Datasheet TS4994FC Datasheet (ST)

1.2 W differential input/output audio power amplifier

Features

■ Differential inputs

■ Near-zero pop & click

■ 100dB PSRR @ 217Hz with grounded inputs

■ Operating range from V

■ 1.2W rail-to-rail output power @ V

THD = 1%, F = 1kHz, with 8Ω

■ 90dB CMRR @ 217Hz

■ Ultra-low consumption in standby mode (10nA)

■ Selectable standby mode (active low or active

high)

■ Ultra fast startup time: 15ms typ.

■ Available in 9-bump flip-chip (300mm bump

diameter)

■ Lead-free package

= 2.5V to 5.5V

CC

load

=5V,

TS4994FC

with selectable standb y

TS4994EIJT - Flip-chip (9 bumps)

Gnd

V

Bypass Stdby

V

765

O-

8

1

IN+

9

2

V

CC

The device is equipped with common mode feedback circu itry allowing outputs to be always biased at V

/2 regardless of the input common

CC

mode voltage.

V

O+

4

V

3

IN-

Stdby Mode

Description

The TS4994 is an audio power amplifier capable

The TS4994 is designed for high quality audio applications such as mobile phones and requir es few external components.

of delivering 1W of continuous RMS output power into an 8Ω load @ 5V. Due to its differential input s,

Applications

it exhibits outstanding noise immunity. 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. An internal thermal shutdown protection is also provided, making the device capable of

■ Mobile phones (cellular / cordless)

■ Laptop / notebook computers

■ PDAs

■ Portable audio devices

sustaining short-circuits.

Order codes

Part number Temperature range Package Packaging Marking

TS4994EIKJT

-40°C, +85°C

TS4994EIJT Lead free flip-chip9 A94

FC9 with back

coating

Tape & reel

A94

December 2006 Rev 2 1/35

www.st.com

35

Contents TS4994FC

Contents

1 Application component information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 4

3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.1 Differential configuration principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.2 Gain in typical application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.3 Common mode feedback loop limitations . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.4 Low and high frequency response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.5 Calculating the influence of mismatching on PSRR performance . . . . . . 25

4.6 CMRR performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.7 Power dissipation and efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.8 Decoupling of the circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

4.9 Wake-up time: t

4.10 Shutdown time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.11 Pop performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.12 Single-ended input configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

WU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2/35

TS4994FC Application component information

1 Application component information

Components Functional description

C

s

C

b

R

feed

R

in

C

in

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 = R Inverting input resistor that sets the closed loop gain in conjunction with R Optional input capacitor making a high pass filter together with Rin.

(FCL= 1/(2πRinCin).

Figure 1. Typical application

Diff. input -

GND

Diff. Input +

Cin1

+

220nF

Cin2

+

220nF

Optional

Rin1 20k

Rin2 20k

GND

+

Cb 1u

.

feed/Rin

VCC

+

Cs

Rfeed1 20k

Vin-

3

Vin+

1

Bypass

8

Mode Stdby TS4994IJ

4

2 VCC

-

+

Standby GND 69

GND

1u

GND

Bias

Rfeed2 20k

Vo+

Vo-

.

feed

5

7

8 Ohms

GND GNDVCC VCC

3/35

Absolute maximum ratings and operating conditions TS4994FC

2 Absolute maximum ratings and operating conditions

Table 1. Absolute maximum ratings

Symbol Parameter Value Unit

(2)

(1)

(3)

6V

GND to V

CC

250 °C/W

V

T

R P

CC

V

oper

stg

T

thja

diss

Supply voltage Input voltage

i

Operating free air tempe rature range -40 to + 85 °C Storage temperature -65 to +150 °C Maximum junction temperature 150 °C

j

Thermal resistance junction to ambient Power dissipation internally limited W Human body model 2 kV

ESD

Machine model 200 V Latch-up immunity 200 mA Lead temperature (soldering, 10sec) 260 °C

1. All voltage values are measured with respect to the ground pin.

2. The magnitude of the input signal must never exceed V

3. The device is protected by a thermal shutdown active at 150°C.

Table 2. Operating conditions

+ 0.3V / GND - 0.3V.

CC

V

Symbol Parameter Value Unit

V

CC

Supply voltage 2.5 to 5.5 V Standby mode voltage input:

V

SM

Standby active LOW Standby active HIGH

=GND

V

SM

VSM=V

CC

Standby voltage input:

V

STBY

T

SD

R

L

R

thja

1. The minimum current consumption (I temperature range.

Device ON (VSM= GND) or device OFF (VSM=VCC) Device OFF (V

= GND) or device ON (VSM=VCC)

SM

Thermal shutdown temperature 150 °C Load resistor ≥ 4 Ω Thermal resistance junction to ambient 100 °C/W

) is guaranteed when V

STBY

=GND or VCC (i.e. supply rails) for the whole

STBY

1.5 ≤ V

GND

≤ V

STBY

≤ VCC

≤ 0.4

(1)

V

4/35

TS4994FC Electrical characteristics

3 Electrical characteristics

Table 3. Electrical characteristics for VCC = +5V, GND = 0V, T

= 25°C (unless otherwise

amb

specified)

Symbol Parameter Min. Typ. Max. Unit

I

CC

I

STBY

V

oo

V

ICM

P

out

THD + N

PSRR

CMRR

SNR

Supply current No input signal, no load

Standby current No input signal, V No input signal, V

= VSM = GND, RL = 8Ω

STBY

= VSM = VCC, RL = 8Ω

STBY

Differential output offset voltage No input signal, RL = 8Ω

Input common mode voltage CMRR ≤ -60dB

Output power THD = 1% Max, F= 1kHz, RL = 8Ω

Total harmonic distortion + noise

=850mW rms, AV=1, 20Hz ≤ F ≤ 20kHz, RL=8Ω

P

out

Power supply rejection ratio with inputs grounded F = 217Hz, R = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF

IG

V

ripple

= 200mV

PP

Common mode rejection ratio F = 217Hz, R

= 200mV

V

ic

= 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF

L

PP

Signal-to-noise ratio (A-weighted filter, A RL = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz

= 2.5)

V

(1)

47mA

10 1000 nA

0.1 10 mV

0.6 V

-0.9 V

CC

0.8 1.2 W

0.5 %

100 dB

90 dB

100 dB

GBP

Gain bandwidth product R

= 8Ω

L

Output voltage noise, 20Hz ≤ F ≤ 20kHz, RL = 8Ω

Unweighted, A A-weighted, A Unweighted, A

V

N

A-weighted, A Unweighted, A A-weighted, A

= 1

V

= 1

V

= 2.5

V

= 2.5

V

= 7.5

V

= 7.5

V

Unweighted, Standby A-weighted, Standby

t

WU

1. Dynamic measurements - 20*log(rms(V

2. Transition time from standby mode to fully operational amplifier.

Wake-up time Cb =1μF

(2)

)/rms (V

out

ripple

)). V

ripple

5/35

2MHz

6

5.5 12

10.5 33 28

1.5 1

15 ms

is the super-imposed sinus signal relative to VCC.

μV

RMS

Electrical characteristics TS4994FC

Table 4. Electrical characteristics for VCC = +3.3V (all electrical values are guaranteed with

correlation measurements at 2.6V and 5V), GND = 0V, T

= 25°C (unless otherwise

amb

specified)

Symbol Parameter Min. Typ. Max. Unit

I

CC

I

STBY

V

oo

V

ICM

P

out

THD + N

PSRR

CMRR

SNR

Supply current no input signal, no load 3 7 mA Standby current

No input signal, V No input signal, V

= VSM = GND, RL = 8Ω

STBY

= VSM = VCC, RL = 8Ω

STBY

Differential output offset voltage No input signal, RL = 8Ω

Input common mode voltage CMRR ≤ -60dB

Output power THD = 1% max, F= 1kHz, R

= 8Ω

L

Total harmonic distortion + noise

= 300mW rms, AV = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω

P

out

Power supply rejection ratio with inputs grounded F = 217Hz, R = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF

IG

V

ripple

= 200mV

PP

0.6 V

300 500 mW

(1)

10 1000 nA

0.1 10 mV

-0.9 V

CC

0.5 %

100 dB

Common mode rejection ratio F = 217Hz, R

= 200mV

V

ic

Signal-to-noise ratio (A-weighted filter, A RL = 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz

= 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF

L

PP

= 2.5)

V

90 dB

100 dB

GBP

Gain bandwidth product R

= 8Ω

L

Output voltage noise, 20Hz ≤ F ≤ 20kHz, RL = 8Ω

Unweighted, A

V

= 1

A-weighted, AV = 1

V

N

A-weighted, A Unweighted, A A-weighted, A

Unweighted, A

= 2.5

V

= 2.5

V

= 7.5

V

= 7.5

V

Unweighted, Standby A-weighted, Standby

t

WU

1. Dynamic measurements - 20*log(rms(V

2. Transition time from standby mode to fully operational amplifier.

Wake-up time Cb =1μF

(2)

)/rms (V

out

ripple

)). V

ripple

2MHz

6

5.5

12

10.5 33 28

1.5 1

15 ms

is the super-imposed sinus signal relative to VCC.

μV

RMS

6/35

TS4994FC Electrical characteristics

Table 5. Electrical characteristics for VCC = +2.6V, GND = 0V, T

= 25°C (unless otherwise

amb

specified)

Symbol Parameter Min. Typ. Max. Unit

I

CC

I

STBY

V

ICM

P

out

THD + N

PSRR

CMRR

SNR

GBP

V

t

WU

Supply current No input signal, no load

Standby current No input signal, V No input signal, V

Differential output offset voltage

oo

No input signal, R

= VSM = GND, RL = 8Ω

STBY

= VSM = VCC, RL = 8Ω

STBY

= 8Ω

L

Input common mode voltage CMRR ≤ -60dB

Output power THD = 1% max, F= 1kHz, RL = 8Ω

Total harmonic distortion + noise

= 225mW rms, AV = 1, 20Hz ≤ F ≤ 20kHz, RL = 8Ω

P

out

Power supply rejection ratio with inputs grounded F = 217Hz, R = 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF

IG

V

= 200mV

ripple

PP

Common mode rejection ratio F = 217Hz, R Vic = 200mV

= 8Ω, AV = 1, Cin = 4.7μF, Cb =1μF

L

PP

Signal-to-noise ratio (A-weighted filter, A

= 8Ω, THD +N < 0.7%, 20Hz ≤ F ≤ 20kHz

R

L

Gain bandwidth product

= 8Ω

R

L

Output voltage noise, 20Hz ≤ F ≤ 20kHz, RL = 8Ω

Unweighted, AV = 1 A-weighted, A

V

= 1

Unweighted, AV = 2.5

N

A-weighted, A Unweighted, A A-weighted, A

= 2.5

V

= 7.5

V

= 7.5

V

Unweighted, Standby A-weighted, Standby

Wake-up time

(2)

Cb =1μF

= 2.5)

V

(1)

37mA

10 1000 nA

0.1 10 mV

0.6 V

- 0.9 V

CC

200 300 mW

0.5 %

100 dB

90 dB

100 dB

2MHz

6

5.5

12

10.5 33 28

1.5 1

15 ms

μV

RMS

1. Dynamic measurements - 20*log(rms(V

2. Transition time from standby mode to fully operational amplifier.

)/rms (V

out

ripple

)). V

ripple

7/35

is the super-imposed sinus signal relative to VCC.

Electrical characteristics TS4994FC

0.0 0.6 1.2 1.8 2.4

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Standby mode=0V

Standby mode=2.6V

Vcc = 2.6V No load Tamb=25°C

Current Consumption (mA)

Standby Voltage (V)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

RL=16

Ω

RL=8

Ω

Vcc=5V F=1kHz THD+N<1%

RL=4

Ω

Power Dissipation (W)

Output Power (W)

Figure 2. Current consumption vs. power

supply voltage

4.0

No load Tamb=25°C

3.5

3.0

2.5

2.0

1.5

1.0

Current Consumption (mA)

0.5

0.0

012345

Power Supply Voltage (V)

Figure 4. Current consumption vs. standby

voltage

3.5

3.0

2.5

2.0

1.5

1.0

Current Consumption (mA)

0.5

0.0

0.0 0.6 1.2 1.8 2.4 3.0

Standby mode=0V

Standby mode=3.3V

Standby Voltage (V)

Vcc = 3.3V No load Tamb=25°C

Figure 3. Current consumption vs. standby

voltage

4.0

3.5

3.0

2.5

2.0

1.5

1.0

Current Consumption (mA)

0.5

0.0 012345

Standby mode=5V

Standby mode=0V

Standby Voltage (V)

Vcc = 5V No load Tamb=25°C

Figure 5. Current consumption vs. standby

voltage

Figure 6. Differential DC output voltage vs.

common mode input voltage

1000

Av = 1 Tamb = 25°C

100

10

Voo (mV)

1

0.1

0.01

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

8/35

Vcc=2.5V

Common Mode Input Voltage (V)

Figure 7. Power dissipation vs. output power

Vcc=3.3V

Vcc=5V

TS4994FC Electrical characteristics

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

RL=4

Ω

RL=8

Ω

Vcc=2.6V F=1kHz THD+N<1%

RL=16

Ω

Power Dissipation (W)

Output Power (W)

2.5 3.0 3.5 4.0 4.5 5.0 5.5

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

THD+N=10%

RL = 8

Ω

F = 1kHz BW < 125kHz Tamb = 25°C

THD+N=1%

Output power (W)

Vcc (V)

2.5 3.0 3.5 4.0 4.5 5.0 5.5

0.0

0.1

0.2

0.3

0.4

0.5

0.6

THD+N=10%

RL = 32

Ω

F = 1kHz BW < 125kHz Tamb = 25°C

THD+N=1%

Output power (W)

Vcc (V)

Figure 8. Power dissipation vs. outpu t power Figure 9. Power dissipation vs. output power

0.6

Vcc=3.3V F=1kHz

0.5

THD+N<1%

0.4

0.3

0.2

Power Dissipation (W)

0.1

0.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

RL=16

Ω

Output Power (W)

Figure 10. Output power vs. power supply

voltage

2.4

RL = 4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

Output power (W)

0.6

0.4

0.2

0.0

Ω

F = 1kHz BW < 125kHz Tamb = 25°C

2.5 3.0 3.5 4.0 4.5 5.0 5.5

THD+N=10%

Vcc (V)

RL=8

Ω

THD+N=1%

RL=4

Ω

Figure 11. Output power vs. power supply

voltage

Figure 12. Output power vs. power supply

voltage

1.2

RL = 16

Ω

F = 1kHz

1.0

BW < 125kHz Tamb = 25°C

0.8

0.6

0.4

Output power (W)

0.2

0.0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

THD+N=10%

Figure 13. Output power vs. power supply

voltage

THD+N=1%

Vcc (V)

9/35

Electrical characteristics TS4994FC

Figure 14. Power derating curves Figure 15. Open loop gain vs. frequency

1.2

1.0

0.8

0.6

0.4

No Heat sink

0.2

Flip-Chip Package Power Dissipation (W)

0.0

0 25 50 75 100 125

Ambiant Temperature ( C)

Heat sink surface ≈ 100mm (See demoboard)

2

60

40

20

Gain (dB)

0

Vcc = 5V

-20

ZL = 8Ω + 500pF Tamb = 25°C

-40

0.1 1 10 100 1000 10000

Gain

Phase

Frequency (kHz)

Figure 16. Open loop gain vs. frequency Figure 17. Open loop gain vs. frequency

0

60

40

20

Gain (dB)

0

Phase

Gain

-40

-80

-120

Phase (°)

60

40

20

Gain (dB)

0

Gain

Phase

0

-40

-80

-120

-160

-200

0

-40

-80

-120

Phase (°)

Vcc = 3.3V

-20

ZL = 8Ω + 500pF Tamb = 25°C

-40

0.1 1 10 100 1000 10000

Frequency (kHz)

-160

-200

Vcc = 2.6V

-20

ZL = 8Ω + 500pF Tamb = 25°C

-40

0.1 1 10 100 1000 10000

Frequency (kHz)

-160

-200

Figure 18. Closed loop gain vs. frequency Figure 19. Closed loop gain vs. frequency

10

Gain

0

-10

-20

Gain (dB)

Vcc = 5V

-30

Av = 1 ZL = 8Ω + 500pF Tamb = 25°C

-40

0.1 1 10 100 1000 10000

Frequency (kHz)

Phase

0

-40

-80

-120

-160

-200

10

Gain

0

-10

Phase (°)

-20

Gain (dB)

Vcc = 3.3V

-30

Av = 1 ZL = 8Ω + 500pF Tamb = 25°C

-40

0.1 1 10 100 1000 10000

Frequency (kHz)

Phase

0

-40

-80

-120

-160

-200

Phase (°)

10/35

TS4994FC Electrical characteristics

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 5V Vripple = 200mVpp Inputs = Grounded Av = 1, Cin = 4.7μF RL ≥ 8

Ω

Tamb = 25°C

PSRR (dB)

Frequency (Hz)

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 2.6V Vripple = 200mVpp Inputs = Grounded Av = 1, Cin = 4.7μF RL ≥ 8

Ω

Tamb = 25°C

PSRR (dB)

Frequency (Hz)

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 3.3V Vripple = 200mVpp Inputs = Grounded Av = 2.5, Cin = 4.7μF RL ≥ 8

Ω

Tamb = 25°C

PSRR (dB)

Frequency (Hz)

Figure 20. Closed loop gain vs. frequency Figure 21. PSRR vs. frequency

10

Gain

0

-10

-20

Gain (dB)

Vcc = 2.6V

-30

Av = 1 ZL = 8Ω + 500pF Tamb = 25°C

-40

0.1 1 10 100 1000 10000

Frequency (kHz)

Phase

0

-40

-80

-120

-160

-200

Phase (°)

Figure 22. PSRR vs. frequency Figure 23. PSRR vs. frequency

0

-10

Vcc = 3.3V Vripple = 200mVpp

-20

Inputs = Grounded

-30

Av = 1, Cin = 4.7μF

-40

RL ≥ 8

-50

-60

-70

PSRR (dB)

-80

-90

-100

-110

-120

Tamb = 25°C

20

Ω

Cb=1μF

100 1000 10000

Frequency (Hz)

Cb=0.1μF

Cb=0.47μF

Cb=0

20k

Figure 24. PSRR vs. frequency Figure 25. PSRR vs. frequency

0

-10

Vcc = 5V Vripple = 200mVpp

-20

Inputs = Grounded

-30

Av = 2.5, Cin = 4.7μF

-40

RL ≥ 8 Tamb = 25°C

20

Ω

100 1000 10000

-50

-60

-70

PSRR (dB)

-80

-90

-100

-110

-120

Cb=1μF

Frequency (Hz)

Cb=0.47μF

Cb=0.1μF

Cb=0

20k

11/35

Electrical characteristics TS4994FC

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 5V Vripple = 200mVpp Inputs = Floating Rfeed = 20k

Ω

RL ≥ 8

Ω

Tamb = 25°C

PSRR (dB)

Frequency (Hz)

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 2.6V Vripple = 200mVpp Inputs = Floating Rfeed = 20k

Ω

RL ≥ 8

Ω

Tamb = 25°C

PSRR (dB)

Frequency (Hz)

0.0 0.6 1.2 1.8 2.4 3.0

-100

-80

-60

-40

-20

0

Cb=1μF Cb=0.47μF Cb=0.1μF

Cb=0

Vcc = 3.3V Vripple = 200mVpp Inputs Grounded F = 217Hz Av = 1 RL ≥ 8

Ω

Tamb = 25°C

PSRR(dB)

Common Mode Input Voltage (V)

Figure 26. PSRR vs. frequency Figure 27. PSRR vs. frequency

0

-10

Vcc = 2.6V

-20

Vripple = 200mVpp Inputs = Grounded

-30

Av = 2.5, Cin = 4.7μF

-40

RL ≥ 8

-50

-60

-70

PSRR (dB)

-80

-90

-100

-110

-120

Tamb = 25°C

20

Ω

Cb=1μF

100 1000 10000

Frequency (Hz)

Cb=0.1μF

Cb=0.47μF

Cb=0

20k

Figure 28. PSRR vs. frequency Figure 29. PSRR vs. frequency

0

-10

Vcc = 3.3V Vripple = 200mVpp

-20

Inputs = Floating

-30

-40

-50

-60

-70

PSRR (dB)

-80

-90

-100

-110

-120

Rfeed = 20k RL ≥ 8 Tamb = 25°C

20

Ω

Cb=1μF

100 1000 10000

Frequency (Hz)

Cb=0.1μF

Cb=0.47μF

Cb=0

20k

Figure 30. PSRR vs. common mode input

voltage

0

Vcc = 5V Vripple = 200mVpp

-20

Inputs Grounded F = 217Hz Av = 1

-40

RL ≥ 8

Ω

Tamb = 25°C

-60

PSRR(dB)

-80

-100

012345

Common Mode Input Voltage (V)

12/35

Cb=0

Cb=1μF Cb=0.47μF Cb=0.1μF

Figure 31. PSRR vs. common mode input

voltage

TS4994FC Electrical characteristics

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=1μF Cb=0.47μF Cb=0.1μF Cb=0

20k

20

Vcc = 5V Vic = 200mVpp Av = 1, Cin = 470μF RL ≥ 8

Ω

Tamb = 25°C

CMRR (dB)

Frequency (Hz)

100 1000 10000

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=1μF Cb=0.47μF Cb=0.1μF Cb=0

20k

20

Vcc = 2.6V Vic = 200mVpp Av = 1, Cin = 470μF RL ≥ 8

Ω

Tamb = 25°C

CMRR (dB)

Frequency (Hz)

100 1000 10000

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=1μF Cb=0.47μF Cb=0.1μF Cb=0

20k

20

Vcc = 3.3V Vic = 200mVpp Av = 2.5, Cin = 470μF RL ≥ 8

Ω

Tamb = 25°C

CMRR (dB)

Frequency (Hz)

Figure 32. PSRR vs. common mode input

Figure 33. CMRR vs. frequency

voltage

0

Vcc = 2.5V Vripple = 200mVpp Inputs Grounded

-20

F = 217Hz Av = 1

-40

RL ≥ 8Ω Tamb = 25°C

-60

PSRR(dB)

-80

-100

0.0 0.5 1.0 1.5 2.0 2.5

Common Mode Input Voltage (V)

Cb=0

Cb=1μF Cb=0.47μF Cb=0.1μF

Figure 34. CMRR vs. frequency Figure 35. CMRR vs. frequency

0

-10

Vcc = 3.3V Vic = 200mVpp

-20

Av = 1, Cin = 470μF

-30

RL ≥ 8

CMRR (dB)

-100

-110

-120

-40

-50

-60

-70

-80

-90

20

Ω

Tamb = 25°C

100 1000 10000

Cb=1μF Cb=0.47μF Cb=0.1μF Cb=0

Frequency (Hz)

20k

Figure 36. CMRR vs. frequency Figure 37. CMRR vs. frequency

0

Vcc = 5V

-10

Vic = 200mVpp

-20

Av = 2.5, Cin = 470μF RL ≥ 8 Tamb = 25°C

20

Ω

Cb=1μF Cb=0.47μF Cb=0.1μF Cb=0

100 1000 10000

Frequency (Hz)

20k

13/35

-30

-40

-50

-60

CMRR (dB)

-70

-80

-90

-100

Electrical characteristics TS4994FC

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

-100

-80

-60

-40

-20

0

Vcc=3.3V

Vcc=2.5V

Vcc=5V

Vic = 200mVpp F = 217Hz Av = 1, Cb = 1μF RL ≥ 8Ω Tamb = 25°C

CMRR(dB)

Common Mode Input Voltage (V)

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 4

Ω

F = 20Hz Av = 1 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 4

Ω

F = 20Hz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 38. CMRR vs. frequency Figure 39. CMRR vs. common mode input

voltage

0

Vcc = 2.6V

-10

Vic = 200mVpp

-20

Av = 2.5, Cin = 470μF RL ≥ 8 Tamb = 25°C

20

Ω

Cb=1μF Cb=0.47μF Cb=0.1μF Cb=0

100 1000 10000

Frequency (Hz)

20k

Figure 41. THD+N vs. output power

-30

-40

-50

-60

CMRR (dB)

-70

-80

-90

-100

Figure 40. CMRR vs. common mode input

voltage

CMRR(dB)

-20

-40

-60

-80

0

Vcc=2.5V

Vcc=3.3V

Vic = 200mVpp F = 217Hz Av = 1, Cb = 0 RL ≥ 8Ω Tamb = 25°C

-100

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Common Mode Input Voltage (V)

Vcc=5V

Figure 42. THD+N vs. output power Figure 43. THD+N vs. output power

10

RL = 4

Ω

F = 20Hz Av = 2.5 Cb = 1μF

1

BW < 125kHz Tamb = 25°C

THD + N (%)

0.1

0.01 1E-3 0.01 0.1 1

14/35

Output Power (W)

Vcc=2.6V

Vcc=3.3V

Vcc=5V

TS4994FC Electrical characteristics

1E-3 0.01 0.1 1

1E-3

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 8

Ω

F = 20Hz Av = 2.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

1E-3

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 16

Ω

F = 20Hz Av = 1 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

1E-3

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 16

Ω

F = 20Hz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 44. THD+N vs. output power Figure 45. THD+N vs. output power

10

RL = 8

Ω

F = 20Hz Av = 1

1

Cb = 1μF BW < 125kHz Tamb = 25°C

0.1

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.01

1E-3

1E-3 0.01 0.1 1

Output Power (W)

Figure 46. THD+N vs. output power Figure 47. THD+N vs. output power

10

RL = 8

Ω

1

THD + N (%)

0.1

F = 20Hz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

Vcc=2.6V

Vcc=3.3V

Vcc=5V

0.01 1E-3 0.01 0.1 1

Output Power (W)

Figure 48. THD+N vs. output power Figure 49. THD+N vs. output power

10

RL = 16

Ω

F = 20Hz Av = 2.5

1

Cb = 1μF BW < 125kHz Tamb = 25°C

0.1

THD + N (%)

0.01

1E-3

1E-3 0.01 0.1 1

Output Power (W)

Vcc=2.6V

Vcc=3.3V

Vcc=5V

15/35

Electrical characteristics TS4994FC

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 4

Ω

F = 1kHz Av = 2.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 8

Ω

F = 1kHz Av = 1 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 8

Ω

F = 1kHz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 50. THD+N vs. output power Figure 51. THD+N vs. output power

10

RL = 4

1

THD + N (%)

0.1

Ω

F = 1kHz Av = 1 Cb = 1μF BW < 125kHz Tamb = 25°C

Vcc=2.6V

Vcc=3.3V

Vcc=5V

0.01

1E-3 0.01 0.1 1

Output Power (W)

Figure 52. THD+N vs. output power Figure 53. THD+N vs. output power

10

RL = 4 F = 1kHz Av = 7.5 Cb = 1μF BW < 125kHz

1

Tamb = 25°C

Ω

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.1

1E-3 0.01 0.1 1

Output Power (W)

Figure 54. THD+N vs. output power Figure 55. THD+N vs. output power

10

RL = 8

Ω

F = 1kHz Av = 2.5 Cb = 1μF

1

BW < 125kHz Tamb = 25°C

THD + N (%)

0.1

0.01

1E-3 0.01 0.1 1

Vcc=2.6V

Vcc=3.3V

Vcc=5V

Output Power (W)

16/35

TS4994FC Electrical characteristics

1E-3 0.01 0.1 1

1E-3

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 16

Ω

F = 1kHz Av = 2.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 4

Ω

F = 20kHz Av = 1 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 4

Ω

F = 20kHz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 56. THD+N vs. output power Figure 57. THD+N vs. output power

10

RL = 16 F = 1kHz Av = 1

1

Cb = 1μF BW < 125kHz Tamb = 25°C

0.1

Ω

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.01

1E-3

1E-3 0.01 0.1 1

Output Power (W)

Figure 58. THD+N vs. output power Figure 59. THD+N vs. output power

10

RL = 16 F = 1kHz Av = 7.5 Cb = 1μF

1

BW < 125kHz Tamb = 25°C

Ω

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.1

0.01

1E-3 0.01 0.1 1

Output Power (W)

Figure 60. THD+N vs. output power Figure 61. THD+N vs. output power

10

RL = 4

Ω

F = 20kHz Av = 2.5 Cb = 1μF BW < 125kHz Tamb = 25°C

1

THD + N (%)

0.1 1E-3 0.01 0.1 1

Output Power (W)

Vcc=2.6V

Vcc=3.3V

Vcc=5V

17/35

Electrical characteristics TS4994FC

1E-3 0.01 0.1 1

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 8

Ω

F = 20kHz Av = 2.5 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

Vcc=5V

Vcc=3.3V

Vcc=2.6V

RL = 16

Ω

F = 20kHz Av = 1 Cb = 1μF BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 62. THD+N vs. output power Figure 63. THD+N vs. output power

10

RL = 8

Ω

F = 20kHz Av = 1 Cb = 1μF BW < 125kHz

1

Tamb = 25°C

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.1

1E-3 0.01 0.1 1

Output Power (W)

Figure 64. THD+N vs. output power Figure 65. THD+N vs. output power

10

RL = 8

Ω

F = 20kHz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

1

Vcc=2.6V Vcc=3.3V

Vcc=5V

THD + N (%)

0.1

1E-3 0.01 0.1 1

Output Power (W)

Figure 66. THD+N vs. output power Figure 67. THD+N vs. output power

10

RL = 16 F = 20kHz Av = 2.5 Cb = 1μF

1

BW < 125kHz Tamb = 25°C

Ω

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.1

0.01 1E-3 0.01 0.1 1

Output Power (W)

10

RL = 16 F = 20kHz Av = 7.5 Cb = 1μF BW < 125kHz Tamb = 25°C

1

Ω

Vcc=2.6V

Vcc=3.3V

Vcc=5V

THD + N (%)

0.1 1E-3 0.01 0.1 1

Output Power (W)

18/35

TS4994FC Electrical characteristics

100 1000 10000

0.01

0.1

1

10

Vcc=2.6V, Po=350mW

Vcc=5V, Po=1W

RL = 4

Ω

Av = 7.5 Cb = 1μF Bw < 125kHz Tamb = 25°C

20k20

THD + N (%)

Frequency (Hz)

100 1000 10000

0.01

0.1

1

10

Vcc=2.6V, Po=225mW

Vcc=5V, Po=850mW

RL = 8

Ω

Av = 7.5 Cb = 1μF Bw < 125kHz Tamb = 25°C

20k20

THD + N (%)

Frequency (Hz)

100 1000 10000

1E-3

0.01

0.1

1

10

Vcc=2.6V, Po=155mW

Vcc=5V, Po=600mW

RL = 16

Ω

Av = 7.5 Cb = 1μF Bw < 125kHz Tamb = 25°C

20k20

THD + N (%)

Frequency (Hz)

Figure 68. THD+N vs. frequency Figure 69. THD+N vs. frequency

10

RL = 4

Ω

Av = 1 Cb = 1μF

1

Bw < 125kHz Tamb = 25°C

Vcc=2.6V, Po=350mW

0.1

THD + N (%)

0.01

Vcc=5V, Po=1W

1E-3

100 1000 10000

20k20

Frequency (Hz)

Figure 70. THD+N vs. frequency Figure 71. THD+N vs. frequency

10

RL = 8

Ω

Av = 1 Cb = 1μF

1

Bw < 125kHz Tamb = 25°C

0.1

Vcc=5V, Po=850mW

THD + N (%)

0.01

1E-3

100 1000 10000

Vcc=2.6V, Po=225mW

20k20

Frequency (Hz)

Figure 72. THD+N vs. frequency Figure 73. THD+N vs. frequency

10

RL = 16

Ω

Av = 1 Cb = 1μF

1

Bw < 125kHz Tamb = 25°C

0.1

THD + N (%)

0.01

1E-3

Vcc=2.6V, Po=155mW

Vcc=5V, Po=600mW

100 1000 10000

Frequency (Hz)

20k20

19/35

Electrical characteristics TS4994FC

1E-3 0.01 0.1 1

0.1

1

10

F=20kHz

F=20Hz

F=1kHz

RL = 4

Ω

Vcc = 5V Av = 7.5, Cb = 0 BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1

0.1

1

10

F=20kHz

F=20Hz

F=1kHz

RL = 4

Ω

Vcc = 2.6V Av = 7.5, Cb = 0 BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

F=20kHz

F=20Hz

F=1kHz

RL = 8

Ω

Vcc = 5V Av = 7.5, Cb = 0 BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 74. THD+N vs. output power Figure 75. THD+N vs. output power

10

RL = 4

Ω

Vcc = 5V Av = 1 Cb = 0

1

BW < 125kHz Tamb = 25°C

THD + N (%)

0.1

0.01 1E-3 0.01 0.1 1

F=20Hz

F=20kHz

F=1kHz

Output Power (W)

Figure 76. THD+N vs. output power Figure 77. THD+N vs. output power

10

RL = 4

Ω

1

0.1

THD + N (%)

Vcc = 2.6V Av = 1, Cb = 0 BW < 125kHz Tamb = 25°C

F=20kHz

F=1kHz

0.01

1E-3

1E-3 0.01 0.1

Figure 78. THD+N vs. output power Figure 79. THD+N vs. output power

10

RL = 8

Ω

Vcc = 5V Av = 1

1

Cb = 0 BW < 125kHz Tamb = 25°C

0.1

THD + N (%)

0.01

1E-3 0.01 0.1 1

20/35

F=20Hz

Output Power (W)

F=20kHz

F=1kHz

F=20Hz

Output Power (W)

TS4994FC Electrical characteristics

1E-3 0.01 0.1

0.01

0.1

1

10

F=20kHz

F=20Hz

F=1kHz

RL = 8

Ω

Vcc = 2.6V Av = 7.5, Cb = 0 BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1 1

0.01

0.1

1

10

F=20kHz

F=20Hz

F=1kHz

RL = 16

Ω

Vcc = 5V Av = 7.5, Cb = 0 BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

1E-3 0.01 0.1

0.01

0.1

1

10

F=20kHz

F=20Hz

F=1kHz

RL = 16

Ω

Vcc = 2.6V Av = 7.5, Cb = 0 BW < 125kHz Tamb = 25°C

THD + N (%)

Output Power (W)

Figure 80. THD+N vs. output power Figure 81. THD+N vs. output power

10

RL = 8

Ω

Vcc = 2.6V Av = 1, Cb = 0

1

BW < 125kHz Tamb = 25°C

0.1

F=20kHz

F=1kHz

THD + N (%)

0.01

F=20Hz

1E-3

1E-3 0.01 0.1

Output Power (W)

Figure 82. THD+N vs. output power Figure 83. THD+N vs. output power

10

RL = 16

Ω

Vcc = 5V Av = 1, Cb = 0

1

0.1

THD + N (%)

BW < 125kHz Tamb = 25°C

F=20kHz

F=1kHz

0.01

1E-3

1E-3 0.01 0.1 1

F=20Hz

Output Power (W)

Figure 84. THD+N vs. output power Figure 85. THD+N vs. output power

10

RL = 16

Ω

Vcc = 2.6V Av = 1, Cb = 0

1

BW < 125kHz Tamb = 25°C

0.1

THD + N (%)

0.01

1E-3

1E-3 0.01 0.1

Output Power (W)

F=20kHz

F=1kHz

F=20Hz

21/35

Electrical characteristics TS4994FC

2.5 3.0 3.5 4.0 4.5 5.0

80

85

90

95

100

105

110

Av = 2.5 Cb = 1μF THD+N < 0.7% Tamb = 25°C

RL=16

Ω

RL=4

Ω

RL=8

Ω

Signal to Noise Ratio (dB)

Power Supply Voltage (V)

Figure 86. SNR vs. power supply voltage with

unweighted filter

110

RL=16

RL=4

Ω

RL=8

Ω

105

100

95

90

Av = 2.5

Signal to Noise Ratio (dB)

Cb = 1μF

85

THD+N < 0.7% Tamb = 25°C

80

2.5 3.0 3.5 4.0 4.5 5.0

Power Supply Voltage (V)

Figure 88. Startup time vs. bypass capacitor

20

Tamb=25°C

15

10

Vcc=5V

Vcc=3.3V

Figure 87. SNR vs. power supply voltage with

A-weighted filter

Startup Time (ms)

5

0

0.0 0.4 0.8 1.2 1.6 2.0

Vcc=2.6V

Bypass Capacitor Cb ( F)

22/35

TS4994FC 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 co nsequence, 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 . Bu t, 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

A typical differential application is shown in Figure 1 on page 3. In the flat region of the frequency-response curve (no C

effect), the differential gain is

in

expressed by the relation:

R

feed

--------------==

R

where R

in

= R

in1

= R

and R

in2

Note: For the rest of this section, Av

VO+VO–

A

------------------------------------------------------

V

diff

Diff

input+

= R

feed

diff

feed1

will be called AV to simplify the expression.

= R

–

feed2

Diff

input-

.

4.3 Common mode feedback loop limitations

As explained pre viously, the common mode feedback loop allows the output DC bias voltage to be averaged at V

However, due to V mode feedback loop can play its role only within a defined rang e. This range depends upon

/2 for any DC common mode bias input voltage.

CC

limitation of the input stage (see Table 3 on page 5), the common

ICM

in

23/35

Application information TS4994FC

the values of VCC, Rin and R

(AV). To have a good estimation of the V

feed

following formula:

V

× 2VicR

CCRin

V

------------------------------------------------------------------------- -

ICM

2R

+()×

inRfeed

with

Diff

input+

------------------------------------------------------ -

V

ic

+

2

Diff

input-

The result of the calculation must be in the range:

If the result of the V

0.6V V

calculation is not in this range, an input coupling capacitor must be

ICM

ICMVCC

used. Example: With V

=2.5V, Rin=R

CC

= 20k and Vic= 2V, we find V

feed

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, Cin starts to have an effect. Cin forms, with Rin, a high-pass filter with a -3dB cut-off frequency. F

is in Hz.

CL

F

CL

=

1

CR2

××π×

value, use the

ICM

××+

feed

(V)=

0.9V–≤≤

= 1.63V. This is

ICM

)Hz(

inin

In the high-frequency region, you can limit the bandwidth by adding a capacitor (C parallel with R

. It forms a low-pass filter with a -3dB cut-of f frequency. FCH is in Hz.

feed

=

F

CH

1

××π×

CR2

feedfeed

)Hz(

feed

) in

While these bandwidth limitations are in theory attractive, in practice, because of low performance in terms of capacitor precision (and by consequen ce 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 and F

= 8kHz. We assume that the mismatching between R

CH

in1,2

and C

feed1,2

=50Hz

CL

can be 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

C

impedance is high enough to be neglected. Due to the tolerance of C

feed

impedance decreases from infinite to a finite value and the

in

in1,2

, we

24/35

TS4994FC Application information

must introduce a mismatch fa ctor (R

in1xCin

≠ R

in2xCin2

) that will decrease the PSRR

performance.

● From 200Hz to 5kHz, the C

compared with R

and the C

in,

impedance is low enough to be neglected when

in

impedance is high enough to be neglected as well. In

feed

this range, we can reach the PSRR performance of the TS4994 itself.

● From 5kHz to 20kHz, the C

and the C

impedance decreases to a finite value. Due to tolerance of C

feed

introduce a mismatching factor (R

impedance is low to be neglected when compared to R

in

feed1xCfeed1

≠ R

feed2xCfeed2

) that will decrease the

PSRR performance.

4.5 Calculating the influence of mismatching on PSRR performance

For calculating PSRR performance, we consider that Cin and C 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 %):

⎡

×≤

Log20PSRR

×Δ ⎢ ⎣

⎤

100R

⎥

2

Δ−

)R10000(

⎦

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.

have no influence. We

feed

)dB(

feed1,2

, we

in,

The complete PSRR equation (ΔR in %, C

PSRR 20 log ×≤

Example: With ΔR = 0.1% and C

--------------------------------------------------------------------------------------------------------(1000 R

= 0, the minimum PSRR is -60dB. With a 100nF bypass

b

in microFarad and F in Hz) is:

b

R 100×Δ

2

) 1F

2

C

b

dB()

22.2××+×Δ–

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.

25/35

Application information TS4994FC

100 1000 10000

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 3.3V, Vripple = 200mVpp Av = 1, Cin = 4.7μF

Δ

R/R = 0.1%, RL ≥ 8

Ω

Tamb = 25°C, Inputs = Grounded

PSRR (dB)

Frequency (Hz)

The three following g raphs show PSRR v ersus frequency and v ersus b ypass capacitor Cb in worst-case conditions (

Figure 89. PSRR vs. frequency (worst case

conditions)

0

-10

Vcc = 5V, Vripple = 200mVpp

-20

Av = 1, Cin = 4.7μF

-30

Δ

R/R = 0.1%, RL ≥ 8

-40

Tamb = 25°C, Inputs = Grounded

-50

-60

-70

-80

PSRR (dB)

-90

-100

-110

-120

-130

-140

Cb=1μF

20

100 1000 10000

Ω

Cb=0.1μF

Cb=0.47μF

Frequency (Hz)

Δ

R = 0.1%).

Cb=0

Figure 90. PSRR vs. frequency (worst case

conditions)

20k

Figure 91. PSRR vs. frequency (worst case

conditions)

0

-10

Vcc = 2.5V, Vripple = 200mVpp

-20

Av = 1, Cin = 4.7μF

-30

Δ

R/R = 0.1%, RL ≥ 8

Tamb = 25°C, Inputs = Grounded

-40

-50

-60

-70

-80

PSRR (dB)

-90

-100

-110

-120

-130

-140

Cb=1μF

20

100 1000 10000

Ω

Cb=0.1μF

Cb=0.47μF

Frequency (Hz)

Cb=0

20k

26/35

TS4994FC Application information

100 1000 10000

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1μF

Cb=1μF

Cb=0

20k

20

Cb=0.47μF

Vcc = 2.5V, Vripple = 200mVpp Av = 1, Cin = 4.7μF

Δ

R/R ≤ 0.1%, RL ≥ 8

Ω

Tamb = 25°C, Inputs = Grounded

PSRR (dB)

Frequency (Hz)

The two followin g graphs sho w typical applications of the TS4994 wit h a random selection of four

Δ

R/R values with a 0.1% tolerance.

Figure 92. PSRR vs. frequency with random

choice condition

0

-10

Vcc = 5V, Vripple = 200mVpp Av = 1, Cin = 4.7μF

-20

Δ

R/R ≤ 0.1%, RL ≥ 8

-30

Tamb = 25°C, Inputs = Grounded

-40

-50

-60

-70

-80

PSRR (dB)

-90

-100

-110

-120

-130

-140

Cb=1μF

20

100 1000 10000

Ω

Cb=0.1μF

Cb=0.47μF

Frequency (Hz)

Figure 93. PSRR vs. frequency with random

choice condition

Cb=0

20k

4.6 CMRR performance

For calculating CMRR performance, we consider that Cin and C 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 %):

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 94 and Figure 95 show CMRR versus frequency and versus bypass capacitor C

worst-case conditions (ΔR=0.1%).

have no influence. Cb

feed

⎡

Log20CMRR

×≤

⎢

×Δ

⎣

⎤

200R

2

)R10000(

Δ−

)dB(

⎥ ⎦

in

b

27/35

Application information TS4994FC

100 1000 10000

-60

-50

-40

-30

-20

-10

0

Cb=1μF Cb=0

20k

20

Vcc = 2.5V Vic = 200mVpp Av = 1, Cin = 470μF

Δ

R/R = 0.1%, RL ≥ 8

Ω

Tamb = 25°C

CMRR (dB)

Frequency (Hz)

100 1000 10000

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=1μF Cb=0

20k

20

Vcc = 2.5V Vic = 200mVpp Av = 1, Cin = 470μF

Δ

R/R ≤ 0.1%, RL ≥ 8

Ω

Tamb = 25°C

CMRR (dB)

Frequency (Hz)

Figure 94. CMRR vs. frequency (worst case

conditions)

0

Vcc = 5V Vic = 200mVpp

-10

Av = 1, Cin = 470μF

Δ

-20

-30

CMRR (dB)

-40

-50

-60

Tamb = 25°C

20

R/R = 0.1%, RL ≥ 8

Ω

Cb=1μF Cb=0

100 1000 10000

Frequency (Hz)

20k

Figure 96 and Figure 97 show CMRR versus frequency for a typical application with a

random selection of four

Δ

R/R values with a 0.1% tolerance.

Figure 96. CMRR vs. frequency with random

selection condition

Figure 95. CMRR vs. frequency (worst case

conditions)

Figure 97. CMRR vs. frequency with random

selection condition

0

Vcc = 5V

-10

Vic = 200mVpp

-20

Av = 1, Cin = 470μF

Δ

-30

-40

-50

CMRR (dB)

-60

-70

-80

-90

Tamb = 25°C

20

R/R ≤ 0.1%, RL ≥ 8

Ω

Cb=1μF Cb=0

100 1000 10000

Frequency (Hz)

20k

4.7 Power dissipation and efficiency

Assumptions:

● Load voltage and current are sinusoidal (V

● Supply voltage is a pure DC source (V

The output voltage is:

V

out

= V

CC

)

peak

and I

out

sinωt (V)

out

)

and

28/35

I

out

=

V

out

------------ -

R

L

(A)

TS4994FC Application information

and

2

V

peak

-------------------- -

P

out

=

2R

(W)

L

Therefore, the average current delivered by the supply voltag e is:

Equation 1

V

peak

---------------- -

AVG

= 2

I

CC

πR

(A)

L

The power delivered by the supply voltage is:

P

supplyVCCICC

AVG

(W)⋅=

Therefore, the power dissipated by each amplifier is:

P

diss

P

supplyPout

(W)–=

Equation 2

P

diss

----------------------

π R

L

–=

P

outPout

22V

CC

and the maximum value is obtained when:

∂P

diss

----------------- = 0 ∂P

out

and its value is:

Equation 3

2

maxPdiss

Vcc2

=

π

)W(

2

R

L

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

P

-------------------

η =

P

supply

The maximum theoretical value is reached when V

η =

out

π

---- -

= 78.5%

4

πV

--------------------

=

peak

4V

CC

= VCC, so:

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.

29/35

Application information TS4994FC

To calculate the maximum ambient temperature T

● The value of the power supply voltage, V

● The value of the load resistor, R

● The R

Example: V

value f or the package type

thja

=5V, RL=8Ω, R

CC

thja-flipchip

Using the power dissipation formula given above in Equation 3 this gives a result of:

P

T

is calculated as follows:

amb

dissmax

= 633mW

Equation 5

T

amb

Therefore, the maximum allowable value for T

T

= 125-80x0.633=62°C

amb

4.8 Decoupling of the circuit

Two capacitors are needed to correctly bypass the TS4994. A power supply bypass capacitor C

C

has particular influence on the THD+N in the high frequency region (abov e 7kHz) and an

s

indirect influence on power supply disturbances. With a value for C similar THD+N performance to that shown in the datasheet.

and a bias voltage bypass capacitor Cb.

s

allowable, you need to know:

amb

CC

L

= 100°C/W (100mm² copper heatsink)

125° CR

×–=

TJHAPdissmax

is:

amb

s

of 1µF, you can expect

In the high frequency region, if C on the power supply rail are less filtered.

On the other hand, if C 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: t

When the standby is released to put the device ON, the bypass capa cit or Cb is not charged immediately. As C properly until the C time or t

and is specified in Table 3 on page 5, with Cb=1µF. During the wake-up time, the

WU

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 88 on page 22 to establish the

b

wake-up time.

is directly linked to the bias of the amplifier, the bias will not work

b

voltage is correct. The time to reach this voltage is called the wake-up

b

is lower than 1µF, it increases THD+N, and disturbances

s

is higher than 1µF, the disturbances on the power supply rail are

s

WU

30/35

TS4994FC 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 micr oseconds.

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 Cin capacitors.

b

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 capacitors C

, some noise might remain at startup. To eliminate the effect of mismatched

in

, R

in

, and external input

feed

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 standb y mode, due to the h igh 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 98 shows an example of this configuration.

Figure 98. Single-ended input typical application

VCC

+

Cs

GND

Rfeed2 20k

1u

Vo+

5

Vo-

7

8 Ohms

Ve

GND

Cin1

220nF

Cin2

220nF

Rfeed1 20k

Rin1

+

20k Rin2

+

20k

+

Cb 1u

GND

3

Vin-

1

Vin+

8

Bypass

Mode Stdby TS4994IJ

4

GND GNDVCC VCC

2 VCC

-

+

Bias

Standby GND 69

GND

The component calculations remain the same, except for the gain. In single-ended input configuration, the formula is:

R

=

Av =

SE

VV

Ve

feedOO

−+

R

in

31/35

Package information TS4994FC

5 Package information

In order to meet environmental requirements, STMicroelectronics offers these devices in ECOPACK category of second level interconnect is marke d on the pa ckage and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related t o soldering conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics trademark. ECOPACK specifications are available at: www.st.com

®

packages. These packages have a Lead-free second level interconnect. The

.

Flip-chip package (9 bumps)

Dimensions in millimeters unless otherwise indicated.

Figure 99. Pinout (top view)

Gnd

V

O-

Bypass Stdby

V

IN+

765

9

8

1

9

2

V

CC

V

O+

4

V

3

Stdby Mode

IN-

* Balls are underneath

Figure 100. Marking (top view)

A94

YWW

E

32/35

TS4994FC Package information

Figure 101. Dimensions

1.63 mm

0.5mm

∅ 0.25mm

100µm

600µm

Figure 102. Tape & reel dimensions

1

1.63 mm

4

● Die size: 1.63mm x 1.63mm ± 30µm

● Die height (including bumps): 600µm

● Bumps diameter: 315µm ±50µm

● Bump diameter before reflow: 300µm

±10µm

● Bump height: 250µm ±40µm

● Back coating height: 40µm ±10µm

● Die height: 350µm ±20µm

● Pitch: 500µm ±50µm

● Coplanarity: 60µm max

1.5

1

A

A1A

8

Die size X + 70µm

All dimensions are in mm

4

User direction of feed

A

A1A

Die size Y + 70µm

33/35

Revision history TS4994FC

6 Revision history

Table 6. Document revision history

Date Revision Changes

17-Mar-2005 1 Initial release. 12-Dec-2006 2 Template update.

34/35

TS4994FC

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35/35