LM4545
AC '97 Codec with Stereo Headphone Amplifier and
National 3D Sound

General Description

The LM4545 is an audio codec for PC systems which per-
forms the analog-intensive function of the Analog Codec '97
Rev 1.03 Architecture. Using 18-Bit

A/D and D/A convert-

ers, the LM4545 provides 90dB of dynamic range.

The LM4545 was designed specifically to provide a high
quality audio path and provide all analog functionality in a PC
audio system. It features full duplex stereo A/D's and D/A's
and an analog mixer with 4 stereo and 3 mono inputs, each
of which has separate gain, attenuation and mute control. In
addition, the LM4545 provides a stereo headphone amplifier
with an independent gain control and National's 3D Sound
stereo enhancement technology.

The LM4545 features AC-Link, a synchronous, fixed rate se-
rial bus for connection to the digital AC '97 Controller. The
separation of the analog and digital functions of the AC '97
architecture allows for system design flexibility and in-
creased overall performance.

Key Specifications

Analog Mixer Dynamic Range

95dB (typ)

D/A Dynamic Range

89dB (typ)

A/D Dynamic Range

90dB (typ)

Headphone THD+N at 50mW into 32

0.02% (typ)

Features

Audio Codec '97 compliant

Stereo 18-Bit

A/D's and D/A's with 128X

oversampling

Stereo headphone amp with separate gain control

National's 3D Sound circuitry

Power management support

Digital Interface 3V and 5V compliant

Applications

Desktop PC Audio Systems

Portable PC Audio Systems

Mobile PC Audio Solutions

Block Diagram

DS100069-1

FIGURE 1. LM4545 Block Diagram

PRELIMINARY

July 1999

LM4545

'97

Codec

with

Stereo

Headphone

Amplifier

and

National

Sound

DS100069

www.national.com

Absolute Maximum Ratings

(Note 3)

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

Supply Voltage

6.0V

Storage Temperature

-65°C to +150°C

Input Voltage

-0.3V to V

+0.3V

ESD Susceptibility (Note 5)

2500V

pins 27, 28, 40

1500V

pin 3

750V

ESD Susceptibility (Note 6)

200V

pin 3

100V

Junction Temperature

150°C

Soldering Information

TQFP Package

Vapor Phase (60 sec.)

215°C

Infrared (15 sec.)

220°C

See AN-450

Surface Mounting and their Effects on

Product Reliability

for other methods of

soldering surface mount devices.

(typ) -- VBH48A

74°C/W

Operating Ratings

Temperature Range

MIN

MAX

-40°C

85°C

Analog Supply Range

4.2V

5.5V

Digital Supply Range

3.0V

5.5V

Electrical Characteristics

(Notes 1, 3)

The following specifications apply for AV

= 5V, DV

= 5V unless otherwise noted. Limits apply for T

= 25°C. The reference

for 0dB is 1Vrms unless otherwise specified.

Symbol

Parameter

Conditions

LM4545

Units

(Limits)

Typical

(Note 7)

Limit

(Note 8)

Analog Supply Range

4.2

V (min)

5.5

V (max)

Digital Supply Range

3.0

V (min)

5.5

V (max)

DDD

Digital Quiescent Power Supply
Current

VDD

= 5V

VDD

= 3.3V

DDA

Analog Quiescent Power Supply
Current

Shutdown Current

1.5

REF

Reference Voltage

2.23

PSRR

Power Supply Rejection Ratio

Analog Loopthru Mode

Dynamic Range (Note 2)

CD Input to Line Output, -60dB Input
THD+N, A-Weighted

dB (min)

THD

Total Harmonic Distortion

= -3dB, f = 1kHz, R

= 10k

0.01

0.02

% (max)

Analog Input Section

Line Input Voltage

Vrms

Mic Input with 20dB Gain

0.1

Vrms

Mic Input with 0dB Gain

Vrms

Xtalk

Crosstalk

CD Left to Right

-85

-70

dB (max)

Input Impedance

(min)

Input Capacitance

Interchannel Gain Mismatch

CD Left to Right

0.04

Record Gain Amplifier - A/D

Step Size

0dB to 22.5dB

1.5

Mixer Section

Step Size

+12dB to -34.5dB

1.5

Mute Attenuation

Analog to Digital Converters

Resolution

Bits

www.national.com

Electrical Characteristics

(Notes 1, 3) (Continued)

The following specifications apply for AV

= 5V, DV

= 5V unless otherwise noted. Limits apply for T

= 25°C. The reference

for 0dB is 1Vrms unless otherwise specified.

Symbol

Parameter

Conditions

LM4545

Units

(Limits)

Typical

(Note 7)

Limit

(Note 8)

Analog to Digital Converters

Dynamic Range (Note 2)

-60dB Input THD+N, A-Weighted

dB (min)

Frequency Response

-1dB Bandwidth

kHz

Digital to Analog Converters

Resolution

Bits

Dynamic Range (Note 2)

-60dB Input THD+N, A-Weighted

dB (min)

THD

Total Harmonic Distortion

= -3dB, f=1kHz, R

= 10k

0.01

0.03

% (max)

Frequency Response

-1dB Bandwidth

kHz

Group Delay (Note 2)

mS (max)

Out of Band Energy

-40

Stop Band Rejection

Discrete Tones

-96

Output Volume and Amplifier Section

Step Size

0dB to -46.5dB

1.5

Mute Attenuation

THD+N

Headphone Amplifier Total Harmonic
Distortion plus Noise

Loopthru Mode, R

= 32

, f=1kHz,

OUT

= 50mW

0.02

Digital I/O (Note 2)

Low level input voltage

0.30 x
DVDD

V (max)

High level input voltage

0.40 x
DVDD

V (min)

High level output voltage

0.50 x
DVDD

V (min)

Low level output voltage

0.20 x
DVDD

V (max)

Input Leakage Current

AC Link inputs

µA (max)

Tri state Leakage Current

High impedance AC Link outputs

µA (max)

Output drive current

AC Link outputs

Digital Timing Specifications (Note 2)

BIT_CLK frequency

12.288

MHz

BCP

BIT_CLK period

81.4

BIT_CLK high

Variation of BIT_CLK period from 50%
duty cycle

% (max)

SYNC

SYNC frequency

kHz

SYNC period

20.8

µS

SYNC high pulse width

1.3

µS

SYNC low pulse width

19.5

µS

SETUP

Setup Time

SDATA_IN, SDATA_OUT to falling
edge of BIT_CLK

nS (min)

HOLD

Hold Time

Hold time of SDATA_IN, SDATA_OUT
from falling edge of BIT_CLK

nS (min)

RISE

Rise Time

BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT

nS (max)

FALL

Fall Time

BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT

nS (max)

RST_LOW

RESET# active low pulse width

For cold reset

1.0

µS (min)

www.national.com

Electrical Characteristics

(Notes 1, 3) (Continued)

The following specifications apply for AV

= 5V, DV

= 5V unless otherwise noted. Limits apply for T

= 25°C. The reference

for 0dB is 1Vrms unless otherwise specified.

Symbol

Parameter

Conditions

LM4545

Units

(Limits)

Typical

(Note 7)

Limit

(Note 8)

Digital Timing Specifications (Note 2)

RST2CLK

RESET# inactive to BIT_CLK start
up

For cold reset

162.8

nS (min)

SYNC active high pulse width

For warm reset

1.3

µS

SYNC2CLK

SYNC inactive to BIT_CLK start up

For warm reset

162.8

nS (min)

SU2RST

Setup to trailing edge of RESET#

For ATE Test Mode

nS (min)

RST2HZ

Rising edge of RESET# to Hi-Z

For ATE Test Mode

nS (max)

Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.

Note 2: These specifications are guaranteed by design and characterization; they are not production tested.

Note 3:

Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is func-

tional, but do not guarantee specific performance limits.

Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guar-

antee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is
given, however, the typical value is a good indication of device performance.

Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by T

JMAX

, and the ambient temperature T

. The maximum

allowable power dissipation is P

DMAX

= (T

JMAX

or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4545, T

JMAX

= 150°C. The

typical junction-to-ambient thermal resistance is 74°C/W for package number VBH48A.

Note 5: Human body model, 100 pF discharged through a 1.5 k

resistor.

Note 6: Machine Model, 220 pF240 pF discharged through all pins.

Note 7: Typicals are measured at 25°C and represent the parametric norm.

Note 8: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).

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