National Semiconductor LM4921 Technical data

LM4921
Low Voltage I2S 16-Bit Stereo DAC with Stereo
Headphone Power Amplifiers and Volume Control

January 2004

LM4921 Low Voltage I

Control

General Description

The LM4921 combines a 16-bit resolution stereo I2S input
digital-to-analog converter (DAC) with a stereo headphone
audio power amplifier. It is primarily designed for demanding
applications in mobile phones and other portable communi­cation device applications. The LM4921 features an I
serial interface for the digital audio information and a 16-bit
SPI serial interface for internal register control and commu­nication. With AV
single-ended load to a 26mW
(THD+N) of the LM4921 will be less than 0.5%. The LM4921
also features a programmable 32-step digital volume control
accessed through an SPI interface.

Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. It is, therefore, ideally suited for mo­bile phone and other low voltage applications where minimal
power consumption is a primary requirement.

The LM4921 features a low-power consumption shutdown
mode, and also has an internal thermal shutdown protection
mechanism.

and DVDD= 3.0VDCand driving a 32Ω

DD

output level the distortion

RMS

2

Key Specifications

j

PSRR at 217Hz, A/DVDD= 3V, (Fig. 1) 52dB (typ)

j

P

at AVDD= 3.0V, 32Ω

OUT

<

0.05% THD 13mW (typ)

S

<

0.5% THD 26mW (typ)

j

Supply voltage range

DV

DD

AV

(Note 8) 2.6V to 5.5V

DD

j

Shutdown current 1µA (typ)

Features

n 16-bit resolution stereo DAC

2

n I

S digital audio data serial interface

n SPI serial interface (control register)
n Volume Control (32 steps; 1.5 dB increments)
n Up to 50mW/channel stereo headphone amplifier
n Zero Crossing Detection for Silent Attenuation Steps
n 2.6V
n 2.6V
n Unity-gain stable headphone amplifiers
n Available in the 20-bump microSMD package

to 5.0VDCdigital supply voltage range

DC

to 5.5VDCanalog supply voltage range (Note 8)

DC

Applications

n Mobile phones
n PDAs
n Portable electronic devices

2.6V to 5.0V

2

S 16-Bit Stereo DAC with Stereo Headphone Power Amplifiers and Volume

Boomer®is a registered trademark of National Semiconductor Corporation.

© 2004 National Semiconductor Corporation DS200486 www.national.com

Typical Application

LM4921

FIGURE 1. Typical Audio Amplifier Application Circuit

200486F6

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Connection Diagrams

LM4921

LM4921 Pin Configuration

Top View

20-Bump micro SMD

Order Number LM4921ITL, LM4921ITLX

See NS Package Number TLA20JKA

NC - No Connection

20-Bump micro SMD Marking

200486F9

X - Date Code
T - Die Traceability
G - Boomer Family

B9 - LM4921ITL

200486F8

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LM4921 I/O Pin Descriptions

LM4921

PIN # (ITL) PIN NAME PIN TYPE

B1 I2S_CLK I/O I2S Clock

C2 I2S_DATA I I2S data

B2 I2S_WS I/O I2S L/R word select

E3 SPI_CLK I SPI clcock

E4 SPI_DATA I SPI data

D3 SPI_ENABLE I SPI Enable

E2 MCLK/XTAL_IN I Master Clock / Xtal input

D2 XTAL_OUT O Xtal output

C4 BYPASS I/O Analog VDD/2 bypass capacitor connection

B4 AV

DD

A3 AGND P Analog Ground

C1 DV

DD

A1 GNDD P Digital ground

D1 VDDX P XTAL Oscillator circuit supply

E1 GNDX P XTAL Oscillator circuit ground

B3 HP_L O HP left output

A4 HP_R O HP right output

A2 No Connect O Must let float

C3 No Connect NC NC

D4 No Connect NC NC

PIN DESCRIPTION
Input-I, Output-O,
Power-P, No Connect-NC

point

P Analog supply

P Digital Supply

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LM4921

Absolute Maximum Ratings (Notes 1, 2)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage 6.0V

Junction Temperature 150˚C

Thermal Resistance

θ

JA

Operating Ratings

Storage Temperature −65˚C to +150˚C

Input Voltage -0.3V to V

DD

+ 0.3V

Power Dissipation (Note 3) Internally Limited

ESD Susceptibility

Human body model (Note 4) 2000V

Machine model (Note 5) 200V

Temperature Range

T

≤ TA≤ T

MIN

MAX

Supply Voltage

DV

DD

AV

DD

−40˚C ≤ TA≤ 85˚C

2.6V ≤ DVDD≤ 5.0V

2.6V ≤ AVDD≤ 5.5V

Electrical Characteristics DVDD= 3.0V, AVDD= 5.0V, RL=32Ω (Notes 1, 2)

The following specifications apply for the circuit shown in Figure 1 unless otherwise specified. Limits apply for T

LM4921

Symbol Parameter Conditions

DV

AV

DI

DD

DD

DD

Digital Power Supply Voltage Note 8 3.0 V

Analog Power Supply Voltage Note 8 5.0 V

Digital Power Supply Quiescent

R

Load

=∞,f

= 11.2896MHz 3.5 7.5 mA (max)

MLCK

Current

AI

DD

Analog Power Supply Quiescent

R

Load

=∞,f

= 0MHz 6 10 mA (max)

MCLK

Current

I

SD

Total Shutdown Power Supply
Current

I

SB

Standby Current Analog and Digital together

SHUTDOWN SPI bits1&2setto
logic 0,
SPI, M

and I2S inputs at GND

CLK

All clocks off

V

FS

THD+N Total Harmonic Distortion + Noise fIN= 1kHz, P

Full-Scale Output Voltage Gain set at max 3.5 V

= 12mW

OUT

(Vol Control = 11111, I
to get 12mW at output)

P

O

PSRR Power Supply Rejection Ratio

SNR Signal-to-Noise Ratio f

DR Dynamic Range f

Headphone Amplifier Output Power THD = (0.5%), f

AV

DDCBYPASS

V

A-weighted-f

= 200mV

RIPPLE

= 1kHz sinewave at -60dBFS,

IN

CONV

= 1kHz sinewave at -60dBFS,

IN

OUT

= 2.0µF

P-P

= 44.1kHz

A-weighted

∆A

X

CH-CH

TALK

Channel-to-Channel Gain Mismatch fIN= 1kHz 0.06 dB

Channel-to-Channel Crosstalk f

= 44.1kHz,

CONV

= 1kHz sinewave at -3dB

f

IN

Volume Control Range Minimum Attenuation

Maximum Attenuation

Volume Control Control Step Size 1.5 dB

Mute Attenuation -102 dB

2

S input adj

= 1kHz 50 40 mW (min)

217Hz

FS

Typical Limit

(Note 6) (Notes 7, 9)

1 5 uA(max)

25 uA

0.03 %

62 45 dB (min)

82 dB

84 dB

72 dB

+3.0

-43.5

= 25˚C.

A

60˚C/W

Units

(Limits)

P-P

dB
dB

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Electrical Characteristics DVDD= 3.0V, AVDD= 3.0V, RL=32Ω (Notes 1, 2)

The following specifications apply for the circuit shown in Figure 1 unless otherwise specified. Limits apply for T

LM4921

LM4921

Symbol Parameter Conditions

DV

AV

DI

DD

DD

DD

Digital Power Supply Voltage Note 8 3.0 V

Analog Power Supply Voltage Note 8 3.0 V

Digital Power Supply Quiescent

R

Load

=∞,f

= 11.2896MHz 3.5 7.5 mA (max)

MLCK

Current

AI

DD

Analog Power Supply Quiescent

R

Load

=∞,f

= 0MHz 5 9.0 mA (max)

MCLK

Current

I

SD

Total Shutdown Power Supply
Current

I

SB

Standby Current Analog and Digital together

SHUTDOWN SPI bits1&2setto
logic 0,
SPI, M

and I2S inputs at GND

CLK

All clocks off

V

FS

THD+N Total Harmonic Distortion + Noise fIN= 1kHz, P

Full-Scale Output Voltage Gain set at max 2.6 V

= 12mW

OUT

(Vol Cont = 11011, I
get 12mW at output)

P

O

PSRR Power Supply Rejection Ratio

SNR Signal-to-Noise Ratio f

DR Dynamic Range f

Headphone Amplifier Output Power THD = (0.5%), f

AV

DDCBYPASS

V

A-weighted-f

= 200mV

RIPPLE

= 1kHz sinewave at -60dBFS,

IN

CONV

= 1kHz sinewave at -60dBFS,

IN

OUT

= 2.0µF

P-P

= 44.1kHz

A-weighted

∆A

X

CH-CH

TALK

Channel-to-Channel Gain Mismatch fIN= 1kHz 0.06 dB

Channel-to-Channel Crosstalk f

= 44.1kHz,

CONV

= 1kHz sinewave at -3dB

f

IN

Volume Control Range Minimum Attenuation

Maximum Attenuation

Volume Control Control Step Size 1.5 dB

Mute Attenuation -100 dB

2

S input adj to

= 1kHz 26 mW (min)

217Hz

FS

Typical Limit

(Note 6) (Notes 7, 9)

1 uA(max)

15 uA

0.05 %

52 dB (min)

79 dB

81 dB

72 dB

0

-43.5

= 25˚C.

A

Units

(Limits)

P-P

dB
dB

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