datasheet for AS1704 by ams AG

datasheet for AS1704 by ams AG

D a ta s h e e t

A S 1 7 0 2 - A S 1 7 0 5

1 . 8 W S i n g l e - C h a n n e l A u d i o P o w e r A m p l i f i e r s

1 General Description

The AS1702 - AS1705 are single-channel differential audio poweramplifiers designed to drive 4 and 8Ω loads. The integrated gain circuitry of these amplifiers and their small size make them ideal for

2.7- to 5V-powered portable audio devices.

The differential input design improves noise rejection and provides common-mode rejection. A bridge-tied load (BTL) design minimizes external component count, while providing high-fidelity audio power amplification.

The devices deliver 1.8W continuous average power per channel to a 4Ω load with less than 1% total harmonic distortion (plus noise), while operating from a single 2.7 to 5V supply.

For reduced component designs, the devices are available with dif-

ferent gain levels as shown in Table 1 .

Table 1. Standard Products

Model Gain

AS1702

AS1703

AS1704

AS1705

Adjustable (via external components)

A

V

= 0dB

A

V

= 3dB

A

V

= 6dB

Integrated shutdown circuitry disables the bias generator and amplifiers, and reduces quiescent current consumption to less than

100nA. The shutdown input can be set active-high or active-low. All devices contain click-and-pop suppression circuitry that reduces audible clicks and pops during power-up and shutdown.

The AS1702 - AS1705 are pin compatible with the LM4895 and the

MAX9718A/B/C/D. The devices are available in a 10-pin MSOP package and a 10-pin DFN package.

Figure 1. Simplified Block Diagram

2 Key Features

2.7V to 5.5V (V

CC

) Single-Supply Operation

THD+N: 1.8W into 4Ω at 1% (per Channel)

Differential Input

Adjustable Gain Option (AS1702)

Internal Fixed Gain to Reduce External Component Count

(AS1703, AS1704, AS1705)

<100nA Low-Power Shutdown Mode

Click and Pop Suppression

Pin-Compatible to National Semiconductor LM4895 (AS1705) and Maxim MAX9718A/B/C/D

Operating Temperature Range: -40 to +85ºC

Package Types

- 10-pin MSOP

- 10-pin DFN

3 Applications

The devices are ideal as audio front-ends for battery powered audio devices such as MP3 and CD players, mobile phones, PDAs, portable DVD players, and any other hand-held battery-powered device.

Single Supply

2.7V to 5.5V

9

VCC

4

IN+

2

IN-

1

SHDN

3

SHDM

+

10

OUT+

6

OUT-

AS1702/AS1703/

AS1704/AS1705

7

GND

R

L =

4 or 8

Ω www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

1 - 20

AS1702 - AS1705

Datasheet - P i n o u t

4 Pinout

Pin Assignments

Figure 2. Pin Assignments (Top View)

SHDN 1

IN2

SHDM 3

IN+ 4

BIAS 5

AS1702/

AS1703/

AS1704/

AS1705

10 OUT+

9 VCC

8 N/C

7 GND

6 OUT-

10-pin MSOP Package

SHDN 1

IN-

2

SHDM 3

IN+ 4

BIAS 5

AS1702V/

AS1703V/

AS1704V/

AS1705V

10 OUT+

9

VCC

8

N/C

7 GND

6

OUT-

10-pin DFN Package

Pin Descriptions

Table 2. Pin Descriptions – MSOP-10 and TDFN-10 Package

3

8

9

10

6

7

4

5

Pin

1

2

Name

SHDN

IN-

SHDM

IN+

BIAS

OUT-

GND

N/C

VCC

OUT+

Description

Shutdown Input. The polarity of this pin is dependent on the state of pin SHDM.

Inverting Input

Shutdown-Mode Polarity Input. This pin controls the polarity of pin SHDN. Connect this pin high for an active-high SHDN input. Connect this pin low for an active-low SHDN input

(see Table 6 on page 11)

.

Non-Inverting Input

DC Bias Bypass

Bridge Amplifier Negative Output

Ground

Not Connected. No internal connection.

Power Supply

Bridge Amplifier Positive Output

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

2 - 20

AS1702 - AS1705

Datasheet - A b s o l u t e M a x i m u m R a t i n g s

5 Absolute Maximum Ratings

Stresses beyond those listed in

Table 3 may cause permanent damage to the device. These are stress ratings only, and functional operation of

the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 4 is not implied. Exposure to absolute

maximum rating conditions for extended periods may affect device reliability.

Table 3. Absolute Maximum Ratings

Parameter

Electrical Parameters

Supply Voltage (V

DD

to V

SS

)

Min Max Units

V

Comments

Supply Voltage (All Other Pins)

-0.3

V

SS

- 0.3

-50

+7

V

DD

+ 0.3

50

V mA Norm: JEDEC 78 Input Current (latch-up immunity)

Electrostatic Discharge

Electrostatic Discharge HBM

Temperature Ranges and Storage Conditions

Continuous Power Dissipation

(T

AMB

= +70ºC)

Continuous Power Dissipation

(T

AMB

= +25ºC)

Storage Temperature Range

Junction Temperature

-65

1

600

1000

+150

+150 kV mW mW

ºC

ºC

Norm: MIL 883 E method 3015

MSOP-10

MSOP-10

Package Body Temperature

+260 ºC

The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/

JEDEC J-STD-020 “Moisture/Reflow Sensitivity

Classification for Non-Hermetic Solid State Surface

Mount Devices”.

The lead finish for Pb-free leaded packages is matte tin

(100% Sn).

Humidity non-condensing

Moisture Sensitive Level

5

1

85 %

Represents a max. floor life time of unlimited

Using PCB metal plane and thermally-conductive paste.

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

3 - 20

AS1702 - AS1705

Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s

6 Electrical Characteristics

All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods.

5V Operation

Table 4. Electrical Characteristics – 5V Supply, T

AMB

= +25ºC (unless otherwise specified)

Symbol

T

V

I

AMB

CC

CC

Parameter

Operating Temperature

Range

Supply Voltage

Supply Current

1

Shutdown Supply

V

IN-

= V

T

IN+

Conditions

AMB

= V

= -40 to +85ºC

BIAS

;T

AMB

= -40 to +85ºC

SHDN = SHDM = GND I

SHDN

V

IH

V

IL

SHDN, SHDM Threshold

V

BIAS

Common-Mode Bias

Voltage

2

V

V

R

OS

IC

IN

Output Offset Voltage

Common-Mode Input

Voltage

3

V

IN-

= V

IN+

= V

BIAS

Inferred from CMRR Test

A

V

= 0dB (AS1703)

A

V

= 3dB (AS1704)

A

V

= 6dB (AS1705)

A

V

= 0dB (AS1703)

A

V

= 3dB (AS1704)

A

V

= 6dB (AS1705)

External Gain AS1702

AS1703, AS1704, AS1705

CMRR

Input Impedance

Common-Mode Rejection

Ratio f

N

= 1kHz

PSRR

P

OUT

THD+N

Power Supply Rejection

Ratio

Output Power

Total Harmonic Distortion plus Noise

5

4

V

IN-

= V

IN+

= V

BIAS

;

V

RIPPL

E = 200mVp-p; R

L

= 8Ω; C

BIAS

= 1µ F f = 217Hz f = 1kHz

THD+N = 1%; f

IN

= 1kHz

R

L

= 8Ω

R

L

= 4Ω

R

L

= 4Ω, f

IN

= 1kHz, P

OUT

= 1.28W,

V

CC

= 5V, A

V

= 6dB

R

L

= 8Ω, f

IN

= 1kHz, P

OUT

= 0.9W,

V

CC

= 5V, A

V

= 6dB

AS1703, AS1704, AS1705 t

SHDN

V t

PU

POP

Gain Accuracy

Thermal Shutdown

Threshold

Thermal Shutdown

Hysteresis

Power-up/Enable from

Shutdown Time

Shutdown Time

Turn-Off Transient

6

Min

-40

2.7

0.7 x V

CC

0.2

0.9

1.5

1.5

10

0.8

Typ

8

0.05

±1

±1

±1

15

64

79

73

1.25

1.8

0.06

0.03

±1

+145

9

Max

+85

5.5

10.4

1

0.3 x V

CC

V

CC

/2 - 5% V

CC

/2 V

CC

/2 + 5%

V mA

µ A

125 ms

3.5

50

±10

±15

±20

V

CC

- 0.2

V

CC

- 0.9

V

CC

- 1.5

V

CC

- 1.5

20

±2

Unit

°C

V

V mV

V kΩ dB dB

W

%

%

ºC

ºC

µ s mV

1. Quiescent power supply current is specified and tested with no load. Quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier.

2. Common-mode bias voltage is the voltage on BIAS and is nominally V

CC

/2.

3. Guaranteed by design.

4. Guaranteed by design.

5. Measurement bandwidth for THD+N is 22Hz to 22kHz.

6. Peak voltage measured at power-on, power-off, into or out of SHDN. Bandwidth defined by A-weighted filters, inputs at AC GND. V

CC

rise and fall times ≥ 1ms.

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

4 - 20

AS1702 - AS1705

Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s

3V Operation

Table 5. Electrical Characteristics – 3V Supply, T

AMB

= +25ºC (unless otherwise specified)

Symbol

I

CC

Parameter

Supply Current

1

Shutdown Supply

Conditions

V

IN-

= V

IN+

= V

BIAS

;

T

AMB

= -40 to +85ºC, per amplifier

SHDN = SHDM = GND per amplifier I

SHDN

V

IH

V

IL

SHDN , SHDM

Threshold

V

V

CMRR

PSRR

P

THD+N t

SHDN

V t

BIAS

V

R

OS

IC

IN

OUT

PU

POP

Common-Mode Bias

Voltage

2

Output Offset Voltage

Common-Mode Input

Voltage

3

V

IN-

= V

IN+

= V

BIAS

A

V

= 0dB (AS1703)

A

V

= 3dB (AS1704)

A

V

= 6dB (AS1705)

A

V

= 0dB (AS1703)

Inferred from CMRR Test A

V

= 3dB (AS1704)

A

V

= 6dB (AS1705)

External gain AS1702

AS1703, AS1704, AS1705 Input Impedance

Common-Mode

Rejection Ratio f

N

= 1kHz

Power Supply Rejection

Ratio

Output Power

4

Total Harmonic

Distortion plus Noise

5

V

IN-

= V

IN+

= V

BIAS

;

V

RIPPLE

= 200mVp-p; R

L

=

8Ω; C

BIAS

= 1µ F f = 217Hz f = 1kHz

R

L

= 4Ω, THD+N = 1%; f

IN

= 1kHz

R

L

= 8Ω, THD+N = 1%; f

IN

= 1kHz

R

L

= 4Ω, f

IN

= 1kHz, P

OUT

= 460mW, A

V

= 6dB

R

L

= 8Ω, f

IN

= 1kHz, P

OUT

= 330mW, A

V

= 6dB

AS1703, AS1704, AS1705 Gain Accuracy

Thermal Shutdown

Threshold

Thermal Shutdown

Hysteresis

Power-up/Enable from

Shutdown Time

Shutdown Time

Turn-Off Transient

6

Min Typ

7.5

0.05

Max

1

0.7 x V

CC

V

0.3 x V

CC

V

CC

/2 - 5% V

CC

/2 V

CC

/2 + 5% V

Unit

mA

µ A

0.2

0.6

1.0

1.0

10

±1

±1

±1

±10

±15

±20

V

CC

- 0.2

V

CC

- 0.6

V

CC

- 1.0

V

CC

- 1.0

20 mV mV kΩ dB

15

64

79

73

640

440

0.06

0.04

±1

+145

±2 dB mW

%

%

ºC

9

125

3.5

50

ºC ms

µ s mV

1. Quiescent power supply current is specified and tested with no load. Quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier. Guaranteed by design.

2. Common-mode bias voltage is the voltage on BIAS and is nominally V

CC

/2.

3. Guaranteed by design.

4. Guaranteed by design.

5. Measurement bandwidth for THD+N is 22Hz to 22kHz.

6. Peak voltage measured at power-on, power-off, into or out of SHDN. Bandwidth defined by A-weighted filters, inputs at AC GND. V

CC

rise and fall times ≥ 1ms.

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

5 - 20

AS1702 - AS1705

Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s

7 Typical Operating Characteristics

Figure 3. THD + Noise vs. Frequency;

V

DD

= 3V, R

L

= 4Ω, AV = 2V

DD

= 3V, R

L

= 8Ω, Av = 2

10

Figure 4. THD + Noise vs. Frequency;

10

1

0.1

P

OUT

= 50mW

P

OUT

= 250mW

0.01

0.001

10 100 1000

Frequency (Hz)

Figure 5. THD + Noise vs. Frequency;

V

DD

=5V, R

L

= 4Ω, Av = 2V

DD

= 5V, R

L

= 8Ω, Av = 2

10000

10

1

0.1

0.01

P

OUT

= 100mW

P

OUT

= 250mW

0.001

10 100 1000

Frequency (Hz)

Figure 6. THD + Noise vs. Frequency;

10

1

0.1

0.01

P

OUT

= 250mW

P

OUT

= 1W

0.001

10 100 1000

Frequency (Hz)

Figure 7. THD + Noise vs. Frequency;

V

DD

= 5V, R

L

= 4Ω, Av = 4V

DD

= 5V, R

L

= 8Ω, Av = 4

10000

10

1

0.1

0.01

0.001

10

P

OUT

= 200mW

P

OUT

= 1W

100 1000

Frequency (Hz)

10000

10000

1

0.1

0.01

P

OUT

= 250mW

P

OUT

= 750mW

0.001

10 100 1000

Frequency [Hz]

Figure 8. THD + Noise vs. Output Power;

10

1

P

OUT

= 200mW

P

OUT

= 800mW

0.1

0.01

0.001

10 100 1000

Frequenzy (Hz)

10000

10000 www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

6 - 20

AS1702 - AS1705

Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s

Figure 9. THD + Noise vs. Output Power;

V

DD

= 3V, R

L

= 4Ω, Av = 2V

DD

= 3V, R

L

= 8Ω, Av = 2

10

Figure 10. THD + Noise vs. Output Power;

10

1 f

IN

= 1kHz

0.1

f

IN

= 100Hz

0.01

0 0.1

0.2 0.3

0.4 0.5 0.6

0.7 0.8

Output Power (W)

Figure 11. THD + Noise vs. Output Power;

V

DD

= 3V, R

L

= 4Ω, Av = 4V

DD

= 3V, R

L

= 8Ω, Av = 4

10

1

0.1

f

IN

= 1kHz

0.01

0 f

IN

= 100Hz

0.1

0.2

0.3

0.4

0.5

0.6

Output Power (W)

Figure 12. THD + Noise vs. Output Power;

10

1

0.1

fIN = 1kHz f

IN

= 100Hz

0.01

0 0.1

0.2 0.3

0.4 0.5 0.6

0.7 0.8

Output Power (W)

Figure 13. THD + Noise vs. Output Power;

V

DD

= 5V, R

L

= 4Ω, Av = 2V

DD

= 5V, R

L

= 8Ω, Av = 2

10

1 f

IN

= 1kHz

0.1

f

IN

= 100Hz

0.01

0 0.1

0.2

0.3

0.4

0.5

0.6

Output Power (W)

Figure 14. THD + Noise vs. Output Power;

10

1 1

0.1

f

IN

= 1kHz

0.01

0 f

IN

= 100Hz

0.4

0.8

1.2

1.6

Output Power (W)

2

0.1

f

IN

= 1kHz f

IN

= 100Hz

0.01

0 0.2

0.4 0.6

0.8

1 1.2

1.4 1.6

Output Power (W) www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

7 - 20

AS1702 - AS1705

Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s

Figure 15. THD + Noise vs. Output Power;

V

DD

= 5V, R

L

= 4Ω, Av = 4V

DD

= 5V, R

L

= 8Ω, Av = 4

10

1 f

IN

= 1kHz

0.1

f

IN

= 100Hz

2.5

2

1.5

1

0.5

0.01

0 0.4

0.8

1.2

1.6

Output Power (W)

Figure 17. Output Power vs. Load Resistance;

V

DD

= 3V V

DD

= 5V

900

800

700

600

500

400

300

200

100

0

1

P

OUT

@ THD = 10%

P

OUT

@ THD = 1%

10

Load Resistance (

Ω

)

Figure 19. Output Power vs. Supply Voltage;

R

L

= 4Ω

R

L

= 8Ω

3

2

100

P

OUT

@ 10% (W)

P

OUT

@ 1% (W)

0

2.5

5.5

3.5

4.5

Supply Voltage (V)

Figure 16. THD + Noise vs. Output Power;

10

1

0.1

f

IN

= 1kHz f

IN

= 100Hz

0.01

0 0.2

0.4 0.6

0.8

1 1.2

1.4 1.6

Output Power (W)

Figure 18. Output Power vs. Load Resistance;

2.4

2

1.6

1.2

P

OUT

@ THD = 10%

0.8

0.4

P

OUT

@ THD = 1%

0

1 10

Load Resistance (

Ω

)

Figure 20. Output Power vs. Supply Voltage;

100

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

2.5

P

OUT

@ 10% (W)

P

OUT

@ 1% (W)

3.5

4.5

Supply Voltage (V)

5.5

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

8 - 20

AS1702 - AS1705

Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s

Figure 21. Power Dissipation vs. Output Power; Figure 22. Power Dissipation vs. Output Power;

V

DD

= 3V, R

L

= 4Ω, Av = 2. f = 1kHzV

DD

= 3V, R

L

= 8Ω, Av = 2, f = 1kHz

700

600

500

400

300

200

100

0

0 100 200 300 400 500 600 700

Output Power (mW)

350

300

250

200

150

100

50

0

0 100 200 300

Output Power (mW)

400

Figure 24. Power Dissipation vs. Output Power;

V

DD

= 5V, R

L

= 8Ω, Av = 2. f = 1kHz

1.0

Figure 23. Power Dissipation vs. Output Power;

V

DD

= 5V, R

L

= 4Ω, Av = 2. f = 1kHz

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

0.0

0.3

0.6

0.9

1.2

Output Power (W)

1.5

1.8

0.8

0.6

0.4

0.2

500

0.0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Output Power (W)

Figure 25. Shutdown Hysteresis Voltage; V

DD

= 3V

3

2.5

2

1.5

1

0.5

0

0 1 2

Shutdown Voltage (V)

3

Figure 26. Shutdown Hysteresis Voltage; V

DD

= 5V

3

2.5

2

1.5

1

0.5

0

0 1 2

Shutdown Voltage (V)

3 www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

9 - 20

AS1702 - AS1705

Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s

Figure 27. Shutdown Current vs. Temperature

10

V

DD

= 5V

8

V

DD

= 3V

6

4

2

0

-40 -20 0 20 40

Temperature (°C)

60 80

Figure 29. Power Supply Rejection Ratio vs. Frequency

100

90

80

70

60

50

40

30

20

10

V

DD

= 5V

V

DD

= 3V

100 1000 10000 100000

Frequency (Hz)

Figure 28. Shutdown Current vs. Temperature

0.03

0.02

0.01

0.00

-0.01

-0.02

V

DD

= 5V

V

DD

= 3V

-0.03

-40 -20 0 20 40 60

Temperature (°C)

80 www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

10 - 20

AS1702 - AS1705

Datasheet - D e t a i l e d D e s c r i p t i o n

8 Detailed Description

The AS1702 - AS1705 are 1.8W high output-current audio amplifiers (configured as BTL amplifiers), and contain integrated low-power shutdown and click- and pop-suppression circuitry. Two inputs (SHDM and SHDN) allow shutdown mode to be configured as active-high or active-low

(see

Shutdown Mode on page 11)

.

Each device has either adjustable or fixed gains (0dB, 3dB, 6dB)

(see Ordering Information on page 19) .

Bias

The devices operate from a single 2.7 to 5.5V supply and contain an internally generated, common-mode bias voltage of:

V

CC

2

(EQ 1)

referenced to ground. Bias provides click-and-pop suppression and sets the DC bias level for the audio outputs. Select the value of the bias bypass capacitor as described in Section BIAS Capacitor on page 15 .

Note:

Do not connect external loads to BIAS as this can adversely affect overall device performance.

Shutdown Mode

All devices implement a 100nA, low-power shutdown circuit which reduces quiescent current consumption. As shutdown mode commences, the bias circuitry is automatically disabled, the device outputs go high impedance, and bias is driven to GND.

The SHDM input controls the polarity of SHDN:

Drive SHDM high for an active-low SHDN input.

Drive SHDM low for an active-high SHDN input.

Table 6. Shutdown Mode Selection Configurations

SHDM

0

0

1

1

SHDN

0

1

0

1

Mode

Shutdown Mode Enabled

Normal Operation Enabled

Normal Operation Enabled

Shutdown Mode Enabled

Click-and-Pop Suppression

During power-up, the device common-mode bias voltage (V

BIAS

(see page 4) ) ramps to the DC bias point. When entering shutdown, the device outputs are driven high impedance to 100kΩ between both outputs minimizing the energy present in the audio band, thus preventing clicks and pops.

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

11 - 20

AS1702 - AS1705

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

Figure 30. AS1702 Typical Application Diagram

2.7 to 5.5V

Supply

10µF

V

9

CC

Inverting

Differential Input

C

IN

*

10µF

R

IN

10k

Ω

Non-Inverting

Differential Input

C

IN

*

10µF

R

IN

10k

Ω

* Optional

2

IN-

4

IN+

C

BIAS

0.1µF

5

BIAS

1

SHDN

3

SHDM

Bias

Generator

Shutdown

Control

R

F

20k

Ω

R

F

20k

Ω

AV = 2

+

AS1702

10

OUT+

6

OUT-

7

GND

Figure 31. AS1703, AS1704, AS1705 Typical Application Diagram

2.7 to 5.5V

Supply

10µF

9

V

CC

Inverting

Differential Input

Non-Inverting

Differential Input

C

IN

*

10µF

C

IN

*

10µF

* Optional

2

IN-

4

IN+

R

1

R

1

C

BIAS

0.1µF

5

BIAS

1

SHDN

3

SHDM

Bias

Generator

Shutdown

Control

R

2

A

V

= 1

A

V

= 1.41

A

V

= 2

+

R

2

AS1703/

AS1704/

AS1705

10

OUT+

6

OUT-

7

GND www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

12 - 20

AS1702 - AS1705

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

BTL Amplifier

All devices are designed to drive loads differentially in a bridge-tied load (BTL) configuration.

Figure 32. Bridge Tied Load Configuration

+1

V

OUT(P-P)

2 x V

OUT(P-P)

V

OUT(P-P)

-1

The BTL configuration doubles the output voltage (illustrated in Figure 32

) compared to a single-ended amplifier under similar conditions. Thus, the differential gain of the device (A

VD

) is twice the closed-loop gain of the input amplifier. The effective gain is given by:

A

VD

= 2 x

R

F

R

IN

(EQ 2)

Substituting 2 x V

OUT(P-P)

for V

OUT(P-P)

into (EQ 3) and (EQ 4) yields four times the output power due to doubling of the output voltage:

V

RMS

=

V

OUT(P-P)

2 2

(EQ 3)

P

OUT

=

V

RMS

2

R

L

(EQ 4)

Since the BTL outputs are biased at mid-supply, there is no net DC voltage across the load. This eliminates the need for the large, expensive, performance degrading DC-blocking capacitors required by single-ended amplifiers.

Power Dissipation and Heat Sinking

Normally, the devices dissipate a significant amount of power. The maximum power dissipation is given in

Table 3

as Continuous Power Dissipation, or it can be calculated by:

P

DISSPKF(MAX)

=

T

J(MAX)

-T

A

Θ

JA

(EQ 5)

where T

J(MAX)

is +150ºC, T

AMB

(see Table 3

) is the ambient temperature, and Θ

JA

is the reciprocal of the derating factor in ºC/W as specified in

Table 3

. For example, Θ

JA

of the TQFN package is +59.2ºC/W.

The increased power delivered by a BTL configuration results in an increase in internal power dissipation versus a single-ended configuration.

The maximum internal power dissipation for a given V

CC

and load is given by:

P

DISSPKF(MAX)

=

2V

CC

2

π

2

R

L

(EQ 6)

If the internal power dissipation exceeds the maximum allowed for a given package, power dissipation should be reduced by increasing the ground plane heat-sinking capabilities and increasing the size of the device traces

(see Layout and Grounding Considerations on page 15)

. Additionally, reducing V

CC

, increasing load impedance, and decreasing ambient temperature can reduce device power dissipation.

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

13 - 20

AS1702 - AS1705

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

The integrated thermal-overload protection circuitry limits the total device power dissipation. Note that if the junction temperature is ≥ +145ºC, the integrated thermal-overload protection circuitry will disable the amplifier output stage. If the junction temperature is reduced by 9°, the amplifiers will be re-enabled.

Note:

A pulsing output under continuous thermal overload results as the device heats and cools.

Fixed Differential Gain (AS1703

,

AS1704, and AS1705)

The AS1703, AS1704, and AS1705 contain different internally-fixed gains (see Ordering Information on page 19)

. A fixed gain facilitates simplified designs, decreased footprint size, and elimination of external gain-setting resistors.

The fixed gain values are achieved using resistors R

1

and R

2

(see Figure 31 on page 12) .

Adjustable Differential Gain (AS1702)

Gain-Setting Resistors

The AS1702 uses external feedback resistors, R

F

and R

IN

( Figure 33 ), to set the gain of the device as:

A

V

=

R

F

R

IN

(EQ 7)

where A

V

is the desired voltage gain. For example, R

IN

= 10kΩ, R

F

= 20kΩ yields a gain of 2V/V, or 6dB.

Note:

R

F

can be either fixed or variable, allowing the gain to be controlled by software (using a AS150x digital potentiometer. For more information on the AS1500 family of digital potentiometers, refer to the latest version of the AS150x data sheet, available from the austriamicrosystems website http://www.austriamicrosystems.com

.)

Figure 33. Setting the AS1702 Gain

R

F

20k

Ω

R

F

20k

Ω

Inverting

Differential Input

Non-Inverting

Differential Input

C

IN

*

10µF

R

IN

10k

Ω

C

IN

*

10µF

R

IN

10k

Ω

* Optional

C

BIAS

0.1µF

2

IN-

4

IN+

5

BIAS

Bias

Generator

+

AS1702

10

OUT+

6

OUT-

Input Filter

The BTL inputs can be biased at voltages other than mid-supply. However, the integrated common-mode feedback circuit adjusts for input bias, ensuring the outputs are still biased at mid-supply. Input capacitors are not required if the common-mode input voltage (V

IC

) is within the range specified in Table 4 and Table 5 .

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

14 - 20

AS1702 - AS1705

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

Input capacitor C

IN

(if used), in conjunction with R

IN

, forms a high-pass filter that removes the DC bias from an incoming signal. The AC coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero-source impedance, the -3dB point of the high-pass filter is given by:

f

-3dB

=

2

π

R

1

IN

C

IN

(EQ 8)

Setting f

-3dB

too high affects the low-frequency response of the amplifier. Capacitors with dielectrics that have low-voltage coefficients such as tantalum or aluminum electrolytic should be used, since capacitors with high-voltage coefficients, such as ceramics, can increase distortion at low frequencies.

BIAS Capacitor

BIAS is the output of the internally generated V

CC

/2 bias voltage. The BIAS bypass capacitor, C

BIAS

, improves PSRR and THD+N by reducing power supply noise and other noise sources at the common-mode bias node, and also generates the click- and pop-less DC bias waveform for the amplifiers. Bypass BIAS with a 0.1µ F capacitor to GND. Larger values of C

BIAS

(up to 1µ F) improve PSRR, but increase t

ON

/t

OFF

times.

For example, a 1µ F C

BIAS

capacitor increases t

ON

/t

OFF

by 10 and improves PSRR by 20dB (at 1kHz).

Note:

Do not connect external loads to BIAS.

Supply Bypassing

Proper power supply bypassing – connect a 10µ F ceramic capacitor (C

BIAS

) from V

CC

to GND – will ensure low-noise, low-distortion performance of the device. Additional bulk capacitance can be added as required.

Note:

Place C

BIAS

as close to the device as possible.

Layout and Grounding Considerations

Well designed PC board layout is essential for optimizing device performance. Use large traces for the power supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance and route heat away from the device.

Good grounding improves audio performance and prevents digital switching noise from coupling onto the audio signal. www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

15 - 20

AS1702 - AS1705

Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s

10 Package Drawings and Markings

Figure 34. 10-pin DFN Marking

Table 7. Packaging Code YYWWQZZ

YY

last two digits of the current year

WW

manufacturing week

Q

plant identifier

ZZ

free choice / traceability code

Figure 35. 10-pin MSOP Marking

Table 8. Packaging Code YYWWRZZ

YY

last two digits of the current year

WW

manufacturing week

R

plant identifier

ZZ

free choice / traceability code www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

16 - 20

AS1702 - AS1705

Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s

Figure 36. 10-pin DFN Package

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

17 - 20

AS1702 - AS1705

Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s

Figure 37. 10-pin MSOP Package

www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

18 - 20

AS1702 - AS1705

Datasheet - O r d e r i n g I n f o r m a t i o n

11 Ordering Information

The devices are available as the standard products shown in Table 9 .

Table 9. Ordering Information

Odering Code

AS1702-T

AS1703-T

AS1704-T

AS1705-T

AS1702V-T

AS1703V-T

AS1704V-T

AS1705V-T

Marking

AS1702

AS1703

AS1704

AS1704

1702

1703

1704

1705

Description

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

1.8W Single-Channel Audio Power Amplifiers

Gain

Adjustable

Av =0dB

Av =3dB

Av =6dB

Adjustable

Av =0dB

Av =3dB

Av =6dB

Delivery Form

Tape and Reel

Tape and Reel

Tape and Reel

Tape and Reel

Tape and Reel

Tape and Reel

Tape and Reel

Tape and Reel

Package

10-pin MSOP

10-pin DFN

Note:

All products are RoHS compliant.

Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect

Technical Support is found at http://www.austriamicrosystems.com/Technical-Support

For further information and requests, please contact us mailto:[email protected]

or find your local distributor at http://www.austriamicrosystems.com/distributor www.austriamicrosystems.com/Audio/Amps/AS1702-05 Revision 1.48

19 - 20

AS1702 - AS1705

Datasheet

Copyrights

Copyright © 1997-2011, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®.

All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner.

All products and companies mentioned are trademarks or registered trademarks of their respective companies.

Disclaimer

Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location.

The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services.

Contact Information

Headquarters austriamicrosystems AG

Tobelbaderstrasse 30

A-8141 Unterpremstaetten, Austria

Tel: +43 (0) 3136 500 0

Fax: +43 (0) 3136 525 01

For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact www.austriamicrosystems.com/Audio/Amps/AS17002-05 Revision 1.48

20 - 20

Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement