lm4546a National Semiconductor Corporation, lm4546a Datasheet

lm4546a

Manufacturer Part Number

lm4546a

Description

Ac ?97 Rev 2 Multi-channel Audio Codec With Sample Rate Conversion And National 3d Sound

Manufacturer

National Semiconductor Corporation

Datasheet

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LM4546A

AC ’97 Rev 2 Multi-Channel Audio Codec with Sample

Rate Conversion and National 3D Sound

General Description

The LM4546A is an audio codec for PC systems which is

fully PC98 compliant and performs the analog intensive

functions of the AC ’97 Rev 2 architecture. Using 18-bit

Sigma-Delta ADCs and DACs, the LM4546A provides 90 dB

of Dynamic Range.

The LM4546A 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 ADCs and DACs

and analog mixers with access to 2 stereo and 2 mono

inputs. Each mixer input has separate gain, attenuation and

mute control and the mixers drive 1 mono and 1 stereo

output, each with attenuation and mute control. The

LM4546A supports National’s 3D Sound stereo enhance-

ment and a comprehensive sample rate conversion capabil-

ity. The sample rate for the ADCs and DACs can be pro-

grammed separately with a resolution of 1 Hz to convert any

rate in the range 4 kHz – 48 kHz. Sample timing from the

ADCs and sample request timing for the DACs are com-

pletely deterministic to ease task scheduling and application

software development. These features together with an ex-

tended temperature range also make the LM4546A suitable

for non-PC codec applications.

The LM4546A features the ability to connect several codecs

together using the Extended AC Link configuration of one

dedicated serial data signal to the Controller per codec.

LM4546A systems support up to 8 simultaneous channels of

streaming data on Input Frames (Codec to Controller) while

Output Frames (Controller to Codec) carry 2 streams to

multiple codecs. The LM4546A may also be used in systems

with the National LM4550 to support up to 6 simultaneous

channels of streaming data on Output Frames.

The AC ’97 architecture separates the analog and digital

functions of the PC audio system allowing both for system

design flexibility and increased performance.

DS200308

Key Specifications

n Analog Mixer Dynamic Range

n DAC Dynamic Range

n ADC Dynamic Range

Features

n AC ’97 Rev 2 compliant

n High quality Sample Rate Conversion from 4 kHz to 48

n Multiple codec support

n National’s 3D Sound stereo enhancement circuitry

n Advanced power management support

n Digital 3.3V and 5V supply options

n Extended Temperature: −40˚C ≤ T

Applications

n Desktop PC audio systems on PCI cards, AMR cards, or

n Portable PC systems as on MDC cards, or with a

n General and Multi-channel audio frequency systems

kHz in 1 Hz increments

with motherboard chips sets featuring AC Link

chipset or accelerator featuring AC Link

≤ 85˚C

www.national.com

March 2005

97 dB (typ)

89 dB (typ)

90 dB (typ)

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