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CS8421
32-bit, 192 kHz Asynchronous Sample Rate Converter
Features
175 dB Dynamic Range -140 dB THD+N No Programming Required No External Master Clock Required Supports Sample Rates up to 211 kHz Input/Output Sample Rate Ratios of 7.5:1 to 1:8 Master Clock Support for 128 x Fs, 256 x Fs, Bypass Mode Time Division Multiplexing (TDM) Mode Attenuates Clock Jitter Multiple Device Outputs are Phase Matched Linear Phase FIR Filter Automatic Soft Mute/Unmute +2.5 V Digital Supply (VD) +3.3 V or 5.0 V Digital Interface (VL) Space-saving 20-pin TSSOP and QFN
384 x Fs, and 512 x Fs (Master Mode)
16-, 20-, 24-, or 32-bit Data I/O 32-bit Internal Signal Processing Dither Automatically Applied and Scaled to
Packages
The CS8421 supports sample rates up to 211 kHz and is available in 20-pin TSSOP and QFN packages in both Commercial (-10 to +70C) and Automotive (-40 to +85C) grades. The CDB8421 Customer Demonstration board is also available for device evaluation and implementation suggestions. Please see "Ordering Information" on page 36 for complete details.
Output Resolution
Flexible 3-wire Serial Digital Audio Input and
Output Ports
Master and Slave Modes for Both Input and
Output
RST Level Translators
BYPASS
SDIN Level Translators ISCLK ILRCK Serial Audio Input Data Sync Info
Time Varying Digital Filters
Level Translators
TDM_IN SDOUT OSCLK OLRCK
Data Sync Info
Serial Data Audio Output
Digital PLL Serial Port Mode Decoder Clock Generator
SRC_UNLOCK MCLK_OUT
MS_SEL SAIF SAOF
3.3 V or 5.0 V (VL)
2.5 V (VD)
GND
XTI
XTO
http://www.cirrus.com
Copyright Cirrus Logic, Inc. 2009 (All Rights Reserved)
APRIL `09 DS641F2
CS8421
General Description
The CS8421 is a 32-bit, high-performance, monolithic CMOS stereo asynchronous sample-rate converter. Digital audio inputs and outputs can be 32, 24, 20, or 16 bits. Input and output data can be completely asynchronous, synchronous to an external data clock, or the part can operate without any external clock by using an integrated oscillator. Audio data is input and output through configurable 3-wire input/output ports. The CS8421 does not require any software control via a control port. Target applications include digital recording systems (DVD-R/RW, CD-R/RW, PVR, DAT, MD, and VTR), digital mixing consoles, high-quality D/A, effects processors, computer audio systems, and automotive audio systems. The CS8421 is also suitable for use as an asynchronous decimation or interpolation filter. See Cirrus Logic Application Note AN270, "Audio A/D Conversion with an Asynchronous Decimation Filter", available at www.cirrus.com for more details.
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CS8421
TABLE OF CONTENTS
1. PIN DESCRIPTIONS ............................................................................................................................ 6 1.1 TSSOP Pin Descriptions ................................................................................................................ 6 1.2 QFN Pin Descriptions ..................................................................................................................... 8 2. CHARACTERISTICS AND SPECIFICATIONS ................................................................................... 10 SPECIFIED OPERATING CONDITIONS ............................................................................................ 10 ABSOLUTE MAXIMUM RATINGS ...................................................................................................... 10 PERFORMANCE SPECIFICATIONS.................................................................................................. 11 DIGITAL FILTER CHARACTERISTICS .............................................................................................. 12 DC ELECTRICAL CHARACTERISTICS ............................................................................................. 12 DIGITAL INPUT CHARACTERISTICS ................................................................................................ 13 DIGITAL INTERFACE SPECIFICATIONS .......................................................................................... 13 SWITCHING SPECIFICATIONS ......................................................................................................... 13 3. TYPICAL CONNECTION DIAGRAMS ................................................................................................ 15 4. APPLICATIONS .................................................................................................................................. 17 4.1 Three-wire Serial input/Output Audio Port .................................................................................... 17 4.2 Mode Selection ............................................................................................................................. 18 4.3 Sample Rate Converter (SRC) ..................................................................................................... 20 4.3.1 Data Resolution and Dither .............................................................................................. 20 4.3.2 SRC Locking and Varispeed ............................................................................................ 20 4.3.3 Bypass Mode ................................................................................................................... 20 4.3.4 Muting .............................................................................................................................. 21 4.3.5 Group Delay and Phase Matching Between Multiple CS8421 Parts ............................... 21 4.3.6 Master Clock .................................................................................................................... 21 4.3.7 Clocking ........................................................................................................................... 22 4.4 Time Division Multiplexing (TDM) Mode ....................................................................................... 22 4.5 Reset, Power-Down, and Start-Up ............................................................................................... 23 4.6 Power Supply, Grounding, and PCB Layout ................................................................................ 24 5. PERFORMANCE PLOTS ................................................................................................................ 25 6. PACKAGE DIMENSIONS ................................................................................................................... 34 TSSOP THERMAL CHARACTERISTICS ........................................................................................... 34 QFN THERMAL CHARACTERISTICS ................................................................................................ 35 7. ORDERING INFORMATION ............................................................................................................... 36 8. REVISION HISTORY .......................................................................................................................... 36
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CS8421
LIST OF FIGURES
Figure 1. Non-TDM Slave Mode Timing..................................................................................................... 14 Figure 2. TDM Slave Mode Timing ............................................................................................................ 14 Figure 3. Non-TDM Master Mode Timing................................................................................................... 14 Figure 4. TDM Master Mode Timing .......................................................................................................... 14 Figure 5. Typical Connection Diagram, No External Master Clock ............................................................ 15 Figure 6. Typical Connection Diagram, Master and Slave Modes ............................................................. 16 Figure 7. Serial Audio Interface Format - IS ............................................................................................. 18 Figure 8. Serial Audio Interface Format - Left-Justified.............................................................................. 18 Figure 9. Serial Audio Interface Format - Right-Justified ........................................................................... 18 Figure 10. Typical Connection Diagram for Crystal Circuit ........................................................................ 22 Figure 11. TDM Slave Mode Timing Diagram............................................................................................ 22 Figure 12. TDM Master Mode Timing Diagram.......................................................................................... 23 Figure 13. TDM Mode Configuration (All CS8421 Outputs are Slave)....................................................... 23 Figure 14. TDM Mode Configuration (First CS8421 Output is Master, All Others are Slave) .................... 23 Figure 15. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 48 kHz:48 kHz ..................................... 25 Figure 16. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 44.1 kHz:192 kHz ................................ 25 Figure 17. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 44.1 kHz:48 kHz .................................. 25 Figure 18. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 48 kHz:44.1 kHz .................................. 25 Figure 19. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 48 kHz:96 kHz ..................................... 25 Figure 20. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 96 kHz:48 kHz ..................................... 25 Figure 21. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 192 kHz:48 kHz ................................... 26 Figure 22. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 48 kHz:96 kHz.................................. 26 Figure 23. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 48 kHz:48 kHz.................................. 26 Figure 24. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 44.1 kHz:192 kHz............................. 26 Figure 25. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 44.1 kHz:48 kHz............................... 26 Figure 26. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 48 kHz:44.1 kHz............................... 26 Figure 27. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 96 kHz:48 kHz.................................. 27 Figure 28. IMD, 10 kHz and 11 kHz -7 dBFS, 96 kHz:48 kHz ................................................................... 27 Figure 29. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 192 kHz:48 kHz................................ 27 Figure 30. IMD, 10 kHz and 11 kHz -7 dBFS, 48 kHz:44.1 kHz ................................................................ 27 Figure 31. IMD, 10 kHz and 11 kHz -7 dBFS, 44.1 kHz:48 kHz ................................................................ 27 Figure 32. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 44.1 kHz:48 kHz ................................ 27 Figure 33. Wideband FFT Plot (16k Points) 0 dBFS 80 kHz Tone, 192 kHz:192 kHz ............................... 28 Figure 34. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 48 kHz:96 kHz ................................... 28 Figure 35. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 48 kHz:48 kHz ................................... 28 Figure 36. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 96 kHz:48 kHz ................................... 28 Figure 37. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 48 kHz:44.1 kHz ................................ 28 Figure 38. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 192 kHz ..................................... 28 Figure 39. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 48 kHz ....................................... 29 Figure 40. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 96 kHz ....................................... 29 Figure 41. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 44.1 kHz .................................... 29 Figure 42. Dynamic Range vs. Output Sample Rate, -60 dBFS 1 kHz Tone, Fsi = 192 kHz .................... 29 Figure 43. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 32 kHz ....................................... 29 Figure 44. Dynamic Range vs. Output Sample Rate, -60 dBFS 1 kHz Tone, Fsi = 32 kHz ...................... 29 Figure 45. Dynamic Range vs. Output Sample Rate, -60 dBFS 1 kHz Tone, Fsi = 96 kHz ...................... 30 Figure 46. Dynamic Range vs. Output Sample Rate, -60 dBFS 1 kHz Tone, Fsi = 44.1 kHz ................... 30 Figure 47. Frequency Response with 0 dBFS Input .................................................................................. 30 Figure 48. Passband Ripple, 192 kHz:48 kHz ........................................................................................... 30 Figure 49. Dynamic Range vs. Output Sample Rate, -60 dBFS 1 kHz Tone, Fsi = 48 kHz ...................... 30 Figure 50. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 48 kHz:48 kHz ........................................ 30 Figure 51. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 48 kHz:44.1 kHz ..................................... 31 Figure 52. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 48 kHz:96 kHz ........................................ 31 4 DS641F2
CS8421
Figure 53. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 96 kHz:48 kHz ........................................ 31 Figure 54. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 44.1 kHz:192 kHz ................................... 31 Figure 55. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 44.1 kHz:48 kHz ..................................... 31 Figure 56. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 192 kHz:44.1 kHz ................................... 31 Figure 57. THD+N vs. Input Amplitude, 1 kHz Tone, 48 kHz:44.1 kHz ..................................................... 32 Figure 58. THD+N vs. Input Amplitude, 1 kHz Tone, 48 kHz:96 kHz ........................................................ 32 Figure 59. THD+N vs. Input Amplitude, 1 kHz Tone, 96 kHz:48 kHz ........................................................ 32 Figure 60. THD+N vs. Input Amplitude, 1 kHz Tone, 44.1 kHz:192 kHz ................................................... 32 Figure 61. THD+N vs. Input Amplitude, 1 kHz Tone, 44.1 kHz:48 kHz ..................................................... 32 Figure 62. THD+N vs. Input Amplitude, 1 kHz Tone, 192 kHz:48 kHz ...................................................... 32 Figure 63. THD+N vs. Frequency Input, 0 dBFS, 48 kHz:44.1 kHz ........................................................... 33 Figure 64. THD+N vs. Frequency Input, 0 dBFS, 48 kHz:96 kHz .............................................................. 33 Figure 65. THD+N vs. Frequency Input, 0 dBFS, 44.1 kHz:48 kHz ........................................................... 33 Figure 66. THD+N vs. Frequency Input, 0 dBFS, 96 kHz:48 kHz .............................................................. 33
LIST OF TABLES
Table 1. Serial Audio Port Master/Slave and Clock Ratio Select Start-Up Options (MS_SEL) ................. 19 Table 2. Serial Audio Input Port Start-Up Options (SAIF) .......................................................................... 19 Table 3. Serial Audio Output Port Start-Up Options (SAOF) ..................................................................... 19
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CS8421 1. PIN DESCRIPTIONS
1.1 TSSOP PIN DESCRIPTIONS
XTO XTI VD GND RST BYPASS ILRCK ISCLK SDIN MCLK_OUT
1 2 3 4 5 6 7 8 9 10
20 19 18 17 16 15 14 13 12 11
SRC_UNLOCK SAIF SAOF VL GND MS_SEL OLRCK OSCLK SDOUT TDM_IN
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Pin Name
XTO XTI VD GND RST
#
1 2 3 4 5
Pin Description
Crystal Out (Output) - Crystal output for Master clock. See "Master Clock" on page 21. Crystal/Oscillator In (Input) - Crystal or digital clock input for Master clock. See "Master Clock" on page 21. Digital Power (Input) - Digital core power supply. Typically +2.5 V. Ground (Input) - Ground for I/O and core logic. Reset (Input) - When RST is low, the CS8421 enters a low-power mode and all internal states are reset. On initial power-up, RST must be held low until the power supply is stable and all input clocks are stable in frequency and phase. Sample Rate Converter Bypass (Input) - When BYPASS is high, the sample rate converter will be bypassed, and any data input through the serial audio input port will be directly output on the serial audio output port. When BYPASS is low, the sample rate converter will operate normally. Serial Audio Input Left/Right Clock (Input/Output) - Word-rate clock for the audio data on the SDIN pin. Serial Audio Bit Clock (Input/Output) - Serial-bit clock for audio data on the SDIN pin. Serial Audio Input Data Port (Input) - Audio data serial input pin. Master Clock Output (Output) - Buffered and level-shifted output for Master clock. If MCLK_OUT is not required, this pin should be pulled high through a 47 k resistor to turn the output off. See "Master Clock" on page 21. Serial Audio TDM Input (Input) - Time Division Multiplexing serial audio data input. Grounded when not used. See "Time Division Multiplexing (TDM) Mode" on page 22. Serial Audio Output Data Port (Output) - Audio data serial output pin. Optionally this pin may be pulled low through a 47 k resistor, but should not be pulled high. Serial Audio Bit Clock (Input/Output) - Serial-bit clock for audio data on the SDOUT pin. Serial Audio Input Left/Right Clock (Input/Output) - Word-rate clock for the audio data on the SDOUT pin. Master/Slave Select (Input) - Used to select Master or Slave for the input and output serial audio ports at startup and reset. See Table 1 on page 19 for settings. Ground (Input) - Ground for I/O and core logic. Logic Power (Input) - Input/Output power supply. Typically +3.3 V or +5.0 V. Serial Audio Output Format Select (Input) - Used to select the serial audio output format at startup and reset. See Table 3 on page 19 for format settings. Serial Audio Input Format Select (Input) - Used to select the serial audio input format at startup and reset. See Table 2 on page 19 for format settings. SRC Unlock Indicator (Output) - Indicates when the SRC is unlocked. See "SRC Locking and Varispeed" on page 20.
BYPASS ILRCK ISCLK SDIN MCLK_OUT TDM_IN SDOUT OSCLK OLRCK MS_SEL GND VL SAOF SAIF SRC_UNLOCK
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
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CS8421
1.2 QFN PIN DESCRIPTIONS SRC_UNLOC
20
19
18
17
SAOF
16
SAIF
XTO
XTI
VD GND RST BYPASS ILRCK
1 2 3 4 5 Thermal Pad Top-Down View 20-pin QFN Package
15 14 13 12 11
VL GND MS_SEL OLRCK OSCLK
6
7
8
9
10
ISCLK
SDIN
8
MCLK_OUT
TDM_IN
SDOUT
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CS8421
Pin Name
VD GND RST
#
1 2 3
Pin Description
Digital Power (Input) - Digital core power supply. Typically +2.5 V. Ground (Input) - Ground for I/O and core logic. Reset (Input) - When RST is low, the CS8421 enters a low-power mode and all internal states are reset. On initial power-up, RST must be held low until the power supply is stable and all input clocks are stable in frequency and phase. Sample Rate Converter Bypass (Input) - When BYPASS is high, the sample-rate converter will be bypassed, and any data input through the serial audio input port will be directly output on the serial audio output port. When BYPASS is low, the sample rate converter will operate normally. Serial Audio Input Left/Right Clock (Input/Output) - Word-rate clock for the audio data on the SDIN pin. Serial Audio Bit Clock (Input/Output) - Serial-bit clock for audio data on the SDIN pin. Serial Audio Input Data Port (Input) - Audio data serial input pin. Master Clock Output (Output) - Buffered and level-shifted output for Master clock. If MCLK_OUT is not required, this pin should be pulled high through a 47 k resistor to turn the output off. See "Master Clock" on page 21. Serial Audio TDM Input (Input) - Time Division Multiplexing serial audio data input. Grounded when not used. See "Time Division Multiplexing (TDM) Mode" on page 22. Serial Audio Output Data Port (Output) - Audio data serial output pin. Optionally this pin may be pulled low through a 47 k resistor, but should not be pulled high. Serial Audio Bit Clock (Input/Output) - Serial bit clock for audio data on the SDOUT pin. Serial Audio Input Left/Right Clock (Input/Output) - Word rate clock for the audio data on the SDOUT pin. Master/Slave Select (Input) - Used to select Master or Slave for the input and output serial audio ports at startup and reset. See Table 1 on page 19 for settings. Ground (Input) - Ground for I/O and core logic. Logic Power (Input) - Input/Output power supply. Typically +3.3 V or +5.0 V. Serial Audio Output Format Select (Input) - Used to select the serial audio output format at startup and reset. See Table 3 on page 19 for format settings. Serial Audio Input Format Select (Input) - Used to select the serial audio input format at startup and reset. See Table 2 on page 19 for format settings. SRC Unlock Indicator (Output) - Indicates when the SRC is unlocked. See "SRC Locking and Varispeed" on page 20. Crystal Out (Output) - Crystal output for Master clock. See "Master Clock" on page 21. Crystal/Oscillator In (Input) - Crystal or digital clock input for Master clock. See "Master Clock" on page 21. Thermal Pad - Thermal relief pad for optimized heat dissipation. This pad must be electrically connected to GND. See "Power Supply, Grounding, and PCB Layout" on page 24 for more information.
BYPASS ILRCK ISCLK SDIN MCLK_OUT TDM_IN SDOUT OSCLK OLRCK MS_SEL GND VL SAOF SAIF SRC_UNLOCK XTO XTI Thermal Pad
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 -
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CS8421 2. CHARACTERISTICS AND SPECIFICATIONS
(All Min/Max characteristics and specifications are guaranteed over the Specified Operating Conditions. Typical performance characteristics and specifications are derived from measurements taken at nominal supply voltages and TA = 25C.)
SPECIFIED OPERATING CONDITIONS
(GND = 0 V, all voltages with respect to 0 V) Parameter
Power Supply Voltage Ambient Operating Temperature: `-CZ' `-CNZ' `-DZ'
Symbol
VD VL TA
Min
2.38 3.14 -10 -10 -40
Nominal
2.5 3.3 or 5.0 -
Max
2.62 5.25 +70 +70 +85
Units
V V C C C
ABSOLUTE MAXIMUM RATINGS
(GND = 0 V; all voltages with respect to 0 V. Operation beyond these limits may result in permanent damage to the device. Normal operation is not guaranteed at these extremes.) Parameter
Power Supply Voltage Input Current, Any Pin Except Supplies Input Voltage Ambient Operating Temperature (power applied) Storage Temperature (Note 1)
Symbol
VD VL Iin Vin TA Tstg
Min
-0.3 -0.3 -0.3 -55 -65
Max
3.5 6.0 10 VL+0.4 +125 +150
Units
V V mA V C C
Notes: 1. Transient currents of up to 100 mA will not cause SCR latch-up. 2. Numbers separated by a colon indicate input and output sample rates. For example, 48 kHz:96 kHz indicates that Fsi = 48 khz and Fso = 96 kHz.
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CS8421 PERFORMANCE SPECIFICATIONS
(XTI/XTO = 27 MHz; Input signal = 1.000 kHz, 0 dBFS, Measurement Bandwidth = 20 to Fso/2 Hz, and Word Width = 32-Bits, unless otherwise stated.) Parameter
Resolution Sample Rate with XTI = 27.000 MHz Sample Rate with other XTI clocks Sample Rate with ring oscillator (XTI to GND or VL, XTO floating) Sample Rate Ratio - Upsampling Sample Rate Ratio - Downsampling Interchannel Gain Mismatch Interchannel Phase Deviation Peak Idle Channel Noise Component (32-bit operation) Slave Master
Min
16 7.2 53
Typ
0.0 0.0 180 177 175 172 180 177 179 176 176 173 175 172 -161 -171 -130 -160 -148 -168 -173
Max
32 207 211 XTI/130 XTI/128 96 1:8 7.5:1 -192 -
Units
bits kHz kHz kHz kHz kHz
Slave XTI/3750 Master XTI/512 12 A-Weighted Unweighted A-Weighted Unweighted A-Weighted Unweighted A-Weighted Unweighted A-Weighted Unweighted A-Weighted Unweighted -
dB Degrees dBFS dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB
Dynamic Range (20 Hz to Fso/2, 1 kHz, -60 dBFS Input)
44.1 kHz:48 kHz 44.1 kHz:192 kHz 48 kHz:44.1 kHz 48 kHz:96 kHz 96 kHz:48 kHz 192 kHz:32 kHz
Total Harmonic Distortion + Noise (20 Hz to Fso/2, 1 kHz, 0 dBFS Input) 32 kHz:48 kHz 44.1 kHz:48 kHz 44.1 kHz:192 kHz 48 kHz:44.1 kHz 48 kHz:96 kHz 96 kHz:48 kHz 192 kHz:32 kHz
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CS8421 DIGITAL FILTER CHARACTERISTICS
Parameter
Passband (Upsampling or Downsampling) Passband Ripple Stopband Stopband Attenuation Group Delay
Min
0.5465*Fso 125
Typ
(Note 3)
Max
0.4535*Fso 0.007 -
Units
Hz dB Hz dB ms
3. The equation for the group delay through the sample-rate converter is (56.581 / Fsi) + (55.658 / Fso). For example, if the input sample rate is 192 kHz and the output sample rate is 96 kHz, the group delay through the sample-rate converter is (56.581/192,000) + (55.658/96,000) =.875 milliseconds.
DC ELECTRICAL CHARACTERISTICS
(GND = 0 V; all voltages with respect to 0 V.) Parameters Power-Down Mode (Note 4)
Supply Current in power-down (Oscillator attached to XTI-XTO) Supply Current in power-down (Crystal attached to XTI-XTO) VD VL = 3.3 V VL = 5.0 V VD VL = 3.3 V VL = 5.0 V VD VL = 3.3 V VL = 5.0 V VD VL = 3.3 V VL = 5.0 V VD VL = 3.3 V VL = 5.0 V VD VL = 3.3 V VL = 5.0 V 50 100 200 100 1.5 4 24 2.5 4 80 8 13 24 3 7 80 4 6.5 A A A A mA mA mA mA mA mA mA mA mA mA mA mA mA mA
Symbol
Min
Typ
Max
Units
Normal Operation (Note 5)
Supply Current at 48 kHz Fsi and Fso (Oscillator attached to XTI-XTO) Supply Current at 192 kHz Fsi and Fso (Oscillator attached to XTI-XTO) Supply Current at 48 kHz Fsi and Fso (Crystal attached to XTI-XTO) Supply Current at 192 kHz Fsi and Fso (Crystal attached to XTI-XTO)
4. Power Down Mode is defined as RST = LOW with all clocks and data lines held static, except when a crystal is attached across XTI-XTO, in which case the crystal will begin oscillating. 5. Normal operation is defined as RST = HI.
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CS8421 DIGITAL INPUT CHARACTERISTICS
Parameters
Input Leakage Current Input Capacitance Input Hysteresis
Symbol
Iin Iin
Min
-
Typ
8 250
Max
10 -
Units
A pF mV
DIGITAL INTERFACE SPECIFICATIONS
(GND = 0 V; all voltages with respect to 0 V.) Parameters
High-Level Output Voltage, except MCLK_OUT and SDOUT (IOH=-4 mA) Low-Level Output Voltage, except MCLK_OUT and SDOUT (IOL=4 mA) High-Level Output Voltage, MCLK_OUT Low-Level Output Voltage, MCLK_OUT High-Level Output Voltage, SDOUT Low-Level Output Voltage, SDOUT High-Level Input Voltage Low-Level Input Voltage (IOH=-6 mA) (IOL=6 mA) (IOH=-8 mA) (IOL=8 mA)
Symbol
VOH VOL VOH VOL VOH VOL VIH VIL
Min
0.77xVL 0.77xVL 0.77xVL 0.6xVL -0.3
Max
.6 .6 .65 VL+0.3 0.8
Units
V V V V V V V V
SWITCHING SPECIFICATIONS
(Inputs: Logic 0 = 0 V, Logic 1 = VL; CL = 20 pF) Parameters
RST pin Low Pulse Width XTI Frequency (Note 7) XTI Pulse Width High/Low MCLK_OUT Duty Cycle (Note 6) Crystal Digital Clock Source
Symbol
Min
1 16.384 1.024 14.8 45 -
Max
27.000 27.000 55 24.576 18 -
Units
ms MHz MHz ns % MHz ns ns ns ns ns ns ns ns ns ns
Slave Mode
I/OSCLK Frequency OLRCK High Time I/OSCLK High Time I/OSCLK Low Time I/OLRCK Edge to I/OSCLK Rising OLRCK Rising Edge to OSCLK Rising Edge (TDM) I/OSCLK Rising Edge to I/OLRCK Edge OSCLK Rising Edge to OLRCK Falling Edge (TDM) OSCLK Falling Edge/OLRCK Edge to SDOUT Output Valid SDIN/TDM_IN Setup Time Before I/OSCLK Rising Edge SDIN/TDM_IN Hold Time After I/OSCLK Rising Edge (Note 8) tlrckh tsckh tsckl tlcks tfss tlckd tfsh tdpd tds tdh 326 9 9 6 5 5 5 3.5 5
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Parameters Master Mode (Note 9)
I/OSCLK Frequency (non-TDM) OSCLK Frequency (TDM) I/OLRCK Duty Cycle I/OSCLK Duty Cycle I/OSCLK Falling Edge to I/OLRCK Edge OSCLK Falling Edge to OLRCK Edge (TDM) OSCLK Falling Edge to SDOUT Output Valid SDIN/TDM_IN Setup Time Before I/OSCLK Rising Edge SDIN/TDM_IN Hold Time After I/OSCLK Rising Edge
I/OLRCK
(input)
Symbol
Min
64*Fsi/o 256*Fso 45 45
Max
Units
MHz MHz
55 55 5 5 7 -
% % ns ns ns ns ns
tlcks tfss tdpd tds tdh
tlrckh
3 5
tlckd
I/OSCLK
(input)
tlcks
tsckh
tsckl
OLRCK
(input)
tfss
OSCLK
(input)
tfsh
tsckh
tsckl
tds
SDIN
(input)
tdh
MSB MSB-1
tds
TDM_IN
(input)
tdh
MSB MSB-1
tdpd
SDOUT
(output)
tdpd
MSB MSB-1
SDOUT
(output)
MSB
MSB-1
Figure 1. Non-TDM Slave Mode Timing
Figure 2. TDM Slave Mode Timing
6. After powering up the CS8421, RST should be held low until the power supplies and clocks are settled. 7. The maximum possible sample rate is XTI/128. 8. OLRCK must remain high for at least 8 OSCLK periods in TDM Mode. 9. Only the input or the output serial port can be set as master at a given time.
I/OLRCK
(output)
tlcks
I/OSCLK
(output)
OLRCK
(output)
tfss
OSCLK
tds
SDIN
(input)
(output)
tdh
MSB MSB-1
TDM_IN
(input)
tds
tdh
MSB MSB-1
tdpd
SDOUT
tdpd
MSB MSB-1
SDOUT
(output)
(output)
MSB
MSB-1
Figure 3. Non-TDM Master Mode Timing
Figure 4. TDM Master Mode Timing
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CS8421 3. TYPICAL CONNECTION DIAGRAMS
+2.5 V
+3.3 V or +5.0 V
0.1 F VD Serial Audio Source ILRCK ISCLK SDIN TDM_IN VL OLRCK OSCLK SDOUT
0.1 F
Serial Audio Input Device
MS_SEL SAIF 1 k *
CS8421
XTI
SAOF SRC_UNLOCK BYPASS
**
RST GND GND
Hardware Control Settings
Figure 5. Typical Connection Diagram, No External Master Clock
* When no external master clock is supplied to the part, both input and output must be set to Slave Mode for the part to operate properly. This is done by connecting the MS_SEL pin to ground through a resistance of 0 to 1 k + 1% as stated in Table 1, "Serial Audio Port Master/Slave and Clock Ratio Select Start-Up Options (MS_SEL)," on page 19. ** The connection (VL or GND) and value of these two resistors determines the mode of operation for the input and output serial ports as described in Table 2 on page 19 and Table 3 on page 19.
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CS8421
+2.5 V
+3.3 V or +5.0 V
0.1 F VD Serial Audio Source ILRCK ISCLK SDIN TDM_IN VL OLRCK OSCLK SDOUT
0.1 F
Serial Audio Input Device
MS_SEL SAIF
CS8421
XTI XTO Crystal /Clock Source
SAOF SRC_UNLOCK BYPASS MCLK_OUT
*
RST GND GND
47 k
**
To external hardware
Hardware Control Settings
Figure 6. Typical Connection Diagram, Master and Slave Modes
* The connection (VL or GND) and value of these three resistors determines the mode of operation for the input and output serial ports as described in Table 1 Serial Audio Port Master/Slave and Clock Ratio Select Start-Up Options (MS_SEL), and Table 2, "Serial Audio Input Port Start-Up Options (SAIF)," on page 19 and Table 3, "Serial Audio Output Port Start-Up Options (SAOF)," on page 19. ** MCLK_OUT pin should be pulled high through a 47 k resistor if an MCLK output is not needed.
16
DS641F2
CS8421 4. APPLICATIONS
The CS8421 is a 32-bit, high-performance, monolithic CMOS stereo asynchronous sample-rate converter. The digital audio data is input and output through configurable 3-wire serial ports. The digital audio input/output ports offer Left-Justified, Right-Justified, and IS serial audio formats. The CS8421 also supports a TDM Mode which allows multiple channels of digital audio data on one serial line. A Bypass Mode allows the data to be passed directly to the output port without sample rate conversion. The CS8421 does not require a control port interface, helping to speed design time by not requiring the user to develop software to configure the part. Pins that are sensed after reset allow the part to be configured. See "Reset, Power-Down, and Start-Up" on page 23. Target applications include digital recording systems (DVD-R/RW, CD-R/RW, PVR, DAT, MD, and VTR), digital mixing consoles, high quality D/A, effects processors and computer audio systems. Figure 5 and 6 show the supply and external connections to the CS8421.
4.1
Three-wire Serial input/Output Audio Port
A 3-wire serial audio input/output port is provided. The interface format should be chosen to suit the attached device through the MS_SEL, SAIF, and SAOF pins. Tables 1, 2, and 3 show the pin functions and their corresponding settings. The following parameters are adjustable: * * * * Master or Slave Master clock (MCLK) frequencies of 128*Fsi/o, 256*Fsi/o, 384*Fsi/o, and 512*Fsi/o (Master Mode) Audio data resolution of 16-, 20-, 24-, or 32-bits Left- or Right-Justification of the data relative to left/right clock (LRCK) as well as IS
Figures 7, 8, and 9 show the input/output formats available. In Master Mode, the left/right clock and the serial bit clock are outputs, derived from the XTI input pin master clock. In Slave Mode, the left/right clock and the serial bit clock are inputs and may be asynchronous to the XTI master clock. The left/right clock should be continuous, but the duty cycle can be less than 50% if enough serial clocks are present in each phase to clock all of the data bits. ISCLK is always set to 64*Fsi when the input is set to master. In normal operation, OSCLK is set to 64*Fso. In TDM Slave Mode, OSCLK must operate at N*64*Fso, where N is the number of CS8421's connected together. In TDM Master Mode, OSCLK is set to 256*Fso For more information about serial audio formats, refer to the Cirrus Logic applications note AN282, "The 2-Channel Serial Audio Interface: A Tutorial", available at www.cirrus.com.
DS641F2
17
CS8421
I/OLRCK I/OSCLK SDIN SDOUT
M SB LSB MSB LSB Channel A Channel B
MSB
Figure 7. Serial Audio Interface Format - IS
I/OLRCK I/OSCLK SDIN SDOUT
M SB
Channel A
Channel B
LSB
MSB
LSB
MSB
Figure 8. Serial Audio Interface Format - Left-Justified
I/OLRCK I/OSCLK SDIN SDOUT
MSB Extended MSB MSB LSB LSB MSB Extended MSB MSB LSB LSB Channel A Channel B
Figure 9. Serial Audio Interface Format - Right-Justified
4.2
Mode Selection
The CS8421 uses the resistors attached to the MS_SEL, SAIF, and SAOF pins to determine the modes of operation. After reset, the resistor value and condition (VL or GND) are sensed. This operation will take approximately 4 s to complete. The SRC_UNLOCK pin will remain high and the SDOUT pin will be muted until the mode detection sequence has completed. After this, if all clocks are stable, SRC_UNLOCK will be brought low when audio output is valid and normal operation will occur. Tables 1, 2, and 3 show the pin functions and their corresponding settings. If the 1.0 k option is selected for MS_SEL, SAIF, or SAOF, the resistor connected to that pin may be replaced by a direct connection to VL or GND as appropriate. The resistor attached to each mode-selection pin should be placed physically close to the CS8421. The end of the resistor not connected to the mode selection pins should be connected as close as possible to VL and GND to minimize noise. Tables 1, 2, and 3 show the pin functions and their corresponding settings.
18
DS641F2
CS8421
MS_SEL pin Input M/S Output M/S
1.0 k 1% to GND Slave Slave 1.96 k 1% to GND Slave Master (128 x Fso) 4.02 k 1% to GND Slave Master (256 x Fso) 8.06 k 1% to GND Slave Master (384 x Fso) 16.2 k 1% to GND Slave Master (512 x Fso) 1.0 k 1% to VL Slave Master (128 x Fsi) 1.96 k 1% to VL Slave Master (256 x Fsi) Slave 4.02 k 1% to VL Master (384 x Fsi) Slave 8.06 k 1% to VL Master (512 x Fsi) Table 1. Serial Audio Port Master/Slave and Clock Ratio Select Start-Up Options (MS_SEL)
SAIF pin
Input Port Configuration
1.0 k 1% to GND IS up to 32-bit data 1.96 k 1% to GND Left-Justified up to 32-bit data 4.02 k 1% to GND Right-Justified 16-bit data 1.0 k 1% to VL Right-Justified 20-bit data 1.96 k 1% to VL Right-Justified 24-bit data 4.02 k 1% to VL Right-Justified 32-bit data Table 2. Serial Audio Input Port Start-Up Options (SAIF)
SAOF pin
Output Port Configuration
1.0 k 1% to GND IS 16-bit data 1.96 k 1% to GND IS 20-bit data 4.02 k 1% to GND IS 24-bit data 8.06 k 1% to GND IS 32-bit data 16.2 k 1% to GND Left-Justified 16-bit data 32.4 k 1% to GND Left-Justified 20-bit data 63.4 k 1% to GND Left-Justified 24-bit data 127.0 k 1% to GND Left-Justified 32-bit data 1.0 k 1% to VL Right-Justified 16-bit data 1.96 k 1% to VL Right-Justified 20-bit data 4.02 k 1% to VL Right-Justified 24-bit data 8.06 k 1% to VL Right-Justified 32-bit data 16.2 k 1% to VL TDM Mode 16-bit data 32.4 k 1% to VL TDM Mode 20-bit data 63.4 k 1% to VL TDM Mode 24-bit data 127.0 k 1% to VL TDM Mode 32-bit data Table 3. Serial Audio Output Port Start-Up Options (SAOF)
DS641F2
19
CS8421
4.3 Sample Rate Converter (SRC)
Multirate digital signal processing techniques are used to conceptually upsample the incoming data to a very high rate and then downsample to the outgoing rate. The internal data path is 32-bits wide even if a lower bit depth is selected at the output. The filtering is designed so that a full input audio bandwidth of 20 kHz is preserved if the input sample and output sample rates are greater than or equal to 44.1 kHz. When the output sample rate becomes less than the input sample rate, the input is automatically band-limited to avoid aliasing products in the output. Careful design ensures minimum ripple and distortion products are added to the incoming signal. The SRC also determines the ratio between the incoming and outgoing sample rates and sets the filter corner frequencies appropriately. Any jitter in the incoming signal has little impact on the dynamic performance of the rate converter and has no influence on the output clock.
4.3.1
Data Resolution and Dither
When using the serial audio input port in Left-Justified and IS Modes, all input data is treated as 32-bits wide. Any truncation that has been done prior to the CS8421 to less than 32-bits should have been done using an appropriate dithering process. If the serial audio input port is in Right-Justified Mode, the input data will be truncated to the bit depth set by SAIF pin setting. If the SAIF bit depth is set to 16-, 20-, or 24bits, and the input data is 32-bits wide, truncation distortion will occur. Similarly, in any serial audio input port mode, if an inadequate number of bit clocks are entered (i.e. 16 clocks instead of 20 clocks), the input words will be truncated, causing truncation distortion at low levels. In summary, there is no dithering mechanism on the input side of the CS8421, and care must be taken to ensure that no truncation occurs. Dithering is used internally where appropriate inside the SRC block. The output side of the SRC can be set to 16-, 20-, 24-, or 32-bits. Dithering is applied and is automatically scaled to the selected output word length. This dither is not correlated between left and right channels.
4.3.2
SRC Locking and Varispeed
The SRC calculates the ratio between the input sample rate and the output sample rate and uses this information to set up various parameters inside the SRC block. The SRC takes some time to make this calculation, approximately 4200/Fso (8.75 ms at Fso of 48 kHz). If Fsi is changing, as in a varispeed application, the SRC will track the incoming sample rate. During this tracking mode, the SRC will still rate convert the audio data, but at increased distortion levels. Once the incoming sample rate is stable, the SRC will return to normal levels of audio quality. The data buffer in the SRC can overflow if the input sample rate changes at greater than 10%/sec. There is no provision for varispeed applications where Fso is changing. The SRC_UNLOCK pin is used to indicate when the SRC is not locked. When RST is asserted, or if there is a change in Fsi or Fso, SRC_UNLOCK will be set high. The SRC_UNLOCK pin will continue to be high until the SRC has reacquired lock and settled, at which point it will transition low. When the SRC_UNLOCK pin is set low, SDOUT is outputting valid audio data. This can be used to signal a DAC to unmute its output.
4.3.3
Bypass Mode
When the BYPASS pin is set high, the input data bypasses the sample rate converter and is sent directly to the serial audio output port. No dithering is performed on the output data. This mode is ideal for passing non-audio data through without a sample-rate conversion. ILRCK and OLRCK should be the same sample rate and synchronous in this mode.
20
DS641F2
CS8421
4.3.4 Muting
The SDOUT pin is set to all zero output (full mute) immediately after the RST pin is set high. When the output from the SRC becomes valid, though the SRC may not have reached full performance, SDOUT is unmuted over a period of approximately 4096 OLRCK cycles (soft unmuted). When the output becomes invalid, depending on the condition, SDOUT is either immediately set to all zero output (hard muted) or SDOUT is muted over a period of approximately 4096 OLRCK cycles until it reaches full mute (soft muted). The SRC will soft mute SDOUT if there is an illegal ratio between ILRCK and the XTI master clock. Conditions that will cause the SRC to hard mute SDOUT include removing OLRCK, the RST pin being set low, or illegal ratios between OLRCK and the XTI master clock. After all invalid states have been cleared, the SRC will soft unmute SDOUT.
4.3.5
Group Delay and Phase Matching Between Multiple CS8421 Parts
The equation for the group delay through the sample rate converter is shown in "Digital Filter Characteristics" on page 12. This phase delay is equal across multiple parts. Therefore, when multiple parts operate at the same Fsi and Fso and use a common XTI/XTO clock, their output data is phase matched.
4.3.6
Master Clock
The CS8421 uses the clock signal supplied through XTI as its master clock (MCLK). MCLK can be supplied from a digital clock source, a crystal oscillator, or a fundamental mode crystal. Figure 10 shows the typical connection diagram for using a fundamental mode crystal. Please refer to the crystal manufacturer's specifications for the external capacitor recommendations. If XTO is not used, such as with a digital clock source or crystal oscillator, XTO should be left unconnected or pulled low through a 47 k resistor to GND. If either serial audio port is set as master, MCLK will be used to supply the sub-clocks to the master SCLK and LRCK. In this case, MCLK will be synchronous to the master serial audio port. If both serial audio ports are set as slave, MCLK can be asynchronous to either or both ports. If the user needs to change the clock source to XTI while the CS8421 is still powered on and running, a RESET must be issued once the XTI clock source is present and valid to ensure proper operation. When both serial ports are configured as slave and operating at sample rates less than 96 kHz, the CS8421 has the ability to operate without a master clock input through XTI. This benefits the design by not requiring extra external clock components (lowering production cost) and not requiring a master clock to be routed to the CS8421, resulting in lowered noise contribution in the system. In this mode, an internal oscillator provides the clock to run all of the internal logic. To enable the internal oscillator, simply tie XTI to GND or VL. In this mode, XTO should be left unconnected. The CS8421 can also provide a buffered MCLK output through the MCLK_OUT pin. This pin can be used to supply MCLK to other system components that operate synchronously to MCLK. If MCLK_OUT is not needed, the output of the pin can be disabled by pulling the pin high through a 47 k resistor to VL. MCLK_OUT is also disabled when using the internal oscillator mode. The MCLK_OUT pin will be set low when disabled by using the internal oscillator mode.
DS641F2
21
CS8421
4.3.7 Clocking
In order to ensure proper operation of the CS8421, the clock or crystal attached to XTI must simultaneously satisfy the requirements of LRCK for both the input and output as follows: * * * If the input is set to master, Fsi XTI/128 and Fso XTI/130. If the output is set to master, Fso XTI/128 and Fsi XTI/130. If both input and output are set to slave, XTI 130*[maximum(Fsi,Fso)], XTI/Fsi < 3750, and XTI/Fso < 3750.
XTI
XTO R
C
C
Figure 10. Typical Connection Diagram for Crystal Circuit
4.4
Time Division Multiplexing (TDM) Mode
TDM Mode allows several CS8421 to be serially connected together allowing their corresponding SDOUT data to be multiplexed onto one line for input into a DSP or other TDM-capable multichannel device. The CS8421 can operate in two TDM modes. The first mode consists of all of the CS8421's output ports set to slave, as shown in Figure 13. The second mode consists of one CS8421 output port set to master and the remaining CS8421's output ports set to slave, as shown in Figure 14. The TDM_IN pin is used to input the data, while the SDOUT pin is used to output the data. The first CS8421 in the chain should have its TDM_IN set to GND. Data is transmitted from SDOUT most significant bit first on the first OSCLK falling edge after an OLRCK transition and is valid on the rising edge of OSCLK. In TDM Slave Mode, the number of channels that can by multiplexed to one serial data line depends on the output sampling rate. For Slave Mode, OSCLK must operate at N*64*Fso, where N is the number of CS8421's connected together. The maximum allowable OSCLK frequency is 24.576 MHz, so for Fso = 48 kHz, N = 8 (16 channels of serial audio data). In TDM Master Mode, OSCLK operates at 256*Fso, which is equivalent to N = 4, so a maximum of 8 channels of digital audio can be multiplexed together. Note that for TDM Master Mode, MCLK must be at least 256*Fso, where Fso 96 kHz. OLRCK identifies the start of a new frame. Each time-slot is 32-bits wide, with the valid data sample left-justified within the time-slot. Valid data lengths are 16-, 20-, 24- or 32-bits. Figures 11 and 12 show the interface format for Master and Slave TDM Modes with a 32-bit word-length.
OLRCK OSCLK SDOUT/ TDM_IN MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB
SDOUT 4, ch A
SDOUT 4, ch B
SDOUT 3, ch A
SDOUT 3, ch B
SDOUT 2, ch A
SDOUT 2, ch B
SDOUT 1, ch A
SDOUT 1, ch B
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
Figure 11. TDM Slave Mode Timing Diagram
22
DS641F2
CS8421
256 OSCLKs
OLRCK OSCLK SDOUT/ TDM_IN MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB MSB LSB
SDOUT 4, ch A
SDOUT 4, ch B
SDOUT 3, ch A
SDOUT 3, ch B
SDOUT 2, ch A
SDOUT 2, ch B
SDOUT 1, ch A
SDOUT 1, ch B
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
32 clks
Figure 12. TDM Master Mode Timing Diagram
Output Clock Source
LRCK SCLK
CS84211
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
CS84212
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
CS84213
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
CS84214
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
DSP
LRCK SCLK SDIN
Slave
SDIN SDIN
Slave
SDIN
Slave
SDIN
Slave
Slave
OLRCK
OSCLK
SDOUT
OLRCK
OSCLK
SDOUT
OLRCK
OSCLK
SDOUT
OLRCK
OSCLK
SDOUT
PCM Source 1
PCM Source 2
PCM Source 3
PCM Source 4
Figure 13. TDM Mode Configuration (All CS8421 Outputs are Slave)
CS84211
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
CS84212
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
CS84213
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
CS84214
OLRCK OSCLK TDM_IN ILRCK ISCLK SDOUT
DSP
LRCK SCLK SDIN
Master
SDIN SDIN
Slave
SDIN
Slave
SDIN
Slave
Slave
OLRCK
OSCLK
SDOUT
OLRCK
OSCLK
SDOUT
OLRCK
OSCLK
SDOUT
OLRCK
OSCLK
SDOUT
PCM Source 1
PCM Source 2
PCM Source 3
PCM Source 4
Figure 14. TDM Mode Configuration (First CS8421 Output is Master, All Others are Slave)
4.5
Reset, Power-Down, and Start-Up
When RST is low, the CS8421 enters a low-power mode, all internal states are reset, and the outputs are disabled. After RST transitions from low to high, the part senses the resistor value on the configuration pins (MS_SEL, SAIF, and SAOF) and sets the appropriate mode of operation. After the mode has been set (approximately 4 s), the part is set to normal operation and all outputs are functional.
DS641F2
23
CS8421
4.6 Power Supply, Grounding, and PCB Layout
The CS8421 operates from a VD = +2.5 V and VL = +3.3 V or +5.0 V supply. These supplies may be set independently. Follow normal supply decoupling practices; see Figure 6. Extensive use of power and ground planes, ground-plane fill in unused areas, and surface-mount decoupling capacitors are recommended. Decoupling capacitors should be mounted on the same side of the board as the CS8421 to minimize inductance effects, and all decoupling capacitors should be as close to the CS8421 as possible. The pin of the configuration resistors not connected to MS_SEL, SAIF, and SAOF should be connected as close as possible to VL or GND. The CS8421 is available in the compact QFN package. The underside of the QFN package reveals a metal pad that serves as a thermal relief to provide for optimal heat dissipation. This pad must mate with an equally dimensioned copper pad on the PCB and must be electrically connected to ground. A series of vias should be used to connect this copper pad to one or more larger ground planes on other PCB layers.
24
DS641F2
CS8421 5. PERFORMANCE PLOTS
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
d B F S +0 -20 -40 -60 -80 -100 -120 -140 -160 -180 -200 20k 40k Hz 60k 80k
Figure 15. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 48 kHz:48 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
Figure 16. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 44.1 kHz:192 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 2.5k 5k 7.5k 10k Hz 12.5k 15k 17.5k 20k
Figure 17. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 44.1 kHz:48 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 10k 20k Hz 30k 40k
Figure 18. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 48 kHz:44.1 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
Figure 19. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 48 kHz:96 kHz
Figure 20. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 96 kHz:48 kHz
DS641F2
25
CS8421
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
-180 -200 d B F S -60 -80 -100 -120 -140 -160
10k
20k Hz
30k
40k
Figure 21. Wideband FFT Plot (16k Points) 0 dBFS 1 kHz Tone, 192 kHz:48 kHz
Figure 22. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 48 kHz:96 kHz
-60 -80 -100 d B F S -120 -140 -160 -180 -200
d B F S
-60 -80 -100 -120 -140 -160 -180 -200
5k
10k Hz
15k
20k
20k
40k Hz
60k
80k
Figure 23. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 48 kHz:48 kHz
Figure 24. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 44.1 kHz:192 kHz
-60 -80 -100 d B F S -120 -140 -160 -180 -200
d B F S
-60 -80 -100 -120 -140 -160 -180 -200
5k
10k Hz
15k
20k
2.5k
5k
7.5k
10k Hz
12.5k
15k
17.5k
20k
Figure 25. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 44.1 kHz:48 kHz
Figure 26. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 48 kHz:44.1 kHz
26
DS641F2
CS8421
+0
-60 -80 -100 d B F S -120 -140 -160 -180 -200
d B F S
-20 -40 -60 -80 -100 -120 -140 -160 -180
5k
10k Hz
15k
20k
-200
5k
10k Hz
15k
20k
Figure 27. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 96 kHz:48 kHz
Figure 28. IMD, 10 kHz and 11 kHz -7 dBFS, 96 kHz:48 kHz
+0
-60 -80 -100 d B F S -120 -140 -160 -180 -200
-20 -40 -60 d B F S -80 -100 -120 -140 -160 -180
5k 10k Hz 15k 20k
-200
2.5k
5k
7.5k
10k Hz
12.5k
15k
17.5k
20k
Figure 29. Wideband FFT Plot (16k Points) -60 dBFS 1 kHz Tone, 192 kHz:48 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
d B F S
Figure 30. IMD, 10 kHz and 11 kHz -7 dBFS, 48 kHz:44.1 kHz
+0 -20 -40 -60 -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
Figure 31. IMD, 10 kHz and 11 kHz -7 dBFS, 44.1 kHz:48 kHz
Figure 32. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 44.1 kHz:48 kHz
DS641F2
27
CS8421
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 20k 40k Hz 60k 80k
-200
10k
20k Hz
30k
40k
Figure 33. Wideband FFT Plot (16k Points) 0 dBFS 80 kHz Tone, 192 kHz:192 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
Figure 34. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 48 kHz:96 kHz
+0 -20 -40 -60 d B F S -80 -100 -120 -140 -160 -180 -200 5k 10k Hz 15k 20k
Figure 35. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 48 kHz:48 kHz
+0 -20 -40
Figure 36. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 96 kHz:48 kHz
-120 -122.5 -125 -127.5
-60 d B F S -80 -100 -120 -140 -160 -180 -200 2.5k 5k 7.5k 10k Hz 12.5k 15k 17.5k 20k
-130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
Figure 37. Wideband FFT Plot (16k Points) 0 dBFS 20 kHz Tone, 48 kHz:44.1 kHz
Figure 38. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 192 kHz
28
DS641F2
CS8421
-120 -122.5 -125 -127.5 -130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
d B F S -120 -122.5 -125 -127.5 -130 -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
Figure 39. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 48 kHz
-120 -122.5 -125 -127.5 -130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
Figure 40. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 96 kHz
-135 -136 -137 -138 d B F S -139 -140 -141 -142 -143 -144 -145 50k 75k 100k Hz 125k 150k 175k
Figure 41. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 44.1 kHz
-120 -122.5 -125 -127.5 -130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
d B F S
Figure 42. Dynamic Range vs. Output Sample Rate, 60 dBFS 1 kHz Tone, Fsi = 192 kHz
-120 -122.5 -125 -127.5 -130 -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
Figure 43. THD+N vs. Output Sample Rate, 0 dBFS 1 kHz Tone, Fsi = 32 kHz
Figure 44. Dynamic Range vs. Output Sample Rate, 60 dBFS 1 kHz Tone, Fsi = 32 kHz
DS641F2
29
CS8421
-120 -122.5 -125 -127.5 -130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
-120 -122.5 -125 -127.5 -130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
Figure 45. Dynamic Range vs. Output Sample Rate, 60 dBFS 1 kHz Tone, Fsi = 96 kHz
+0
Figure 46. Dynamic Range vs. Output Sample Rate, 60 dBFS 1 kHz Tone, Fsi = 44.1 kHz
+0 -0.02
-20 -40 d B F S -60
192 kHz:96 kHz
-0.04 -0.06
192 kHz:48 kHz
-80 -100
192 kHz:32 kHz
d B F S
-0.08 -0.1 -0.12 -0.14 -0.16 -0.18
-120 -140 0 10k 20k 30k Hz 40k 50k 60k
-0.2 0
5k
10k Hz
15k
20k
25k
Figure 47. Frequency Response with 0 dBFS Input
Figure 48. Passband Ripple, 192 kHz:48 kHz
-120
+0
-122.5 -125 -127.5 -130 d B F S -132.5 -135 -137.5 -140 -142.5 -145 -147.5 -150 50k 75k 100k Hz 125k 150k 175k
d B F S
-10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 49. Dynamic Range vs. Output Sample Rate, 60 dBFS 1 kHz Tone, Fsi = 48 kHz
Figure 50. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 48 kHz:48 kHz
30
DS641F2
CS8421
+0 -10 -20 -30 -40 -50 d B F S -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
d B F S
+0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 51. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 48 kHz:44.1 kHz
+0 -10 -20 -30 -40 -50 d B F S -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 52. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 48 kHz:96 kHz
+0 -10 -20 -30 -40 -50 d B F S -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 53. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 96 kHz:48 kHz
+0 -10 -20 -30 -40 -50 d B F S -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
d B F S
Figure 54. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 44.1 kHz:192 kHz
+0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 55. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 44.1 kHz:48 kHz
Figure 56. Linearity Error, 0 to -140 dBFS Input, 200 Hz Tone, 192 kHz:44.1 kHz
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CS8421
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 57. THD+N vs. Input Amplitude, 1 kHz Tone, 48 kHz:44.1 kHz
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 58. THD+N vs. Input Amplitude, 1 kHz Tone, 48 kHz:96 kHz
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 59. THD+N vs. Input Amplitude, 1 kHz Tone, 96 kHz:48 kHz
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
d B F S
Figure 60. THD+N vs. Input Amplitude, 1 kHz Tone, 44.1 kHz:192 kHz
-110 -115 -120 -125 -130 -135 -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 61. THD+N vs. Input Amplitude, 1 kHz Tone, 44.1 kHz:48 kHz
Figure 62. THD+N vs. Input Amplitude, 1 kHz Tone, 192 kHz:48 kHz
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-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 0 2.5k 5k 7.5k 10k Hz 12.5k 15k 17.5k 20k
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 -140 -120 -100 -80 dBFS -60 -40 -20 +0
Figure 63. THD+N vs. Frequency Input, 0 dBFS, 48 kHz:44.1 kHz
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 0 2.5k 5k 7.5k 10k Hz 12.5k 15k 17.5k 20k
Figure 64. THD+N vs. Frequency Input, 0 dBFS, 48 kHz:96 kHz
-110 -115 -120 -125 -130 -135 d B F S -140 -145 -150 -155 -160 -165 -170 -175 -180 0 2.5k 5k 7.5k 10k Hz 12.5k 15k 17.5k 20k
Figure 65. THD+N vs. Frequency Input, 0 dBFS, 44.1 kHz:48 kHz
Figure 66. THD+N vs. Frequency Input, 0 dBFS, 96 kHz:48 kHz
All performance plots represent typical performance. Measurements for all performance plots were taken under the following conditions, unless otherwise stated: * * * * * * * * VD = 2.5 V, VL = 3.3 V Serial Audio Input port set to slave Serial Audio Output port set to slave Input and output clocks and data are asynchronous XTI/XTO = 27 MHz Input signal = 1.000 kHz, 0 dBFS Measurement Bandwidth = 20 to (Fso/2) Hz Word Width = 24 Bits
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CS8421 6. PACKAGE DIMENSIONS 20L TSSOP (4.4 MM BODY) PACKAGE DRAWING
N
D
E11 A2 A1
L
E
A
e b2 SIDE VIEW
123
END VIEW
SEATING PLANE
TOP VIEW
INCHES DIM A A1 A2 b D E E1 e L MIN -0.002 0.03346 0.00748 0.252 0.248 0.169 -0.020 0 NOM -0.004 0.0354 0.0096 0.256 0.2519 0.1732 -0.024 4 MAX 0.043 0.006 0.037 0.012 0.259 0.256 0.177 0.026 0.028 8 MIN -0.05 0.85 0.19 6.40 6.30 4.30 -0.50 0
MILLIMETERS NOM --0.90 0.245 6.50 6.40 4.40 -0.60 4 MAX 1.10 0.15 0.95 0.30 6.60 6.50 4.50 0.65 0.70 8
NOTE
2,3 1 1
JEDEC #: MO-153
Controlling Dimension is Millimeters.
Notes:
1. "D" and "E1" are reference datums and do not included mold flash or protrusions, but do include mold mismatch and are measured at the parting line, mold flash or protrusions shall not exceed 0.20 mm per side. 2. Dimension "b" does not include dambar protrusion/intrusion. Allowable dambar protrusion shall be 0.13 mm total in excess of "b" dimension at maximum material condition. Dambar intrusion shall not reduce dimension "b" by more than 0.07 mm at least material condition. 3. These dimensions apply to the flat section of the lead between 0.10 and 0.25 mm from lead tips.
TSSOP THERMAL CHARACTERISTICS
Parameter
Junction to Ambient Thermal Impedance 2 Layer Board 4 Layer Board
Symbol
JA
Min
-
Typ
48 38
Max
-
Units
C/Watt C/Watt
34
DS641F2
CS8421 20-PIN QFN (5 x 5 MM BODY) PACKAGE DRAWING
D b e Pin #1 Corner
Pin #1 Corner
E
E2
A1 A
L
D2
Top View
Side View
Bottom View
DIM
A A1 b D D2 E E2 e L
MIN
-0.0000 0.0091 0.1201 0.1202 0.0197
INCHES NOM
--0.0110 0.1969 BSC 0.1220 0.1969 BSC 0.1221 0.0256 BSC 0.0236
MAX
0.0394 0.0020 0.0130 0.1240 0.1241 0.0276
MIN
-0.00 0.23 3.05 3.05 0.50
MILLIMETERS NOM
--0.28 5.00 BSC 3.10 5.00 BSC 3.10 0.65 BSC 0.60
NOTE MAX
1.00 0.05 0.33 3.15 3.15 0.70 1 1 1, 2 1 1 1 1 1 1
JEDEC #: MO-220 Controlling Dimension is Millimeters.
1. Dimensioning and tolerance per ASME Y 14.5M-1995. 2. Dimensioning lead width applies to the plated terminal and is measured between 0.23mm and 0.33mm from the terminal tip.
QFN THERMAL CHARACTERISTICS
Parameter
Junction to Ambient Thermal Impedance 2 Layer Board 4 Layer Board
Symbol
JA
Min
-
Typ
128 35
Max
-
Units
C/Watt C/Watt
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CS8421 7. ORDERING INFORMATION
ORDERING INFORMATION Product Description Package
20-TSSOP -10 to +70C CS8421 32-bit Asynchronous Sample Rate Converter 20-QFN 20-TSSOP CDB8421 Evaluation Board for CS8421 YES -40 to +85C Pb-Free Temp Range
Container
Rail Tape and Reel Rail Tape and Reel Rail Tape and Reel -
Order# CS8421-CZZ CS8421-CZZR CS8421-CNZ CS8421-CNZR CS8421-DZZ CS8421-DZZR CDB8421
8. REVISION HISTORY
Release
A1 Initial Advance Release -Updated "Features" on page 1. -Updated "Sample Rate with other XTI clocks" on page 11. -Updated "DC Electrical Characteristics" on page 12. -Updated "Digital Input Characteristics" on page 13. -Updated "Digital Interface Specifications" on page 13 -Updated Figure 6. "Typical Connection Diagram, Master and Slave Modes" on page 16. -Added Figure 5. "Typical Connection Diagram, No External Master Clock" on page 15. -Corrected reference to Bypass Mode to output only data on page 17. -Added Section 4.3.7 "Clocking" on page 22. -Updated "Master Clock" on page 21. -Updated "Time Division Multiplexing (TDM) Mode" on page 22. -Added Thermal Pad label "Pin Descriptions" on page 6. -Added Thermal Pad pin description to "QFN Pin Descriptions" on page 8. -Updated "Performance Plots" on page 25. -Updated "Characteristics and Specifications" on page 10. -Corrected Section 4.3.7 "Clocking" on page 22. -Corrected "QFN Thermal Characteristics" on page 35. -Updated "Digital Interface Specifications" on page 13. -Updated "Switching Specifications" on page 13. Final Release -Updated Thermal Pad pin description in "QFN Pin Descriptions" on page 8. -Updated "Power Supply, Grounding, and PCB Layout" on page 24.
Changes
PP1
PP2 PP3 F1 F2
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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 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.
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