Cirrus Logic AN260 User Manual

AN260

Transitioning from the CS4362 to the CS4362A or CS4365

1. Introduction

This application note describes how to transition easily to the CS4365 or CS4362A from an existing
design that uses the CS4362. The CS4362A was designed to give a simple upgrade path from the
CS4362, whereas the CS4365 adds some additional features. Please refer to the CS4362A and CS4365
data sheets for supplemental information and specifications concerning operation of the device. A brief
comparison between the product families is shown in Table 1.

1.1 What the CS4362A offers over the CS4362:

• Sixth order multi-bit delta-sigma modulator for lower out of band noise

• Increased full-scale output level for ease of board level noise management

• Improved lower latency PCM digital filter

• Non-decimating DSD processor with on chip 50 kHz filtering

• Uses identical register mapping

1.2 Changes from the CS4362 that the CS4362A requires:

• The VD supply must be changed to 2.5 V from either the 3.3 V or 5 V of the CS4362.

•

Depending on the desired output voltage require ments, attenuation may need to be added to the off-chip filter.

• Loss of simultaneous support for two synchronous sample rates mode which was available in the CS43 62.
This mode provided for dual sample rates such as 192 kHz front channels with 96 kHz surrounds for DVD
audio and required the use of LRCK2 and SCLK2. This mode is not offered in the CS4362A or CS4365.

• Additional resistors on MUTEC pins.

1.3 What the CS4365 offers over the CS4362A:

• Additional DSD functions of Volume control, Mute pattern detect, support for phase modulation mode, and

offers a direct to switched capacitor path

• 1/2 dB volume control steps (vs. 1 dB in CS4362/62A)

• One-Line and TDM modes

• Auto-mute polarity detection

• Auto-speed mode detection

1.4 Changes from the CS4362 that the CS4365 requires:

• The VD supply must be changed to 2.5 V from the either 3.3 V or 5 V of the CS4362.

•

Depending on the desired output voltage requirements, attenuation may need to be added to the off-chip filter.

• Simultaneous support for two synchronous sample rates is no longer available.

• Additional resistors on MUTEC pins.

• Four pins change location or function for hardware mode. The chang es aren't necessary for so ftware mode.

• Requires different register mapping from the CS4362.

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Copyright © Cirrus Logic, Inc. 2009

(All Rights Reserved)

AN260REV2

JAN ‘09

1

AN260

CS4365 CS4362A CS4362
Dynamic Range
THD+N
Resolution
Sample Rate
Pow er Suppl y

Volume Control 0.5 dB
Auto F s De tect Yes
Package 48-LQFP

Table 1. Product Comparison

dB
dB

bits

kHz

VA
VD

114

-100
24

192

5

2.5

For users of the CS4362, the CS4365 is a simple, yet affordable, upgrade to a richer feature set and lower
out-of-band noise performance.

2. The Design Transition

2.1 Transitioning from the CS4362 to CS4362A

2.1.1 Hardware changes

The CS4362A pinout was primarily based on the CS4362 with only 2 pins changing function.
Other pins have new recommended components but the circuit topologies remain the same and
thus do not require modification to the PCB. The most significant change is that the VD core of
the CS4362A requires 2.5 V for operation, whereas the CS4362 was able to run from 3.3 V to
5 V. The CS4362A will NOT operate off of a VD supply of 3.3 V or 5 V.

Figure 1 and Figure 2 show the CS4362 and CS4362A pinouts respectively. The changes to
the two pinouts are highlighted. Figure 1 highlights the pins which have changed function and
which may require a PCB change. Figure 2 highlights the pins which have new recommended
components.

114 114

-100 -100
24 24

192 192

55

2.5 3.3 to 5

1 dB 1 dB

No No

48-LQFP 48-LQFP

2 AN260REV2

AN260

AOUTA1-

VQ

AOUTA1+

MUTEC6

AOUTB1-

AOUTB1+

36

AOUTA2-

35

AOUTA2+
AOUTB2+

34

AOUTB2-

33

32

VA

31

GND

AOUTA3-

30

AOUTA3+

29

AOUTB3+

28

27

AOUTB3­MUTEC2

26

MUTEC3

25

MUTEC4

MUTEC5

DSDA2
DSDB1
DSDA1

VD
GND
MCLK

LRCK1(DSD_EN)

SDIN1

SCLK1

TST

SDIN2

TST

48 47 46 45 44 43 42 41 40 39 38 37

1
2
3
4
5
6
7
8
9
10
11
12

13 14 15 16 17 18 19 20 21 22 23 24

= denotes pins which require changes

TST

DSDB3

DSDB2

DSDA3

CS4362A

TST

SDIN3

M1(SDA/CDIN)

M2(SCL/CCLK)

to components or voltages

MUTEC1

VLS

M3(DSD_SCLK)

TST

VLC

RST

FILT+

M0(AD0/CS)

AOUTA1-

VQ

AOUTB1-

AOUTB1+

AOUTA1+

36

AOUTA2­AOUTA2+

35

AOUTB2+

34
33

AOUTB2-

32

VA

31

GND

AOUTA3-

30

AOUTA3+

29

AOUTB3+

28
27

AOUTB3­MUTEC2

26

MUTEC3

25

MUTEC4

MUTEC6

MUTEC5

Figure 2. CS4362A pinout

DSDA2
DSDB1
DSDA1

VD

GND
MCLK

LRCK1(DSD_EN)

SDIN1

SCLK1

LRCK2

SDIN2

SCLK2

MUTEC1

VLS

M3(DSD_SCLK)

TST

TST

DSDB3

DSDB2

DSDA3

48 47 46 45 44 43 42 41 40 39 38 37

1

2

3

4

5

6

7

8

9

10

11

12

13 14 15 16 17 18 19 20 21 22 23 24

SDIN3

= denotes location or function changes

when trasitioning to CS4362A

TST

CS4362

M1(SDA/CDIN)

M2(SCL/CCLK)

RST

VLC

FILT+

M0(AD0/CS)

Figure 1. CS4362 pinout

Location or function changes as denoted in Figure 1 are as follows:

• The CS4365 does not support the simultaneous synchronous sample rate function of the CS4362. Pins 10
and 12 are now Test inputs.

Pins which require changes to external components or voltages as denoted in Figure 2 are as
follows:

• Pin 4 (VD) requires 2.5 V for recommended operation. The CS4362 used either 3.3 V or 5 V, which, if left
unchanged, would damage the CS4362A.

• Pins 22-26 and pin 41 (MUTEC#) require an add itiona l pull- up or down in order to mute during reset. While
reset is asserted these pins are high impedance and will not drive the mute circuitry. It is recommended that
the pull-up/down resistance properly biases the off-chip mute circuit into muting.

• Pins 27 - 30, 33 - 40 (AOUTs) have a new recommended filter circuit. This filter uses the same filter topology
as the CS4362. The component values have been changed to account for the extra output level from the
CS4362A and still provide 2 Vrms on the output. A general optimization was also made in order to reduce
the thermal noise contribution of the resistances (using smaller resistances where possible). Please refer to
the CS4362A datasheet for details on the new recommended filter.

2.1.2 Functional changes

- With the addition of the non-decimating DSD processor mode comes the added benefits of

matched PCM and DSD output levels and an on chip 50 kHz filter.

- The CS4362A uses a new multi-bit Delta-Sigma modulator core with mis-match shaping which al-

lows for lower over-all out-of-band noise and improved audio quality.

- The CS4362A gained new digital filters with improved stop-band performance and lower latency.

- The full-scale differential output voltage has increased which needs to be accounted for in the an-

AN260REV2 3

AN260

alog filter gain (if similar output level to the CS4362 is desired).

- The mute control pins are high impedance while reset is asserted. An external pull-up or down is
required to properly bias the off-chip mute circuitry into muting during reset.

- The dual serial port function of the CS4362 which accepted two simultaneous synchronous sam­ple rates (such as 192 kHz front and 96 kHz surrounds) is not supported.

2.2 Transitioning from the CS4362 to CS4365

2.2.1 Hardware changes

The CS4365 pinout was primarily based on the CS4362 with only 3 pins changing function. Oth­er pins have new recommended components but the circuit topologies remain the same and
thus do not require modification to the PCB. The most significant change is that the VD core of
the CS4365 requires 2.5 V for operation, whereas the CS4362 was able to run from 3.3 V to
5 V. The CS4365 will NOT operate off of a VD supply of 3.3 V or 5 V.

Figure 3 and Figure 4 show the CS4362 and CS4365 pinouts respectively. The changes to the
two pinouts are highlighted. Figure 3 highlights the pins which have changed function and which
may require a PCB change. Figure 4 highlights the pins which have new recommended com­ponents.

AOUTB1+

AOUTA1-

VQ

AOUTA1+

23 24

MUTEC6

MUTEC5

AOUTB1-

36

35

34

33

32

31

30

29

28

27

26

25

MUTEC4

AOUTA2­AOUTA2+
AOUTB2+
AOUTB2­VA
GND
AOUTA3­AOUTA3+
AOUTB3+
AOUTB3­MUTEC2
MUTEC3

DSDA2
DSDB1

DSDA1

VD

GND
MCLK

LRCK1(DSD_EN)

SDIN1

SCLK1

LRCK2

SDIN2
SCLK2

MUTEC1

AOUTA1-

VLS

M3(DSD_SCLK)

TST

TST

DSDB3

DSDB2

DSDA3

48 47 46 45 44 43 42 41 40 39 38 37

1

2

3

4

5

6

7

8

9

10

11

12

13 14 15 16 17 18 19 20 21 22 23 24

SDIN3

= denotes location or function changes

when trasitioning to CS4365

TST

CS4362

M1(SDA/CDIN)

M2(SCL/CCLK)

VQ

RST

VLC

FILT+

M0(AD0/CS)

Figure 3. CS4362 pinout

VLS

TST

M0(AD0/CS)

VLC

MUTEC1

DSD_SCLK

RST

FILT+

DSDB3

DSDA3

TST

AOUTB1-

AOUTB1+

AOUTA1+

36

AOUTA2­AOUTA2+

35

AOUTB2+

34

AOUTB2-

33

32

VA

31

GND

AOUTA3-

30

AOUTA3+

29

AOUTB3+

28

27

AOUTB3­MUTEC2

26

MUTEC3

25

MUTEC4

MUTEC6

MUTEC5

DSDA2

DSDB1
DSDA1

VD

GND
MCLK
LRCK

SDIN1

SCLK

M4

SDIN2

M3

DSDB2

48 47 46 45 44 43 42 41 40 39 38 37

1

2

3

4

5

6

7

8

9

10

11

2

1

13 14 15 16 17 18 19 20 21 22

SDIN3

CS4365

TST

M1(SDA/CDIN)

M2(SCL/CCLK)

= denotes pins which require changes

to components or voltages

Figure 4. CS4365 pinout

Location or function changes as denoted in Figure 3 are as follows:

• Pin 7 is no longer DSD_EN in hardware mode. In order to enter DSD mode on the CS436 5 you mu st either
set the M4 and M3 pins accordingly or use SPI™ or I

2

C configuration.

• The CS4365 does not support the simultaneous synchronous sample rate function of the CS4362. Pins 10
and 12 are now dedicated for stand-alone configuration (voltage input on these pins are still referenced to
VLS).

4 AN260REV2

AN260

• Pin 42 no longer functions as M3 in stand-alone PCM modes. It is now a dedicated DSD_SCLK pin.

Pins which require changes to external components or voltages as denoted in Figure 4 are as
follows:

• Pin 4 (VD) requires 2.5 V for recommended operation. The CS4362 used either 3.3 V or 5 V, which, if left
unchanged, would damage the CS4365.

• Pins 22-26 and pin 41 (MUTEC#) require an additional pull-up or down in order to indicate the desire d
direction of mute polarity. While reset is asserted these pins are high impedance and will not drive the mute
circuitry. It is recommended that the pull-up/down res ist ance properly biases the off-chip mute circuit into
muting.

• Pins 27 - 30, 33 - 40 (AOUTs) have a new recommended filter circuit. This filter uses the same filter topology
as the CS4362. The component values have been changed to account for the extra output level from the
CS4365 and still provide 2 Vrms on the output. A general optimization was also made in order to reduce the
thermal noise contribution of the resistances (using smaller resistances where possible). Please refer to the
CS4365 datasheet for details on the new recommended filter.

2.2.2 Functional changes

- The CS4365 uses a new register mapping in order to accommodate the additio nal features which

it provides over the CS4362. Please refer to the CS4365 datasheet for the new mapping.

- With the addition of the non-decimating DSD processor mode comes the added benefits of

matched PCM and DSD output levels, DSD volume control, an on chip 50 kHz filter, Phase Mod­ulation input mode, and DSD mute pattern detection. A direct DSD path to the switched capacitor
array is also offered. All of the features are accessed through the configuration registers.

- The CS4365 supports a setting for auto-selection of the speed mode to set what sample rate range

the DAC is to expect. This allows the CS4365 to operate at sample rates from 4 kHz on up to
192 kHz without intervention (Note: there are a few reserved frequencies, see datasheet for de­tails). This setting is available in both stand-alone and control-port operation.

- The volume control in the CS4365 offers 0.5 dB step sizes for more volume setting resolution.

- The CS4365 offers TDM and One-Line modes for compatibility with various multi-channel sur-

round sound DSPs which helps reduce board real-estate from the additional data lines. These
modes are not available in stand-alone mode.

- The CS4365 uses a new multi-bit Delta-Sigma modulator core with mis-match shaping which al-

lows for lower over-all out-of-band noise and improved audio quality.

- The CS4365 gained new digital filters with improved stop-band performance and lower latency.

- The full-scale differential output voltage has increased which needs to be accounted for in the an-

alog filter gain (if similar output level to the CS4362 is desired).

- The mute control pins now support auto polarity detection. This allows for selection of active high

or low mute circuitry without the need to set registers. An external pull-up or down is required to
set the mute polarity.

- The MCLK divide by 2 bit is no longer necessary to access the 1024x MCLK/LRCK ratio (SSM),

512x MCLK/LRCK ratio (DSM) and 256x MCLK/LRCK ratio. A new ratio of 1152x has been added
for 32 kHz operation.

- The dual serial port function of the CS4362 which accepted two simultaneous synchronous sam-

ple rates (such as 192 kHz front and 96 kHz surrounds) is not supported.

AN260REV2 5

AN260

Table 2. Revision History

Release Date Changes

REV1 FEB 2005 Initial Release
REV2 JAN 2009 Added text to indicate MUTEC pins of the CS4362A are high impedance

during reset

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

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6 AN260REV2