CS42438
108 dB, 192 kHz 6-In, 8-Out TDM CODEC
FEATURES
GENERAL DESCRIPTION
Six 24-bit A/D, Eight 24-bit D/A Converters
The CS42438 CODEC provides six multi-bit analog-todigital and eight multi-bit digital-to-analog delta-sigma
converters. The CODEC is capable of operation with either differential or single-ended inputs and outputs, in a
52-pin MQFP package.
ADC Dynamic Range
–
–
105 dB Differential
102 dB Single-Ended
DAC Dynamic Range
–
–
Six fully differential, or single-ended, inputs are available on stereo ADC1, ADC2, and ADC3. When
operating in Single-ended Mode, an internal MUX before ADC3 allows selection from up to four single-ended
inputs. Digital volume control is provided for each ADC
channel, with selectable overflow detection.
108 dB Differential
105 dB Single-Ended
ADC/DAC THD+N
–
–
-98 dB Differential
-95 dB Single-Ended
All eight DAC channels provide digital volume control
and can operate with differential or single-ended
outputs.
Compatible with Industry-Standard Time
Division Multiplexed (TDM) Serial Interface
An auxiliary serial input is available for an additional two
channels of PCM data.
DAC Sampling Rates up to 192 kHz
ADC Sampling Rates up to 96 kHz
The CS42438 is available in a 52-pin MQFP package in
Commercial (-10° to +70°) and Automotive (-40° to
+105°) grades. The CDB42438 Customer Demonstration board is also available for device evaluation and
implementation suggestions. Please refer to “Ordering
Information” on page 61 for complete ordering
information.
Programmable ADC High-Pass Filter for DC
Offset Calibration
Logarithmic Digital Volume Control
Hardware Mode or Software I²C® & SPI™
Supports Logic Levels Between 5 V and 1.8 V
TDM Serial Audio
Input
Auxilliary Serial
Audio Input
Input Master
Clock
Analog Supply =
3.3 V to 5 V
Internal Voltage
Reference
Volume
Controls
Digital
Filters
Multibit
DAC1-4 and
Analog Filters
∆Σ
Modulators
High Pass
Filter
Digital
Filters
Multibit
Oversampling
ADC1&2
High Pass
Filter
Digital
Filters
Multibit
Oversampling
ADC3
8
Differential or
Single-Ended
Outputs
8
4
4
4:2*
TDM Serial Audio
Output
Digital Supply =
3.3 V
Register
Configuration
TDM Serial
Interface
Reset
Level Translator
Hardware Mode or
I2C/SPI Software Mode
Control Data
Level Translator
Control Port & Serial
Audio Port Supply =
1.8 V to 5 V
The CS42438 is ideal for audio systems requiring wide
dynamic range, negligible distortion and low noise, such
as A/V receivers, DVD receivers, and automotive audio
systems.
Differential or
Single-Ended
Analog Inputs
2
2
*Optional MUX allows selection from up to 4 single-ended inputs.
http://www.cirrus.com
Copyright © Cirrus Logic, Inc. 2006
(All Rights Reserved)
AUGUST '06
DS646F1
CS42438
TABLE OF CONTENTS
1. PIN DESCRIPTIONS - SOFTWARE MODE ........................................................................................... 6
1.1 Digital I/O Pin Characteristics ........................................................................................................... 8
2. PIN DESCRIPTIONS - HARDWARE MODE .......................................................................................... 9
3. TYPICAL CONNECTION DIAGRAMS ................................................................................................. 11
4. CHARACTERISTICS AND SPECIFICATIONS..................................................................................... 13
RECOMMENDED OPERATING CONDITIONS ................................................................................... 13
ABSOLUTE MAXIMUM RATINGS ....................................................................................................... 13
ANALOG INPUT CHARACTERISTICS (COMMERCIAL) .................................................................... 14
ANALOG INPUT CHARACTERISTICS (AUTOMOTIVE) ..................................................................... 15
ADC DIGITAL FILTER CHARACTERISTICS ....................................................................................... 16
ANALOG OUTPUT CHARACTERISTICS (COMMERCIAL) ................................................................ 17
ANALOG OUTPUT CHARACTERISTICS (AUTOMOTIVE) ................................................................. 18
COMBINED DAC INTERPOLATION & ON-CHIP ANALOG FILTER RESPONSE .............................. 20
SWITCHING SPECIFICATIONS - ADC/DAC PORT ............................................................................ 21
SWITCHING CHARACTERISTICS - AUX PORT ................................................................................. 22
SWITCHING SPECIFICATIONS - CONTROL PORT - I²C MODE ....................................................... 23
SWITCHING SPECIFICATIONS - CONTROL PORT - SPI FORMAT ................................................. 24
DC ELECTRICAL CHARACTERISTICS .............................................................................................. 25
DIGITAL INTERFACE SPECIFICATIONS & CHARACTERISTICS ..................................................... 25
5. APPLICATIONS .................................................................................................................................... 26
5.1 Overview ......................................................................................................................................... 26
5.2 Analog Inputs .................................................................................................................................. 27
5.2.1 Line-Level Inputs ................................................................................................................... 27
5.2.1.1 Hardware Mode ......................................................................................................... 27
5.2.1.2 Software Mode ........................................................................................................... 27
5.2.2 ADC3 Analog Input ................................................................................................................ 28
5.2.3 Hardware Mode ..................................................................................................................... 29
5.2.4 Software Mode ...................................................................................................................... 29
5.2.5 High-Pass Filter and DC Offset Calibration ........................................................................... 29
5.2.5.1 Hardware Mode ......................................................................................................... 29
5.2.5.2 Software Mode ........................................................................................................... 29
5.3 Analog Outputs ............................................................................................................................... 30
5.3.1 Initialization ............................................................................................................................ 30
5.3.2 Line-Level Outputs and Filtering ............................................................................................ 30
5.3.3 Digital Volume Control ........................................................................................................... 32
5.3.3.1 Hardware Mode ......................................................................................................... 32
5.3.3.2 Software Mode ........................................................................................................... 32
5.3.4 De-Emphasis Filter ................................................................................................................ 32
5.4 System Clocking ............................................................................................................................. 33
5.4.1 Hardware Mode ..................................................................................................................... 33
5.4.2 Software Mode ...................................................................................................................... 33
5.5 CODEC Digital Interface ................................................................................................................. 33
5.5.1
TDM ................................................................................................................................ 33
5.5.2 I/O Channel Allocation ........................................................................................................... 34
5.6 AUX Port Digital Interface Formats ................................................................................................. 34
5.6.1 Hardware Mode ..................................................................................................................... 34
5.6.2 Software Mode ...................................................................................................................... 34
5.6.3 I²S .......................................................................................................................................... 34
5.6.4 Left-Justified .......................................................................................................................... 35
5.7 Control Port Description and Timing ............................................................................................... 35
5.7.1 SPI Mode ............................................................................................................................... 35
5.7.2 I²C Mode ................................................................................................................................ 36
2
DS646F1
CS42438
5.8 Recommended Power-Up Sequence ............................................................................................. 37
5.8.1 Hardware Mode ..................................................................................................................... 37
5.8.2 Software Mode ...................................................................................................................... 38
5.9 Reset and Power-Up ...................................................................................................................... 38
5.10 Power Supply, Grounding, and PCB Layout ................................................................................. 38
6. REGISTER QUICK REFERENCE ......................................................................................................... 39
7. REGISTER DESCRIPTION ................................................................................................................... 41
7.1 Memory Address Pointer (MAP) ..................................................................................................... 41
7.1.1 Increment (INCR) .................................................................................................................. 41
7.1.2 Memory Address Pointer (MAP[6:0]) ..................................................................................... 41
7.2 Chip I.D. and Revision Register (Address 01h) (Read Only) .......................................................... 41
7.2.1 Chip I.D. (CHIP_ID[3:0]) ........................................................................................................ 41
7.2.2 Chip Revision (REV_ID[3:0]) ................................................................................................. 41
7.3 Power Control (Address 02h) ......................................................................................................... 42
7.3.1 Power Down ADC Pairs (PDN_ADCX) ................................................................................. 42
7.3.2 Power Down DAC Pairs (PDN_DACX) ................................................................................. 42
7.3.3 Power Down (PDN) ............................................................................................................... 42
7.4 Functional Mode (Address 03h) ...................................................................................................... 43
7.4.1 MCLK Frequency (MFREQ[2:0]) ........................................................................................... 43
7.5 Miscellaneous Control (Address 04h) ............................................................................................. 43
7.5.1 Freeze Controls (FREEZE) ................................................................................................... 43
7.5.2 Auxiliary Digital Interface Format (AUX_DIF) ........................................................................ 43
7.6 ADC Control & DAC De-Emphasis (Address 05h) ......................................................................... 44
7.6.1 ADC1-2 High-Pass Filter Freeze (ADC1-2_HPF FREEZE) .................................................. 44
7.6.2 ADC3 High Pass Filter Freeze (ADC3_HPF FREEZE) ......................................................... 44
7.6.3 DAC De-Emphasis Control (DAC_DEM) ............................................................................... 44
7.6.4 ADC1 Single-Ended Mode (ADC1 SINGLE) ......................................................................... 44
7.6.5 ADC2 Single-Ended Mode (ADC2 SINGLE) ......................................................................... 45
7.6.6 ADC3 Single-Ended Mode (ADC3 SINGLE) ......................................................................... 45
7.6.7 Analog Input Ch. 5 Multiplexer (AIN5_MUX) ......................................................................... 45
7.6.8 Analog Input Ch. 6 Multiplexer (AIN6_MUX) ......................................................................... 45
7.7 Transition Control (Address 06h) .................................................................................................... 46
7.7.1 Single Volume Control (DAC_SNGVOL, ADC_SNGVOL) .................................................... 46
7.7.2 Soft Ramp and Zero Cross Control (ADC_SZC[1:0], DAC_SZC[1:0]) .................................. 46
7.7.3 Auto-Mute (AMUTE) .............................................................................................................. 47
7.7.4 Mute ADC Serial Port (MUTE ADC_SP) ............................................................................... 47
7.8 DAC Channel Mute (Address 07h) ................................................................................................. 47
7.8.1 Independent Channel Mute (AOUTX_MUTE) ....................................................................... 47
7.9 AOUTX Volume Control (Addresses 08h- 0Fh) .......................................................................... 47
7.9.1 Volume Control (AOUTX_VOL[7:0]) ...................................................................................... 47
7.10 DAC Channel Invert (Address 10h) .............................................................................................. 48
7.10.1 Invert Signal Polarity (INV_AOUTX) .................................................................................... 48
7.11 AINX Volume Control (Address 11h-16h) ..................................................................................... 48
7.11.1 AINX Volume Control (AINX_VOL[7:0]) .............................................................................. 48
7.12 ADC Channel Invert (Address 17h) .............................................................................................. 49
7.12.1 Invert Signal Polarity (INV_AINX) ........................................................................................ 49
7.13 Status (Address 19h) (Read Only) ................................................................................................ 49
7.13.1 CLOCK ERROR (CLK ERROR) .......................................................................................... 49
7.13.2 ADC Overflow (ADCX_OVFL) ............................................................................................. 49
7.14 Status Mask (Address 1Ah) .......................................................................................................... 49
8. EXTERNAL FILTERS............................................................................................................................ 50
8.1 ADC Input Filter .............................................................................................................................. 50
8.1.1 Passive Input Filter ................................................................................................................ 51
8.1.2 Passive Input Filter w/Attenuation ......................................................................................... 51
DS646F1
3
CS42438
8.2 DAC Output Filter ........................................................................................................................... 53
9. ADC FILTER PLOTS............................................................................................................................. 54
10. DAC FILTER PLOTS........................................................................................................................... 56
11. PARAMETER DEFINITIONS............................................................................................................... 58
12. REFERENCES..................................................................................................................................... 59
13. PACKAGE INFORMATION................................................................................................................. 60
13.1 Thermal Characteristics ............................................................................................................. 60
14. ORDERING INFORMATION ............................................................................................................... 61
15. REVISION HISTORY ........................................................................................................................... 61
LIST OF FIGURES
Figure 1.Typical Connection Diagram (Software Mode) ........................................................................... 11
Figure 2.Typical Connection Diagram (Hardware Mode) .......................................................................... 12
Figure 3.Output Test Circuit for Maximum Load ....................................................................................... 19
Figure 4.Maximum Loading ....................................................................................................................... 19
Figure 5.TDM Serial Audio Interface Timing ............................................................................................. 21
Figure 6.Serial Audio Interface Slave Mode Timing .................................................................................. 22
Figure 7.Control Port Timing - I²C Format ................................................................................................. 23
Figure 8.Control Port Timing - SPI Format ................................................................................................ 24
Figure 9.Full-Scale Input ........................................................................................................................... 28
Figure 10.ADC3 Input Topology ................................................................................................................ 28
Figure 11.Audio Output Initialization Flow Chart ....................................................................................... 31
Figure 12.Full-Scale Output ...................................................................................................................... 32
Figure 13.De-Emphasis Curve .................................................................................................................. 33
Figure 14.TDM Serial Audio Format ......................................................................................................... 34
Figure 15.AUX I²S Format ......................................................................................................................... 34
Figure 16.AUX Left-Justified Format ......................................................................................................... 35
Figure 17.Control Port Timing in SPI Mode .............................................................................................. 36
Figure 18.Control Port Timing, I²C Write ................................................................................................... 36
Figure 19.Control Port Timing, I²C Read ................................................................................................... 37
Figure 20.Single to Differential Active Input Filter ..................................................................................... 50
Figure 21.Single-Ended Active Input Filter ................................................................................................ 50
Figure 22.Passive Input Filter ................................................................................................................... 51
Figure 23.Passive Input Filter w/Attenuation ............................................................................................. 52
Figure 24.Active Analog Output Filter ....................................................................................................... 53
Figure 25.Passive Analog Output Filter .................................................................................................... 53
Figure 26.SSM Stopband Rejection .......................................................................................................... 54
Figure 27.SSM Transition Band ................................................................................................................ 54
Figure 28.SSM Transition Band (Detail) ................................................................................................... 54
Figure 29.SSM Passband Ripple .............................................................................................................. 54
Figure 30.DSM Stopband Rejection .......................................................................................................... 54
Figure 31.DSM Transition Band ................................................................................................................ 54
Figure 32.DSM Transition Band (Detail) ................................................................................................... 55
Figure 33.DSM Passband Ripple .............................................................................................................. 55
Figure 34.SSM Stopband Rejection .......................................................................................................... 56
Figure 35.SSM Transition Band ................................................................................................................ 56
Figure 36.SSM Transition Band (detail) .................................................................................................... 56
Figure 37.SSM Passband Ripple .............................................................................................................. 56
Figure 38.DSM Stopband Rejection .......................................................................................................... 56
Figure 39.DSM Transition Band ................................................................................................................ 56
Figure 40.DSM Transition Band (detail) .................................................................................................... 57
Figure 41.DSM Passband Ripple .............................................................................................................. 57
Figure 42.QSM Stopband Rejection ......................................................................................................... 57
4
DS646F1
CS42438
Figure 43.QSM Transition Band ................................................................................................................ 57
Figure 44.QSM Transition Band (detail) .................................................................................................... 57
Figure 45.QSM Passband Ripple .............................................................................................................. 57
LIST OF TABLES
Table 1. I/O Power Rails ............................................................................................................................. 8
Table 2. Hardware Configurable Settings ................................................................................................. 26
Table 3. AIN5 Analog Input Selection ....................................................................................................... 29
Table 4. AIN6 Analog Input Selection ....................................................................................................... 29
Table 5. MCLK Frequency Settings .......................................................................................................... 33
Table 6. Serial Audio Interface Channel Allocations ................................................................................. 34
Table 7. MCLK Frequency Settings .......................................................................................................... 43
Table 8. Example AOUT Volume Settings ................................................................................................ 48
Table 9. Example AIN Volume Settings .................................................................................................... 48
DS646F1
5
CS42438
AIN2+
AIN2-
AIN3-
AIN3+
AIN4-
AIN4+
VA
FILT+
AGND
AIN5-/AIN5B
AIN5+/AIN5A
AIN6-/AIN6B
AIN6+/AIN6A
1. PIN DESCRIPTIONS - SOFTWARE MODE
52 51 50 49 48 47 46 45 44 43 42 41 40
SCL/CCLK
1
39
AIN1+
SDA/CDOUT
2
38
AIN1-
AD0/CS
AD1/CDIN
3
37
VA
4
VQ
RST
VLC
5
36
35
34
33
AOUT8AOUT7+
AGND
FS
6
7
VD
8
32
DGND
9
31
AOUT7-
VLS
10
30
AOUT6-
SCLK
11
12
29
AOUT6+
MCLK
AOUT5+
ADC_SDOUT
13
28
27
42438
AOUT8+
AOUT5-
#
AOUT4+
AOUT4-
AOUT3+
AOUT3-
AOUT2-
AOUT2+
AOUT1+
AOUT1-
DGND
AUX_SDIN
AUX_SCLK
DAC_SDIN
Pin Name
AUX_LRCK
14 15 16 17 18 19 20 21 22 23 24 25 26
Pin Description
SCL/CCLK
1
Serial Control Port Clock (Input) - Serial clock for the control port interface.
SDA/CDOUT
2
Serial Control Data I/O (Input/Output) - Input/Output for I²C data. Output for SPI data.
AD0/CS
3
Address Bit [0]/ Chip Select (Input) - Chip address bit in I²C Mode. Control signal used to select
the chip in SPI Mode.
AD1/CDIN
4
Address Bit [1]/ SPI Data Input (Input) - Chip address bit in I²C Mode. Input for SPI data.
RST
5
Reset (Input) - The device enters a low-power mode and all internal registers are reset to their
default settings when low.
VLC
6
Control Port Power (Input) - Determines the required signal level for the control port interface.
See “Digital I/O Pin Characteristics” on page 8.
FS
7
Frame Sync (Input) - Signals the start of a new TDM frame in the TDM digital interface format.
VD
8
Digital Power (Input) - Positive power supply for the digital section.
DGND
9,18
Digital Ground (Input) -
VLS
10
Serial Port Interface Power (Input) - Determines the required signal level for the serial port interfaces. See “Digital I/O Pin Characteristics” on page 8.
SCLK
11
Serial Clock (Input) - Serial clock for the serial audio interface. Input frequency must be 256 x Fs.
MCLK
12
Master Clock (Input) - Clock source for the delta-sigma modulators and digital filters.
ADC_SDOUT
13
Serial Audio Data Output (Output) - TDM output for two’s complement serial audio data.
DAC_SDIN
14
DAC Serial Audio Data Input (Input) - TDM Input for two’s complement serial audio data.
AUX_LRCK
15
Auxiliary Left/Right Clock (Output) - Determines which channel, Left or Right, is currently active
on the Auxiliary serial audio data line.
6
DS646F1
CS42438
AUX_SCLK
16
Auxiliary Serial Clock (Output) - Serial clock for the Auxiliary serial audio interface.
AUX_SDIN
17
Auxiliary Serial Input (Input) - The 42438 provides an additional serial input for two’s complement serial audio data.
AOUT1 +,AOUT2 +,AOUT3 +,AOUT4 +,AOUT5 +,AOUT6 +,AOUT7 +,AOUT8 +,-
20,19
21,22
24,23
Differential Analog Output (Output) - The full-scale differential analog output level is specified in
25,26
the Analog Characteristics specification table. Each positive leg of the differential outputs may
28,27
also be used single-ended.
29,30
31,32
33,34
AGND
35,48 Analog Ground (Input) - Ground reference for the analog section.
VQ
36
Quiescent Voltage (Output) - Filter connection for internal quiescent reference voltage.
VA
37,46 Analog Power (Input) - Positive power supply for the analog section.
AIN1 +,AIN2 +,AIN3 +,AIN4 +,AIN5 +,AIN6 +,-
39,38
41,40
43,42
45,44
50,49
52,51
AIN5 A,B
AIN6 A,B
Single-Ended Analog Input (Input) - In Single-Ended Mode, an internal analog mux allows
50,49 selection between two channels for both analog inputs AIN5 and AIN6 (see Sections 7.6.6-7.6.8
52,51 for details). The unused leg of each input is internally connected to common mode. The full-scale
input level is specified in the Analog Characteristics specification table.
FILT+
DS646F1
47
Differential Analog Input (Input) - Signals are presented differentially to the delta-sigma modulators. The full-scale input level is specified in the Analog Characteristics specification table. Singleended inputs may be applied to the positive terminals when the ADCx SINGLE bit is enabled.
Once in Single-Ended Mode, the negative terminal of AIN1-AIN4 must be externally driven to
common mode. See below for a description of AIN5-AIN6 in Single-Ended Mode.
Positive Voltage Reference (Output) - Positive reference voltage for the internal sampling circuits.
7
CS42438
1.1
Digital I/O Pin Characteristics
Various pins on the CS42438 are powered from separate power supply rails. The logic level for each input
should adhere to the corresponding power rail and should not exceed the maximum ratings.
Power
Rail
Pin Name
SW/(HW)
I/O
Driver
Receiver
VLC
RST
Input
-
1.8 V - 5.0 V, CMOS
SCL/CCLK
(AIN5_MUX)
Input
-
1.8 V - 5.0 V, CMOS, with Hysteresis
SDA/CDOUT
(AIN6_MUX)
Input/
Output
1.8 V - 5.0 V, CMOS/Open Drain
1.8 V - 5.0 V, CMOS, with Hysteresis
AD0/CS
(MFREQ)
Input
-
1.8 V - 5.0 V, CMOS
Input
-
1.8 V - 5.0 V, CMOS
AD1/CDIN
(ADC3_HPF)
VLS
MCLK
Input
-
1.8 V - 5.0 V, CMOS
LRCK
Input
-
1.8 V - 5.0 V, CMOS
SCLK
Input
-
1.8 V - 5.0 V, CMOS
1.8 V - 5.0 V, CMOS
-
ADC_SDOUT3 Input/
(ADC3_SINGLE) Output
DAC_SDIN
Input
-
1.8 V - 5.0 V, CMOS
AUX_LRCK
Output
1.8 V - 5.0 V, CMOS
-
AUX_SCLK
Output
1.8 V - 5.0 V, CMOS
-
AUX_SDIN
Input
-
1.8 V - 5.0 V, CMOS
Table 1. I/O Power Rails
8
DS646F1
CS42438
AIN2+
AIN2-
AIN3-
AIN3+
AIN4-
AIN4+
FILT+
VA
AIN5-/AIN5B
AGND
AIN5+/AIN5A
AIN6-/AIN6B
AIN6+/AIN6A
2. PIN DESCRIPTIONS - HARDWARE MODE
52 51 50 49 48 47 46 45 44 43 42 41 40
AIN5_MUX
1
39
AIN1+
AIN6_MUX
2
38
AIN1-
MFREQ
ADC3_HPF
3
37
VA
4
VQ
RST
VLC
5
36
35
34
33
AOUT8-
FS
6
7
VD
8
32
AOUT7+
DGND
9
31
AOUT7-
VLS
10
30
AOUT6-
SCLK
11
12
29
AOUT6+
28
27
AOUT5-
13
AOUT5+
AOUT4+
AOUT4-
AOUT3+
AOUT3-
AOUT2-
AOUT2+
AOUT1-
AOUT1+
DGND
AUX_SDIN
AUX_SCLK
DAC_SDIN
Pin Name
AOUT8+
14 15 16 17 18 19 20 21 22 23 24 25 26
AUX_LRCK
MCLK
ADC_SDOUT/
ADC3_SINGLE
42438
AGND
#
Pin Description
AIN5_MUX
AIN6_MUX
1
2
Analog Input Multiplexer (Input) - Allows selection between the A and B single-ended inputs of
ADC3. See Section 7.6.7 and 7.6.8 for details.
MFREQ
3
MCLK Frequency (Input) - Sets the required frequency range of the input Master Clock. See
Section 5.4 for the appropriate settings.
ADC3_HPF
4
ADC3 High-Pass Filter Freeze (Input) - When this pin is driven high, the internal high-pass filter
will be disabled for ADC3. The current DC offset value will be frozen and continue to be subtracted from the conversion result. See “ADC Digital Filter Characteristics” on page 16.
RST
5
Reset (Input) - The device enters a low-power mode and all internal registers are reset to their
default settings when low.
VLC
6
Control Port Power (Input) - Determines the required signal level for the control port interface.
See “Digital I/O Pin Characteristics” on page 8.
FS
7
Frame Sync (Input) - Signals the start of a new TDM frame in the TDM digital interface format.
VD
8
Digital Power (Input) - Positive power supply for the digital section.
VLS
10
Serial Port Interface Power (Input) - Determines the required signal level for the serial port interfaces.
SCLK
11
Serial Clock (Input) - Serial clock for the serial audio interface. Input frequency must be 256 x Fs.
ADC_SDOUT/
ADC3_SINGLE
13
Serial Audio Data Output (Output) - TDM output for two’s complement serial audio data. Startup Option for Hardware Mode: Pull-up to VLS enables Single-Ended Mode for AIN5-AIN6.
DAC_SDIN
14
DAC Serial Audio Data Input (Input) - Input for two’s complement serial audio data.
AUX_LRCK
15
Auxiliary Left/Right Clock (Output) - Determines which channel, Left or Right, is currently active
on the Auxiliary serial audio data line.
DS646F1
9
CS42438
AUX_SCLK
16
Auxiliary Serial Clock (Output) - Serial clock for the Auxiliary serial audio interface.
AUX_SDIN
17
Auxiliary Serial Input (Input) - The 42438 provides an additional serial input for two’s complement serial audio data.
AOUT1 +,AOUT2 +,AOUT3 +,AOUT4 +,AOUT5 +,AOUT6 +,AOUT7 +,AOUT8 +,-
20,19
21,22
24,23
Differential Analog Output (Output) - The full-scale differential analog output level is specified in
25,26
the Analog Characteristics specification table. Each positive leg of the differential outputs may
28,27
also be used single-ended.
29,30
31,32
33,34
AGND
35,48 Analog Ground (Input) - Ground reference for the analog section.
VQ
36
Quiescent Voltage (Output) - Filter connection for internal quiescent reference voltage.
VA
37,46 Analog Power (Input) - Positive power supply for the analog section.
AIN1 +,AIN2 +,AIN3 +,AIN4 +,AIN5 +,AIN6 +,AIN7 +,AIN8 +,-
39,38
41,40
43,42
45,44
50,49
52,51
52,53
AIN5 A,B
AIN6 A,B
Single-Ended Analog Input (Input) - In Single-Ended Mode, an internal analog mux allows
50,49 selection between 2 channels for both analog inputs AIN5 and AIN6 (see Sections 7.6.6-7.6.8 for
52,51 details). The unused leg of each input is internally connected to common mode. The full-scale
input level is specified in the Analog Characteristics specification table.
FILT+
10
47
Differential Analog Input (Input) - Signals are presented differentially to the delta-sigma modulators. The full-scale input level is specified in the Analog Characteristics specification table.
Single-ended inputs may be applied to the positive terminals when the ADCx SINGLE pin is
enabled. Once in Single-Ended Mode, the negative terminal of AIN1-AIN4 must be externally
driven to common mode. See below for a description of AIN5-AIN6 in Single-Ended Mode.
Positive Voltage Reference (Output) - Positive reference voltage for the internal sampling circuits.
DS646F1
CS42438
3. TYPICAL CONNECTION DIAGRAMS
+3.3 V
10 µF
0.01 µF
0.01 µF
+
+
+3.3 V to +5 V
10 µF
0.01 µF
8
37
VD
10
VA
16
15
17
12
11
7
+1.8 V
to +5.0 V
Digital Audio
Processor
14
13
VA
VLS
0.01 µF
CS5341
A/D
Converter
46
AUX_SCLK
AUX_LRCK
AUX_SDIN
AOUT1+
AOUT1-
20
19
Analog Output Filter 2
AOUT2+
AOUT2-
21
22
Analog Output Filter 2
AOUT3+
AOUT3-
24
23
Analog Output Filter 2
AOUT4+
AOUT4-
25
26
Analog Output Filter 2
AOUT5+
AOUT5-
28
27
Analog Output Filter 2
AOUT6+
AOUT6-
29
30
Analog Output Filter 2
AOUT7+
AOUT7-
32
31
Analog Output Filter 2
AOUT8+
AOUT8-
33
34
Analog Output Filter 2
AIN1+
39
AIN1-
38
AIN2+
41
AIN2-
40
AIN3+
43
AIN3-
42
AIN4+
45
AIN4-
44
AIN5+/AIN5A
50
AIN5-/AIN5B
49
SCLK
FS
DAC_SDIN
ADC_SDOUT
52
5
RST
1
SCL/CCLK
2
SDA/CDOUT
4
3
**
2 kΩ
AIN6-/AIN6B
51
AD1/CDIN
AD0/CS
**
2 kΩ
+1.8 V
to +5 V
6
Analog Input 1
Input
Filter 1
Analog Input 2
Input
Filter 1
Analog Input 3
Input
Filter 1
Analog Input 4
MCLK
AIN6+/AIN6A
MicroController
Input
Filter 1
VLC
0.1 µF
VQ
FILT+
** Resistors are required for
I2C control port operation
Input
Filter 1
Analog Input 5
Input
Filter 1
Analog Input 6
Input
Filter 1
Analog Input 5A
Input
Filter 1
Analog Input 5B
Input
Filter 1
Analog Input 6A
Input
Filter 1
Analog Input 6B
37
47
+
DGND DGND
9
18
AGND
35
AGND
0.1 µF
+
100 µF
0.1 µF
4.7 µF
48
Connect DGND and AGND at Codec
1. See the ADC Input Filter section in the Appendix.
2. See the DAC Output Filter section in the Appendix.
Figure 1. Typical Connection Diagram (Software Mode)
DS646F1
11
CS42438
+3.3 V
10 µF
+
0.01 µF
0.01 µF
+
+3.3 V to +5 V
10 µF
0.01 µF
8
37
VD
10
16
AUX_SCLK
AUX_LRCK
AUX_SDIN
15
17
12
20
19
Analog Output Filter 2
AOUT2+
AOUT2-
21
22
Analog Output Filter 2
AOUT3+
AOUT3-
24
23
Analog Output Filter 2
AOUT4+
AOUT4-
25
26
Analog Output Filter 2
AOUT5+
AOUT5-
28
AOUT6+
AOUT6-
29
30
Analog Output Filter 2
AOUT7+
AOUT7-
32
31
Analog Output Filter 2
AOUT8+
AOUT8-
33
34
Analog Output Filter 2
Analog Output Filter 2
27
AIN1+
39
AIN1-
38
AIN2+
41
AIN2-
40
AIN3+
43
AIN3-
42
AIN4+
45
AIN4-
44
AIN5+/AIN5A
50
AIN5-/AIN5B
49
SCLK
7
FS
DAC_SDIN
14
VLS
* 13
Digital Audio
Processor
AOUT1+
AOUT1-
Input
Filter 1
Analog Input 1
Input
Filter 1
Analog Input 2
Input
Filter 1
Analog Input 3
Input
Filter 1
Analog Input 4
MCLK
11
+1.8 V
to +5.0 V
VA
VLS
0.01 µF
CS5341
A/D
Converter
46
VA
ADC_SDOUT/
ADC3_SINGLE
*
Input
Filter 1
Analog Input 5
Input
Filter 1
Analog Input 6
Input
Filter 1
Analog Input 5A
Input
Filter 1
Analog Input 5B
Input
Filter 1
Analog Input 6A
Input
Filter 1
Analog Input 6B
52
AIN6+/AIN6A
5
RST
1
AIN5_MUX
2
AIN6_MUX
4
ADC3_HPF
3
51
AIN6-/AIN6B
MFREQ
6
VLC
VQ
0.1 µF
FILT+
37
47
+
* MUX configuration settings for AIN5-AIN6. See
the ADC Input MUX section.
DGND DGND
9
18
AGND
35
AGND
0.1 µF
+
100 µF
0.1 µF
4.7 µF
48
Connect DGND and AGND at Codec
1. See the ADC Input Filter section in the Appendix.
2. See the DAC Output Filter section in the Appendix.
Figure 2. Typical Connection Diagram (Hardware Mode)
12
DS646F1
CS42438
4. CHARACTERISTICS AND SPECIFICATIONS
RECOMMENDED OPERATING CONDITIONS
(AGND=DGND=0 V, all voltages with respect to ground.)
Parameters
DC Power Supply
Analog
Digital
Serial Audio Interface
Control Port Interface
Ambient Temperature
Commercial
Automotive
(Note 1)
(Note 2)
-CMZ
-DMZ
Symbol
Min
Max
Units
VA
VD
VLS
VLC
3.14
3.14
1.71
1.71
5.25
3.47
5.25
5.25
V
V
V
V
TA
-10
-40
+70
+105
°C
°C
Symbol
VA
VD
VLS
VLC
Iin
VIN
VIND-S
VIND-C
TA
Min
-0.3
-0.3
-0.3
-0.3
AGND-0.7
-0.3
-0.3
-50
Max
6.0
6.0
6.0
6.0
±10
VA+0.7
VLS+ 0.4
VLC+ 0.4
+125
Units
V
V
V
V
mA
V
V
V
°C
Tstg
-65
+150
°C
ABSOLUTE MAXIMUM RATINGS
(AGND = DGND = 0 V; all voltages with respect to ground.)
Parameters
DC Power Supply
Input Current
Analog Input Voltage
Digital Input Voltage
(Note 4)
Ambient Operating Temperature
(power applied)
Storage Temperature
Analog
Digital
Serial Port Interface
Control Port Interface
(Note 3)
(Note 4)
Serial Port Interface
Control Port Interface
WARNING: Operation at or beyond these limits may result in permanent damage to the device. Normal operation
is not guaranteed at these extremes.
Notes:
1. Typical Analog input/output performance will slightly degrade at VA = 3.3 V.
2. The ADC_SDOUT may not meet timing requirements in Double-Speed Mode.
3. Any pin except supplies. Transient currents of up to ±100 mA on the analog input pins will not cause
SCR latch-up.
4. The maximum over/under voltage is limited by the input current.
DS646F1
13
CS42438
ANALOG INPUT CHARACTERISTICS (COMMERCIAL)
(Test Conditions (unless otherwise specified): TA = -10 to +70°C; VD = VLS = VLC = 3.3 V±5%, VA = 5 V±5%;
Full-scale input sine wave: 1 kHz through the active input filter in Figure 20 on page 50 and Figure 21 on page 50;
Measurement Bandwidth is 10 Hz to 20 kHz.)
Differential
Parameter
Fs=48 kHz, 96 kHz
Dynamic Range
Min
Typ
Single-Ended
Max
Min
Typ
Max
Unit
A-weighted
99
105
96
102
dB
unweighted
96
102
93
99
dB
40 kHz bandwidth unweighted
99
96
dB
dB
-89
-95
-92
-98
Total Harmonic Distortion + Noise
-1 dB
dB
-79
-82
(Note 5)
-20 dB
dB
-39
-42
-60 dB
dB
-90
-90
40 kHz bandwidth
-1 dB
ADC1-3 Interchannel Isolation
90
90
dB
ADC3 MUX Interchannel Isolation
90
90
dB
DC Accuracy
Interchannel Gain Mismatch
0.1
0.1
dB
Gain Drift
±100
±100
ppm/°C
Analog Input
Full-Scale Input Voltage
1.06*VA 1.12*VA 1.18*VA 0.53*VA 0.56*VA 0.59*VA
Vpp
Differential Input Impedance (Note 6)
18
kΩ
Single-Ended Input Impedance (Note 7)
18
kΩ
Common Mode Rejection Ratio (CMRR)
82
dB
14
DS646F1
CS42438
ANALOG INPUT CHARACTERISTICS (AUTOMOTIVE)
(Test Conditions (unless otherwise specified): TA = -40 to +85°C; VD = VLS = VLC = 3.3 V±5%, VA = 5 V±5%;
Full-scale input sine wave: 1 kHz through the active input filter in Figure 20 on page 50 and Figure 21 on page 50;
Measurement Bandwidth is 10 Hz to 20 kHz.)
Differential
Parameter
Fs=48 kHz, 96 kHz
Dynamic Range
Min
Typ
Single-Ended
Max
Min
Typ
Max
Unit
A-weighted
97
105
94
102
dB
unweighted
94
102
91
99
dB
40 kHz bandwidth unweighted
99
96
dB
dB
-87
-95
-90
-98
Total Harmonic Distortion + Noise
-1 dB
dB
-79
-82
(Note 5)
-20 dB
dB
-39
-42
-60 dB
dB
-87
-87
40 kHz bandwidth
-1 dB
ADC1-3 Interchannel Isolation
90
90
dB
ADC3 MUX Interchannel Isolation
85
85
dB
DC Accuracy
Interchannel Gain Mismatch
0.1
0.1
dB
Gain Drift
±100
±100
ppm/°C
Analog Input
Full-Scale Input Voltage
1.04*VA 1.12*VA 1.20*VA 0.52*VA 0.56*VA 0.60*VA
Vpp
Differential Input Impedance
(Note 6)
18
kΩ
Single-Ended Input Impedance
(Note 7)
18
kΩ
Common Mode Rejection Ratio (CMRR)
82
dB
Notes:
5. Referred to the typical full-scale voltage.
6. Measured between AINx+ and AINx-.
7. Measured between AINxx and AGND.
DS646F1
15
CS42438
ADC DIGITAL FILTER CHARACTERISTICS
Parameter (Notes 8, 9)
Min
Typ
Max
Unit
0
-
0.4896
Fs
-
-
0.08
dB
0.5688
-
-
Fs
Single-Speed Mode (Note 9)
Passband (Frequency Response)
to -0.1 dB corner
Passband Ripple
Stopband
Stopband Attenuation
Total Group Delay
70
-
-
dB
-
12/Fs
-
s
0
-
0.4896
Fs
Double-Speed Mode (Note 9)
Passband (Frequency Response)
Passband Ripple
Stopband
Stopband Attenuation
Total Group Delay
to -0.1 dB corner
-
-
0.16
dB
0.5604
-
-
Fs
69
-
-
dB
-
9/Fs
-
s
High-Pass Filter Characteristics
Frequency Response
-3.0 dB
-0.13 dB
-
1
20
-
Hz
Hz
Phase Deviation
@ 20 Hz
-
10
-
Deg
-
-
0
dB
-
5
0
s
Passband Ripple
Filter Settling Time
10 /Fs
Notes:
8. Filter response is guaranteed by design.
9. Response is clock-dependent and will scale with Fs. Note that the response plots (Figures 26 to 33) have
been normalized to Fs and can be de-normalized by multiplying the X-axis scale by Fs.
16
DS646F1
CS42438
ANALOG OUTPUT CHARACTERISTICS (COMMERCIAL)
(Test Conditions (unless otherwise specified): TA = -10 to +70°C; VD = VLS = VLC = 3.3 V±5%, VA = 5 V±5%;
Full-scale 997 Hz output sine wave (see Note 11) into passive filter in Figure 26 on page 54 and active filter in Figure 26 on page 54; Measurement Bandwidth is 10 Hz to 20 kHz.)
Parameter
Min
Fs = 48 kHz, 96 kHz, 192 kHz
Dynamic Range
102
18 to 24-Bit
A-weighted
99
unweighted
16-Bit
A-weighted
unweighted
Total Harmonic Distortion + Noise
18 to 24-Bit
0 dB
-20 dB
-60 dB
16-Bit
0 dB
-20 dB
-60 dB
Interchannel Isolation
(1 kHz)
Analog Output
Full-Scale Output
1.235•VA
Interchannel Gain Mismatch
Gain Drift
Output Impedance
DC Current draw from an AOUT pin
(Note 10)
AC-Load Resistance (RL) (Note 12)
3
Load Capacitance (CL)
DS646F1
(Note 12)
-
Differential
Typ
Max
Min
Single-Ended
Typ
Max
Unit
108
105
99
96
-
99
96
-
105
102
96
93
-
dB
dB
dB
dB
-98
-85
-45
-93
-76
-36
100
-92
-
-
-95
-82
-42
-90
-73
-33
100
-89
-
dB
dB
dB
dB
dB
dB
dB
-
1.300•VA 1.365•VA 0.618•VA 0.650•VA 0.683•VA
Vpp
0.1
0.25
0.1
0.25
dB
±100
±100
ppm/°C
100
100
Ω
10
10
µA
-
-
3
-
-
kΩ
-
100
-
-
100
pF
17
CS42438
ANALOG OUTPUT CHARACTERISTICS (AUTOMOTIVE)
(Test Conditions (unless otherwise specified): TA = -40 to +85°C; VD = VLS = VLC = 3.3 V±5%, VA = 5 V±5%;
Full-scale 997 Hz output sine wave (see Note 11) in Figure 26 on page 54 and Figure 26 on page 54; Measurement Bandwidth is 10 Hz to 20 kHz.)
Parameter
Min
Fs = 48 kHz, 96 kHz, 192 kHz
Dynamic Range
100
18 to 24-Bit
A-weighted
97
unweighted
16-Bit
A-weighted
unweighted
Total Harmonic Distortion + Noise
18 to 24-Bit
0 dB
-20 dB
-60 dB
16-Bit
0 dB
-20 dB
-60 dB
Interchannel Isolation
(1 kHz)
Analog Output
Full-Scale Output
1.210•VA
Interchannel Gain Mismatch
Gain Drift
Output Impedance
DC Current draw from an AOUT pin
(Note 10)
AC-Load Resistance (RL) (Note 12)
3
Load Capacitance (CL)
(Note 12)
-
Differential
Typ
Max
Min
Single-Ended
Typ
Max
Unit
108
105
99
96
-
97
94
-
105
102
96
93
-
dB
dB
dB
dB
-98
-85
-45
-93
-76
-36
100
-90
-
-
-95
-82
-42
-90
-73
-33
100
-87
-
dB
dB
dB
dB
dB
dB
dB
1.300•VA 1.392•VA 0.605•VA 0.650•VA 0.696•VA
Vpp
0.1
0.25
0.1
0.25
dB
±100
±100
ppm/°C
100
100
Ω
10
10
µA
-
-
3
-
-
kΩ
-
100
-
-
100
pF
Notes:
10. Guaranteed by design. The DC current draw represents the allowed current draw from the AOUT pin
due to typical leakage through the electrolytic DC-blocking capacitors.
11. One-half LSB of triangular PDF dither is added to data.
12. Guaranteed by design. See Figure 3. RL and CL reflect the recommended minimum resistance and
maximum capacitance required for the internal op-amp's stability and signal integrity. In this circuit topology, CL will effectively move the dominant pole of the two-pole amp in the output stage. Increasing
this value beyond the recommended 100 pF can cause the internal op-amp to become unstable. See
“External Filters” on page 50 for a recommended output filter.
18
DS646F1
CS42438
DAC1-4
AOUTxx
3.3 µF
Analog
Output
+
RL
CL
Capacitive Load -- C L (pF)
125
100
75
Safe Operating
Region
50
25
AGND
2.5
3
Figure 3. Output Test Circuit for Maximum Load
DS646F1
5
10
15
20
Resistive Load -- RL (kΩ )
Figure 4. Maximum Loading
19
CS42438
COMBINED DAC INTERPOLATION & ON-CHIP ANALOG FILTER RESPONSE
Parameter (Notes 8, 13)
Min
Typ
Max
Unit
0
0
-
0.4780
0.4996
Fs
Fs
-0.2
-
+0.08
dB
0.5465
-
-
Fs
50
-
-
dB
-
s
Single-Speed Mode
Passband (Frequency Response)
to -0.05 dB corner
to -3 dB corner
Frequency Response 10 Hz to 20 kHz
StopBand
StopBand Attenuation
(Note 14)
Group Delay
De-emphasis Error (Note 15)
-
10/Fs
Fs = 32 kHz
Fs = 44.1 kHz
Fs = 48 kHz
-
-
to -0.1 dB corner
to -3 dB corner
0
0
-
0.4650
0.4982
Fs
Fs
+1.5/+0
dB
+0.05/-0.25 dB
-0.2/-0.4
dB
Double-Speed Mode
Passband (Frequency Response)
Frequency Response 10 Hz to 20 kHz
-0.2
-
+0.7
dB
0.5770
-
-
Fs
55
-
-
dB
-
5/Fs
-
s
0
0
-
0.397
0.476
Fs
Fs
Frequency Response 10 Hz to 20 kHz
-0.2
-
+0.05
dB
StopBand
0.7
-
-
Fs
StopBand
StopBand Attenuation
(Note 14)
Group Delay
Quad-Speed Mode
Passband (Frequency Response)
StopBand Attenuation
to -0.1 dB corner
to -3 dB corner
(Note 14)
Group Delay
51
-
-
dB
-
2.5/Fs
-
s
Notes:
13. Response is clock-dependent and will scale with Fs. Note that the response plots (Figures 34 to 45) have
been normalized to Fs and can be de-normalized by multiplying the X-axis scale by Fs.
14. Single- and Double-Speed Mode Measurement Bandwidth is from Stopband to 3 Fs.
Quad-Speed Mode Measurement Bandwidth is from Stopband to 1.34 Fs.
15. De-emphasis is only available in Single-Speed Mode.
20
DS646F1
CS42438
SWITCHING SPECIFICATIONS - ADC/DAC PORT
(Inputs: Logic 0 = DGND, Logic 1 = VLS, ADC_SDOUT CLOAD = 15 pF.)
Parameters
Symbol
Min
Max
Units
1
0.512
45
4
50
100
45
8
8
5
16
3
5
5
10
15
-
ms
50
55
50
100
200
55
-
MHz
%
kHz
kHz
kHz
%
ns
ns
ns
ns
ns
ns
ns
ns
ns
Slave Mode
RST pin Low Pulse Width
MCLK Frequency
MCLK Duty Cycle
Input Sample Rate (FS pin)
(Note 16)
(Note 17)
Single-Speed Mode
Double-Speed Mode (Note 18)
Quad-Speed Mode (Note 19)
Fs
Fs
Fs
SCLK Duty Cycle
SCLK High Time
SCLK Low Time
FS Rising Edge to SCLK Rising Edge
SCLK Rising Edge to FS Falling Edge
DAC_SDIN Setup Time Before SCLK Rising Edge
DAC_SDIN Hold Time After SCLK Rising Edge
DAC_SDIN Hold Time After SCLK Rising Edge
ADC_SDOUT Hold Time After SCLK Rising Edge
ADC_SDOUT Valid Before SCLK Rising Edge
tsckh
tsckl
tfss
tfsh
tds
tdh
tdh1
tdh2
tdval
Notes:
16. After powering up the CS42438, RST should be held low after the power supplies and clocks are settled.
17. See Table 7 on page 43 for suggested MCLK frequencies.
18. VLS is limited to nominal 2.5 V to 5.0 V operation only.
19. ADC does not meet timing specification for Quad-Speed Mode.
FS
(input)
tfss
tfsh
tsckh
tsckl
SCLK
(input)
tds
tdh1
DAC_SDIN
tdh2
ADC_SDOUT
MSB-1
MSB
MSB
tdval
MSB-1
Figure 5. TDM Serial Audio Interface Timing
DS646F1
21
CS42438
SWITCHING CHARACTERISTICS - AUX PORT
(Inputs: Logic 0 = DGND, Logic 1 = VLS.)
Parameters
Symbol
Min
Fs
Max
Units
Master Mode
Output Sample Rate (AUX_LRCK)
All Speed Modes
-
LRCK
kHz
AUX_SCLK Frequency
-
64·LRCK
kHz
AUX_SCLK Duty Cycle
45
55
%
AUX_LRCK Edge to SCLK Rising Edge
tlcks
-
5
ns
AUX_SDIN Setup Time Before SCLK Rising Edge
tds
3
-
ns
AUX_SDIN Hold Time After SCLK Rising Edge
tdh
5
-
ns
AUX_LRCK
tlcks
tsckh
tsckl
AUX_SCLK
tds
AUX_SDIN
tdh
MSB
MSB-1
Figure 6. Serial Audio Interface Slave Mode Timing
22
DS646F1
CS42438
SWITCHING SPECIFICATIONS - CONTROL PORT - I²C MODE
(VLC = 1.8 V - 5.0 V, VLS = VD = 3.3 V, VA = 5.0 V; Inputs: Logic 0 = DGND, Logic 1 = VLC, SDA CL = 30 pF)
Parameter
Symbol
Min
Max
Unit
SCL Clock Frequency
fscl
-
100
kHz
RST Rising Edge to Start
tirs
500
-
ns
Bus Free Time Between Transmissions
tbuf
4.7
-
µs
Start Condition Hold Time (prior to first clock pulse)
thdst
4.0
-
µs
Clock Low time
tlow
4.7
-
µs
Clock High Time
thigh
4.0
-
µs
Setup Time for Repeated Start Condition
tsust
4.7
-
µs
thdd
0
-
µs
tsud
250
-
ns
SDA Hold Time from SCL Falling
(Note 20)
SDA Setup time to SCL Rising
Rise Time of SCL and SDA
(Note 21)
trc
-
1
µs
Fall Time SCL and SDA
(Note 21)
tfc
-
300
ns
Setup Time for Stop Condition
tsusp
4.7
-
µs
Acknowledge Delay from SCL Falling
tack
300
1000
ns
Notes:
20. Data must be held for sufficient time to bridge the transition time, tfc, of SCL.
21. Guaranteed by design.
RST
t
irs
Stop
R e p e a te d
Sta rt
Start
t rd
t fd
Stop
SDA
t
buf
t
t
hdst
t
high
t fc
hdst
t susp
SCL
t
lo w
t
hdd
t sud
t ack
t sust
t rc
Figure 7. Control Port Timing - I²C Format
DS646F1
23
CS42438
SWITCHING SPECIFICATIONS - CONTROL PORT - SPI FORMAT
(VLC = 1.8 V - 5.0 V, VLS = VD = 3.3 V, VA = 5.0 V; Inputs: Logic 0 = DGND, Logic 1 = VLC, CDOUT CL = 30 pF)
Parameter
Symbol
Min
Max
Units
CCLK Clock Frequency
fsck
0
6.0
MHz
RST Rising Edge to CS Falling
tsrs
20
-
ns
CS Falling to CCLK Edge
tcss
20
-
ns
CS High Time Between Transmissions
tcsh
1.0
-
µs
CCLK Low Time
tscl
66
-
ns
CCLK High Time
tsch
66
-
ns
CDIN to CCLK Rising Setup Time
tdsu
40
-
ns
tdh
15
-
ns
CCLK Falling to CDOUT Stable
tpd
-
50
ns
Rise Time of CDOUT
tr1
-
25
ns
Fall Time of CDOUT
tf1
-
25
ns
CCLK Rising to DATA Hold Time
(Note 22)
Rise Time of CCLK and CDIN
(Note 23)
tr2
-
100
ns
Fall Time of CCLK and CDIN
(Note 23)
tf2
-
100
ns
Notes:
22. Data must be held for sufficient time to bridge the transition time of CCLK.
23. For fsck <1 MHz.
RST
tsrs
CS
tcsh
tcss
tsch
tscl
tr2
CCLK
tf2
tdsu
tdh
MSB
CDIN
tpd
CDOUT
MSB
Figure 8. Control Port Timing - SPI Format
24
DS646F1
CS42438
DC ELECTRICAL CHARACTERISTICS
(AGND = 0 V; all voltages with respect to ground.)
Parameters
Normal Operation (Note 24)
Power Supply Current
VA = 5.0 V
VLS = VLC = VD = 3.3 V
(Note 25)
Power Dissipation
VLS = VLC = VD = 3.3 V, VA = 5 V
Power Supply Rejection Ratio
1 kHz
(Note 26)
60 Hz
Power-Down Mode (Note 27)
Power Dissipation
VLS = VLC = VD = 3.3 V, VA = 5 V
VQ Characteristics
Nominal Voltage
Output Impedance
DC Current Source/Sink (Note 28)
FILT+ Nominal Voltage
Symbol
Min
Typ
Max
Units
IA
-
80
-
mA
IDT
-
60.6
600
60
40
850
-
mA
mW
dB
dB
-
1.25
-
mW
-
0.5•VA
23
VA
10
-
V
kΩ
µA
V
PSRR
Notes:
24. Normal operation is defined as RST = HI with a 997 Hz, 0 dBFS input to the DAC and AUX port, and a
1 kHz, -1 dB analog input to the ADC port sampled at the highest Fs for each speed mode. DAC outputs
are open, unless otherwise specified.
25. IDT measured with no external loading on pin 2 (SDA).
26. Valid with the recommended capacitor values on FILT+ and VQ. Increasing the capacitance will also
increase the PSRR.
27. Power-Down Mode is defined as RST = LO with all clocks and data lines held static and no analog input.
28. Guaranteed by design. The DC current draw represents the allowed current draw from the VQ pin due
to typical leakage through the electrolytic de-coupling capacitors.
DIGITAL INTERFACE SPECIFICATIONS & CHARACTERISTICS
Parameters (Note 29)
High-Level Output Voltage at Io=2 mA
Low-Level Output Voltage at Io=2 mA
High-Level Input Voltage
Low-Level Input Voltage
Leakage Current
Input Capacitance (Note 21)
Symbol
Serial Port
Control Port
Serial Port
Control Port
Serial Port
Control Port
Serial Port
Control Port
VOH
VOL
VIH
VIL
Iin
Min
VLS-1.0
VLC-1.0
0.7xVLS
0.7xVLC
-
Typ
-
Max
0.4
0.4
0.2xVLS
0.2xVLC
±10
10
Units
V
V
V
V
V
V
V
V
µA
pF
Notes:
29. See “Digital I/O Pin Characteristics” on page 8 for serial and control port power rails.
DS646F1
25
CS42438
5. APPLICATIONS
5.1
Overview
The CS42438 is a highly integrated mixed signal 24-bit audio CODEC comprised of 6 analog-to-digital converters (ADC) implemented using multi-bit delta-sigma techniques and 8 digital-to-analog converters (DAC)
also implemented using multi-bit delta-sigma techniques.
Other functions integrated within the CODEC include independent digital volume controls for each DAC, digital de-emphasis filters for the DAC, digital volume control with gain on each ADC channel, ADC high-pass
filters, and an on-chip voltage reference,.
The serial audio interface ports allow up to 8 DAC channels and 8 ADC channels in a Time-Division Multiplexed (TDM) interface format. The CS42438 features an Auxiliary Port used to accommodate an additional
two channels of PCM data on the ADC_SDOUT data line in the TDM digital interface format. See “AUX Port
Digital Interface Formats” on page 34 for details.
The CS42438 operates in one of three oversampling modes based on the input sample rate. Mode selection
is determined automatically based on the MCLK frequency setting. Single-Speed Mode (SSM) supports input sample rates up to 50 kHz and uses a 128x oversampling ratio. Double-Speed Mode (DSM) supports
input sample rates up to 100 kHz and uses an oversampling ratio of 64x. Quad-Speed Mode (QSM) supports input sample rates up to 200 kHz and uses an oversampling ratio of 32x (Note: QSM for the ADC is
only supported in the I²S, Left-Justified, Right-Justified interface formats. QSM is not supported for the
ADC). Note: QSM is only available in Software Mode (see “System Clocking” on page 33 for details).
All functions can be configured through software via a serial control port operable in SPI Mode or in I²C
Mode. A Hardware, Stand-Alone Mode is also available, allowing configuration of the CODEC on a more
limited basis. See Table 2 for the default configuration in Hardware Mode.
Figure 1 on page 11 and Figure 2 on page 12 show the recommended connections for the CS42438 in
Software and Hardware Mode, respectively. See “Register Description” on page 41 for the default register
settings and options in Software Mode.
Hardware Mode Feature Summary
Function
Power Down ADC
Power Down DAC
Power Down Device
MCLK Frequency Select
Freeze Control
AUX Serial Port Interface Format
ADC1/ADC2 High Pass Filter Freeze
ADC3 High Pass Filter Freeze
DAC De-Emphasis
ADC1/ADC2 Single-Ended Mode
ADC3 Single-Ended Mode
AIN5 Multiplexer
Default Configuration
Hardware Control
All ADC’s are enabled
All DAC’s are enabled
Device is powered up
Selectable between 256Fs and
512Fs
N/A
Left-Justified
High Pass Filter is always
enabled
High Pass Filter can be
enabled/disabled
No De-Emphasis applied
Disabled
Selectable between Differential
and Single-Ended
Selects between AIN5A and
AIN5B when ADC3 in SingleEnded Mode
“MFREQ” pin 3
Note
see Section 5.4
-
-
-
-
“ADC3_HPF” pin 4
“ADC_SDOUT/
ADC3_SINGLE” pin 13
“AIN5_MUX” pin 1
see Section 5.2.5
see Section 5.2.2
see Section 5.2.2
Table 2. Hardware Configurable Settings
26
DS646F1
CS42438
Hardware Mode Feature Summary
Function
Default Configuration
AIN6 Multiplexer
DAC Volume Control/Mute/Invert
ADC Volume Control
DAC Soft Ramp/Zero Cross
ADC Soft Ramp/Zero Cross
DAC Auto-Mute
Status Interrupt
Selects between AIN6A and
AIN6B when ADC3 in SingleEnded Mode
All DAC Volume = 0 dB, unmuted, not inverted
All ADC Volume = 0 dB
Immediate Change
Immediate Change
Enabled
N/A
Hardware Control
Note
“AIN6_MUX” pin 2
see Section 5.2.2
-
-
-
-
Table 2. Hardware Configurable Settings (Continued)
5.2
Analog Inputs
5.2.1
Line-Level Inputs
AINx+ and AINx- are the line-level differential analog inputs internally biased to VQ, approximately VA/2.
Figure 9 on page 28 shows the full-scale analog input levels. The CS42438 also accommodates singleended signals on all inputs, AIN1-AIN6. See “ADC Input Filter” on page 50 for the recommended input
filters.
5.2.1.1
Hardware Mode
AIN Volume Control and ADC Overflow status are not accessible in Hardware Mode. Single-ended operation is only supported for ADC3. See Section 5.2.2.
5.2.1.2
Software Mode
For single-ended operation on ADC1-ADC3 (AIN1 to AIN6), the ADCx_SINGLE bit in the register “ADC
Control & DAC De-Emphasis (Address 05h)” on page 44 must be set appropriately (see Figure 21 on
page 50 for required external components).
The gain/attenuation of the signal can be adjusted for each AINx independently through the “AINX Volume
Control (Address 11h-16h)” on page 48. The ADC output data is in 2’s complement binary format. For inputs above positive full scale or below negative full scale, the ADC will output 7FFFFFH or 800000H, respectively, and cause the ADC Overflow bit in the register “Status (Address 19h) (Read Only)” on page 49
to be set to a ‘1’.
DS646F1
27
CS42438
5.0 V
3.9 V
VA
2.5 V
AINx+
2.5 V
AINx-
1.1 V
3.9 V
1.1 V
Full-Scale Differential Input Level =
(AINx+) - (AINx-) = 5.6 VPP = 1.98 VRMS
Figure 9. Full-Scale Input
5.2.2
ADC3 Analog Input
ADC3 accommodates differential as well as single-ended inputs. In Single-Ended Mode, an internal MUX
selects from up to four single-ended inputs.
AIN5A
ADC3
Single-Ended Input Filter
AIN5_MUX
AIN5B
ADC3 SINGLE
Single-Ended Input Filter
1
0
1
50
AIN5+/-
Differential
Input Filter
0
+
AIN5
49
0
VQ
-
1
AIN6_MUX
1
0
1
52
AIN6+/-
Differential
Input Filter
0
AIN6
51
0
VQ
AIN6A
AIN6B
+
-
1
Single-Ended Input Filter
Single-Ended Input Filter
Figure 10. ADC3 Input Topology
28
DS646F1
CS42438
5.2.3
Hardware Mode
Single-Ended Mode is selected using a pull-up on the ADC_SDOUT/ADC3_SINGLE pin during startup.
Analog input selection is then made via the AINx_MUX pins. See Tables 3-4 for ADC3 set-up options.
Refer to Figure 10 on page 28 for the internal ADC3 analog input topology.
Configuration Setting
ADC_SDOUT
(pin 13)
47 kΩ Pull-down
47 kΩ Pull-up
47 kΩ Pull-up
AIN5_MUX
(pin 1)
X
Low
High
AIN5 Input Selection
Differential Input (pins 50 & 49)
AIN5A Input (pin 50)
AIN5B Input (pin 49)
Table 3. AIN5 Analog Input Selection
Configuration Setting
ADC_SDOUT
(pin 13)
47 kΩ Pull-down
47 kΩ Pull-up
47 kΩ Pull-up
AIN6_MUX
(pin 2)
X
Low
High
AIN6 Input Selection
Differential Input (pins 52 & 51)
AIN5A Input (pin 52)
AIN5B Input (pin 51)
Table 4. AIN6 Analog Input Selection
5.2.4
Software Mode
Single-Ended Mode is selected using the ADC3_SINGLE bit. Analog input selection is then made via the
AINx_MUX bits. See register “ADC Control & DAC De-Emphasis (Address 05h)” on page 44 for all bit selections. Refer to Figure 11 on page 31 for the internal ADC3 analog input topology.
5.2.5
High-Pass Filter and DC Offset Calibration
The high-pass filter continuously subtracts a measure of the DC offset from the output of the decimation
filter. If the high-pass filter is disabled during normal operation, the current value of the DC offset for the
corresponding channel is frozen and this DC offset will continue to be subtracted from the conversion result. This feature makes it possible to perform a system DC offset calibration by:
1. Running the CS42438 with the high-pass filter enabled until the filter settles. See the Digital Filter
Characteristics for filter settling time.
2. Disabling the high-pass filter and freezing the stored DC offset.
5.2.5.1
Hardware Mode
The high pass filters for ADC1 and ADC2 are permanently enabled in Hardware Mode. The high pass
filter for ADC3 is enabled by driving the ADC3_HPF (pin 4) high.
5.2.5.2
Software Mode
The high-pass filter for ADC1/ADC2 can be enabled and disabled. The high pass filter for ADC3 can
be independently enabled and disabled. The high-pass filters are controlled using the HPF_FREEZE
bit in the register “ADC Control & DAC De-Emphasis (Address 05h)” on page 44.
DS646F1
29
CS42438
5.3
5.3.1
Analog Outputs
Initialization
The initialization and Power-Down sequence flow chart is shown in Figure 11 on page 31. The CS42438
enters a power-down state upon initial power-up. The interpolation and decimation filters, delta-sigma
modulators and control port registers are reset. The internal voltage reference, multi-bit digital-to-analog
and analog-to-digital converters and switched-capacitor low-pass filters are powered down.
The device remains in the power-down state until the RST pin is brought high. The control port is accessible once RST is high, and the desired register settings can be loaded per the interface descriptions in
the “Control Port Description and Timing” on page 35. In Hardware Mode operation, the Hardware Mode
pins must be set up before RST is brought high. All features will default to the Hardware Mode defaults
as listed in Table 2.
Once MCLK is valid, VQ will quickly charge to VA/2, and the internal voltage reference, FILT+, will begin
powering up to normal operation. Power is applied to the D/A converters and switched-capacitor filters, and
the analog outputs are clamped to the quiescent voltage, VQ. Once LRCK is valid, MCLK occurrences are
counted over one LRCK period to determine the MCLK/LRCK frequency ratio. After an approximate 2000
sample period delay, normal operation begins.
5.3.2
Line-Level Outputs and Filtering
The CS42438 contains on-chip buffer amplifiers capable of producing line-level differential as well as single-ended outputs on AOUT1-AOUT8. These amplifiers are biased to a quiescent DC level of approximately VQ.
The delta-sigma conversion process produces high-frequency noise beyond the audio passband, most of
which is removed by the on-chip analog filters. The remaining out-of-band noise can be attenuated using
an off-chip low-pass filter.
See “DAC Output Filter” on page 53 for recommended output filter. The active filter configuration accounts
for the normally differing AC loads on the AOUTx+ and AOUTx- differential output pins. Also shown is a
passive filter configuration which minimizes costs and the number of components.
Figure 12 shows the full-scale analog output levels. All outputs are internally biased to VQ, approximately
VA/2.
30
DS646F1
CS42438
No Power
1. VQ = ?
2. Aout bias = ?
3. No audio signal
generated.
PDN bit = '1'b?
Yes
Power-Down
1. VQ discharge to 0 V.
2. Aout bias = Hi-Z.
3. No audio signal generated.
4. Control Port Registers retain
settings.
No
Power-Down (Power Applied)
1. VQ = 0 V.
2. Aout = Hi-Z.
3. No audio signal generated.
4. Control Port Registers reset
to default.
Power-Up
1. VQ = VA/2.
2. Aout bias = VQ.
Yes
RST = Low?
No
Control Port
Accessed
No
Sub-Clocks Applied
1. LRCK valid.
2. SCLK valid.
3. Audio samples
processed.
Control Port
Access Detected?
Yes
No
Hardware Mode
H/W pins setup to
desired settings.
Valid
MCLK/LRCK
Ratio?
Software Mode
Registers setup to
desired settings.
Yes
No
No
Valid MCLK
Applied?
Valid MCLK
Applied?
2000 LRCK delay
Yes
Yes
RST = Low
ERROR: Power removed
Normal Operation
1. VQ = VA/2.
2. Aout bias = VA/2.
3. Audio signal generated per register settings.
PDN bit set
to '1'b
ERROR: MCLK/LRCK ratio change
ERROR: MCLK removed
Analog Output Mute
1. VQ = VA/2.
2. Aout bias = VA/2.
3. No audio signal generated.
Analog Output Freeze
1. VQ = VA/2.
2. Aout bias = VA/2 + last audio sample.
3. No audio signal generated.
Figure 11. Audio Output Initialization Flow Chart
DS646F1
31
CS42438
5.0 V
4.125 V
VA
AOUTx+
2.5 V
0.875 V
4.125 V
AOUTx-
2.5 V
0.875 V
Full-Scale Differential Output Level =
(AOUTx+) - (AOUTx-) = 6.5 VPP = 2.3 VRMS
Figure 12. Full-Scale Output
5.3.3
Digital Volume Control
5.3.3.1
Hardware Mode
DAC Volume Control and Mute are not accessible in Hardware Mode.
5.3.3.2
Software Mode
Each DAC’s output level is controlled via the Volume Control registers operating over the range of 0 to
-127.5 dB attenuation with 0.5 dB resolution. See “AOUTX Volume Control (Addresses 08h- 0Fh)” on
page 47. Volume control changes are programmable to ramp in increments of 0.125 dB at the rate controlled by the SZC[1:0] bits in the Digital Volume Control register. See “Transition Control (Address 06h)”
on page 46.
Each output can be independently muted via mute control bits in the register “DAC Channel Mute (Address 07h)” on page 47. When enabled, each AOUTx_MUTE bit attenuates the corresponding DAC to its
maximum value (-127.5 dB). When the AOUTx_MUTE bit is disabled, the corresponding DAC returns to
the attenuation level set in the Volume Control register. The attenuation is ramped up and down at the
rate specified by the SZC[1:0] bits.
5.3.4
De-Emphasis Filter
The CS42438 includes on-chip digital de-emphasis optimized for a sample rate of 44.1 kHz. The filter response is shown in Figure 13. The de-emphasis feature is included to accommodate audio recordings
that utilize 50/15 µs pre-emphasis equalization as a means of noise reduction.
De-emphasis is only available in Single-Speed Mode. Please see “DAC De-Emphasis Control
(DAC_DEM)” on page 44 for de-emphasis control.
32
DS646F1
CS42438
Gain
dB
T1=50 µs
0dB
T2 = 15 µs
-10dB
F1
3.183 kHz
Frequency
F2
10.61 kHz
Figure 13. De-Emphasis Curve
5.4
System Clocking
The CODEC serial audio interface ports operate as a slave andaccept externally generated clocks.
The CODEC requires external generation of the master clock (MCLK). The frequency of this clock must be
an integer multiple of, and synchronous with, the system sample rate, Fs.
5.4.1
Hardware Mode
The allowable ratios include 256Fs and 512Fs in Single-Speed Mode and 256Fs in Double-Speed Mode.
The frequency of MCLK must be specified using the MFREQ (pin 3). See Table 5 for the required frequency range.
Ratio (xFs)
MFREQ
Description
SSM
DSM
QSM
0
1.5360 MHz to 12.8000 MHz
256
N/A
N/A
1
2.0480 MHz to 25.6000 MHz
512
256
N/A
Table 5. MCLK Frequency Settings
5.4.2
Software Mode
The frequency range of MCLK must be specified using the MFREQ bits in register “MCLK Frequency
(MFREQ[2:0])” on page 43.
5.5
CODEC Digital Interface
The ADC and DAC serial ports operate as a slave and support the TDM digital interface formats with varying
bit depths from 16 to 32 as shown in . Data is clocked out of the ADC on the falling edge of SCLK and
clocked into the DAC on the rising edge.
TDM is the only interface supported in Hardware and Software Mode.
5.5.1
TDM
TDM data is received most significant bit (MSB) first, on the second rising edge of the SCLK occurring
after a an FS rising edge. All data is valid on the rising edge of SCLK. The AIN1 MSB is transmitted early,
but is guaranteed valid for a specified time after SCLK rises. All other bits are transmitted on the falling
edge of SCLK. Each time slot is 32 bits wide, with the valid data sample left ‘justified within the time slot.
Valid data lengths are 16, 18, 20, or 24.
SCLK must operate at 256Fs. FS identifies the start of a new frame and is equal to the sample rate, Fs.
DS646F1
33
CS42438
FS is sampled as valid on the rising SCLK edge preceding the most significant bit of the first data sample
and must be held valid for at least 1 SCLK period.
Note:
The ADC does not meet the timing requirements for proper operation in Quad-Speed Mode.
256 clks
Bit or Word Wide
FS
SCLK
DAC_SDIN
LSB MSB
LSB MSB
AOUT1
32 clks
ADC_SDOUT
MSB
LSB MSB
AOUT2
LSB MSB
AOUT3
LSB MSB
AOUT4
LSB MSB
LSB MSB
AOUT6
AOUT5
LSB MSB
LSB MSB
AOUT7
AOUT8
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
LSB MSB
LSB MSB
LSB MSB
LSB MSB
LSB MSB
LSB MSB
LSB MSB
LSB MSB
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AUX1
AUX2
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
Figure 14. TDM Serial Audio Format
5.5.2
I/O Channel Allocation
Interface
Digital Input/Output
Format
DAC_SDIN
TDM
ADC_SDOUT
TDM
Analog Output/Input Channel Allocation
from/to Digital I/O
AOUT 1,2,3,4,5,6,7,8
,5,6AIN 1,2,3,4,5,6; (2 additional channels from AUX_SDIN)
Table 6. Serial Audio Interface Channel Allocations
5.6
AUX Port Digital Interface Formats
These serial data lines are used when supporting the TDM Mode of operation with an external ADC or
S/PDIF receiver attached. The AUX serial port operates only as a clock master. The AUX_SCLK will operate
at 64xFs, where Fs is equal to the ADC sample rate (FS on the TDM interface). If the AUX_SDIN signal is
not being used, it should be tied to AGND via a pull-down resistor.
5.6.1
Hardware Mode
The AUX port will only operate in the Left-Justified digital interface format and supports bit depths ranging
from 16 to 24 bits (see Figure 18 on page 36 for timing relationship between AUX_LRCK and
AUX_SCLK).
5.6.2
Software Mode
The AUX port will operate in either the Left-Justified or I²S digital interface format with bit depths ranging
from 16 to 24 bits. Settings for the AUX port are made through the register “Miscellaneous Control (Address 04h)” on page 43.
5.6.3
I²S
AUX_LRCK
L eft C h a n n el
R ig ht C h a n n el
AUX_SCLK
AUX_SDIN
MSB
LS B
M SB
LS B
MSB
AUX2
AUX1
Figure 15. AUX I²S Format
34
DS646F1
CS42438
5.6.4
Left-Justified
AUX_LRCK
L e ft C h a n n el
R ig ht C h a n n el
AUX_SCLK
AUX_SDIN
MSB
LS B
M SB
LS B
MSB
AUX2
AUX1
Figure 16. AUX Left-Justified Format
5.7
Control Port Description and Timing
The control port is used to access the registers, in Software Mode, allowing the CS42438 to be configured
for the desired operational modes and formats. The operation of the control port may be completely asynchronous with respect to the audio sample rates. However, to avoid potential interference problems, the
control port pins should remain static if no operation is required.
The control port has two modes: SPI and I²C, with the CS42438 acting as a slave device. SPI Mode is selected if there is a high-to-low transition on the AD0/CS pin, after the RST pin has been brought high. I²C
Mode is selected by connecting the AD0/CS pin through a resistor to VLC or DGND, thereby permanently
selecting the desired AD0 bit address state.
5.7.1
SPI Mode
In SPI Mode, CS is the CS42438 chip-select signal, CCLK is the control port bit clock (input into the
CS42438 from the microcontroller), CDIN is the input data line from the microcontroller, CDOUT is the
output data line to the microcontroller. Data is clocked in on the rising edge of CCLK and out on the falling
edge.
Figure 17 shows the operation of the control port in SPI Mode. To write to a register, bring CS low. The
first seven bits on CDIN form the chip address and must be 1001111. The eighth bit is a read/write indicator (R/W), which should be low to write. The next eight bits form the Memory Address Pointer (MAP),
which is set to the address of the register that is to be updated. The next eight bits are the data which will
be placed into the register designated by the MAP. During writes, the CDOUT output stays in the Hi-Z
state. It may be externally pulled high or low with a 47 kΩ resistor, if desired.
There is a MAP auto-increment capability, enabled by the INCR bit in the MAP register. If INCR is a zero,
the MAP will stay constant for successive read or writes. If INCR is set to a 1, the MAP will auto-increment
after each byte is read or written, allowing block reads or writes of successive registers.
To read a register, the MAP has to be set to the correct address by executing a partial write cycle which
finishes (CS high) immediately after the MAP byte. The MAP auto-increment bit (INCR) may be set or not,
as desired. To begin a read, bring CS low, send out the chip address and set the read/write bit (R/W) high.
The next falling edge of CCLK will clock out the MSB of the addressed register (CDOUT will leave the high
impedance state). If the MAP auto-increment bit is set to 1, the data for successive registers will appear
consecutively.
DS646F1
35
CS42438
CS
CC LK
C H IP
ADDRESS
MAP
1001111
C D IN
C H IP
ADDRESS
DATA
1001111
LSB
MSB
R/W
b y te 1
R/W
b y te n
High Impedance
LSB MSB
MSB
CDOUT
LSB
MAP = Memory Address Pointer, 8 bits, MSB first
Figure 17. Control Port Timing in SPI Mode
5.7.2
I²C Mode
In I²C Mode, SDA is a bidirectional data line. Data is clocked into and out of the part by the clock, SCL.
There is no CS pin. Pins AD0 and AD1 form the two least-significant bits of the chip address and should
be connected through a resistor to VLC or DGND as desired. The state of the pins is sensed while the
CS42438 is being reset.
The signal timings for a read and write cycle are shown in Figure 18 and Figure 19. A Start condition is
defined as a falling transition of SDA while the clock is high. A Stop condition is a rising transition while
the clock is high. All other transitions of SDA occur while the clock is low. The first byte sent to the
CS42438 after a Start condition consists of a 7-bit chip address field and a R/W bit (high for a read, low
for a write). The upper 5 bits of the 7-bit address field are fixed at 10010. To communicate with a CS42438,
the chip address field, which is the first byte sent to the CS42438, should match 10010 followed by the
settings of the AD1 and AD0. The eighth bit of the address is the R/W bit. If the operation is a write, the
next byte is the Memory Address Pointer (MAP) which selects the register to be read or written. If the operation is a read, the contents of the register pointed to by the MAP will be output. Setting the auto-increment bit in MAP allows successive reads or writes of consecutive registers. Each byte is separated by an
acknowledge bit. The ACK bit is output from the CS42438 after each input byte is read, and is input to the
CS42438 from the microcontroller after each transmitted byte.
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18
19
24 25 26 27 28
SCL
CHIP ADDRESS (WRITE)
1
SDA
0
0
1
0 AD1 AD0 0
MAP BYTE
INCR
ACK
6
5
4
3
1
0
7
ACK
6
1
DATA +n
DATA +1
DATA
2
0
7
ACK
START
6
1
0
7
6
1
0
ACK
STOP
Figure 18. Control Port Timing, I²C Write
36
DS646F1
CS42438
0
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
SCL
CHIP ADDRESS (WRITE)
SDA
1
0
0
1
STOP
MAP BYTE
0 AD1 AD0 0
INCR
6
5
4
3
2
1
ACK
CHIP ADDRESS (READ)
1
0
ACK
START
0
0
1
DATA
0 AD1 AD0 1
7
ACK
DATA +1
0
7
ACK
START
0
DATA + n
7
0
NO
ACK
STOP
Figure 19. Control Port Timing, I²C Read
Since the read operation cannot set the MAP, an aborted write operation is used as a preamble. As shown
in Figure 19, the write operation is aborted after the acknowledge for the MAP byte by sending a stop condition. The following pseudocode illustrates an aborted write operation followed by a read operation.
Send start condition.
Send 10010xx0 (chip address & write operation).
Receive acknowledge bit.
Send MAP byte, auto increment off.
Receive acknowledge bit.
Send stop condition, aborting write.
Send start condition.
Send 10010xx1(chip address & read operation).
Receive acknowledge bit.
Receive byte, contents of selected register.
Send acknowledge bit.
Send stop condition.
Setting the auto-increment bit in the MAP allows successive reads or writes of consecutive registers. Each
byte is separated by an acknowledge bit.
5.8
Recommended Power-Up Sequence
5.8.1
Hardware Mode
1. Hold RST low until the power supply, clocks and hardware control pins are stable. In this state, the
control port is reset to its default settings and VQ will remain low.
2. Bring RST high. The device will initially be in a low power state with VQ low.
3. The device will initiate the Hardware Mode power up sequence. All features will default to the
Hardware Mode defaults as listed in Table 2 on page 26 according to the Hardware Mode control
pins. VQ will quick-charge to approximately VA/2 and the analog output bias will clamp to VQ.
4. Following approximately 2000 sample periods, the device is initialized and ready for normal operation.
Note: During the Hardware Mode power-up sequence, there must be no transitions on any of the hardware control pins.
DS646F1
37
CS42438
5.8.2
Software Mode
1. Hold RST low until the power supply and clocks are stable. In this state, the control port is reset to its
default settings and VQ will remain low.
2. Bring RST high. The device will initially be in a low power state with VQ low. All features will default as
described in the “Register Quick Reference” on page 39.
3. Perform a write operation to the Power Control register (“Power Control (Address 02h)” on page 42) to
set bit 0 to a ‘1’b. This will place the device in a power down state.
4. Load the desired register settings while keeping the PDN bit set to ‘1’b.
5. Mute all DACs. Muting the DACs suppresses any noise associated with the CODEC's first initialization
after power is applied.
6. Set the PDN bit in the power control register to ‘0’b.Following approximately 2000 LRCK cycles, the device is initialized and ready for normal operation.
7. After the CODEC is initialized, wait ~90 LRCK cycles (~1.9 ms @48 kHz) and then unmute the DACs.
8. Normal operation begins.
5.9
Reset and Power-Up
It is recommended that reset be activated if the analog or digital supplies drop below the recommended operating condition to prevent power-glitch-related issues.
The delta-sigma modulators settle in a matter of microseconds after the analog section is powered, either
through the application of power or by setting the RST pin high. However, the voltage reference will take
much longer to reach a final value due to the presence of external capacitance on the FILT+ pin. A time
delay of approximately 400 ms is required after applying power to the device or after exiting a reset state.
During this voltage reference ramp delay, all serial ports and DAC outputs will be automatically muted.
5.10
Power Supply, Grounding, and PCB Layout
As with any high-resolution converter, the CS42438 requires careful attention to power supply and grounding arrangements if its potential performance is to be realized. Figures 1 and 2 show the recommended
power arrangements, with VA connected to clean supplies. VD, which powers the digital circuitry, may be
run from the system logic supply.
Extensive use of power and ground planes, ground plane fill in unused areas and surface mount decoupling
capacitors are recommended. Decoupling capacitors should be as near to the pins of the CS42438 as possible. The low value ceramic capacitor should be the nearest to the pin and should be mounted on the same
side of the board as the CS42438 to minimize inductance effects. All signals, especially clocks, should be
kept away from the FILT+, VQ pins in order to avoid unwanted coupling into the modulators. The FILT+ and
VQ decoupling capacitors, particularly the 0.1 µF, must be positioned to minimize the electrical path from
FILT+ and AGND. The CDB42438 evaluation board demonstrates the optimum layout and power supply
arrangements.
For optimal heat dissipation from the package, it is recommended that the area directly under the part be
filled with copper and tied to the ground plane. The use of vias connecting the topside ground to the backside ground is also recommended.
38
DS646F1
CS42438
6. REGISTER QUICK REFERENCE
Software Mode register defaults are as shown. Note: The default value in all “Reserved” registers must be preserved.
Addr Function
7
6
5
4
3
2
1
0
Chip_ID3
Chip_ID2
Chip_ID1
Chip_ID0
Rev_ID3
Rev_ID2
Rev_ID1
Rev_ID0
01h
ID
p 41 default
0
0
0
0
0
0
0
1
02h
Power Control
PDN_ADC3
PDN_ADC2
PDN_ADC1
PDN_DAC4
PDN_DAC3
PDN_DAC2
PDN_DAC1
PDN
p 42 default
03h
04h
05h
Functional
Mode
0
0
0
0
0
0
0
0
Reserved
Reserved
Reserved
Reserved
MFreq2
MFreq1
MFreq0
Reserved
p 43 default
1
1
1
1
0
0
0
0
Misc Control
FREEZE
AUX_DIF
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
p 43 default
0
0
1
1
0
1
1
0
ADC Control
ADC1-2_HPF
FREEZE
ADC3_HPF
FREEZE
DAC_DEM
ADC1
SINGLE
ADC2
SINGLE
ADC3
SINGLE
AIN5_MUX
AIN6_MUX
(w/DAC_DEM)
p 44 default
0
0
0
0
0
0
0
0
DAC_SNG
VOL
DAC_SZC1
DAC_SZC0
AMUTE
MUTE
ADC_SP
ADC_SNG
VOL
ADC_SZC1
ADC_SZC0
06h
Transition
Control
07h
Channel
Mute
p 47 default
0
0
0
0
0
0
0
0
08h
Vol. Control
AOUT1
AOUT1
VOL7
AOUT1
VOL6
AOUT1
VOL5
AOUT1
VOL4
AOUT1
VOL3
AOUT1
VOL2
AOUT1
VOL1
AOUT1
VOL0
p 47 default
0
0
0
0
0
0
0
0
09h
Vol. Control
AOUT2
AOUT2
VOL7
AOUT2
VOL6
AOUT2
VOL5
AOUT2
VOL4
AOUT2
VOL3
AOUT2
VOL2
AOUT2
VOL1
AOUT2
VOL0
p 47 default
0
0
0
0
0
0
0
0
0Ah
Vol. Control
AOUT3
AOUT3
VOL7
AOUT3
VOL6
AOUT3
VOL5
AOUT3
VOL4
AOUT3
VOL3
AOUT3
VOL2
AOUT3
VOL1
AOUT3
VOL0
p 47 default
0
0
0
0
0
0
0
0
0Bh
Vol. Control
AOUT4
AOUT4
VOL7
AOUT4
VOL6
AOUT4
VOL5
AOUT4
VOL4
AOUT4
VOL3
AOUT4
VOL2
AOUT4
VOL1
AOUT4
VOL0
p 47 default
0
0
0
0
0
0
0
0
0Ch
Vol. Control
AOUT5
AOUT5
VOL7
AOUT5
VOL6
AOUT5
VOL5
AOUT5
VOL4
AOUT5
VOL3
AOUT5
VOL2
AOUT5
VOL1
AOUT5
VOL0
p 47 default
0
0
0
0
0
0
0
0
0Dh
Vol. Control
AOUT6
AOUT6
VOL7
AOUT6
VOL6
AOUT6
VOL5
AOUT6
VOL4
AOUT6
VOL3
AOUT6
VOL2
AOUT6
VOL1
AOUT6
VOL0
p 47 default
0
0
0
0
0
0
0
0
0Eh
Vol. Control
AOUT7
AOUT7
VOL7
AOUT7
VOL6
AOUT7
VOL5
AOUT7
VOL4
AOUT7
VOL3
AOUT7
VOL2
AOUT7
VOL1
AOUT7
VOL0
p 46 default
0
0
0
1
0
0
0
0
AOUT8 MUTE
AOUT7
MUTE
AOUT6
MUTE
AOUT5
MUTE
AOUT4
MUTE
AOUT3
MUTE
AOUT2
MUTE
AOUT1
MUTE
p 47 default
0
0
0
0
0
0
0
0
0Fh
Vol. Control
AOUT8
AOUT8
VOL7
AOUT8
VOL6
AOUT8
VOL5
AOUT8
VOL4
AOUT8
VOL3
AOUT8
VOL2
AOUT8
VOL1
AOUT8
VOL0
0
0
0
0
0
0
10h
DAC Channel Invert
p 47 default
p 48 default
DS646F1
0
0
INV_AOUT8
INV_AOUT7
0
0
INV_AOUT6 INV_AOUT5 INV_AOUT4 INV_AOUT3 INV_AOUT2 INV_AOUT1
0
0
0
0
0
0
39
CS42438
Addr Function
11h
12h
13h
14h
15h
16h
17h
7
6
5
4
3
2
1
0
Vol. Control
AIN1
AIN1
VOL7
AIN1
VOL6
AIN1
VOL5
AIN1
VOL4
AIN1
VOL3
AIN1
VOL2
AIN1
VOL1
AIN1
VOL0
p 47 default
0
0
0
0
0
0
0
0
Vol. Control
AIN2
AIN2
VOL7
AIN2
VOL6
AIN2
VOL5
AIN2
VOL4
AIN2
VOL3
AIN2
VOL2
AIN2
VOL1
AIN2
VOL0
p 48 default
0
0
0
0
0
0
0
0
Vol. Control
AIN3
AIN3
VOL7
AIN3
VOL6
AIN3
VOL5
AIN3
VOL4
AIN3
VOL3
AIN3
VOL2
AIN3
VOL1
AIN3
VOL0
p 47 default
0
0
0
0
0
0
0
0
Vol. Control
AIN4
AIN4
VOL7
AIN4
VOL6
AIN4
VOL5
AIN4
VOL4
AIN4
VOL3
AIN4
VOL2
AIN4
VOL1
AIN4
VOL0
p 48 default
0
0
0
0
0
0
0
0
Vol. Control
AIN5
AIN5
VOL7
AIN5
VOL6
AIN5
VOL5
AIN5
VOL4
AIN5
VOL3
AIN5
VOL2
AIN5
VOL1
AIN5
VOL0
p 47 default
0
0
0
0
0
0
0
0
Vol. Control
AIN6
AIN6
VOL7
AIN6
VOL6
AIN6
VOL5
AIN6
VOL4
AIN6
VOL3
AIN6
VOL2
AIN6
VOL1
AIN6
VOL0
p 48 default
0
0
0
0
0
0
0
0
Reserved
Reserved
INV_A6
INV_A5
INV_A4
INV_A3
INV_A2
INV_A1
0
0
0
0
0
0
0
0
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
0
0
0
0
0
0
0
0
Reserved
Reserved
Reserved
Reserved
CLK
Error
ADC3
OVFL
ADC2
OVFL
ADC1
OVFL
ADC Channel Invert
p 48 default
18h
Reserved
default
19h
Status
p 49 default
0
0
0
X
X
X
X
X
1Ah
Status Mask
Reserved
Reserved
Reserved
Reserved
CLK
Error_M
ADC3
OVFL_M
ADC2
OVFL_M
ADC1
OVFL_M
p 49 default
0
0
0
0
0
0
0
0
40
DS646F1
CS42438
7. REGISTER DESCRIPTION
All registers are read/write except for the I.D. and Revision Register and Interrupt Status Register which are read
only. See the following bit-definition tables for bit assignment information. The default state of each bit after a powerup sequence or reset is listed in each bit description.
7.1
Memory Address Pointer (MAP)
Not a register
7
6
5
4
3
2
1
0
INCR
MAP6
MAP5
MAP4
MAP3
MAP2
MAP1
MAP0
7.1.1
Increment (INCR)
Default = 1
Function:
Memory address pointer auto increment control
0 - MAP is not incremented automatically.
1 - Internal MAP is automatically incremented after each read or write.
7.1.2
Memory Address Pointer (MAP[6:0])
Default = 0000001
Function:
Memory address pointer (MAP). Sets the register address that will be read or written by the control port.
7.2
Chip I.D. and Revision Register (Address 01h) (Read Only)
7
6
5
4
3
2
1
0
Chip_ID3
Chip_ID2
Chip_ID1
Chip_ID0
Rev_ID3
Rev_ID2
Rev_ID1
Rev_ID0
7.2.1
Chip I.D. (CHIP_ID[3:0])
Default = 0000
Function:
I.D. code for the CS42438. Permanently set to 0000.
7.2.2
Chip Revision (REV_ID[3:0])
Default = 0001
Function:
CS42438 revision level. Revision A is coded as 0001.
DS646F1
41
CS42438
7.3
Power Control (Address 02h)
7
6
5
4
3
2
1
0
PDN_ADC3
PDN_ADC2
PDN_ADC1
PDN_DAC4
PDN_DAC3
PDN_DAC2
PDN_DAC1
PDN
7.3.1
Power Down ADC Pairs (PDN_ADCX)
Default = 0
0 - Disable
1 - Enable
Function:
When enabled, the respective ADC channel pair (ADC1 - AIN1/AIN2; ADC2 - AIN3/AIN4; and ADC3 AIN5/AIN6) will remain in a reset state.
7.3.2
Power Down DAC Pairs (PDN_DACX)
Default = 0
0 - Disable
1 - Enable
Function:
When enabled, the respective DAC channel pair (DAC1 - AOUT1/AOUT2; DAC2 - AOUT3/AOUT4; DAC3
- AOUT5/AOUT6; and DAC4 - AOUT7/AOUT8) will remain in a reset state. It is advised that any change
of these bits be made while the DACs are muted or the power down bit (PDN) is enabled to eliminate the
possibility of audible artifacts.
7.3.3
Power Down (PDN)
Default = 0
0 - Disable
1 - Enable
Function:
The entire device will enter a low-power state when this function is enabled. The contents of the control
registers are retained in this mode.
42
DS646F1
CS42438
7.4
Functional Mode (Address 03h)
7
6
5
4
3
2
1
0
Reserved
Reserved
Reserved
Reserved
MFreq2
MFreq1
MFreq0
Reserved
7.4.1
MCLK Frequency (MFREQ[2:0])
Default = 000
Function:
Sets the appropriate frequency for the supplied MCLK. For TDM operation, SCLK must equal 256Fs.
MCLK can be equal to or greater than SCLK.
MFreq2
MFreq1
MFreq0
0
0
0
0
1
0
0
1
1
X
0
1
0
1
X
Description
1.0290 MHz to 12.8000 MHz
1.5360 MHz to 19.2000 MHz
2.0480 MHz to 25.6000 MHz
3.0720 MHz to 38.4000 MHz
4.0960 MHz to 51.2000 MHz
SSM
256
384
512
768
1024
Ratio (xFs)
DSM
N/A
N/A
256
384
512
QSM
N/A
N/A
N/A
N/A
256
Table 7. MCLK Frequency Settings
7.5
MISCELLANEOUS CONTROL (Address 04h)
7
6
5
4
3
2
1
0
FREEZE
AUX_DIF
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
7.5.1
Freeze Controls (FREEZE)
Default = 0
Function:
This function will freeze the previous settings of, and allow modifications to be made to the channel mutes,
the DAC and ADC Volume Control/Channel Invert registers without the changes taking effect until the
FREEZE is disabled. To have multiple changes in these control port registers take effect simultaneously,
enable the FREEZE bit, make all register changes, then disable the FREEZE bit.
7.5.2
Auxiliary Digital Interface Format (AUX_DIF)
Default = 0
0 - Left Justified
1 - I²S
Function:
This bit selects the digital interface format used for the AUX Serial Port. The required relationship between
the Left/Right clock, serial clock and serial data is defined by the Digital Interface Format and the options
are detailed in Figures 17-18.
DS646F1
43
CS42438
7.6
ADC Control & DAC De-Emphasis (Address 05h)
7
6
5
4
3
2
1
0
ADC1-2_HPF
FREEZE
ADC3_HPF
FREEZE
DAC_DEM
ADC1
SINGLE
ADC2
SINGLE
ADC3
SINGLE
AIN5_MUX
AIN6_MUX
7.6.1
ADC1-2 High-Pass Filter Freeze (ADC1-2_HPF FREEZE)
Default = 0
Function:
When this bit is set, the internal high-pass filter will be disabled for ADC1 and ADC2.The current DC offset
value will be frozen and continue to be subtracted from the conversion result. See “ADC Digital Filter
Characteristics” on page 16.
7.6.2
ADC3 High Pass Filter Freeze (ADC3_HPF FREEZE)
Default = 0
Function:
When this bit is set, the internal high-pass filter will be disabled for ADC3.The current DC offset value will
be frozen and continue to be subtracted from the conversion result. See “ADC Digital Filter Characteristics” on page 16.
7.6.3
DAC De-Emphasis Control (DAC_DEM)
Default = 0
0 - No De-Emphasis
1 - De-Emphasis Enabled (Auto-Detect Fs)
Function:
Enables the digital filter to maintain the standard 15µs/50µs digital de-emphasis filter response at the
auto-detected sample rate of either 32, 44.1, or 48 kHz. De-emphasis will not be enabled, regardless of
this register setting, at any other sample rate.
7.6.4
ADC1 Single-Ended Mode (ADC1 SINGLE)
Default = 0
0 - Disabled; Differential input to ADC1
1 - Enabled; Single-Ended input to ADC1
Function:
When enabled, this bit allows the user to apply a single-ended input to the positive terminal of ADC1. A
+6 dB digital gain is automatically applied to the serial audio data of ADC1. The negative leg must be driven to the common mode of the ADC. See Figure 21 on page 50 for a graphical description.
44
DS646F1
CS42438
7.6.5
ADC2 Single-Ended Mode (ADC2 SINGLE)
Default = 0
0 - Disabled; Differential input to ADC2
1 - Enabled; Single-Ended input to ADC2
Function:
When enabled, this bit allows the user to apply a single-ended input to the positive terminal of ADC2. A
+6 dB digital gain is automatically applied to the serial audio data of ADC2. The negative leg must be driven to the common mode of the ADC. See Figure 21 on page 50 for a graphical description.
7.6.6
ADC3 Single-Ended Mode (ADC3 SINGLE)
Default = 0
0 - Disabled; Differential input to ADC
1 - Enabled; Single-Ended input to ADC
Function:
When disabled, this bit removes the 4:2 multiplexer from the signal path of ADC3 allowing a differential
input. When enabled, this bit allows the user to choose between four single-ended inputs to ADC3, using
the AIN5_MUX and AIN6_MUX bits. See Figure 11 on page 31 and Figure 21 on page 50 for graphical
descriptions.
7.6.7
Analog Input Ch. 5 Multiplexer (AIN5_MUX)
Default = 0
0 - Single-Ended Input AIN5A
1 - Single-Ended Input AIN5B
Function:
ADC3 can accept single-ended input signals when the ADC3 SINGLE bit is enabled. The AIN5_MUX bit
selects between two input channels (AIN5A or AIN5B) to be sent to ADC3 in Single-Ended Mode. This bit
is ignored when the ADC3_SINGLE bit is disabled. See Figure 11 on page 31 for a graphical description.
7.6.8
Analog Input Ch. 6 Multiplexer (AIN6_MUX)
Default = 0
0 - Single-Ended Input AIN6A
1 - Single-Ended Input AIN6B
Function:
ADC3 can accept a single-ended input signal when the ADC3 SINGLE bit is enabled. The AIN6_MUX bit
selects between two input channels (AIN6A or AIN6B) to be sent to ADC3 in Single-Ended Mode. This bit
is ignored when the ADC3_SINGLE bit is disabled. See Figure 11 on page 31 for a graphical description.
DS646F1
45
CS42438
7.7
Transition Control (Address 06h)
7
6
5
4
3
2
1
0
DAC_SNGVOL
DAC_SZC1
DAC_SZC0
AMUTE
MUTE ADC_SP
ADC_SNGVOL
ADC_SZC1
ADC_SZC0
7.7.1
Single Volume Control (DAC_SNGVOL, ADC_SNGVOL)
Default = 0
Function:
The individual channel volume levels are independently controlled by their respective Volume Control registers when this function is disabled. When enabled, the volume on all channels is determined by the
AOUT1 and AIN1 Volume Control register and the other Volume Control registers are ignored.
7.7.2
Soft Ramp and Zero Cross Control (ADC_SZC[1:0], DAC_SZC[1:0])
Default = 00
00 - Immediate Change
01 - Zero Cross
10 - Soft Ramp
11 - Soft Ramp on Zero Crossings
Function:
Immediate Change
When Immediate Change is selected, all volume-level changes will take effect immediately in one step.
Zero Cross
Zero Cross Enable dictates that signal level changes, either by gain changes, attenuation changes or muting, will occur on a signal zero crossing to minimize audible artifacts. The requested level change will occur after a timeout period between 512 and 1024 sample periods (10.7 ms to 21.3 ms at 48 kHz sample
rate) if the signal does not encounter a zero crossing. The zero cross function is independently monitored
and implemented for each channel.
Soft Ramp
Soft Ramp allows level changes, either by gain changes, attenuation changes or muting, to be implemented by incrementally ramping, in 1/8 dB steps, from the current level to the new level at a rate of 1 dB per
8 left/right clock periods.
Soft Ramp on Zero Crossing
Soft Ramp and Zero Cross Enable dictates that signal level changes, either by gain changes, attenuation
changes or muting, will occur in 1/8 dB steps and be implemented on a signal zero crossing. The 1/8 dB
level change will occur after a timeout period between 512 and 1024 sample periods (10.7 ms to 21.3 ms
at 48 kHz sample rate) if the signal does not encounter a zero crossing. The zero cross function is independently monitored and implemented for each channel.
46
DS646F1
CS42438
7.7.3
Auto-Mute (AMUTE)
Default = 1
0 - Disabled
1 - Enabled
Function:
The Digital-to-Analog converters of the CS42438 will mute the output following the reception of 8192 consecutive audio samples of static 0 or -1. A single sample of non-static data will release the mute. Detection
and muting is done independently for each channel. The quiescent voltage on the output will be retained
during the mute period. The muting function is affected, similar to volume control changes, by the Soft and
Zero Cross bits (SZC[1:0]).
7.7.4
Mute ADC Serial Port (MUTE ADC_SP)
Default = 0
0 - Disabled
1 - Enabled
Function:
When enabled, the ADC Serial Port will be muted.
7.8
DAC Channel Mute (Address 07h)
7
6
5
4
3
2
1
0
AOUT8_MUTE
AOUT7_MUTE
AOUT6_MUTE
AOUT5_MUTE
AOUT4_MUTE
AOUT3_MUTE
AOUT2_MUTE
AOUT1_MUTE
7.8.1
Independent Channel Mute (AOUTX_MUTE)
Default = 0
0 - Disabled
1 - Enabled
Function:
The respective Digital-to-Analog converter outputs of the CS42438 will mute when enabled. The quiescent voltage on the outputs will be retained. The muting function is affected by the DAC Soft and Zero
Cross bits (DAC_SZC[1:0]).
7.9
AOUTX Volume Control (Addresses 08h- 0Fh)
7
6
5
4
3
2
1
0
AOUTx_VOL7
AOUTx_VOL6
AOUTx_VOL5
AOUTx_VOL4
AOUTx_VOL3
AOUTx_VOL2
AOUTx_VOL1
AOUTx_VOL0
7.9.1
Volume Control (AOUTX_VOL[7:0])
Default = 00h
Function:
The AOUTx Volume Control registers allow independent setting of the signal levels in 0.5 dB increments
from 0 dB to -127.5 dB. Volume settings are decoded as shown in Table 8. The volume changes are im-
DS646F1
47
CS42438
plemented as dictated by the Soft and Zero Cross bits (DAC_SZC[1:0]). All volume settings less than 127.5 dB are equivalent to enabling the AOUTx_MUTE bit for the given channel.
Binary Code
00000000
00101000
01010000
01111000
10110100
Volume Setting
0 dB
-20 dB
-40 dB
-60 dB
-90 dB
Table 8. Example AOUT Volume Settings
7.10
DAC Channel Invert (Address 10h)
7
6
5
4
3
2
1
0
INV_AOUT8
INV_AOUT7
INV_AOUT6
INV_AOUT5
INV_AOUT4
INV_AOUT3
INV_AOUT2
INV_AOUT1
7.10.1 Invert Signal Polarity (INV_AOUTX)
Default = 0
0 - Disabled
1 - Enabled
Function:
When enabled, these bits will invert the signal polarity of their respective channels.
7.11
AINX Volume Control (Address 11h-16h)
7
6
5
4
3
2
1
0
AINx_VOL7
AINx_VOL6
AINx_VOL5
AINx_VOL4
AINx_VOL3
AINx_VOL2
AINx_VOL1
AINx_VOL0
7.11.1
AINX Volume Control (AINX_VOL[7:0])
Default = 00h
Function:
The level of AIN1 - AIN6 can be adjusted in 0.5 dB increments as dictated by the ADC Soft and Zero Cross
bits (ADC_SZC[1:0]) from +24 to -64 dB. Levels are decoded in two’s complement, as shown in Table 9.
Binary Code
0111 1111
···
0011 0000
···
0000 0000
1111 1111
1111 1110
···
1000 0000
Volume Setting
+24 dB
···
+24 dB
···
0 dB
-0.5 dB
-1 dB
···
-64 dB
Table 9. Example AIN Volume Settings
48
DS646F1
CS42438
7.12
ADC Channel Invert (Address 17h)
7
6
5
4
3
2
1
0
Reserved
Reserved
INV_AIN6
INV_AIN5
INV_AIN4
INV_AIN3
INV_AIN2
INV_AIN1
7.12.1 Invert Signal Polarity (INV_AINX)
Default = 0
0 - Disabled
1 - Enabled
Function:
When enabled, these bits will invert the signal polarity of their respective channels.
7.13
Status (Address 19h) (Read Only)
7
6
5
4
3
2
1
0
Reserved
Reserved
Reserved
Reserved
CLK Error
ADC3_OVFL
ADC2_OVFL
ADC1_OVFL
For all bits in this register, a “1” means the associated error condition has occurred at least once since the
register was last read. A”0” means the associated error condition has NOT occurred since the last reading
of the register. Reading the register resets all bits to 0. Status bits that are masked off in the associated
mask register will always be “0” in this register.
7.13.1 CLOCK ERROR (CLK ERROR)
Default = x
Function:
Indicates an invalid MCLK to FS ratio. This status flag is set to “Level Active Mode” and becomes active
during the error condition. See “System Clocking” on page 33 for valid clock ratios.
7.13.2 ADC Overflow (ADCX_OVFL)
Default = x
Function:
Indicates that there is an over-range condition anywhere in the CS42438 ADC signal path of each of the
associated ADC’s.
7.14
Status Mask (Address 1Ah)
7
6
5
4
3
2
1
0
Reserved
Reserved
Reserved
Reserved
CLK Error_M
ADC3_OV
FL_M
ADC2_OVFL_M
ADC1_OVFL_M
Default = 0000
Function:
The bits of this register serve as a mask for the error sources found in the register “Status (Address 19h)
(Read Only)” on page 49. If a mask bit is set to 1, the error is unmasked, meaning that its occurrence will
affect the status register. If a mask bit is set to 0, the error is masked, meaning that its occurrence will not
affect status register. The bit positions align with the corresponding bits in the Status register.
DS646F1
49
CS42438
8. EXTERNAL FILTERS
8.1
ADC Input Filter
The analog modulator samples the input at 6.144 MHz (internal MCLK=12.288 MHz). The digital filter will
reject signals within the stopband of the filter. However, there is no rejection for input signals which are multiples of the digital passband frequency (n × 6.144 MHz), where n=0,1,2,... Refer to Figures 20 and 21 for
a recommended analog input filter that will attenuate any noise energy at 6.144 MHz, in addition to providing
the optimum source impedance for the modulators. Refer to Figures 22 and 23 for low-cost, low-componentcount passive input filters. The use of capacitors that have a large voltage coefficient (such as general-purpose ceramics) must be avoided since these can degrade signal linearity
634 Ω
470 pF
C0G
ADC1-3
91 Ω
-
4.7 µF
AINx+
+
100 k Ω
634 Ω
634 Ω
VA
2700 pF
C0G
470 pF
C0G
10 k Ω
100 k Ω
91 Ω
-
AINx-
+
100 k Ω
0.1 µF
100 µF
332 Ω
Figure 20. Single to Differential Active Input Filter
634 Ω
VA
100 kΩ
470 pF
-
4.7 µF
C0G
ADC1-2
91 Ω
AIN1+,2+,3+,4+
+
100 kΩ
2700 pF
C0G
100 kΩ
4.7 µF
AIN1-,2-,3-,4-
634 Ω
VA
100 kΩ
470 pF
-
4.7 µF
C0G
ADC3
91 Ω
AIN5A,6A
+
100 kΩ
2700 pF
C0G
100 kΩ
634 Ω
VA
100 kΩ
470 pF
-
4.7 µF
C0G
91 Ω
AIN5B,6B
+
100 kΩ
100 kΩ
2700 pF
C0G
Figure 21. Single-Ended Active Input Filter
50
DS646F1
CS42438
8.1.1
Passive Input Filter
The passive filter implementation shown in Figure 22 will attenuate any noise energy at 6.144 MHz but
will not provide optimum source impedance for the ADC modulators. Full analog performance will therefore not be realized using a passive filter. Figure 22 illustrates the unity gain, passive input filter solution.
In this topology the distortion performance is affected, but the dynamic range performance is not limited.
150 Ω
ADC1-2
10 µF
AIN1+,2+,3+,4+
2700 pF
100 kΩ
C0G
AIN1-,2-,3-,44.7 µF
150 Ω
ADC3
10 µF
AIN5A,6A
2700 pF
100 kΩ
C0G
150 Ω
10 µF
AIN5B,6B
2700 pF
100 kΩ
C0G
Figure 22. Passive Input Filter
8.1.2
Passive Input Filter w/Attenuation
Some applications may require signal attenuation prior to the ADC. The full-scale input voltage will scale
with the analog power supply voltage. For VA = 5.0 V, the full-scale input voltage is approximately
2.8 Vpp, or 1 Vrms (most consumer audio line-level outputs range from 1.5 to 2 Vrms).
Figure 23 shows a passive input filter with 6 dB of signal attenuation. Due to the relatively high input impedance on the analog inputs, the full distortion performance cannot be realized. Also, the resistor divider
circuit will determine the input impedance into the input filter. In the circuit shown in Figure 23, the input
impedance is approximately 5 kΩ. By doubling the resistor values, the input impedance will increase to
10 kΩ. However, in this case the distortion performance will drop due to the increase in series resistance
on the analog inputs.
DS646F1
51
CS42438
10 µF
2.5 kΩ
ADC1-2
AIN1+,2+,3+,4+
2.5 k Ω
2700 pF
C0G
AIN1-,2-,3-,44.7 µF
10 µF
2.5 kΩ
ADC3
AIN5A,6A
2.5 k Ω
2700 pF
C0G
10 µF
2.5 kΩ
AIN5B,6B
2.5 k Ω
2700 pF
C0G
Figure 23. Passive Input Filter w/Attenuation
52
DS646F1
CS42438
8.2
DAC Output Filter
The CS42438 is a linear phase design and does not include phase or amplitude compensation for an external filter. Therefore, the DAC system phase and amplitude response will be dependent on the external analog circuitry. Shown below is the recommended active and passive output filters.
1800 pF
DAC1-4
4.75 kΩ
390 pF
C0G
AOUTx -
5.49 kΩ
2.94 kΩ
1.65 kΩ
887 Ω
AOUTx +
C0G
+
562Ω
47.5 k Ω
1200 pF
5600 pF
C0G
22 µF
C0G
1.87 kΩ
22 µF
Figure 24. Active Analog Output Filter
DAC1-4
3.3 µF
AOUTx+
560 Ω
+
10 kΩ
C
C=
R ext
Rext+ 560
4 πFSRext560
Figure 25. Passive Analog Output Filter
DS646F1
53
CS42438
9. ADC FILTER PLOTS
Figure 27. SSM Transition Band
0
0.10
-1
0.08
-2
0.06
-3
0.04
Amplitude (dB)
Amplitude (dB)
Figure 26. SSM Stopband Rejection
-4
-5
-6
-7
0.02
0.00
-0.02
-0.04
-8
-0.06
-9
-0.08
-10
0.45
-0.10
0.46
0.47
0.48
0.49
0.5
0.51
0.52
0.53
0.54
0.55
0
0.05
0
0
-10
-10
-20
-20
-30
-30
-40
-40
-50
-60
-70
-80
-90
-100
0.7
0.8
0.9
Frequency (normalized to Fs)
Figure 30. DSM Stopband Rejection
54
0.45
0.5
-90
-130
-140
0.6
0.4
-100
-120
0.5
0.35
-80
-130
0.4
0.3
-70
-110
0.3
0.25
-60
-120
0.2
0.2
-50
-110
0.1
0.15
Figure 29. SSM Passband Ripple
Amplitude (dB)
Amplitude (dB)
Figure 28. SSM Transition Band (Detail)
0.0
0.1
Frequency (normalized to Fs)
Frequency (normalized to Fs)
1.0
-140
0.40
0.42
0.44
0.46
0.48
0.50
0.52
0.54
0.56
0.58
0.60
Frequency (normalized to Fs)
Figure 31. DSM Transition Band
DS646F1
CS42438
‘
0
0 .10
-1
0 .0 8
0 .0 6
Amplitude (dB)
Amplitude (dB)
-2
-3
-4
-5
-6
-7
0 .0 4
0 .0 2
0 .0 0
-0 .0 2
-0 .0 4
-0 .0 6
-8
-0 .0 8
-9
-10
0.46
-0 .10
0 .0 0
0.47
0.48
0.49
0.50
0.51
Frequency (normalized to Fs)
Figure 32. DSM Transition Band (Detail)
DS646F1
0.52
0 .0 5
0 .10
0 .15
0 .2 0
0 .2 5
0 .3 0
0 .3 5 0 .4 0
0 .4 5
0 .50
Fr e que ncy (norm alize d to Fs )
Figure 33. DSM Passband Ripple
55
CS42438
10.DAC FILTER PLOTS
Figure 34. SSM Stopband Rejection
Figure 35. SSM Transition Band
0.05
0
Amplitude dB
-0.05
-0. 1
-0.15
-0. 2
-0.25
0
56
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (normalized to Fs)
0.35
0.4
0.45
Figure 36. SSM Transition Band (detail)
Figure 37. SSM Passband Ripple
Figure 38. DSM Stopband Rejection
Figure 39. DSM Transition Band
0.5
DS646F1
CS42438
0.8
0.7
0.6
0.5
Amplitude dB
0.4
0.3
0.2
0.1
0
-0. 1
-0. 2
0
Figure 40. DSM Transition Band (detail)
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (normalized to Fs)
0.35
0.4
0.45
0.5
Figure 41. DSM Passband Ripple
0
0
-10
-10
-20
-30
-20
Amplitude (dB)
Amplitude (dB)
-40
-50
-60
-30
-40
-70
-50
-80
-60
-90
-100
0
0.1
0.2
0.3
0.4
0.5
0.6
Frequency(normalized to Fs)
0.7
0.8
0.9
1
0.35
Figure 42. QSM Stopband Rejection
0.4
0.45
0.5
0.55
0.6
Frequency(normalized to Fs)
0.65
0.7
0.75
Figure 43. QSM Transition Band
0
0
-5
-10
-0. 5
-20
Amplitude dB
Amplitude (dB)
-15
-25
-30
-1
-35
-40
-45
-50
0.4
0.45
0.5
0.55
0.6
Frequency(normalized to Fs)
0.65
Figure 44. QSM Transition Band (detail)
DS646F1
0.7
-1. 5
0
0.05
0.1
0.15
0.2
0.25
0.3
Frequency (normalized to Fs)
0.35
0.4
0.45
0.5
Figure 45. QSM Passband Ripple
57
CS42438
11.PARAMETER DEFINITIONS
Dynamic Range
The ratio of the rms value of the signal to the rms sum of all other spectral components over the specified
bandwidth. Dynamic Range is a signal-to-noise ratio measurement over the specified band width made with
a -60 dBFS signal. 60 dB is added to resulting measurement to refer the measurement to full-scale. This
technique ensures that the distortion components are below the noise level and do not affect the measurement. This measurement technique has been accepted by the Audio Engineering Society, AES17-1991,
and the Electronic Industries Association of Japan, EIAJ CP-307. Expressed in decibels.
Total Harmonic Distortion + Noise
The ratio of the rms value of the signal to the rms sum of all other spectral components over the specified
band width (typically 10 Hz to 20 kHz), including distortion components. Expressed in decibels. Measured
at -1 and -20 dBFS as suggested in AES17-1991 Annex A.
Frequency Response
A measure of the amplitude response variation from 10 Hz to 20 kHz relative to the amplitude response at
1 kHz. Units in decibels.
Interchannel Isolation
A measure of crosstalk between the left and right channel pairs. Measured for each channel at the converter's output with no signal to the input under test and a full-scale signal applied to the other channel. Units in
decibels.
Interchannel Gain Mismatch
The gain difference between left and right channel pairs. Units in decibels.
Gain Error
The deviation from the nominal full-scale analog output for a full-scale digital input.
Gain Drift
The change in gain value with temperature. Units in ppm/°C.
Offset Error
The deviation of the mid-scale transition (111...111 to 000...000) from the ideal. Units in mV.
58
DS646F1
CS42438
12.REFERENCES
1. Cirrus Logic, AN18: Layout and Design Rules for Data Converters and Other Mixed Signal Devices,
Version 6.0, February 1998.
2. Cirrus Logic, Techniques to Measure and Maximize the Performance of a 120 dB, 96 kHz A/D Converter
Integrated Circuit, by Steven Harris, Steven Green and Ka Leung. Presented at the 103rd Convention of the
Audio Engineering Society, September 1997.
3. Cirrus Logic, A Stereo 16-bit Delta-Sigma A/D Converter for Digital Audio, by D.R. Welland, B.P. Del Signore, E.J. Swanson, T. Tanaka, K. Hamashita, S. Hara, K. Takasuka. Paper presented at the 85th Convention
of the Audio Engineering Society, November 1988.
4. Cirrus Logic, The Effects of Sampling Clock Jitter on Nyquist Sampling Analog-to-Digital Converters, and
on Oversampling Delta Sigma ADC's, by Steven Harris. Paper presented at the 87th Convention of the Audio Engineering Society, October 1989.
5. Cirrus Logic, An 18-Bit Dual-Channel Oversampling Delta-Sigma A/D Converter, with 19-Bit Mono Application Example, by Clif Sanchez. Paper presented at the 87th Convention of the Audio Engineering Society,
October 1989.
6. Cirrus Logic, How to Achieve Optimum Performance from Delta-Sigma A/D and D/A Converters, by Steven
Harris. Presented at the 93rd Convention of the Audio Engineering Society, October 1992.
7. Cirrus Logic, A Fifth-Order Delta-Sigma Modulator with 110 dB Audio Dynamic Range, by I. Fujimori, K. Hamashita and E.J. Swanson. Paper presented at the 93rd Convention of the Audio Engineering Society, October 1992.
8. Philips Semiconductor, The I²C-Bus Specification: Version 2.1, January 2000.
http://www.semiconductors.philips.com
DS646F1
59
CS42438
13.PACKAGE INFORMATION
52L MQFP PACKAGE DRAWING
E
E1
D D1
1
e
B
∝
A
A1
L
DIM
A
A1
B
D
D1
E
E1
e*
L
∝
MIN
--0.000
0.009
----------0.029
0.00°
INCHES
NOM
------0.519
0.394
0.519
0.394
0.026
0.035
4°
MAX
0.096
0.010
0.016
----------0.041
7.00°
MILLIMETERS
NOM
------13.20 BSC
10.00 BSC
13.20 BSC
10.00 BSC
0.65 BSC
0.88
4°
MIN
--0.00
0.22
----------0.73
0.00°
MAX
2.45
0.25
0.40
----------1.03
7.00°
* Nominal pin pitch is 0.65 mm
Controlling dimension is mm.
JEDEC Designation: MS022
13.1
Thermal Characteristics
Parameter
Junction to Ambient Thermal Impedance
60
2 Layer Board
4 Layer Board
Symbol
Min
Typ
Max
Units
qJA
θJA
-
47
38
-
°C/Watt
°C/Watt
DS646F1
CS42438
14.ORDERING INFORMATION
Product
Description
Package
Pb-Free
CS42438
6-in, 8-out, TDM CODEC
for Surround Sound Apps
52L-MQFP
YES
-
-
CDB42438 CS42438 Evaluation Board
Grade
Temp Range
Container
Order #
Rail
CS42438-CMZ
Commercial -10° to +70° C
Tape & Reel CS42438-CMZR
Rail
CS42438-DMZ
Automotive -40° to +105° C
Tape & Reel CS42438-DMZR
CDB42438
15.REVISION HISTORY
Revision
Changes
A1
Initial Release
A2
Corrected I²C Address in Section 5.7.2 on page 36.
Corrected Chip I.D. in Section 7.2.1 on page 41.
PP1
Initial Preliminary Product (PP) Release subject to legal notice below.
Added pin numbers to “Typical Connection Diagram (Software Mode)” on page 11 and “Typical Connection
Diagram (Hardware Mode)” on page 12.
Changed ADC Double-Speed Mode parameters. See Note 2 on page 13 and Note 18 on page 21.
Added ADC3 MUX Interchannel Isolation characteristic in “Characteristics and Specifications” beginning on
page 13.
Changed ADC Passband Ripple maximum specifications for SSM, DSM & QSM in section “Characteristics
and Specifications” beginning on page 13.
Changed DAC Frequency Response specifications for SSM, DSM & QSM in “Characteristics and Specifications” beginning on page 13.
Removed ADC Quad-Speed Mode feature. See Note 19 on page 21.
Added section “De-Emphasis Filter” on page 32.
Corrected section “TDM data is received most significant bit (MSB) first, on the second rising edge of the
SCLK occurring after a an FS rising edge. All data is valid on the rising edge of SCLK. The AIN1 MSB is
transmitted early, but is guaranteed valid for a specified time after SCLK rises. All other bits are transmitted
on the falling edge of SCLK. Each time slot is 32 bits wide, with the valid data sample left ‘justified within the
time slot. Valid data lengths are 16, 18, 20, or 24.” on page 33.
Changed AIN1-6 Volume Control range from (+12 dB to -115.5 dB) to (+24 dB to -64 dB) in register “AINX
Volume Control (AINX_VOL[7:0])” on page 48.
Removed the register “Status Control (address 18h)”. See “CLOCK ERROR (CLK ERROR)” on
page 49 and “ADC Overflow (ADCX_OVFL)” on page 49 for the Active Mode setting.
PP2
Corrected Figures 21-23.
Added “Ordering Information” on page 61.
F1
DS646F1
Updated temperature and voltage specifications in the “Recommended Operating Conditions” on page 13.
Added test conditions to the Analog Input and Analog Output Characteristics tables.
61
CS42438
Contacting Cirrus Logic Support
For all product questions and inquiries, contact a Cirrus Logic Sales Representative.
To find the one nearest to you, go to www.cirrus.com.
IMPORTANT NOTICE
Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe 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). Customers are advised to obtain the latest version of relevant
information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus
for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third
parties. This document is the property of Cirrus and by furnishing this information, Cirrus grants no license, express or implied under any patents, mask work rights,
copyrights, trademarks, trade secrets or other intellectual property rights. Cirrus owns the copyrights associated with the information contained herein and gives consent for copies to be made of the information only for use within your organization with respect to Cirrus integrated circuits or other products of Cirrus. This consent
does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). CIRRUS PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED FOR USE
IN AIRCRAFT SYSTEMS, MILITARY APPLICATIONS, PRODUCTS SURGICALLY IMPLANTED INTO THE BODY, AUTOMOTIVE SAFETY OR SECURITY DEVICES, LIFE SUPPORT PRODUCTS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF CIRRUS PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK AND CIRRUS DISCLAIMS AND MAKES NO WARRANTY, EXPRESS, STATUTORY OR IMPLIED,
INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR PARTICULAR PURPOSE, WITH REGARD TO ANY CIRRUS PRODUCT
THAT IS USED IN SUCH A MANNER. IF THE CUSTOMER OR CUSTOMER’S CUSTOMER USES OR PERMITS THE USE OF CIRRUS PRODUCTS IN CRITICAL
APPLICATIONS, CUSTOMER AGREES, BY SUCH USE, TO FULLY INDEMNIFY CIRRUS, ITS OFFICERS, DIRECTORS, EMPLOYEES, DISTRIBUTORS AND
OTHER AGENTS FROM ANY AND ALL LIABILITY, INCLUDING ATTORNEYS’ FEES AND COSTS, THAT MAY RESULT FROM OR ARISE IN CONNECTION
WITH THESE USES.
Cirrus Logic, Cirrus, and the Cirrus Logic logo designs are trademarks of Cirrus Logic, Inc. All other brand and product names in this document may be trademarks
or service marks of their respective owners.
I²C is a registered trademark of Philips Semiconductor.
SPI is a registered trademark of Motorola, Inc.
62
DS646F1