CIRRUS CRD4205-2

CRD4205-2
CrystalClear® PC Audio Docking Station Companion Board
Features
Description
l Companion board to CRD4205-1
l Emulates Docking Station Environment
The CRD4205-2 reference design is a companion card
to the CRD4205-1. The CRD4205-2 emulates the audio
sub-system in a PC digital docking station, and the
CRD4205-1 simulates the audio sub-system in a PC
notebook computer.
– Simulates audio portion of PC docking station.
– Digital Interface to CRD4205-1
l High quality, low cost analog to digital (ADCs)
and digital to analog (DACs) converters
– CS5334 18-bit serial ADCs
– CS4334 24-bit serial DACs
l PCI Slot card (power only)
l Two stereo inputs
l One microphone input
l Four channel audio output
This reference design features stereo analog inputs for
Line, CD, and a mono input for Microphone. The card
also has four channel analog audio outputs. The docking
port is completely digital. The analog inputs in the
CRD4205-2 are processed by high quality 18-bit serial
ADCs. The analog outputs are processed by high quality
serial 24-bit DACs.
The CRD4205-2 is available by ordering the CMK42053 manufacturing kit. This kit includes a full set of schematics (OrCAD® 7.2 format), PCB job files (PADS®
ASCII), PCB Gerber files, bill of materials and WDM audio drivers that support Windows 98se, Millennium® and
Windows 2000.
ORDERING INFORMATION
CMK4205-3 Manufacturing Kit for the CRD4205-2
CD IN
MIC IN
LINE IN
CS5331A
JP1
LINE OUT1
CS4334
LINE OUT2
DOCKING
PORT
CS4205
CRD4205-1
CRD4205-2
Preliminary Product Information
P.O. Box 17847, Austin, Texas 78760
(512) 445 7222 FAX: (512) 445 7581
http://www.cirrus.com
This document contains information for a new product.
Cirrus Logic reserves the right to modify this product without notice.
Copyright  Cirrus Logic, Inc. 2000
(All Rights Reserved)
DEC ‘00
DS489RD2A1
1
CRD4205-2
TABLE OF CONTENTS
1.
2.
3.
4.
5.
6.
GENERAL INFORMATION .......................................................................... 3
SCHEMATIC DESCRIPTION ....................................................................... 3
2.1 Block Diagram ...................................................................................... 3
2.2 Analog Inputs ...................................................................................... 3
2.3 Analog Output ...................................................................................... 3
2.4 PCI Bus ............................................................................................... 4
2.5 Component Selection ........................................................................... 4
2.6 EMC Components ................................................................................ 4
GROUNDING AND LAYOUT ....................................................................... 4
REFERENCES ............................................................................................. 5
ADDENDUM ................................................................................................. 5
BILL OF MATERIALS ............................................................................ 15
Printed Circuit Board Assembly ................................................................. 15
Mechanical Assembly ................................................................................ 16
LIST OF FIGURES
Figure 1. Block Diagram........................................................................................... 6
Figure 2. Analog In ................................................................................................... 7
Figure 3. Analog Out ................................................................................................ 8
Figure 4. PCI Bus ..................................................................................................... 9
Figure 5. Assembly Drawing .................................................................................. 10
Figure 6. Silkscreen................................................................................................ 11
Figure 7. Top Layer ................................................................................................ 12
Figure 8. Bottom Layer........................................................................................... 13
Figure 9. Drill Drawing............................................................................................ 14
LIST OF TABLES
Table 1. Microphone Input Jumper JP1 ................................................................... 3
Contacting Cirrus Logic Support
For a complete listing of Direct Sales, Distributor, and Sales Representative contacts, visit the Cirrus Logic web site at:
http://www.cirrus.com/corporate/contacts/
Microsoft, Windows 95, Windows 98 and Windows Millenium and WHQL is registered trademark of Microsoft.
CrystalClear is a trademark of Cirrus Logic, Inc.
Intel is a registered trademark of Intel Corporation.
OrCAD is a registered trademark of OrCAD, Inc.
PADS is a registered trademark of, PADS Software, Inc.
Preliminary product information describes products which are in production, but for which full characterization data is not yet available. Advance product information
describes products which are in development and subject to development changes. Cirrus Logic, Inc. has made best efforts to ensure that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided “AS IS” without warranty of any kind
(express or implied). No responsibility is assumed by Cirrus Logic, Inc. for the use of this information, nor for infringements of patents or other rights of third parties.
This document is the property of Cirrus Logic, Inc. and implies no license under patents, copyrights, trademarks, or trade secrets. No part of this publication may
be copied, reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photographic, or otherwise) without the
prior written consent of Cirrus Logic, Inc. Items from any Cirrus Logic website or disk may be printed for use by the user. However, no part of the printout or
electronic files may be copied, reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photographic, or
otherwise) without the prior written consent of Cirrus Logic, Inc.Furthermore, no part of this publication may be used as a basis for manufacture or sale of any items
without the prior written consent of Cirrus Logic, Inc. The names of products of Cirrus Logic, Inc. or other vendors and suppliers appearing in this document may
be trademarks or service marks of their respective owners which may be registered in some jurisdictions. A list of Cirrus Logic, Inc. trademarks and service marks
can be found at http://www.cirrus.com.
2
DS489RD2A1
CRD4205-2
1. GENERAL INFORMATION
The CRD4205-2 is designed to emulate a high
quality PC audio docking station. This is not a
stand-alone card but used in conjunction with the
CRD4205-1. The CRD4205-1 contains a CS4205
audio codec and simulates the audio sub-system in
a PC notebook computer.
The CRD4205-2 has all the circuitry typically
found in a high quality PC digital docking audio
sub-system. In addition, this reference design includes four channel analog audio outputs driven by
24-bit serial DACs. Microphone, stereo Line, and
stereo CD inputs feature high quality serial 18-bit
ADCs.
2. SCHEMATIC DESCRIPTION
This section describes the CRD4205-2 schematics
shown in figures 1 through 4. These schematics are
also available in the CMK4205-3 manufacturing
kit as ORCAD 7.2 files.
2.1
The MIC IN circuit complies with PC-99 requirements for microphone phantom power and recommendations for frequency response roll-off. The
3 dB roll-off frequencies are 60 Hz and 15 kHz.
Phantom power for the microphones is derived
from the +5 V analog supply and filtered by R11,
C13, and R12.
Jumper JP1 controls how the microphone signal is
routed to the ADC, U3.
JP1 Position
Out
1-2
2-3
Analog Inputs
The Analog Input page in Figure 2 illustrates the
Mic, stereo Line and stereo CD inputs and their associated ADCs. The LINE inputs connect to a divider circuit that reduces the voltage by 6 dB to
allow for line level sources up to 2 Vrms. The
100 pF capacitors are provided on Line In and Mic
In for EMI suppression. These may be removed if
EMC testing determines they are not required.
Since the analog inputs of the CS5331 ADCs are
DC biased, all of the analog inputs must be AC coupled. The microphone input is coupled with a
0.1 µF capacitor. The Line and CD inputs are AC
coupled with 2.2 µF capacitors to minimize the
low frequency roll-off.
DS489RD2A1
Description
Microphone signal routed to AINL of
the CS5331A. The AINR is floating.
Not Used!
Microphone signal routed to both
AINL and AINR of the CS5331A.
Table 1. Microphone Input Jumper JP1
Block Diagram
The block diagram in Figure 1, shows the interconnection between schematic pages. The schematic is
divided into three blocks: Analog In, Analog Out,
and PCI Bus.
2.2
The analog audio input signals are converted to
digital data by three CS5331A 18-bit ADCs. The
ADCs share a common clock, but have independent data outputs. The clock and serial data signals
are routed to the docking port header.
2.3
Analog Output
The CS4205 sends audio to the docking port
through I2S serial digital outputs, as shown in
figure 3. These signals are converted to analog audio through two CS4334 serial DACs. Both
CS4334s share common clocks but have independent data inputs. All clocks originate from the
CS4205 on the CRD4205-1 card.
The output of the DACs are connected to a Motorola MC34072 dual op-amp which is capable of
driving high impedance (10 kΩ or higher) line level signals. This circuit has a gain of 3 dB.
It is possible to drive headphones with impedances
as low as 32 Ω by replacing the MC34072 with a
TDA1308 and increasing the values of C23, C24,
C29, and C30 to 220 µF. These op-amps are pin
compatable.
3
CRD4205-2
2.4
PCI Bus
The PCI bus is only used to supply power to the
board, so that an external supply is not required.
The PCI bus connections are shown in Figure 4.
The digital power is supplied from the PCI bus. A
Motorola MC78M05C regulates the +12 V supply
from the PCI bus down to a clean +5 V analog supply. For the best audio performance, the analog
voltage regulator is located over the analog ground
plane near the partition between the analog and digital planes. The regulator ground pin is connected
to the analog ground.
Figure 4 also shows the docking port header. This
connector couples the serial data from the
CRD4205-1 and is buffered by a 74HC244 octal
buffer.
2.5
Component Selection
Great attention was given to the particular components used on the CRD4205-2 board with cost, performance, and package selection as the most
important factors. Listed are some of the guidelines
used in the selection of components:
•
No components smaller than 0805 package.
•
Only single package components; no resistor
packs.
•
All ICs are in surface mount packages.
2.6
EMC Components
A number of capacitors and inductors are included
to help the board meet EMI compliance tests, such
as FCC Part 15. The EMC part values are only
4
meant as starting points. Modify these values to
meet individual EMC requirements.
3. GROUNDING AND LAYOUT
One of the most critical aspects of PC audio design
is good PC board layout. The PC is a hostile environment for audio, and good layout is essential for
achieving high audio quality.
The CRD4205-2 is partitioned into a digital and analog sections to help isolate noisy digital circuitry
from quiet analog audio circuitry. The most important rule for successful PC audio layout is to keep
all digital signal traces and components over the
digital ground plane, and all analog signal traces
and components over an analog ground plane.
These planes are separated by a minimum of 60 to
100 mils (0.060 to 0.100 inches).
When digital and analog signals cross planes, they
introduce noise into the audio section reducing performance. The CS4334 DACs and CS5331A
ADCs are placed over the partition of the analog
and digital ground planes. The ADCs and DACs
both have their analog and digital signals partitioned to opposite sides of the ICs to help simplify
PCB layout. Digital and analog ground are tied together by a wide trace (over 50 mils or
0.050 inches) at a single point underneath the converters in order to provide a common ground reference.
For more information on layout specifically for the
CS4334 and the CS5331A, see their respective
datasheets.
DS489RD2A1
CRD4205-2
4. REFERENCES
4) Cirrus Logic, CS4205 Data Sheet
1) Intel, Audio Codec ‘97 Component Specification, Revision 2.1, May 22, 1998. http://developer.intel.com/ial/scalableplatforms/audio/
5) Cirrus Logic, CS4334/5/6/7/8/9 Data Sheet
http://www.crystal.com/pubs/4334.pdf
2) Communication and Network Riser Specification revision 1.0, Feb 7, 2000 http://developer.intel.com/technology/cnr/
3) Steve Harris, Clif Sanchez, Personal Computer
Audio Quality Measurements, Ver 1.0
http://www.crystal.com/pubs/meas100.pdf
DS489RD2A1
6) Cirrus Logic, CS5330A/31A Data Sheet
http://www.crystal.com/pubs/5330a.pdf
5. ADDENDUM
•
Schematic drawings
•
Layout drawings
5
6
Analog_In
Analog_Out
>Mic In
DSMCK
DSLRCK
DSSCK
DSMCK
DSLRCK
DSSCK
Analog_In
Line1 Out >
SDATA1
SDATA2
>CD In
DSSDI1
DSSDI2
DSSDI3
>Line In
Line2 Out >
Analog_Out
Main
Board
>
>
>
<
<
<
SDATA1
SDATA2
DSMCK
DSLRCK
DSSCK
DSSDI1
DSSDI2
DSSDI3
PCI_Bus
Clocks
SDO1
SDO2
SDI1
SDI2
SDI3
PCI_Bus
CRD4205-2
DS489RD2A1
Figure 1. Block Diagram
+5VA
6.8K
R1
LINE IN
J1
R4
4
3
5
2
1
U1
6.8K
6.8K
8
7
6
5
C 4 2.2uF
ELEC
+
DS489RD2A1
R2
>Rt
>Lt
R3
6.8K
C3
AINL
VA+
AGND
AINR
SDATA
SCLK
LRCK
MCLK
+
Dock CDIn
C2
100pF
NPO
PHONO-1/8
+5VA
Dock MicIn
AGND
DSSDI1
DSSDI2
DSSDI3
Vcc
C1
100pF
NPO
DSSCK
DSLRCK
DSMCK
Dock LineIn
CS5331A
2.2uF
ELEC
1
2
3
4
C12
0.1uF
Z5U
AGND
Vee
CGND
+5VA
+5VA
MIC IN
AGND
J3
R12
2.2K
R11
1.5K
4
R5
5
2
1
C9
100pF
NPO
PHONO-1/8
Connect CGND
to AGND at
the jack
100
C14
100pF
NPO
U3
C8
+ C13
10uF
ELEC
C7
8
7
6
5
0.1uF
X7R
-3 dB corners at
60 Hz and 16 kHz
(Ri = 28 k, Rs=350ohm)
CD IN
1
2
3
4
JP1
1
2
3
CGND
SDATA
SCLK
LRCK
MCLK
CS5331A
0.022uF
X7R
AGND
AINL
VA+
AGND
AINR
=Gnd
RightIn
=Left
3x1HDR
AGND
+5VA
U2
L1
4
3
2
1
31@100MHz
L2
C11
AINL
VA+
AGND
AINR
SDATA
SCLK
LRCK
MCLK
1
2
3
4
CS5331A
4.7uF
ELEC
+
31@100MHz
LtCD
L3
C5
2.2uF
ELEC
AGND
+
31@100MHz
Figure 2. Analog In
7
CRD4205-2
4X1HDR-AU
2.2uF
ELEC
+
RtCD
J2
C6
8
7
6
5
8
R24
33K
+5VA
DSSCK
DSLRCK
DSMCK
SDATA
DEM#/SCLK
LRCK
MCLK
3
R22
27K
2
U4A
1
+
-
R41
10uF
ELEC
100
C25
100pF
NPO
MC34072D
C35
SDATA2
R36
10K
AGND
+
10uF
ELEC
R37
C36
100pF
NPO
Vcc
C21
22pF
NPO
R35
10K
R21
+
6
-
27K
U4B
7
R30
MC34072D
AGND
CGND
33K
SDATA
DEM#/SCLK
LRCK
MCLK
AOUTL
VA+
AGND
AOUTR
R44
C29
8
7
6
5
3
2
R28
27K
+
-
U5A
1
R43
10uF
ELEC
100
C31
100pF
NPO
MC34072D
Vcc
33K
C27
22pF
NPO
R27
27K
6
-
U5B
7
MC34072D
LINE
OUT2
CGND
CRD4205-2
DS489RD2A1
Figure 3. Analog Out
PHONO-1/8
AGND
AGND
8-pin Heaphone Amp
(e.g. TDA1308)can be
substituted for MC34072
R32
220K
2
1
Vee
+
R31
220K
C32
100pF
NPO
C38
0.1uF
Z5U
AGND
5
Rt >
Lt >
10uF
ELEC
+5VA
R29
J22
4
100
+
1
2
3
4
22pF
NPO
CS4334
+
C30
C28
U7
LINE
OUT1
R26
220K
AGND
+5VA
PHONO-1/8
C37
0.1uF
Z5U
2.2K
5
R25
220K
2
1
C26
100pF
NPO
Vee
SDATA1
33K
Rt >
Lt >
10uF
ELEC
+5VA
R23
J21
4
100
C23
8
7
6
5
AOUTL
VA+
AGND
AOUTR
R42
+
1
2
3
4
22pF
NPO
CS4334
+
C24
C22
U6
Side A
PCI BUS 5V A
P1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
-12V
TCK
GND11
TDO
+5V(8)
+5V(9)
INTB#
INTD#
PRSNT1#
RSVD(4)
PRSNT2#
GND(12)
GND(13)
RSVD(5)
GND(14)
CLK
GND(15)
REQ#
+5V(10)
AD[31]
AD[29]
GND(16)
AD[27]
AD[25]
+3.3V(7)
C/BE[3]#
AD[23]
GND(17)
AD[21]
AD[19]
+3.3V(8)
AD[17]
C/BE[2]#
GND(18)
IRDY#
+3.3V(9)
DEVSEL#
GND(19)
LOCK#
PERR#
+3.3V(10)
SERR#
+3.3V(11)
C/BE[1]#
AD[14]
GND(20)
AD[12]
AD[10]
GND(21)
KEY3
KEY4
AD[8]
AD[7]
+3.3V(12)
AD[5]
AD[3]
GND(22)
AD[1]
+5V(11)
ACK64#
+5V(12)
+5V(13)
J14
DS MicIn
DS CDIn
DS
LineIn
13
11
9
7
5
3
1
/OBE
DSMCK
DSLRCK
DSSCK
SDATA1
SDATA2
n.c.
(reserved)
7x2CON
To Main
Board
DGND
U9
2
4
6
8
DSSDI3
DSSDI2
DSSDI1
11
13
15
17
1
19
+12VD
+5VA
+5VD
20
U8
1A1
1A2
1A3
1A4
1Y1
1Y2
1Y3
1Y4
2A1
2A2
2A3
2A4
2Y1
2Y2
2Y3
2Y4
18
16
14
12
SDATA1
SDATA2
9
7
5
3
DSMCK
DSLRCK
DSSCK
1OE
2OE
VCC
GND
10
74HC244
1
C41
0.1uF
Z5U
+ C42
10uF
ELEC
IN
OUT
3
GND
MC78M05C
+ C43
10uF
ELEC
DGND
AGND
Side B
DGND
14
12
10
8
6
4
2
PCI BUS 5V B
Figure 4. PCI Bus
9
CRD4205-2
TRST#
+12V
TMS
TDI
+5V(1)
INTA#
INTC#
+5V(2)
RSVD(1)
+5V(3)
RSVD(2)
GND(1)
GND(2)
RSVD(3)
RST#
+5V(4)
GNT#
GND(3)
PME#
AD[30]
+3.3V(1)
AD[28]
AD[26]
GND(4)
AD[24]
IDSEL
+3.3V(2)
AD[22]
AD[20]
GND(5)
AD[18]
AD[16]
+3.3V(3)
FRAME#
GND(6)
TRDY#
GND(7)
STOP#
+3.3V(4)
SDONE
SBO#
GND(8)
PAR
AD[15]
+3.3V(5)
AD[13]
AD[11]
GND(9)
AD[9]
KEY1
KEY2
C/BE[0]#
+3.3V(6)
AD[6]
AD[4]
GND(10)
AD[2]
AD[0]
+5V(5)
REQ64#
+5V(6)
+5V(7)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
+5VD
2
DS489RD2A1
+12VD
P2
10
CRD4205-2
DS489RD2A1
Figure 5. Assembly Drawing
DS489RD2A1
11
CRD4205-2
Figure 6. Silkscreen
12
CRD4205-2
DS489RD2A1
Figure 7. Top Layer
DS489RD2A1
13
CRD4205-2
Figure 8. Bottom Layer
CRD4205-2
Figure 9. Drill Drawing
14
DS489RD2A1
DS489RD2A1
6. BILL OF MATERIALS
PRINTED CIRCUIT BOARD ASSEMBLY
Item Quantity
Reference
9
2
3
4
5
6
4
1
5
1
8
7
8
4
1
C1,C2,C9,C14,C25,C26,C31.
C32,C36.
C3,C4,C5,C6.
C7.
C8,C12,C37,C38,C41.
C11.
C13,C23,C24,C29,C30,C35.
C42,C43.
C21,C22,C27,C28.
JP1.
9
1
J1.
10
1
J2.
11
1
J3.
12
1
J14.
13
2
J21,J22.
14
15
16
17
18
19
20
21
22
23
24
25
26
27
3
1
1
4
1
2
4
4
4
2
5
3
2
2
L1,L2,L3.
P1.
P2.
R1,R2,R3,R4.
R11.
R37,R12.
R21,R22,R27,R28.
R23,R24,R29,R30.
R25,R26,R31,R32.
R36,R35.
R41,R42,R43,R44,R5.
U1,U2,U3.
U5,U4.
U6,U7.
28
1
U8.
29
1
U9.
CAP, 0805, COG, 100pF, 5%, 50V.
.
CAP, SMT A, ELEC, 2.2uF, 20%, 35V.
CAP, 0805, X7R, .022uF, 10%, 50V.
CAP, 0805, X7R, .1uF, 10%, 50V.
CAP, SMT A, ELEC, 4.7uF, 20%, 25V.
CAP, SMT B, ELEC, 10uF, 20%, 16V.
.
CAP, 0805, C0G, 22pF, 10%, 50V.
HDR, 3x1, 0.025" PIN, 0.1" CTR.
Manufacturer
KEMET.
.
PANASONIC.
KEMET.
KEMET.
PANASONIC.
PANASONIC.
.
KEMET.
SAMTEC.
LZR ELECTRONCONN, 1/8" DOUBLE SW. STEREO PHONE JACK.
ICS.
HDR, 4X1, 0.025" PIN, 0.1" CTR, 15u" AU.
MOLEX.
LZR ELECTRONCONN, 1/8" SINGLE SW. STEREO PHONE JACK.
ICS.
CONN, 7x2 RIBBON, MALE, STRAIGHT, SHROUDED.
AMP.
LZR ELECTRONCONN, 1/8" NON-SW. STEREO PHONE JACK.
ICS.
IND, FBEAD, 1206, 31@100MHz, 25%.
TDK.
PCI BUS 5V SIDE B.
.
PCI BUS 5V SIDE A.
.
RES, SO, 0805, 6.8K, 1%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805, 1.5K, 1%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805, 2.2K, 1%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805, 27K, 1%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805, 33K, 1%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805, 220K, 5%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805, 10K, 1%, 1/10W, METAL FILM.
PHILIPS.
RES, SO, 0805,100, 1%, 1/10W, METAL FILM.
PHILIPS.
IC, CS5331A, 18-BIT ADC.
CIRRUS LOGIC.
IC, SO, SOIC8, 34072, SINGLE SUPPLY DUAL OP AMP. MOTOROLA.
IC, SO, SOIC8, CS4334, DAC, STEREO.
CIRRUS LOGIC.
IC, SO, +5V REGULATOR, MC78M05C, DPAK, 4%,
MOTOROLA.
500mA.
IC, 74HC244.
MOTOROLA.
Manufacturer PN
C0805C101J5GAC.
.
ECE-V1VS2R2SR.
C0805C223K5RAC.
C0805C104K5RAC.
ECE-V1ES4R7SR.
ECE-V1CA100R.
.
C0805C220K5GAC.
TSW-103-07-T-S.
SJ372.
70553-0003.
SJ374.
103309-2.
SJ373.
HF50ACB321611-T.
.
.
9C08052A6801F.
9C08052A1501F.
9C08052A2201F.
9C08052A2702F.
9C08052A3302F.
9C08052A2203J.
9C08052A1002F.
9C08052A1000F.
CS5331A-KS.
MC34072D.
CS4334-KS.
MC78M05CDT.
MC74HC244ADW.
15
CRD4205-2
1
Description
DS489RD2A1
MECHANICAL ASSEMBLY
Item Quantity
Name
Manufacturer
PN
1
1
Printed Circuit Board (PCB).
.
CRD4205-2 Rev A.
2
1
PCI Bracket.
Globe.
.
3
1
Label.
Internal Crystal.
NA.
Comments
PN located in upper left
corner of PCB.
.
Label content "CRD42052".
CRD4205-2
16
• Notes •