ANALOG DEVICES AD1990 Service Manual

Audio Switching Amplifier

FEATURES

Integrated stereo modulator and power stage
<0.002% THD + N
101 dB dynamic range (A-weighted)
2 × 5 W output power (4 Ω, <0.01% THD + N)

< 0.3 Ω (per transistor)

R

DS-ON

PSRR > 65 dB
On-off-mute pop noise suppression
EMI optimized modulator
Short-circuit protection
Overtemperature protection
Low cost DMOS process

APPLICATIONS

Advanced televisions
Compact multimedia systems
Minicomponents

PGA1 PGA0

AV

GENERAL DESCRIPTION

The AD1990 is a 2-channel, bridge tied load (BTL), switching
audio power amplifier with integrated Σ-Δ modulator. The
modulator accepts a single-ended, analog input signal and
converts it to a switching waveform to drive speakers directly. A
digital, microprocessor-compatible interface provides control of
reset, mute, and PGA gain, as well as feedback signals for thermal
and overcurrent error conditions. The output stage can operate
over a power supply voltages range of 8 V to 12 V. The analog
modulator and digital logic operate from a 5 V supply.

FUNCTIONAL BLOCK DIAGRAM

NFL–

DD

NFL+

DV

DD

FEEDBACK

NETWO RK

PV

DD

AD1990

AINL

AINR

CLKI

CLKO

REF_FILT

AD1990

OSCILLATOR

REFERENCE

VOLTAGE

AGND

PGA

PGA

MODE CONT ROL

LOGI C AND
POP/CLICK

SUPPRESSION

ERR2

MUTE

ERR1

RESET

MODULAT OR

MODULAT OR

ERR0

Σ-Δ

LEVEL

SHIFTER

AND

DEAD TIME

CONTROL

Σ-Δ

NFR–

NFR+

DCTRL2

DCTRL1

DCTRL0

A1

A2

B1

B2

H-BRIDGE

C1

C2

D1

D2

PGND

Figure 1.

FEEDBACK

NETWO RK

OUTL+

OUTL–

OUTR+

OUTR–

05380-001

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2006 Analog Devices, Inc. All rights reserved.

AD1990

TABLE OF CONTENTS

Features .............................................................................................. 1

Overview ..................................................................................... 11

Applications....................................................................................... 1

General Description ......................................................................... 1

Functional Block Diagram .............................................................. 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Absolute Maximum Ratings............................................................ 5

ESD Caution.................................................................................. 5

Pin Configuration and Function Descriptions............................. 6

Typical Performance Characteristics ............................................. 8

Theory of Operation ...................................................................... 11

REVISION HISTORY

4/06—Revision 0: Initial Version

Σ-Δ Modulator............................................................................ 11

and

RESET

..................................................................... 11

MUTE

Gain Structure............................................................................. 11

Power Stage ................................................................................. 13

Clocking....................................................................................... 13

Protection Circuits and Error Reporting ................................ 14

Application Circuits ....................................................................... 15

Outline Dimensions ....................................................................... 16

Ordering Guide .......................................................................... 16

Rev. 0 | Page 2 of 16

AD1990

SPECIFICATIONS

Test conditions, unless otherwise specified.

Table 1.

Parameter Ratings

SUPPLY VOLTAGES

AV

DD

DV

DD

PV

DD

AMBIENT TEMPERATURE 25°C
LOAD IMPEDANCE 6 Ω
CLOCK FREQUENCY 12.288 MHz
PGA GAIN 0 dB
MEASUREMENT BANDWIDTH 20 Hz to 20 kHz

Table 2.

Parameter Min Typ Max Unit Test Conditions/Comments

R

DS-ON

Per High-Side Transistor 260 355 mΩ T = 25°C

Per Low-Side Transistor 210 265 mΩ T = 25°C
MAXIMUM CURRENT THROUGH OUTx 5 A Peak
THERMAL WARNING ACTIVE 135 °C Die temperature
THERMAL SHUTDOWN ACTIVE 150 °C Die temperature
RESTORE TEMPERATURE AFTER THERMAL SHUTDOWN 120 °C Die temperature

Table 3. Performance Specifications

Parameter Typ Unit Test Conditions/Comments

TOTAL HARMONIC DISTORTION AND NOISE (THD + N) 0.003 % PGA = 0 dB, PO = 1 W, 1 kHz

0.006 % PGA = 6 dB, PO = 1 W, 1 kHz

0.01 % PGA = 12 dB, PO = 1 W, 1 kHz

0.02 % PGA = 18 dB, PO = 1 W, 1 kHz
SIGNAL-TO-NOISE RATIO (SNR) 102 dB 1 kHz, A-weighted, 0 dB referred to 1% THD + N output
DYNAMIC RANGE (DNR) 102 dB 1 kHz, A-weighted, −60 dB referred to 1% THD + N output
CROSSTALK (LEFT-TO-RIGHT OR RIGHT-TO-LEFT) −100 dB PGA = 0 dB, PO = 5 W, 1 kHz

Table 4. DC Specifications

Parameter Typ Unit Test Conditions/Comments

INPUT IMPEDANCE 20 kΩ AINL, AINR input pins
OUTPUT DC OFFSET ±4 mV Independent of PGA setting

5 V
5 V
12 V

Rev. 0 | Page 3 of 16

AD1990

Table 5. Power Supplies

Parameter Min Typ Max Unit Test Conditions/Comments

ANALOG SUPPLY, AV
DIGITAL SUPPLY, DV
POWER TRANSISTOR SUPPLY, PV

DD

DD

DD

RESET/POWER-DOWN CURRENT

AV

DD

DV

DD

PV

DD

QUIESCENT CURRENT Inputs grounded, nonoverlap = minimum

AV

DD

DV

DD

PV

DD

OPERATING CURRENT VIN = 1 V rms, RL = 6 Ω, PO = 1 W

AV

DD

DV

DD

PV

DD

Table 6. Digital I/O

Parameter Min Typ Max Unit Test Conditions/Comments

INPUT LOGIC HIGH 2.0 V
INPUT LOGIC LOW 0.8 V
OUTPUT LOGIC HIGH 2.4 V @ 4 mA
OUTPUT LOGIC LOW 0.4 V @ 4 mA
LEAKAGE CURRENT ON DIGITAL OUTPUTS 10 μA

Table 7. Digital Timing

Parameter Typ Unit Test Conditions/Comments

t

MD

t

UD

10 μs
34 μs

4.5 5.0 5.5 V

4.5 5.0 5.5 V

6.5 8 to 12 15 V
RESET held low

0.6 1 μA 5 V

7.5 11 μA 5 V

19 40 μA 12 V

20 mA 5 V

5.5 mA 5 V

30 mA 12 V

20 27 mA 5 V

5.5 7 mA 5 V

218 260 mA 12 V

Delay after
Delay after

MUTE is asserted until output stops switching
MUTE is deasserted until output starts switching

t

UD

05380-002

MUTE

OUTx

t

MD

Figure 2. Mute and Unmute Delay Timing

Rev. 0 | Page 4 of 16

AD1990

ABSOLUTE MAXIMUM RATINGS

Table 8.

Parameter Rating

AVDD, DVDD to AGND, DGND −0.3 V to +6.5 V
PVDDx to PGNDx
AGND to DGND to PGNDx −0.3 V to +0.3 V
AVDD, to DVDD −0.5 V to +0.5 V
Operating Temperature Range –40°C to +85°C
Storage Temperature Range –65°C to +150°C
Maximum Junction Temperature 150°C
Thermal Resistance

θ

JA

θJC (at the Exposed Pad Surface) 0.9°C/W
θJB (on JEDEC Standard PCB) 9.7°C/W

1

Including any induced voltage due to inductive load.

1

−0.3 V to +22.5 V

19.2°C/W

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.

Rev. 0 | Page 5 of 16