LM4545 Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – AC ’97 Codec with Stereo Headphone Amplifier and National 3D Sound

PRELIMINARY
July 1999
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 Σ∆ 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
n Analog Mixer Dynamic Range
n D/A Dynamic Range
n A/D Dynamic Range
n Headphone THD+N at 50mW into 32Ω
95dB (typ)
89dB (typ)
90dB (typ)
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
FIGURE 1. LM4545 Block Diagram
© 1999 National Semiconductor Corporation DS100069
DS100069-1
www.national.com