
Pout = 220mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 3.3V
Gv = 10
Pout = 200mW
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Cb = 0.1µF
Cb = 1µF
RL = 8Ω, Vcc = 2.6V
Gv = 2
Pout = 110mW
BW < 125kHz
Tamb =25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1Cb = 0.1µF
Cb = 1µF
RL =8Ω, Vcc = 2.6V
Gv =10
Pout = 110mW
BW < 125kHz
Tamb =25°C
THD + N (%)
Frequency (Hz)
TS4871
16/28
Fig. 63 : THD + N vs Frequency
Fig. 65 : THD + N vs Frequency
Fig. 67 : THD + N vs Frequency
Fig. 64 : THD + N vs Frequency
Fig. 66 : THD + N vs Frequency
Fig. 68 : THD + N vs Frequency
20 100 1000 10000
0.01
0.1
1
Pout = 310mW
Pout = 620mW
RL = 16Ω, Vcc = 5V
Gv = 2, Cb = 1µF
BW < 125kHz
Tamb =25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.01
0.1
1
Pout = 135mW
Pout = 270mW
RL = 16Ω, Vcc = 3.3V
Gv = 2, Cb = 1µF
BW <125kHz
Tamb =25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.01
0.1
1
Pout =80mW
Pout = 160mW
RL = 16Ω, Vcc = 2.6V
Gv = 2, Cb = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.01
0.1
1
Pout = 310mW
Pout = 620mW
RL = 16Ω, Vcc = 5V
Gv = 10, Cb = 1µF
BW <125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.1
1
Pout = 135mW
Pout =270mW
RL = 16Ω, Vcc = 3.3V
Gv = 10
Cb = 1µF
BW < 125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
20 100 1000 10000
0.01
0.1
1
Pout = 80mW
Pout = 160mW
RL = 16Ω, Vcc = 2.6V
Gv = 10, Cb = 1µF
BW <125kHz
Tamb = 25°C
THD + N (%)
Frequency (Hz)
TS4871
17/28
Fig. 69 : Signal to Noise Ratio vs Power Supply
with Unweighted Filter (20Hz to 20kHz)
Fig. 71 : Signal to Noise Ratio vs Power Supply
with Weighted Filter type A
Fig. 73 : Frequency Response Gain vs Cin, &
Cfeed
Fig. 70 :SignaltoNoiseRatio Vs Power Supply
with Unweighted Filter (20Hz to 20kHz)
Fig. 72: Signalto NoiseRatio vs Power Supply
with Weighted Filter Type A
Fig. 74 : Current Consumption vs Power
Supply Voltage
2.5 3.0 3.5 4.0 4.5 5.0
50
60
70
80
90
100
RL=8ΩRL=4ΩRL=16Ω
Gv = 2
Cb = Cin = 1µF
THD+N < 0.4%
Tamb = 25°C
SNR (dB)
Vcc (V)
2.5 3.0 3.5 4.0 4.5 5.0
60
70
80
90
100
110
RL=8ΩRL=4Ω
RL=16Ω
Gv = 2
Cb = Cin = 1µF
THD+N < 0.4%
Tamb = 25°C
SNR (dB)
Vcc (V)
10 100 1000 10000
-25
-20
-15
-10
-5
0
5
10
Rin = Rfeed = 22kΩ
Tamb = 25 C
Cfeed = 2.2nF
Cfeed =680pF
Cfeed = 330pF
Cin = 470nF
Cin = 82nF
Cin = 22nF
Gain (dB)
Frequency(Hz)
2.5 3.0 3.5 4.0 4.5 5.0
50
60
70
80
90
RL=16ΩRL=4ΩRL=8Ω
Gv = 10
Cb = Cin = 1µF
THD+N < 0.7%
Tamb = 25°C
SNR (dB)
Vcc (V)
2.5 3.0 3.5 4.0 4.5 5.0
60
70
80
90
100
RL=16ΩRL=4ΩRL=8Ω
Gv = 10
Cb = Cin = 1µF
THD+N < 0.7%
Tamb = 25°C
SNR (dB)
Vcc (V)
012345
0
1
2
3
4
5
6
7
Vstandby = 0V
Tamb = 25°C
Icc (mA)
Vcc (V)
TS4871
18/28
Fig. 75 : Current Consumption vs Standby
Voltage @ Vcc = 5V
Fig. 77 : Current Consumption vs Standby
Voltage @ Vcc = 2.6V
Fig. 79 : Clipping Voltage vs Power Supply
Voltage and Load Resistor
Fig. 76 : Current Consumption vs Standby
Voltage @ Vcc = 3.3V
Fig. 78 : Clipping Voltage vs Power Supply
Voltage and Load Resistor
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0
1
2
3
4
5
6
7Vcc =5V
Tamb = 25°C
Icc (mA)
Vstandby (V)
0.0 0.5 1.0 1.5 2.0 2.5
0
1
2
3
4
5
6Vcc= 2.6V
Tamb= 25°C
Icc (mA)
Vstandby (V)
2.5 3.0 3.5 4.0 4.5 5.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 Tamb=
25
C
RL = 16Ω
RL = 8ΩRL = 4Ω
Vout1 & Vout2
Clipping Voltage High side (V)
Power supply Voltage (V)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0
1
2
3
4
5
6Vcc = 3.3V
Tamb= 25°C
Icc (mA)
Vstandby (V)
2.5 3.0 3.5 4.0 4.5 5.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0 Tamb =
25
C
RL = 16Ω
RL = 8Ω
RL = 4Ω
Vout1 & Vout2
Clipping Voltage Low side (V)
Power supply Voltage (V)
TS4871
19/28
APPLICATION INFORMATION
Fig. 80 : Demoboard Schematic
Fig. 81 : SO8 & MiniSO8 Demoboard Components Side
4
3
2
1
5
8
Vin-
Vin+
-
+
-
+
Bypass
Standby Bias
6
Vout1
Vout2
Av=-1
TS4871
Vcc
GND
Vcc
7
+
470µ
S6
OUT1
S3
GND
S4
GND
S7
C10
+
470µ
C9
C7
100n
C6
100µ+
R1
R2 C2
C1
C8
C12
1u
C11
Vcc
R7
330k
S8
Standby
D1
PW ON
R8
Vcc
S5
Positive Input mode
R6
Posinput
P2
Neg. input
P1
C4 R5
R4 C5
R3 C3
GND
S2
Vcc S1 Vcc
+
TS4871
20/28
Fig. 82 : SO8 & MiniSO8 Demoboard Top
Solder Layer
Fig. 83 : SO8 & MiniSO8 Demoboard Bottom Solder
Layer
■BTL Configuration Principle
The TS4871 is a monolithic power amplifierwith a
BTL output type. BTL (Bridge Tied Load) 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:
For the same power supply voltage, the output
power in BTL configuration is four times higher
than the output power in single ended
configuration.
■Gain In Typical Application Schematic
(cf. page 1)
In flat region (no effect of Cin), the output voltage
of the first stage is:
For the second stage : Vout2= -Vout1 (V)
The differential output voltage is:
The differential gain named gain (Gv) for more
convenient usage is:
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 withRinforms a high pass filter witha -3dB cut
off frequency.
In high frequency region, you can limit the
bandwidth by adding a capacitor (Cfeed) in
parallel on Rfeed. Its form a low pass filter with a
-3dB cut offfrequency.
)W(
R)Vout2(
Pout L
2
RMS
=
Vout1 = Vin–Rfeed
Rin
-------------------- (V)
Vout2 Vout1 = 2Vin–Rfeed
Rin
-------------------- (V)
Gv = Vout2 Vout1–
Vin
-------------------------------------- - = 2 Rfeed
Rin
--------------------
FCL =1
2πRin Cin
-------------------------------- H z()
FCH =1
2πRfeed Cfeed
-----------------------------------------------Hz()
TS4871
21/28
■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:
and
and
Then, theaverage current delivered bythe supply
voltage is:
The power delivered by the supply voltage is
Psupply = Vcc IccAVG (W)
Then, the power dissipated by the amplifier is
Pdiss = Psupply - Pout (W)
and the maximum value is obtained when:
and its value is:
Remark : This maximum value is only depending
on power supply voltage and load values.
The efficiency is the ratio between the output
power and the power supply
The maximum theoretical value is reached when
Vpeak = Vcc, so
■Decoupling of the circuit
Twocapacitors are needed to bypass properly the
TS4871, 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 anddisturbances 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 aninfluence onTHD+N in lowerfrequency,
but its function iscritical 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 anon-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 thesize ofthe 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.
Moreover, Cb determines the speed that the
amplifier turns ON. The slower the speed is, the
softer the turn ON noise is.
VOUT =V
PEAK sinωt(V)
IOUT =VOUT
RL
----------------- (A)
POUT =VPEAK2
2RL
---------------------- (W)
ICC AVG =2
VPEAK
πRL
-------------------- (A)
Pdiss =22Vcc
πRL
---------------------- P OUT POUT (W)–
∂Pdiss
∂POUT
---------------------- = 0
)W(
R
Vcc2
maxPdiss L
2
2
π
=
η=POUT
Psupply
------------------------ = πVPEAK
4VCC
-----------------------
π4
----- = 78.5%
TS4871
22/28
The charge time of Cb is directly proportional to
the internal generator resistance 50kΩ.
Then, the charge time constant for Cbis
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 valuesof Cin, the pop and click phenomenaat
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 powerON 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.
At power OFF of the supply, Csis dischargedby a
constant current Icc. The discharge time from 5V
to 0V of Cs is:
Now, we must consider the discharge time of Cb.
At powerOFF or standby ON, Cb is discharged by
a 100kΩresistor. So the discharge time is about
τbDisch ≈3xCbx100kΩ(s).
In the majority of application, Cb=1µF, then
τbDisch≈300ms >> tdischCs.
■Power amplifier design examples
Given :
•Load impedance : 8Ω
•Output power @ 1% THD+N : 0.5W
•Input impedance : 10kΩmin.
•Input voltage peak to peak : 1Vpp
•Bandwidth frequency : 20Hz to 20kHz (0, -3dB)
•Ambient temperature max = 50°C
•SO8 package
First of all, we must calculate the minimum power
supply voltage to obtain 0.5W into 8Ω. Withcurves
in fig. 15, we can read 3.5V. Thus, the power
supply voltage value min. will be 3.5V.
Following the maximum power dissipation
equation
with 3.5V we have Pdissmax=0.31W.
Refer to power derating curves (fig. 20), with
0.31W the maximum ambient temperature will be
100°C. This last value could be higher if you follow
the example layout shown on the demoboard
(better dissipation).
The gain of the amplifier in flat region will be:
tDischCs =5Cs
Icc
-------------- = 83 ms
)W(
R
Vcc2
maxPdiss L
2
2
π
=
GV=VOUTPP
VINPP
---------------------=
22RLPOUT
VINPP
----------------------------------- - = 5.65
TS4871
23/28
We have Rin > 10kΩ. Let’s take Rin = 10kΩ, then
Rfeed =28.25kΩ. We could use for Rfeed = 30kΩ
in normalized value and the gain will be Gv = 6.
In lower frequency we want 20 Hz (-3dB cut off
frequency). Then:
So, we could use for Cin a 1µF capacitor value
which gives 16Hz.
In Higher frequency we want 20kHz (-3dB cut off
frequency). The Gain Bandwidth Product of the
TS4871 is 2MHz typical and doesn’t change when
the amplifier delivers power into the load.
The first amplifier has a gain of:
and the theoretical value of the-3dB cut-offhigher
frequency is 2MHz/3 = 660kHz.
We can keep this value or limit the bandwidth by
adding a capacitor Cfeed, in parallel on Rfeed.
Then:
So, we could use for Cfeed a 220pF capacitor
value that gives 24kHz.
Now, we can calculate the value of Cb with the
formula τb = 50kΩxCb >> τin = (Rin+Rfeed)xCin
which permits to reduce the pop and click effects.
Then Cb >> 0.8µF.
We canchoose for Cb a normalizedvalue of 2.2µF
that gives good results in THD+N and PSRR.
In the following tables, you could find three
another examples with values required for the
demoboard.
Remark : components with (*) marking are
optional.
Application n°1 : 20Hz to 20kHz bandwidth and
6dB gain BTL power amplifier.
Components :
Application n°2 : 20Hz to 20kHz bandwidth and
20dB gain BTL power amplifier.
Components :
CIN =1
2πRinFCL
------------------------------ = 795nF
Rfeed
Rin
----------------- = 3
CFEED =1
2πRFEEDFCH
--------------------------------------- = 265pF
Designator Part Type
R1 22k / 0.125W
R4 22k / 0.125W
R6 Short Cicuit
R7 330k / 0.125W
R8* (Vcc-Vf_led)/If_led
C5 470nF
C6 100µF
C7 100nF
C9 Short Circuit
C10 Short Circuit
C12 1µF
S1, S2, S6, S7 2mm insulated Plug
10.16mm pitch
S8 3 pts connector 2.54mm
pitch
P1 PCB Phono Jack
D1* Led 3mm
U1 TS4871ID or TS4871IS
Designator Part Type
R1 110k / 0.125W
R4 22k / 0.125W
R6 Short Cicuit
R7 330k / 0.125W
R8* (Vcc-Vf_led)/If_led
C5 470nF
C6 100µF
C7 100nF
TS4871
24/28
Application n°3 : 50Hz to 10kHz bandwidth and
10dB gain BTL power amplifier.
Components :
Application n°4 : Differential inputsBTL power
amplifier.
In this configuration, we need to place these
components : R1, R4, R5, R6, R7, C4, C5, C12.
We have also : R4 = R5, R1 = R6, C4 = C5.
The gain of the amplifier is:
For a 20Hz to 20kHz bandwidth and 6dB gain BTL
power amplifier you could follow the bill of material
below.
Components :
C9 Short Circuit
C10 Short Circuit
C12 1µF
S1, S2, S6, S7 2mm insulated Plug
10.16mm pitch
S8 3 pts connector 2.54mm
pitch
P1 PCB Phono Jack
D1* Led 3mm
U1 TS4871ID or TS4871IS
Designator Part Type
R1 33k / 0.125W
R2 Short Circuit
R4 22k / 0.125W
R6 Short Cicuit
R7 330k / 0.125W
R8* (Vcc-Vf_led)/If_led
C2 470pF
C5 150nF
C6 100µF
C7 100nF
C9 Short Circuit
C10 Short Circuit
C12 1µF
S1, S2, S6, S7 2mm insulated Plug
10.16mm pitch
S8 3 pts connector 2.54mm
pitch
P1 PCB Phono Jack
D1* Led 3mm
U1 TS4871ID or TS4871IS
Designator Part Type
Designator Part Type
R1 22k / 0.125W
R4 22k / 0.125W
R5 22k / 0.125W
R6 22k / 0.125W
R7 330k / 0.125W
R8* (Vcc-Vf_led)/If_led
C4 470nF
C5 470nF
C6 100µF
C7 100nF
C9 Short Circuit
C10 Short Circuit
C12 1µF
D1* Led 3mm
S1, S2, S6, S7 2mm insulated Plug
10.16mm pitch
S8 3 pts connector 2.54mm
pitch
P1, P2 PCB Phono Jack
U1 TS4871ID or TS4871IS
GVDIFF =2R1
R4
-------- (Pos. Input - Neg.Input)
TS4871
25/28
■Note on how to use the PSRR curves
(page 7)
We have finished a design and we have chosen
the components values :
•Rin=Rfeed=22kΩ
•Cin=100nF
•Cb=1µF
Now, on fig. 13, we can see the PSRR (input
grounded) vs frequency curves. At 217Hz we have
a PSRR value of -36dB.
In reality we want a value 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.
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 the next
figure.
Fig. 84 : PSRR changes with Cb
10 100 1000 10000 100000
−70
−60
−50
−40
−30
Cin=100nF
Cb=100µF
Cin=100nF
Cb=1µF
Vcc = 5, 3.3 & 2.6V
Rfeed = 22k, Rin = 22k
Rg = 100Ω,RL=8Ω
Tamb =25°C
PSRR (dB)
Frequency (Hz)
TS4871
26/28
■Note on PSRR measurement
What is the PSRR ?
The PSRR is the Power Supply Rejection Ratio.
It’s a kind of SVR in adetermined frequency range.
The PSRR of a device, is the ratio between a
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 we measure the PSRR ?
Fig. 85 : PSRR measurement schematic
■Principle of operation
•We fixed the DC voltage supply (Vcc)
•We fixed the AC sinusoidal ripple voltage
(Vripple)
•No bypass capacitor Cs is used
The PSRR value for each frequency is:
Remark :The measure of the Rms voltageis not a
Rms selective measure but a full range (2 Hz to
125 kHz) Rms measure. It means that we
measure the effective Rms signal + the noise.
Vripple
Vcc
Rin
Cin
Rg
100 Ohms
Cb
Rfeed
4
3
2
1
5
8
Vin-
Vin+
-
+
-
+
Bypass
Standby Bias
6
Vout1
Vout2
Av=-1
TS4871
Vs-
Vs+
RL
Vcc
GND
7
PSRR dB()= 20 x Log10 Rms Vripple()
Rms Vs+-Vs
-
()
---------------------------------------------
TS4871
27/28
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO)
Dimensions Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
A 1.75 0.069
a1 0.1 0.25 0.004 0.010
a2 1.65 0.065
a3 0.65 0.85 0.026 0.033
b 0.35 0.48 0.014 0.019
b1 0.19 0.25 0.007 0.010
C 0.25 0.5 0.010 0.020
c1 45°(typ.)
D 4.8 5.0 0.189 0.197
E 5.8 6.2 0.228 0.244
e 1.27 0.050
e3 3.81 0.150
F 3.8 4.0 0.150 0.157
L 0.4 1.27 0.016 0.050
M 0.6 0.024
S8°(max.)
b
e3
A
a2
s
L
C
E
c1
a3
b1
a1
D M
8 5
1 4
F
TS4871
28/28
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (miniSO)
Dimensions Millimeters Inches
Min. Typ. Max. Min. Typ. Max.
A 1.100 0.043
A1 0.050 0.100 0.150 0.002 0.004 0.006
A2 0.780 0.860 0.940 0.031 0.034 0.037
b 0.250 0.330 0.400 0.010 0.013 0.016
c 0.130 0.180 0.230 0.005 0.007 0.009
D 2.900 3.000 3.100 0.114 0.118 0.122
E 4.750 4.900 5.050 0.187 0.193 0.199
E1 2.900 3.000 3.100 0.114 0.118 0.122
e 0.650 0.026
L 0.400 0.550 0.700 0.016 0.022 0.028
L1 0.950 0.037
k 0d3d6d0d3d6d
aaa 0.100 0.004
0,25mm
.010inch
GA GEPLANE
C ccc
C
PLANE
SEA TING
E A
A2
A1
D
b
e
E1
L
k
c
1
4
8
5
PIN1IDENTIFICA
TION
L1
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