Document Outline
- FEATURES
- DESCRIPTION
- GENERAL INFORMATION
- BOARD AUDIO INTERCONNECTIONS
- CIRCUIT DESCRIPTIONS
- Reference design:
- Trademarks
- Schematics
- Figure 1. CS4235- 1E Schematic Block Diagram
- Figure 2. CS4235
- Figure 3. ISA Bus
- Figure 4. Game Port / Wavetable
- Figure 5. CD Analog and Line Inputs
- Figure 6. Line / Headphone Output
- Figure 7. Microphone Input
- Figure 8. Speaker Amplifier
- Figure 9. Analog Power and EEPROM
- Figure 10. Silk Screen
- Figure 11. Top Side
- Figure 12. Bottom Side
- Bill Of Materials
Copyright
Cirrus Logic, Inc. 1998
(All Rights Reserved)
CRD4235-6
Advanced Product Databook
CrystalClearTM
16-bit Low-Cost Audio
Adapter Reference Design
FEATURES
s
MPC3 compliant (with enhancements), Windows
Sound System
TM
, DOS Games and AdLib
TM
compatible
s
Low Cost Two-Sided Board that Maintains Quality
s
Crystal Single-Chip CS9236 Wavetable Music
Synthesizer
s
Design accepts the CS4235 , or CS4236B,
CS4237B, CS4238B family of devices with simple
Bill-of-Material changes
s
Jumper selectable output amplifier option.
Switch between a high quality headphone capa-
ble amplifier, or a speaker driver.
s
MODEM audio connection for Audio Telephony
Applications (Requires a separate Modem Card)
s
Fully Plug-and-Play Compliant
DESCRIPTION
The CD-quality CRD4235-6 reference design is fully
MPC3 compliant, Ad Lib, DOS Games and Windows
Sound System compatible. The design is a half size
two-sided ISA-bus PC adapter board, based on the
CS4235 Multimedia Audio Codec. The CS9236 is a
high quality low-cost way to add Wavetable music syn-
thesis to the sound card and can be soldered down
during the production process, or added later if a PLCC
socket is installed.
The CRD4235-6 reference design is backed by a cus-
tomer ready manufacturing kit. Included in the kit are full
schematic and library design files, PWB job files, and
PWB artwork files. The OEM has the option of quickly
modifying the existing design for their specific require-
ments or implementing the design as is. Documentation
source files are available to allow the OEM to quickly
create an accurate end user manual.
ORDERING INFO
CMK4235-6
DS252RD6C2
MAY `98
2
DS252RD6C2
CRD4235-6
16-bit Low-Cost Audio Adapter Reference Design
GENERAL INFORMATION
The CRD4235-6 is a reference design of a produc-
tion-grade PC-AT adapter card using the Crystal-
Clear CS4235 Multimedia Audio Codec. This card
is designed to provide the highest possible func-
tionality, along with superlative audio performance
at a low manufacturing cost. The CRD4235-6 is
FCC class B and CISPR certified. All logical sub-
systems are fully Plug and Play compliant and
ready for all Microsoft
Operating Systems. The
design provides a full set of features required for
today's multimedia applications.
The CRD4235-6 reference design includes many
features that make it possible to manufacture one
board and actively compete in different markets.
All of the following features can be eliminated
from the design during the manufacturing process
if a cost reduction is desired.
-
The microphone input feature allows the use of
both internal and external microphone sources.
-
Jumper selectable ouput amplifier. The
CRD4235-6 can be manufactured with both
amplifiers, or the OEM has the option to only
populate the desired amplifier at the time of
manufacture, and hard-wire the jumper for a
fixed configuration.
-
The CD-ROM audio input has been designed to
provide two popular header sizes, since both
connectors cannot be used simultaneously, the
OEM can elect to only populate the desired CD-
ROM Audio jack.
-
The MODEM audio circuitry has been designed
to interface to a audio capable modem board,
and can be completely removed from the
CRD4235-6 if this feature is not required.
-
A dual joystick and MIDI interface is available
with an industry standard 15-pin D-sub
connector.
-
Wavetable audio is available with the on-board
CS9236 single chip Wavetable IC.
Software drivers are available for the CS4235 that
support all major operating systems. The Windows
95TM drivers are fully Plug and Play compatible,
and like the Windows NTTM drivers, will utilize the
embedded multimedia applets provided by Mi-
crosoft. Cirrus Logic provides the essential multi-
media applets and drivers required for the
Windows
3.1 and OS/2
operating systems on the
drivers diskette. DOS utilities are also available
which allow the computer to play a CD-ROM and
control the sound volume.
All aspects of the design have been optimized to
ensure top performance at the lowest cost. Care
was taken with signal routing and component
placement to minimize sources which can degrade
performance. Cirrus' analog design know-how has
resulted in a board which preserves the exceptional
analog performance of the CS4235 audio Codec.
BOARD AUDIO INTERCONNECTIONS
Three external stereo jacks (listed top to bottom) al-
low connection to a mono Microphone input, a ste-
reo Line input, and a stereo Line/Headphone or
speaker output. Headers for internal microphone,
two common styles of CD-ROM audio, and a MO-
DEM audio interface are also supported.
The first jack, designated MIC IN, is a single-ended
microphone (as opposed to differential) input, sup-
porting most common types of dynamic or phan-
tom powered microphones. The microphone input
circuitry provides no signal amplification, but a
20 dB gain block inside the CS4235 can be soft-
ware enabled (the "Boost" button in the Windows
input applet) if signal levels are too low. In many
cases, the additional "Boost" will be required with
the CRD4235-6 implementation in order to achieve
a desirable audio level.
The second input jack, designated LINE IN, is for
line inputs and is connected to the AUX1 inputs of
the CS4235. Each channel has an input impedance
of approximately 15 k
. The maximum full scale
input that the LINE IN function can tolerate is
2 V
RMS
.
The third jack is LINE OUT/SPEAKER OUT. The
line output from the CS4235 is either amplified by
DS252RD6C2
3
CRD4235-6
16-bit Low-Cost Audio Adapter Reference Design
a low-noise, low-distortion amplifier, or by a
speaker amplifier. The unused amplifier need not
be populated at manufacturing time in order to sim-
plify this output function.
The CS4235 CD-ROM audio input headers are
connected in parallel, which means that only one
can be active at a time. The OEM will need to make
this clear to end users, or delete the unused connec-
tor entirely.
The MODEM header provides an audio interface
between the sound card and a modem. Mono out
and Mic out signals transfer audio from the sound
card to the modem, and a mono in signal transfers
audio from the modem to the sound card.
CIRCUIT DESCRIPTIONS
The functional block diagram is shown in Figure 1.
The CS4235 (as shown in Figure 2) is the heart of
the CRD4235-6 reference design. The CS4235 is a
Plug-and-Play aware device that controls all as-
pects of the sound card. See CS4235 Datasheet for
complete information on this device.
The interconnections for ISA bus signals are de-
tailed in Figure 3.
The DB-15 connector shown in Figure 4, provides
an interface to an external joystick and MIDI I/O.
The joystick interface supports two joysticks: two
pair of X/Y coordinates and four buttons. The inter-
nal resistors and 1000 pF caps provide the correct
debounce period for the joystick buttons. The tim-
ing for the joystick position is determined by the
joystick potentiometer, the series 2.2 k
resistor
and the 5600 pF capacitor. Deviation from the
2.2 k
and 5600 pF component values will result
in improper joystick positioning. The MIDI TXD
and MIDI RXD signals are TTL level signals and
not compatible with direct MIDI cabling. An exter-
nal "break-out" box attached to the 15-pin D-sub
connector interfaces the TTL MIDI signals to an
isolated MIDI connector.
On-board music synthesis is furnished by an FM syn-
thesizer internal to the CS4235. For enhanced synthe-
sis support, the CS9236 single-chip Wavetable
Synthesis IC can be populated. The CS9236 pro-
vides a digital signal to the CS4235 via a serial in-
terface, which is internally converted to an analog
signal. The CS9236 interface is enabled by setting
the WTEN bit in the EEPROM.
The Line and CD analog inputs shown in Figure 5
are both routed through 6 dB attenuators, and DC
blocking capacitors. This circuitry provides input
protection for the CS4235, and isolation from the
analog input DC bias. 100 pF capacitors can be
populated on the line input to provide better FCC
filtering.
The output (Figure 6) of the CS4235 mixer is only
capable of driving impedances greater than 10 k
with a maximum voltage of 1 V
RMS
. Some form of
output amplifier is usually required to drive pow-
ered speakers or headphones. The CRD4235-6 has
the several output amplifier options. A low-cost
LM1458, or a high-quality NE5532 amplifier can
be populated at location U7. Both amplifier options
are not capable of driving non-amplified (4
-
16
) speakers. The other output option is dis-
cussed in detail under Figure 8. The header which
selects the output amplifier is J8 (Left) and J9
(Right).
An alternate output circuit configuration is based
around U13. The LM1458N (Figure 6) provides
left and right mixing to supply a mono-out signal to
an external modem. This option would normally
be used in addition to one or more of the above
mentioned options, instead of as a replacement.
The microphone circuit (Figure 7) was designed to
be low cost, with a low component count. No am-
plification of the incoming signal is provided. The
+5 VA supply is reduced to 2.5 V with a resistive
voltage divider. This reference is used to provide a
low-noise source for phantom powered micro-
phones. Phantom power is permanently applied
4
DS252RD6C2
CRD4235-6
16-bit Low-Cost Audio Adapter Reference Design
through a 2.2 k
resistor to either the right or left
channels of the stereo jack. This provides for mi-
crophones that require bias on either the tip or ring
of the microphone's plug. The choice of right or left
phantom power is a hardware population option.
Placing phantom power on the ring connection of
the jack is the typical configuration. An internal
microphone can be connected to a header, in place
of the external microphone jack input.
The U13 LM1458N (Figure 7) circuitry has been
provided to supply an amplified microphone signal
to an external modem. The U13 device can be non-
populated if the modem function is not required.
The TDA1517 can provide amplified audio power
to a set of non-powered speakers (Figure 8). It is
also capable of driving headphones, and powered
speakers. This device can be used as the only out-
put amplifier on the CRD4235-6, but the overall
audio performance is not as good as that provided
by the LM1458N.
An "L" series 5 V regulator (Figure 9) provides a
clean low noise supply for the analog subsections
of the CRD4235-6. The TO-92 package is adequate
to provide the current and power dissipation re-
quired. If cost is the deciding factor, the LM78L05
can be non-populated and replaced with R44, with
a loss of audio quality. The 3.3 VD supply is re-
quired for the CS9236 and can be non-populated
when the CS9236 is not used. Two different meth-
ods are provided for generating the 3.3V supply
voltage. A 3.3 V regulator is available by populat-
ing the LT1121CZ-3.3 (U10), or by using the low-
er-cost configuration of an MPS2222 (Q1),
1N5228 (D1) and a 100
resistor (R45). The
+12 V and -12 V power are filtered through a sim-
ple LC filter.
An external serial EEPROM (also shown in
Figure 9) contains the Plug-and-Play configuration
table. The CRD4235-6 includes a footprint for both
a DIP and a SOIC EEPROM. Only one of these
should be populated. After a power-on-reset, the
data within the EEPROM is serially transferred to
the CS4235. The XA0 pin serves as the serial clock
while the XD0 pin functions as the bi-directional
serial data-path. The EEPROM's data pin and the
CS4235 XD0 pin are open collectors; a pull-up re-
sistor is mandatory. If a Microsoft WHQL logo is
not required, then the EEPROM can be removed
and the CRD4235-6 will function based on internal
resources.
Reference design:
-- silk screen. (Figure 10)
-- (component) top side. (Figure 11)
-- (solder) bottom side. (Figure 12)
Microsoft and Windows are registered trademarks
Windows NT, Windows 95 and Windows Sound System are trademarks of Microsoft.
OS/2 is a registered trademark of International Business Machines Corporation.
Ad Lib is a trademark of Adlib Corporation.
CrystalClear is a trademark of Cirrus Logic, Inc.
DS252RD6C2
5
CRD
4
235-
6
16-bit Low-C
o
s
t
Audio Adapte
r
Re
fe
r
e
nc
e
De
s
ign
Figure 1. CS4235-1E Schematic Block Diagram
6
DS252RD6C2
C
R
D
4235-
6
16
-b
i
t
Low-C
o
s
t
Audi
o Ada
pt
e
r
Re
f
e
r
e
nc
e
De
s
i
g
n
CS4235
only
CS4235
only
CS423XB
only
CS423XB
only
CS423XB
only
not populated
Figure 2. CS4235
DS252RD6C2
7
CRD
4
235-
6
16-bit Low-C
o
s
t
Audio Adapte
r
Re
fe
r
e
nc
e
De
s
ign
Figure 3. ISA Bus
8
DS252RD6C2
C
R
D
4235-
6
16
-b
i
t
Low-C
o
s
t
Audi
o Ada
pt
e
r
Re
f
e
r
e
nc
e
De
s
i
g
n
not populated
Figure 4. Game Port / Wavetable
DS252RD6C2
9
CRD
4
235-
6
16-bit Low-C
o
s
t
Audio Adapte
r
Re
fe
r
e
nc
e
De
s
ign
Figure 5. CD Analog and Line Inputs
10
DS252RD6C2
C
R
D
4235-
6
16
-b
i
t
Low-C
o
s
t
Audi
o Ada
pt
e
r
Re
f
e
r
e
nc
e
De
s
i
g
n
Figure 6. Line / Headphone Output
DS252RD6C2
11
CRD
4
235-
6
16-bit Low-C
o
s
t
Audio Adapte
r
Re
fe
r
e
nc
e
De
s
ign
Figure 7. Microphone Input
12
DS252RD6C2
C
R
D
4235-
6
16
-b
i
t
Low-C
o
s
t
Audi
o Ada
pt
e
r
Re
f
e
r
e
nc
e
De
s
i
g
n
Figure 8. Speaker Amplifier
DS252RD6C2
13
CRD
4
235-
6
16-bit Low-C
o
s
t
Audio Adapte
r
Re
fe
r
e
nc
e
De
s
ign
08
08
not populated
NOTE: The Analog (AGND) and the Digital (GND)
Ground Planes MUST be connected together
Figure 9. Analog Power and EEPROM
14
DS252RD6C2
C
R
D
4235-
6
16
-b
i
t
Low-C
o
s
t
Audi
o Ada
pt
e
r
Re
f
e
r
e
nc
e
De
s
i
g
n
Figure 10. Silk Screen
DS252RD6C2
15
CRD
4
235-
6
16-bit Low-C
o
s
t
Audio Adapte
r
Re
fe
r
e
nc
e
De
s
ign
Figure 11. Top Side
16
DS252RD6C2
C
R
D
4235-
6
16
-b
i
t
Low-C
o
s
t
Audi
o Ada
pt
e
r
Re
f
e
r
e
nc
e
De
s
i
g
n
Figure 12. Bottom Side
DS252RD6C2
17
CRD
423
5-
6
16
-
b
it Low-C
o
s
t
Audio
Adapte
r Re
fe
r
e
nc
e
De
s
i
g
n
Bill Of Materials October 13,1997 11:52:59
Item Quan.
Reference
Part
PN
Manufacturer
Description
1
12
C11,C12,C13,C14,C15,C41,C53,
C55,C56,C78,C79,C80
10uF
ECE-A1CN100S
PANASONIC
CAP,ELEC,10UF,TH,CASE C,20%,16V
2
18
C2,C3,C6,C10,C20,C21,C22,C27,
C33,C34,C36,C38,C40,C43,
C58,C59,C60,C68
.1uF
C0805C104K5RAC
KEMET
CAP,.1UF,SO,0805,10%,50V,X7R
3
2
C5,C9
100uF ELEC ECE-A1CKA101
PANASONIC
CAP,ELEC,100uF,TH,CASE C,20%,16V
4
2
C24,C72
1.0uF
GRM40-6Y5V105Z016AD MURATA
CAP,1.0UF,SO,0805,+80/-20%,16V,Y5V
5
2
C17,C18
22pF
C0805C220J5GAC
KEMET
CAP,22pF,SO,0805,5%,50V,COG
6
7
C31,C32,C44,C45,C46,C47,C73
1000pF
C0805C102J5GAC
KEMET
CAP,1000pF,SO,0805,5%,50V,COG
7
4
C48,C49,C50,C51
5600pF
C0805C562K5RAC
KEMET
CAP,5600pF,SO,0805,10%,50V,X7R
8
1
C71
0.01uF
O8052R103K9BB2
PHILIPS
CAP,0.01uF,SO,0805,10%,50V,X7R
9
2
C74,C75
470uF ELEC ECE-A1CGE471
PANASONIC
CAP,ELEC,470UF,SO,CASE E,20%,16V
10
2
C76,C77
0.33uF
GRM40-6X7R334K016AL MURATA
CAP,0.33uF,0805,+/-10%,16V,X7R
12
1
J1
4X1HDR
TSW-104-07-T-S
SAMTEC
HDR,4X1,0.025"PIN,0.1"CTR
13
3
J2,J7,J11
PHONO-1/8
AJ-0356A-5P
A/D ELECTRONICS CONN,1/8" SWITCHED STEREO PHONE
JACK
14
1
J3
4X1/80 HDR B4B-PH-K
JSF
HDR,4X1/80,0.025"PIN,0.08"CTR
15
1
J6
DB15
747845-3
AMP
CONN,15D SHELL,FEMALE,RT ANGLE
PC MOUNT
16
2
J9,J8
3X1HDR
TSW-103-07-T-S
SAMTEC
HDR,3X1,0.025"PIN,0.1"CTR
17
6
L1,L2,L3,L4,L5,L6
FERRITE
EXC-ELSA35
PANASONIC
IND,FBEAD,TH,AXIAL
19
2
R2,R46
3.3K
9C08052A3301J
PHILIPS
RES,3.3K,SO,0805,5%,1/10,METAL FILM
20
13
R4,R5,R32,R33,R35,R36,R40,R41,
R47,R48,R49,R50,R53
6.8K
9C08052A6801J
PHILIPS
RES,6.8K,SO,0805,5%,1/10W
21
3
R13,R51,R52
4.7K
9C08052A4701J
PHILIPS
RES,4.7K,SO,0805,5%,1/10W
23
4
R25,R26,R27,R28
2.2K
9C08052A2201J
PHILIPS
RES,2.2K,SO,0805,5%,1/10
24
2
R29,R31
68K
9C08052A6802J
PHILIPS
RES,68K,SO,0805,5%,1/10W,METAL FILM
25
4
R30,R34,R54,R55
33K
9C08052A3302J
PHILIPS
RES,33K,SO,0805,5%,1/10,METAL FILM
26
2
R39,R38
10
9C08052A10R0J
PHILIPS
RES,10,SO,0805,5%,1/10W
27
1
R43
0
9C08052A0R00J
PHILIPS
RES,0,SO,0805
28
2
R56,R57
15K
9C08052A1502J
PHILIPS
RES,15K,SO,0805,5%,1/10W
29
2
R66,R67
100K
9C08052A1003J
PHILIPS
RES,100K,SO,0805,5%,1/10W,METAL
FILM
30
1
U1
LM78L05
uA78L05CLP
TI
IC,78L05,TH,TO-226AA,+ 5V VOLTAGE
REGULATOR
31
1
U3
X24C08 SO
AT24C08N-10SC
ATMEL
IC,24C08,SO,SOIC8,EEPROM
18
DS252RD6C2
CRD
4235-
6
1
6
-bit Low
-
C
o
s
t
A
udio A
dapte
r
Re
fe
r
e
nc
e
De
s
i
gn
33
1
U7
LM1458N
LM1458N
NATIONAL
IC,1458,TH,DIP,DUAL OP AMP
34
1
U9
CS4235-KQ
CS4235-KQ-Prelim
CRYSTAL
IC,SO,TQFP100,MULTIMEDIA CODEC
35
1
U12
TDA1517P
TDA1517P
PHILIPS
SOT398-1,DIP-18
36
1
Y1
16.9344 MHz HC49S-16.9344
FOX
CRYSTAL
Bill Of Materials October 13,1997 11:52:59
Item Quan.
Reference
Part
PN
Manufacturer
Description
Notes
PDF 
ZIP