CRD4299-1 Cirrus Logic, Inc., CRD4299-1 Datasheet - Page 4

• Manufacturer Part Number: CRD4299-1
• Description: AC 97 AMR Reference Design
• Manufacturer: Cirrus Logic, Inc.

1. GENERAL INFORMATION
The CRD4299-1 AMR is a production-grade
AMR audio card reference design using the
CS4299 SoundFusion Audio Codec ‘97. The de-
sign supports the functionally compatible CS4299,
CS4297A, or CS4297 AC ‘97 SoundFusion Audio
Codecs.
The AMR board advantage lies in the complete
separation of the analog section from the noisy dig-
ital environment of a personal computer. A 5-wire
digital link is all that is required to connect the au-
dio codec to the PCI bus-based AC ‘97 controller.
This allows the audio section to reach the required
dynamic range of ~90 dB FS A while making the
layout and placement of the audio section easier to
implement. The CS4299 performs the Digital-to-
Analog Conversion (DAC) for the digital audio
output stream and also provides multiple analog
audio inputs and outputs, analog mixing and Ana-
log-to-Digital Conversion (ADC).
This card is designed to provide the highest possi-
ble functionality, along with industry leading audio
performance at a low manufacturing cost. Care was
taken with component placement and signal rout-
ing to minimize sources that can degrade audio per-
formance. Cirrus’ analog design know-how has
resulted in a board that preserves the exceptional
analog performance of the CS4299.
2. REFERENCE DESIGN FEATURES
The CRD4299-1 AMR reference design illustrates
a high quality, low cost two-layer add-in card lay-
out. The card is sectioned into three main parts: the
AMR bus section, the CS4299 Audio Codec ‘97
section, and the Analog I/O section.
2.1 Digital Audio Out
The AMR bus provides digital out in a format com-
patible with the consumer portion of IEC 958. An
older version of this standard is also known as
S/PDIF. Depending upon the codec, the SPDIF sig-
nal originates either from the AMR bus or the co-
4
dec. Digital out is provided through a Toshiba
TOTX173 optical TOS-LINK jack on the board
edge. There are many advantages in using a fiber
optic link versus the traditional coaxial link. Fiber
optic is a non-metallic insulator thereby preventing
ground loops and electromagnetic interference.
For signal transmission, it offers low attenuation,
high bandwidth, low propagation delay, low bit er-
ror rates, small size, and cost efficiency. The signal
is IEC 958 and CP-1201 compliant.
2.2 CS4299 Audio Codec
The CS4299 is a mixed-signal serial Codec based
on the AC ‘97 specification revision 2.1 [1]. It is
designed to be paired with a digital controller, lo-
cated on the PCI bus. The AC ‘97 Controller is re-
sponsible for all communications between the
CS4299 and the rest of the system. The CS4299
functions as an analog mixer, a stereo ADC, a ste-
reo DAC, and a control and digital audio stream in-
terface to the AC ‘97 controller.
The CS4299 contains two distinct functional sec-
tions: digital and analog. The digital section in-
cludes the AC-link registers, power management
support, SYNC detection circuitry, AC-link serial
port interface logic, and the 24.576 MHz crystal
master clock. The analog section includes the ana-
log input multiplexer (mux), stereo input mixer,
stereo output mixer, mono output mixer, stereo
ADC, stereo DAC, and analog volume controls.
For more information refer to the CS4299
Datasheet [3]. The capacitors required for the
CS4299 and their placement are discussed in the
CS4299 Datasheet [3]. Refer to the Grounding and
Layout section of the data sheet for the recom-
mended routing of the audio section.
2.2.1 Power Requirements
The CS4299 requires both a digital +3.3 V and an
analog +5 V supply. The digital power is supplied
from the AMR bus. A voltage regulator is recom-
mended for the analog supply. A Motorola
CRD4299-1 AMR
‘97
DS319RD1A1