NSC LM4545VHX, LM4545VH Datasheet

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

General Description

The LM4545 is an audio codec for PC systems which per­forms the analog-intensive function of the Analog Codec ’97
Rev 1.03 Architecture. Using 18-Bit Σ∆ A/D and D/A convert­ers, 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 se­rial 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 in­creased overall performance.

Key Specifications

n Analog Mixer Dynamic Range 95dB (typ)
n D/A Dynamic Range 89dB (typ)
n A/D Dynamic Range 90dB (typ)
n Headphone THD+N at 50mW into 32Ω 0.02%(typ)

Features

n Audio Codec ’97 compliant
n Stereo 18-Bit Σ∆ A/D’s and D/A’s with 128X

oversampling

n Stereo headphone amp with separate gain control
n National’s 3D Sound circuitry
n Power management support
n Digital Interface 3V and 5V compliant

Applications

n Desktop PC Audio Systems
n Portable PC Audio Systems
n Mobile PC Audio Solutions

Block Diagram

DS100069-1

FIGURE 1. LM4545 Block Diagram

PRELIMINARY

July 1999

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

© 1999 National Semiconductor Corporation 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

DD

+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.

θ

JA

(typ)—VBH48A 74˚C/W

Operating Ratings

Temperature Range

T

MIN

≤ TA≤ T

MAX

−40˚C ≤ TA≤ 85˚C

Analog Supply Range 4.2V ≤ AV

DD

≤ 5.5V

Digital Supply Range 3.0V ≤ DV

DD

≤ 5.5V

Electrical Characteristics (Notes 1, 3)

The following specifications apply for AVDD= 5V, DVDD= 5V unless otherwise noted. Limits apply for TA= 25˚C. The reference
for 0dB is 1Vrms unless otherwise specified.

Symbol Parameter Conditions

LM4545

Units

(Limits)

Typical

(Note 7)

Limit

(Note 8)

AV

DD

Analog Supply Range 4.2 V (min)

5.5 V (max)

DV

DD

Digital Supply Range 3.0 V (min)

5.5 V (max)

I

DDD

Digital Quiescent Power Supply
Current

D

VDD

=5V 38 mA

D

VDD

= 3.3V 20 mA

I

DDA

Analog Quiescent Power Supply
Current

55 mA

I

SD

Shutdown Current 1.5 mA

V

REF

Reference Voltage 2.23 V

PSRR Power Supply Rejection Ratio 40 dB

Analog Loopthru Mode

Dynamic Range (Note 2)

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

95 90 dB (min)

THD Total Harmonic Distortion V

O

= -3dB, f = 1kHz, RL= 10kΩ 0.01 0.02

%

(max)

Analog Input Section

V

IN

Line Input Voltage 1 Vrms
Mic Input with 20dB Gain 0.1 Vrms

Mic Input with 0dB Gain 1 Vrms
Xtalk Crosstalk CD Left to Right -85 -70 dB (max)
Z

IN

Input Impedance 40 10 kΩ (min)
C

IN

Input Capacitance 15 pF

Interchannel Gain Mismatch CD Left to Right 0.04 dB

Record Gain Amplifier - A/D

A

S

Step Size 0dB to 22.5dB 1.5 dB

Mixer Section

A

S

Step Size +12dB to -34.5dB 1.5 dB
A

M

Mute Attenuation 86 dB

Analog to Digital Converters

Resolution 18 Bits

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Electrical Characteristics (Notes 1, 3) (Continued)

The following specifications apply for AVDD= 5V, DVDD= 5V unless otherwise noted. Limits apply for TA= 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 90 75 dB (min)
Frequency Response -1dB Bandwidth 20 kHz

Digital to Analog Converters

Resolution 18 Bits
Dynamic Range (Note 2) -60dB Input THD+N, A-Weighted 89 85 dB (min)

THD Total Harmonic Distortion V

IN

= -3dB, f=1kHz, RL= 10kΩ 0.01 0.03

%

(max)
Frequency Response -1dB Bandwidth 21 kHz
Group Delay (Note 2) 1 mS (max)
Out of Band Energy -40 dB
Stop Band Rejection 70 dB

D

T

Discrete Tones -96 dB

Output Volume and Amplifier Section

A

S

Step Size 0dB to -46.5dB 1.5 dB

A

M

Mute Attenuation 86 dB

THD+N

Headphone Amplifier Total Harmonic
Distortion plus Noise

Loopthru Mode, R

L

=32Ω, f=1kHz,

P

OUT

= 50mW

0.02

%
Digital I/O (Note 2)
V

IL

Low level input voltage

0.30 x
DVDD

V (max)

V

HI

High level input voltage

0.40 x
DVDD

V (min)

V

OH

High level output voltage

0.50 x
DVDD

V (min)

V

OL

Low level output voltage

0.20 x
DVDD

V (max)

I

L

Input Leakage Current AC Link inputs

±

10 µA (max)

I

L

Tri state Leakage Current High impedance AC Link outputs

±

10 µA (max)

I

DR

Output drive current AC Link outputs 5 mA
Digital Timing Specifications (Note 2)
F

BC

BIT_CLK frequency 12.288 MHz
T

BCP

BIT_CLK period 81.4 nS
T

CH

BIT_CLK high

Variation of BIT_CLK period from 50

%

duty cycle

±

20

%

(max)

F

SYNC

SYNC frequency 48 kHz
T

SP

SYNC period 20.8 µS
T

SH

SYNC high pulse width 1.3 µS
T

SL

SYNC low pulse width 19.5 µS
T

SETUP

Setup Time

SDATA_IN, SDATA_OUT to falling
edge of BIT_CLK

15 nS (min)

T

HOLD

Hold Time

Hold time of SDATA_IN, SDATA_OUT
from falling edge of BIT_CLK

5 nS (min)

T

RISE

Rise Time

BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT

6 nS (max)

T

FALL

Fall Time

BIT_CLK, SYNC, SDATA_IN or
SDATA_OUT

6 nS (max)

T

RST_LOW

RESET# active low pulse width For cold reset 1.0 µS (min)

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Electrical Characteristics (Notes 1, 3) (Continued)

The following specifications apply for AVDD= 5V, DVDD= 5V unless otherwise noted. Limits apply for TA= 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)
T

RST2CLK

RESET# inactive to BIT_CLK start
up

For cold reset 162.8 nS (min)

T

SH

SYNC active high pulse width For warm reset 1.3 µS

T

SYNC2CLK

SYNC inactive to BIT_CLK start up For warm reset 162.8 nS (min)

T

SU2RST

Setup to trailing edge of RESET# For ATE Test Mode 15 nS (min)

T

RST2HZ

Rising edge of RESET# to Hi-Z For ATE Test Mode 25 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 MaximumRatings

indicate limitsbeyondwhich 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 guar­antee 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

, θJA, and the ambient temperature TA. The maximum

allowable power dissipation is P

DMAX

=(T

JMAX–TA

)/θJAor the number given inAbsolute 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 kΩ resistor.

Note 6: Machine Model, 220 pF–240 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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Timing Diagrams

Clocks

DS100069-10

Data Setup and Hold

DS100069-11

Digital Rise and Fall

DS100069-12

Cold Reset

DS100069-13

Warm Reset

DS100069-14

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