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Four ADCs/Eight DACs with PLL, 192 kHz, 24-Bit Codec AD1937
FEATURES
PLL-generated clock or direct master clock Low EMI design 112 dB DAC/107 dB ADC dynamic range and SNR -96 dB THD + N Single 3.3 V supply Tolerance for 5 V logic inputs Supports 24-bits and 8 kHz to 192 kHz sample rates Differential ADC input Differential DAC output Log volume control with autoramp function I2C-controllable for flexibility Software-controllable clickless mute Software power-down Right-justified, left-justified, I2S, and TDM modes Master and slave modes up to 16-channel input/output Available in a 64-lead LQFP AECQ-100 qualified
GENERAL DESCRIPTION
The AD1937 is a high performance, single-chip codec that provides four analog-to-digital converters (ADCs) with differential input and eight digital-to-analog converters (DACs) with differential output, using the Analog Devices, Inc., patented multibit sigmadelta (-) architecture. An I2C(R) port is included, allowing a microcontroller to adjust volume and many other parameters. The AD1937 operates from 3.3 V digital and analog supplies. The AD1937 is available in a 64-lead (differential output) LQFP. The AD1937 is designed for low EMI. This consideration is apparent in both the system and circuit design architectures. By using the on-board PLL to derive the master clock from the LR (frame) clock or from an external crystal, the AD1937 eliminates the need for a separate high frequency master clock and can also be used with a suppressed bit clock. The DACs and ADCs are designed using the latest Analog Devices continuous time architecture to further minimize EMI. By using 3.3 V supplies, power consumption is minimized and further reduces emissions.
APPLICATIONS
Automotive audio systems Home theater systems Set-top boxes Digital audio effects processors
FUNCTIONAL BLOCK DIAGRAM
DIGITAL AUDIO INPUT/OUTPUT
AD1937
SERIAL DATA PORT DAC DAC ADC ANALOG AUDIO INPUTS ADC ADC ADC DIGITAL FILTER SDATA OUT SDATA IN CLOCKS TIMING MANAGEMENT AND CONTROL (CLOCK AND PLL) DAC DIGITAL FILTER AND VOLUME CONTROL DAC DAC DAC DAC DAC PRECISION VOLTAGE REFERENCE I2C CONTROL PORT ANALOG AUDIO OUTPUTS
CONTROL DATA INPUT/OUTPUT
Figure 1.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2008 Analog Devices, Inc. All rights reserved.
07414-001
AD1937 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Test Conditions ............................................................................. 3 Analog Performance Specifications ........................................... 3 Crystal Oscillator Specifications................................................. 5 Digital Specifications ................................................................... 6 Power Supply Specifications........................................................ 6 Digital Filters ................................................................................. 7 Timing Specifications .................................................................. 8 Timing Diagrams.......................................................................... 9 Absolute Maximum Ratings.......................................................... 10 Thermal Resistance .................................................................... 10 ESD Caution ................................................................................ 10 Pin Configuration and Function Descriptions ........................... 11 Typical Performance Characteristics ........................................... 13 Theory of Operation ...................................................................... 15 Analog-to-Digital Converters (ADCs) .................................... 15 Digital-to-Analog Converters (DACs) .................................... 15 Clock Signals ............................................................................... 15 Reset and Power-Down ............................................................. 16 I2C Control Port.......................................................................... 16 Power Supply and Voltage Reference....................................... 18 Serial Data Ports--Data Format ............................................... 19 Time-Division Multiplexed (TDM) Modes ............................ 20 Daisy-Chain Mode ..................................................................... 23 Additional Modes ....................................................................... 26 Control Registers ............................................................................ 27 Definitions ................................................................................... 27 PLL and Clock Control Registers ............................................. 27 DAC Control Registers .............................................................. 28 ADC Control Registers .............................................................. 30 Applications Circuits...................................................................... 32 Outline Dimensions ....................................................................... 33 Ordering Guide .......................................................................... 33
REVISION HISTORY
9/08--Revision 0: Initial Version
Rev. 0 | Page 2 of 36
AD1937 SPECIFICATIONS
TEST CONDITIONS
Performance of all channels is identical, exclusive of the interchannel gain mismatch and interchannel phase deviation specifications. Table 1.
Parameter Supply Voltages (AVDD, DVDD) Temperature Master Clock Input Sample Rate Measurement Bandwidth Word Width Load Capacitance (Digital Output) Load Current (Digital Output) Input Voltage High Input Voltage Low Value 3.3 V As specified in Table 2 and Table 3 12.288 MHz (48 kHz fS, 256 x fS mode) 48 kHz 20 Hz to 20 kHz 24 bits 20 pF 1 mA or 1.5 k to 1/2 DVDD supply 2.0 V 0.8 V
ANALOG PERFORMANCE SPECIFICATIONS
Specifications guaranteed at a TA of 25C. Table 2.
Parameter ANALOG-TO-DIGITAL CONVERTERS ADC Resolution Dynamic Range No Filter (RMS) With A-Weighted Filter (RMS) Total Harmonic Distortion + Noise Full-Scale Input Voltage (Differential) Gain Error Interchannel Gain Mismatch Offset Error Gain Drift Interchannel Isolation CMRR Input Resistance Input Capacitance Input Common-Mode Bias Voltage DIGITAL-TO-ANALOG CONVERTERS DAC Resolution Dynamic Range No Filter (RMS) With A-Weighted Filter (RMS) With A-Weighted Filter (Average) Conditions/Comments All ADCs 20 Hz to 20 kHz, -60 dB input 96 98 -1 dBFS -10 -0.25 -10 Min Typ 24 102 105 -96 1.9 Max Unit Bits dB dB dB V rms % dB mV ppm/C dB dB dB k pF V Bits dB dB dB
-87 +10 +0.25 +10
100 mV rms, 1 kHz 100 mV rms, 20 kHz
0 100 -110 55 55 14 10 1.5 24
All DACs 20 Hz to 20 kHz, -60 dB input 102 105
107 110 112
Rev. 0 | Page 3 of 36
AD1937
Parameter Total Harmonic Distortion + Noise Conditions/Comments 0 dBFS Two channels running Eight channels running Min Typ -94 -86 1.76 (4.96) -10 -0.2 -25 -30 Max Unit dB dB V rms (V p-p) % dB mV ppm/C dB Degrees dB dB dB V V V V V
-76 +10 +0.2 +25 +30
Full-Scale Output Voltage Gain Error Interchannel Gain Mismatch Offset Error Gain Drift Interchannel Isolation Interchannel Phase Deviation Volume Control Step Volume Control Range De-emphasis Gain Error Output Resistance at Each Pin REFERENCE Internal Reference Voltage External Reference Voltage Common-Mode Reference Output REGULATOR Input Supply Voltage Regulated Output Voltage
-6 100 0 0.375 95
0.6 100 FILTR pin FILTR pin CM pin VSUPPLY pin VSENSE pin 1.50 1.50 1.50 5 3.37
1.32
1.68
4.5 3.19
5.5 3.55
Rev. 0 | Page 4 of 36
AD1937
Specifications measured at a TC of 130C. Table 3.
Parameter ANALOG-TO-DIGITAL CONVERTERS ADC Resolution Dynamic Range No Filter (RMS) With A-Weighted Filter (RMS) Total Harmonic Distortion + Noise Full-Scale Input Voltage (Differential) Gain Error Interchannel Gain Mismatch Offset Error DIGITAL-TO-ANALOG CONVERTERS DAC Resolution Dynamic Range No Filter (RMS) With A-Weighted Filter (RMS) With A-Weighted Filter (Average) Total Harmonic Distortion + Noise Conditions/Comments All ADCs 20 Hz to 20 kHz, -60 dB input 93 96 -1 dBFS -10 -0.25 -10 All DACs 20 Hz to 20 kHz, -60 dB input 101 104 0 dBFS Two channels running Eight channels running -10 -0.2 -25 -30 FILTR pin FILTR pin CM pin VSUPPLY pin VSENSE pin Min Typ 24 102 104 -96 1.9 Max Unit Bits dB dB dB V rms % dB mV Bits dB dB dB dB dB V rms (V p-p) % dB mV ppm/C V V V V V
-87 +10 +0.25 +10
0 24 107 110 112 -94 -86 1.76 (4.96)
-70 +10 +0.2 +25 +30
Full-Scale Output Voltage Gain Error Interchannel Gain Mismatch Offset Error Gain Drift REFERENCE Internal Reference Voltage External Reference Voltage Common-Mode Reference Output REGULATOR Input Supply Voltage Regulated Output Voltage
-6
1.32
1.50 1.50 1.50 5 3.43
1.68
4.5 3.2
5.5 3.65
CRYSTAL OSCILLATOR SPECIFICATIONS
Table 4.
Parameter Transconductance Min Typ 3.5 Max Unit mmhos
Rev. 0 | Page 5 of 36
AD1937
DIGITAL SPECIFICATIONS
-40C < TA < +130C, DVDD = 3.3 V 10%. Table 5.
Parameter INPUT High Level Input Voltage (VIH) Low Level Input Voltage (VIL) Input Leakage Input Capacitance OUTPUT High Level Output Voltage (VOH) Low Level Output Voltage (VOL) Conditions/Comments Min 2.0 2.2 0.8 10 10 5 DVDD - 0.60 0.4 Typ Max Unit V V V A A pF V V
MCLKI/MCLKXI pin IIH @ VIH = 2.4 V IIL @ VIL = 0.8 V
IOH = 1 mA IOL = 1 mA
POWER SUPPLY SPECIFICATIONS
Table 6.
Parameter SUPPLIES Voltage Conditions/Comments DVDD AVDD VSUPPLY Master clock = 256 fS fS = 48 kHz fS = 96 kHz fS = 192 kHz fS = 48 kHz to 192 kHz Min 3.0 3.0 4.5 Typ 3.3 3.3 5.0 56 65 95 2.0 74 23 Master clock = 256 fS, 48 kHz 429 185 244 83 1 kHz, 200 mV p-p 20 kHz, 200 mV p-p 50 50 mW mW mW mW dB dB Max 3.6 3.6 5.5 Unit V V V mA mA mA mA mA mA
Digital Current Normal Operation
Power-Down Analog Current Normal Operation Power-Down DISSIPATION Operation All Supplies Digital Supply Analog Supply Power-Down, All Supplies POWER SUPPLY REJECTION RATIO Signal at Analog Supply Pins
Rev. 0 | Page 6 of 36
AD1937
DIGITAL FILTERS
Table 7.
Parameter ADC DECIMATION FILTER Pass Band Pass-Band Ripple Transition Band Stop Band Stop-Band Attenuation Group Delay DAC INTERPOLATION FILTER Pass Band Mode All modes, typical @ 48 kHz Factor 0.4375 x fS 0.5 x fS 0.5625 x fS 79 22.9844 / fS 48 kHz mode, typical @ 48 kHz 96 kHz mode, typical @ 96 kHz 192 kHz mode, typical @ 192 kHz 48 kHz mode, typical @ 48 kHz 96 kHz mode, typical @ 96 kHz 192 kHz mode, typical @ 192 kHz 48 kHz mode, typical @ 48 kHz 96 kHz mode, typical @ 96 kHz 192 kHz mode, typical @ 192 kHz 48 kHz mode, typical @ 48 kHz 96 kHz mode, typical @ 96 kHz 192 kHz mode, typical @ 192 kHz 48 kHz mode, typical @ 48 kHz 96 kHz mode, typical @ 96 kHz 192 kHz mode, typical @ 192 kHz 48 kHz mode, typical @ 48 kHz 96 kHz mode, typical @ 96 kHz 192 kHz mode, typical @ 192 kHz 0.4535 x fS 0.3646 x fS 0.3646 x fS 479 22 35 70 0.01 0.05 0.1 0.5 x fS 0.5 x fS 0.5 x fS 0.5465 x fS 0.6354 x fS 0.6354 x fS 70 70 70 25 / fS 11 / fS 8 / fS 521 115 42 24 48 96 26 61 122 Min Typ 21 0.015 24 27 Max Unit kHz dB kHz kHz dB s kHz kHz kHz dB dB dB kHz kHz kHz kHz kHz kHz dB dB dB s s s
Pass-Band Ripple
Transition Band
Stop Band
Stop-Band Attenuation
Group Delay
Rev. 0 | Page 7 of 36
AD1937
TIMING SPECIFICATIONS
-40C < TA < +130C, DVDD = 3.3 V 10%. Table 8.
Parameter INPUT MASTER CLOCK (MCLK) AND RESET tMH tMH fMCLK fMCLK tPDR tPDRR PLL Lock Time 256 fS VCO Clock, Output Duty Cycle, MCLKO/MCLKXO Pin I2C fSCL tSCLL tSCLH tSCS tSCH tSSH tDS tSR tSF tBFT DAC SERIAL PORT tDBH tDBL tDLS tDLH tDDS tDDH ADC SERIAL PORT tABH tABL tALS tALH tABDD AUXILIARY INTERFACE tAXDS tAXDH tDXDD tXBH tXBL tDLS tDLH MCLK frequency Low Recovery MCLK or LRCLK 40 See Figure 13 and Figure 14 SCL clock frequency SCL low SCL high Setup time (start condition) Hold time (start condition) Setup time (stop condition) Data setup time SDA and SCL rise time SDA and SCL fall time Bus-free time DBCLK high DBCLK low DLRCLK setup DLRCLK skew DLRCLK hold DSDATA setup DSDATA hold ABCLK high ABCLK low ALRCLK setup ALRCLK skew ALRCLK hold ASDATA delay AAUXDATA setup AAUXDATA hold DAUXDATA delay AUXBCLK high AUXBCLK low AUXLRCLK setup AUXLRCLK hold 400 1.3 0.6 0.6 0.6 0.6 100 300 300 Between stop and start See Figure 2 Slave mode Slave mode To DBCLK rising, slave mode From DBCLK falling, master mode From DBCLK rising, slave mode To DBCLK rising From DBCLK rising See Figure 3 Slave mode Slave mode To ABCLK rising, slave mode From ABCLK falling, master mode From ABCLK rising, slave mode From ABCLK falling, any mode To AUXBCLK rising From AUXBCLK rising From AUXBCLK falling 1.3 10 10 10 -8 5 10 5 10 10 10 -8 5 kHz s s s s s ns ns ns s ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns Condition MCLK duty cycle Comments DAC/ADC clock source = PLL clock @ 256 fS, 384 fS, 512 fS, and 768 fS DAC/ADC clock source = direct MCLK @ 512 fS (bypass on-chip PLL) PLL mode, 256 fS reference Direct 512 fS mode Reset to active output Min 40 40 6.9 15 4096 10 60 Max 60 60 13.8 27.6 Unit % % MHz MHz ns tMCLK ms %
Relevent for repeated start condition First clock generated after this period
+8
+8 18
10 5 18 10 10 10 5
To AUXBCLK rising From AUXBCLK rising
Rev. 0 | Page 8 of 36
AD1937
TIMING DIAGRAMS
tDBH
DBCLK
tDBL tDLS
DLRCLK
tDLH
DSDATAx LEFT-JUSTIFIED MODE
tDDS
MSB MSB - 1
tDDH
DSDATAx I2S-JUSTIFIED MODE
tDDS
MSB
tDDH tDDS tDDS
07414-025
DSDATAx RIGHT-JUSTIFIED MODE
MSB
LSB
tDDH
tDDH
Figure 2. DAC Serial Timing
tABH
ABCLK
tABL tALS
ALRCLK
tALH
tABDD
ASDATAx LEFT-JUSTIFIED MODE MSB MSB - 1
tABDD
ASDATAx I2S-JUSTIFIED MODE MSB
tABDD
LSB
07414-026
ASDATAx RIGHT-JUSTIFIED MODE
MSB
Figure 3. ADC Serial Timing
Rev. 0 | Page 9 of 36
AD1937 ABSOLUTE MAXIMUM RATINGS
Table 9.
Parameter Analog (AVDD) Digital (DVDD) VSUPPLY Input Current (Except Supply Pins) Analog Input Voltage (Signal Pins) Digital Input Voltage (Signal Pins) Operating Temperature Range (Case) Storage Temperature Range Rating -0.3 V to +3.6 V -0.3 V to +3.6 V -0.3 V to +6.0 V 20 mA -0.3 V to AVDD + 0.3 V -0.3 V to DVDD + 0.3 V -40C to +125C -65C to +150C
THERMAL RESISTANCE
JA represents junction-to-ambient thermal resistance; JC represents the junction-to-case thermal resistance. All characteristics are for a 4-layer board. Table 10.
Package Type 64-Lead LQFP JA 47 JC 11.1 Unit C/W
ESD CAUTION
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Rev. 0 | Page 10 of 36
AD1937 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
ADC2RN ADC1RN ADC2RP ADC1RP ADC2LN ADC1LN ADC2LP ADC1LP AVDD AVDD CM NC NC NC
50 64 63 62 61 60 59 58 57 56 55 54 53 52 51
AGND MCLKI/MCLKXI MCLKO/MCLKXO AGND AVDD DAC3LP DAC3LN DAC3RP DAC3RN
NC
49 48 47 46 45 44 43
LF
1 2 3 4 5 6 7 8 9
AGND FILTR AGND AVDD AGND DAC2RN DAC2RP DAC2LN DAC2LP DAC1RN DAC1RP DAC1LN DAC1LP ADDR1 SCL DGND
TOP VIEW (Not to Scale) DIFFERENTIAL OUTPUT
AD1937
42 41 40 39 38 37 36 35 34 33
DAC4LP 10 DAC4LN 11 DAC4RP 12 DAC4RN 13 PD/RST 14 DSDATA4 15 DGND 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
VSUPPLY
DLRCLK
ALRCLK
VSENSE
VDRIVE
DVDD
SDA
DBCLK
DSDATA3
DSDATA2
DSDATA1
ASDATA2
ASDATA1
ABCLK
NC = NO CONNECT
ADDR0
DVDD
Figure 4. Pin Configuration
Table 11. Pin Function Descriptions
Pin No. 1, 4, 44, 46, 48 2 3 5, 45, 51, 62 6 7 8 9 10 11 12 13 14 15 16, 33 17, 32 18 19 20 21 22 Type 1 I I O I O O O O O O O O I I/O I I I/O I/O I I/O I/O Mnemonic AGND MCLKI/MCLKXI MCLKO/MCLKXO AVDD DAC3LP DAC3LN DAC3RP DAC3RN DAC4LP DAC4LN DAC4RP DAC4RN PD/RST DSDATA4 DGND DVDD DSDATA3 DSDATA2 DSDATA1 DBCLK DLRCLK Description Analog Ground. Master Clock Input/Crystal Oscillator Input. Master Clock Output/Crystal Oscillator Output. Analog Power Supply. Connect this pin to analog 3.3 V supply. DAC3 Left Positive Output. DAC3 Left Negative Output. DAC3 Right Positive Output. DAC3 Right Negative Output. DAC4 Left Positive Output. DAC4 Left Negative Output. DAC4 Right Positive Output. DAC4 Right Negative Output Power-Down Reset (Active Low). DAC Serial Data Input 4. Data input to DAC4 data in/TDM DAC2 data out (dual-line mode)/ AUX DAC2 data out (to external DAC2). Digital Ground. Digital Power Supply. Connect this pin to digital 3.3 V supply. DAC Serial Data Input 3. Data input to DAC3 data in/TDM DAC2 data in (dual-line mode)/AUX ADC2 data in (from external ADC2). DAC Serial Data Input 2. Data input to DAC2 data in/TDM DAC data out/AUX ADC1 data in (from external ADC1). DAC Serial Data Input 1. Data input to DAC1 data in/TDM DAC data in/TDM data in. Bit Clock for DACs. Can be programmed as input or output in all modes. Frame Clock for DACs. Can be programmed as input or output in all modes.
Rev. 0 | Page 11 of 36
07414-002
AD1937
Pin No. 23 24 25 26 27 28 29 30 31 34 35 36 37 38 39 40 41 42 43 47 49, 50, 63, 64 52 53 54 55 56 57 58 59 60 61
1
Type 1 I I O I/O O I/O I/O I I/O I I O O O O O O O O O O I I I I I I I I O
Mnemonic VSUPPLY VSENSE VDRIVE ASDATA2 ASDATA1 ABCLK ALRCLK ADDR0 SDA SCL ADDR1 DAC1LP DAC1LN DAC1RP DAC1RN DAC2LP DAC2LN DAC2RP DAC2RN FILTR NC CM ADC1LP ADC1LN ADC1RP ADC1RN ADC2LP ADC2LN ADC2RP ADC2RN LF
Description 5 V Input to Regulator, Emitter of Pass Transistor. Connect 3.3 V Regulator Output, Collector of Pass Transistor, to This Pin. Drive for Base of Pass Transistor. ADC Serial Data Output 2. Data Output from ADC2/TDM ADC data in/AUX DAC1 data out (to external DAC1). ADC Serial Data Output 1. Data Output from ADC1/TDM ADC data out/TDM data out. Bit Clock for ADCs. Can be programmed as input or output in all modes. Frame Clock for ADCs. Can be programmed as input or output in all modes. I2C Address Assignment. Control Data Port (I2C). Control Clock Port (I2C). I2C Address Assignment. DAC1 Left Positive Output. DAC1 Left Negative Output. DAC1 Right Positive Output. DAC1 Right Negative Output. DAC2 Left Positive Output. DAC2 Left Negative Output. DAC2 Right Positive Output. DAC2 Right Negative Output. Analog Voltage Reference Filter Capacitor Connection. Bypass with 10 F||100 nF to AGND. No Connect. Common-Mode Reference Filter Capacitor Connection. Bypass with 47 F||100 nF to AGND. ADC1 Left Positive Input. ADC1 Left Negative Input. ADC1 Right Positive Input. ADC1 Right Negative Input. ADC2 Left Positive Input. ADC2 Left Negative Input. ADC2 Right Positive Input. ADC2 Right Negative Input. PLL Loop Filter, Return to AVDD.
I = input, O = output.
Rev. 0 | Page 12 of 36
AD1937 TYPICAL PERFORMANCE CHARACTERISTICS
0.10 0.08 0.06
MAGNITUDE (dB)
0
0.04
MAGNITUDE (dB)
-50
0.02 0 -0.02 -0.04 -0.06 -0.08 0 2 4 6 8 10 12 14 16 18
07414-003
-100
0
12
24 FREQUENCY (kHz)
36
48
FREQUENCY (kHz)
Figure 5. ADC Pass-Band Filter Response, 48 kHz
0 -10 -20
0.05 0.10
Figure 8. DAC Stop-Band Filter Response, 48 kHz
-30
MAGNITUDE (dB)
-40 -50 -60 -70 -80 -90
07414-004
MAGNITUDE (dB)
0
-0.05
0
5
10
15
20
25
30
35
40
0
24
48 FREQUENCY (kHz)
72
96
FREQUENCY (kHz)
Figure 6. ADC Stop-Band Filter Response, 48 kHz
0.06
Figure 9. DAC Pass-Band Filter Response, 96 kHz
0
0.04
MAGNITUDE (dB)
0.02
MAGNITUDE (dB)
-50
0
-0.02
-100
-0.04
-150
0
8
16 FREQUENCY (kHz)
24
07414-005
0
24
48 FREQUENCY (kHz)
72
96
Figure 7. DAC Pass-Band Filter Response, 48 kHz
Figure 10. DAC Stop-Band Filter Response, 96 kHz
Rev. 0 | Page 13 of 36
07414-008
-0.06
07414-007
-100
-0.10
07414-006
-0.10
-150
AD1937
0.5 0.4 0.3 -2
MAGNITUDE (dB) MAGNITUDE (dB)
0
0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 0 8 16 32 64
07414-009
-4
-6
-8
64
80
96
FREQUENCY (kHz)
FREQUENCY (kHz)
Figure 11. DAC Pass-Band Filter Response, 192 kHz
Figure 12. DAC Stop-Band Filter Response, 192 kHz
Rev. 0 | Page 14 of 36
07414-010
-0.5
-10 48
AD1937 THEORY OF OPERATION
ANALOG-TO-DIGITAL CONVERTERS (ADCs)
There are four ADC channels in the AD1937 configured as two stereo pairs with differential inputs. The ADCs can operate at a nominal sample rate of 48 kHz, 96 kHz, or 192 kHz. The ADCs include on-board digital antialiasing filters with 79 dB stopband attenuation and linear phase response, operating at an oversampling ratio of 128 (48 kHz, 96 kHz, and 192 kHz modes). Digital outputs are supplied through two serial data output pins (one for each stereo pair): a common frame clock (ALRCLK) and a common bit clock (ABCLK). Alternatively, the TDM modes can be used to access up to 16 channels on a single TDM data line. The ADCs must be driven from a differential signal source for best performance. The input pins of the ADCs connect to internal switched capacitors. To isolate the external driving op amp from the glitches caused by the internal switched capacitors, each input pin should be isolated by using a series-connected external 100 resistor and a 1 nF capacitor connected from each input to ground. Use a high quality capacitor such as a ceramic NP0/C0G, or polypropylene film. The differential inputs have a nominal common-mode voltage of 1.5 V. The voltage at the common-mode reference pin (CM) can be used to bias external op amps to buffer the input signals (see the Power Supply and Voltage Reference section). The inputs can also be ac-coupled and in that case do not need an external dc bias to CM. A digital high-pass filter can be switched in line with the ADCs (ADC Control 0 Register) to remove residual dc offsets. It has a 1.4 Hz, 6 dB per octave cutoff at a 48 kHz sample rate. The cutoff frequency scales directly with sample frequency. Each output pin has a nominal common-mode dc level of 1.5 V and swings 1.27 V for a 0 dBFS digital input signal. A single op amp, third-order, external, low-pass filter is recommended to remove high frequency noise present on the output pins, as well as to provide a differential-to-single-ended conversion for the differential output. Note that the use of op amps with low slew rates or low bandwidth can cause high frequency noise and tones to fold down into the audio band; exercise care in selecting these components. The voltage at CM can be used to bias the external op amps that buffer the output signals (see the Power Supply and Voltage Reference section).
CLOCK SIGNALS
The on-chip phase-locked loop (PLL) can be selected to reference the input sample rate from either of the LRCLK pins or 256x, 384x, 512x, or 768x sample rate s (fS), referenced to the 48 kHz mode from the MCLKI/MCLKXI pin. The default at power-up is 256 x fS from the MCLKI/MCLKXI pin. In 96 kHz mode, the master clock frequency stays at the same absolute frequency; therefore, the actual multiplication rate is divided by 2. In 192 kHz mode, the actual multiplication rate is divided by 4. For example, if the AD1937 is programmed in 256 x fS mode, the frequency of the master clock input is 256 x 48 kHz = 12.288 MHz. If the AD1937 is then switched to 96 kHz operation (by writing to the I2C port), the frequency of the master clock should remain at 12.288 MHz, which is 128 x fS in this example. In 192 kHz mode, this becomes 64 x fS. The internal clock for the ADCs is 256 x fS for all clock modes. The internal clock for the DACs varies by mode: 512 x fS (48 kHz mode), 256 x fS (96 kHz mode), or 128 x fS (192 kHz mode). By default, the on-board PLL generates this internal master clock from an external clock. A direct 512 x fS (referenced to 48 kHz mode) master clock can be used for either the ADCs or DACs, if selected in the PLL and Clock Control 1 register. Note that it is not possible to use a direct clock for the ADCs set to the 192 kHz mode. It is required that the on-chip PLL be used in this mode. The PLL can be powered down in the PLL and Clock Control 0 Register. To ensure reliable locking when changing PLL modes, or if the reference clock is unstable at power-on, power down the PLL and then power it back up after the reference clock has stabilized. The internal master clock (MCLK) can be disabled in the PLL and Clock Control 0 register to reduce power dissipation when the AD1937 is idle. The clock should be stable before it is enabled. Unless a standalone mode is selected (see the I2C Control Port section), the clock is disabled by reset and must be enabled by writing to the I2C port for normal operation.
DIGITAL-TO-ANALOG CONVERTERS (DACs)
The AD1937 DAC channels are arranged in four stereo pairs, giving eight analog outputs; the outputs are differential for improved noise and distortion performance. The DACs include on-board digital reconstruction filters with 70 dB stop-band attenuation and linear phase response, operating at an oversampling ratio of 4 (48 kHz or 96 kHz modes) or 2 (192 kHz mode). Each channel has its own independently programmable attenuator, adjustable in 255 steps in increments of 0.375 dB. Digital inputs are supplied through four serial data input pins (one for each stereo pair), a common frame clock (DLRCLK), and a common bit clock (DBCLK). Alternatively, one of the TDM modes can be used to access up to 16 channels on a single TDM data line.
Rev. 0 | Page 15 of 36
AD1937
To maintain the highest performance possible, limit the clock jitter of the internal master clock signal to less than a 300 ps rms time interval error (TIE). Even at these levels, extra noise or tones can appear in the DAC outputs if the jitter spectrum contains large spectral peaks. If the internal PLL is not used, it is best to use an independent crystal oscillator to generate the master clock. In addition, it is especially important that the clock signal not pass through an FPGA, CPLD, or other large digital chip (such as a DSP) before being applied to the AD1937. In most cases, this induces clock jitter due to the sharing of common power and ground connections with other unrelated digital output signals. When the PLL is used, jitter in the reference clock is attenuated above a certain frequency depending on the loop filter. The I2C interface of the AD1937 is a 2-wire interface that consists of a clock line (SCL) and a data line (SDA). SDA is bidirectional and the AD1937 drives SDA either to acknowledge the master (ACK) or to send data during a read operation. The SDA pin for the I2C port is an open-drain collector and requires a 2 k pull-up resistor. A write or read access occurs when the SDA line is pulled low while the SCL line is high, indicated by start in the timing diagrams. SDA is only allowed to change when SCL is low except when a start or stop condition occurs, as shown in Figure 13 and Figure 14. The first eight bits of the data-word consist of the device address and the R/W bit. The device address consists of an internal built-in address (0x08) OR'ed with the two address bits, ADDR1 and ADDR0, and the R/W bit. The two address bits allow four AD1937s to be used in a system. Tie I2C ADDR0 and ADDR1 low or high and program the ADDR bits accordingly as 0 or 1. Initiating a write operation to the AD1937 involves sending a start condition and then sending the device address with the R/W bit set low. The AD1937 responds by issuing an acknowledge to indicate that it has been addressed. The user then sends a second frame telling the AD1937 which register is required to be written to. Another acknowledge is issued by the AD1937. Finally, the user can send another frame with the eight data bits required to be written to the register. A third acknowledge is issued by the AD1937 after which the user can send a stop condition to complete the data transfer. A read operation requires that the user first write to the AD1937 to point to the correct register and then read the data. This is achieved by sending a start condition followed by the device address frame, with the R/W bit low; the AD1937 returns an acknowledge. The master then sends the register address frame. Following the acknowledge from the AD1937, the user must issue a repeated start condition. The next frame is the device address with the R/W bit set high; the AD1937 returns an acknowledge. On the next frame, the AD1937 outputs the register data on the SDA line; the master should send an acknowledge. A stop condition completes the read operation. Figure 13 and Figure 14 show examples of writing to and reading from the DAC1L volume control register, Address 0x06 (see Table 28).
RESET AND POWER-DOWN
The function of the PD/RST pin sets all the control registers to their default settings. To avoid audio pops, PD/RST does not power down the analog outputs. After PD/RST is deasserted and the PLL acquires lock condition, an initialization routine runs inside the AD1937. This initialization lasts for approximately 256 master clock cycles. Once the routine is complete, the registers can be programmed. The power-down bits in the PLL and Clock Control 0, DAC Control 1, and ADC Control 1 registers power down their respective sections. All other register settings are retained. To guarantee proper startup, the PD/RST pin should be pulled low by an external resistor.
I C CONTROL PORT
The AD1937 has an I2C-compatible control port that permits programming and reading back the internal control registers for the ADCs, DACs, and clock system. There is also a standalone mode available for operation without serial control, configured at reset using the serial control pins. All registers are set to default except internal MCLK enable, which is set to 1 and ADC BCLK and LRCLK master/slave is set by SDA (see Table 12 for details). Table 12. Hardware Selection of Standalone Mode
ADC Clocks Slave Master ADDR0 (Pin 30) 0 0 SDA (Pin 31) 0 1 SCL (Pin 34) 0 0 ADDR1 (Pin 35) 0 0
2
Rev. 0 | Page 16 of 36
AD1937
SCK
SDA START BY MASTER (S)
0
0
0
0
1
ADDR1
ADDR0
R/W
0
0
0
0
0
1
1
0 ACK. BY MASTER (AM)
FRAME 1 CHIP ADDRESS BYTE
ACK. BY AD1937 (AS)
FRAME 2 REGISTER ADDRESS BYTE
SCK (CONTINUED)
SDA (CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0
07414-011
FRAME 3 DATA BYTE TO AD1937
ACK. BY MASTER (AM)
STOP BY MASTER (P)
Figure 13. I2C Write Format
SCK
SDA START BY MASTER (S)
0
0
0
0
1
ADDR1
ADDR0
R/W
0
0
0
0
0
1
1
0 ACK. BY AD1937 (AS)
FRAME 1 CHIP ADDRESS BYTE
ACK. BY AD1937 (AS)
FRAME 2 REGISTER ADDRESS BYTE
SCL (CONTINUED)
SDA (CONTINUED)
0
0
0
0
1
ADDR1 ADDR0
R/W ACK. BY AD1937 (AS)
D7
D6
D5
D4
D3
D2
D1
D0
07414-012
REPEATED START BY MASTER (S)
FRAME 3 CHIP ADDRESS BYTE
FRAME 4 REGISTER DATA
ACK. BY STOP BY MASTER (AM) MASTER (P)
Figure 14. I2C Read Format
Rev. 0 | Page 17 of 36
AD1937
Table 13. I2C Abbreviation Table
Abbreviation S P AM AS Condition Repeated start by master Stop by master Acknowledge by master Acknowledge by AD1937
Table 14. Single Word I2C Write
S Chip Address, R/W = 0 AS Register Address AS Data Word AS P
Table 15. Burst Mode I2C Write
S Chip Address, R/W = 0 AS Register Address AS Data Word 1 AS Data Word 2 AS Data Word N AS P
Table 16. Single Word I2C Read
S Chip Address, R/W = 0 AS Register Address AS S Chip Address, R/W = 1 AS Data Word AM P
Table 17. Burst Mode I2C Read
S Chip Address, R/W = 0 AS Register Address AS S Chip Address, R/W = 1 AS Data Word 1 AM Data Word 2 AM Data Word N AM P
POWER SUPPLY AND VOLTAGE REFERENCE
The AD1937 is designed for a 3.3 V supply. Separate power supply pins are provided for the analog and digital sections. To minimize noise pickup, these pins should be bypassed with 100 nF ceramic chip capacitors placed as close to the pins as possible. A bulk aluminum electrolytic capacitor of at least 22 F should also be provided on the same printed circuit board (PCB) as the codec. For critical applications, improved performance is obtained with separate supplies for the analog and digital sections. If this is not possible, it is recommended that the analog and digital load pins be isolated by means of a ferrite bead in series with the supply. It is important that the analog supply be as clean as possible. The AD1937 includes a 3.3 V regulator driver that only requires an external pass transistor, a resistor, and bypass capacitors to turn a 5 V supply into 3.3 V. If the regulator driver is not used, connect VSUPPLY, VDRIVE, and VSENSE to DGND. All digital inputs are compatible with TTL and CMOS levels. All outputs are driven from the 3.3 V DVDD supply and are compatible with TTL and 3.3 V CMOS levels.
The ADC and DAC internal analog voltage reference (VREF) is brought out on the FILTR pin and should be bypassed as close as possible to the chip with a parallel combination of 10 F and 100 nF capacitors. Any external current drawn should be limited to less than 50 A. The internal reference can be disabled in the PLL and Clock Control 1 register, and FILTR can be driven from an external source. This can be used to scale the DAC output to the clipping level of a power amplifier based on its power supply voltage. The ADC input gain varies by the inverse ratio. It is not advisable to drive the FILTR pin with more than (AVDD/2) V. The total gain from ADC input to DAC output remains constant. The CM pin should be bypassed as close as possible to the chip, with a parallel combination of 47 F and 100 nF capacitors. This voltage can be used to bias external op amps to the common-mode voltage of the input and output signal pins. The output current should be limited to less than 0.5 mA source and 2 mA sink.
Rev. 0 | Page 18 of 36
AD1937
SERIAL DATA PORTS--DATA FORMAT
The eight DAC channels use a common serial bit clock (DBCLK) and a common left-right framing clock (DLRCLK) in the serial data port. The four ADC channels use a common serial bit clock (ABCLK) and left-right framing clock (ALRCLK) in the serial data port. The clock signals are all synchronous with the sample rate. The normal stereo serial modes are shown in Figure 15. The ADC and DAC serial data modes default to I2S stereo. The ports can also be programmed for left-justified stereo, right-justified stereo, and TDM modes. The word width is 24 bits by default and can be set to 16 or 20 bits in the DAC Control 2 and ADC Control 1 registers. The DAC serial formats are programmable in the DAC Control 0 register. The polarity of DBCLK and DLRCLK is programmable in the DAC Control 1 register. The ADC serial format is programmable in ADC Control 1 register. The ABCLK and ALRCLK clock polarities are programmed in ADC Control 2 register. In Figure 2, Figure 3, and Figure 15 all of the clocks are shown with their normal polarity. Both DAC and ADC serial ports can be programmed to become the bus masters according to DAC Control 1 and ADC Control 2 registers. By default, both ADC and DAC serial ports are in the slave mode.
RIGHT CHANNEL
LRCLK BCLK SDATA MSB
LEFT CHANNEL
LSB
MSB
LSB
LEFT-JUSTIFIED MODE--16 BITS TO 24 BITS PER CHANNEL
LRCLK BCLK SDATA MSB
LEFT CHANNEL
RIGHT CHANNEL
LSB
MSB
LSB
I2S-JUSTIFIED MODE--16 BITS TO 24 BITS PER CHANNEL
LRCLK BCLK SDATA
LEFT CHANNEL
RIGHT CHANNEL
MSB
LSB
MSB
LSB
RIGHT-JUSTIFIED MODE--SELECT NUMBER OF BITS PER CHANNEL LRCLK BCLK SDATA MSB LSB MSB LSB
DSP MODE--16 BITS TO 24 BITS PER CHANNEL 1/fS
07414-024
NOTES 1. DSP MODE DOES NOT IDENTIFY CHANNEL. 2. LRCLK NORMALLY OPERATES AT fS EXCEPT FOR DSP MODE, WHICH IS 2 x fS. 3. BCLK FREQUENCY IS NORMALLY 64 x LRCLK BUT MAY BE OPERATED IN BURST MODE.
Figure 15. Stereo Modes
Rev. 0 | Page 19 of 36
AD1937
TIME-DIVISION MULTIPLEXED (TDM) MODES
The serial ports of the AD1937 have several different TDM serial data modes. Single-line TDM mode is the most commonly used configuration (see Figure 16 and Figure 17). These figures show 8-channel configuration; other possible options are 4- and 16-channel configurations. In Figure 16, the eight on-chip DAC data slots are packed into one I2S TDM stream. In this mode, both DBCLK and ABCLK are 256 fS. In Figure 17, the ADC serial port outputs one data stream consisting of four on-chip ADCs followed by four unused slots.
DLRCLK 256 BCLKs DBCLK 32 BCLKs SLOT 1 LEFT 1 SLOT 2 RIGHT 1 SLOT 3 LEFT 2 SLOT 4 SLOT 5 SLOT 6 SLOT 7 SLOT 8 RIGHT 2 LEFT 3 RIGHT 3 LEFT 4 RIGHT 4
The I/O pin functions of the serial ports are defined according to the serial mode that is selected. For a detailed description of the function of each pin in TDM and TDM/AUX modes, see Table 18. The AD1937 allows systems with more than eight DAC channels to be easily configured by the use of an auxiliary serial data port. The TDM/AUX mode 16-channel configuration is shown in Figure 18. In this mode, the AUX channels are the last four slots of the TDM data stream. These slots are extracted and output to the AUX serial port. It should be noted that due to the high DBCLK frequency, this mode is available only in the 48 kHz/44.1 kHz/32 kHz sample rates. An 8-channel DAC configuration cannot be TDM/AUX because there are no extra data slots for the AUX packets; this would be singleline TDM mode. The AD1937 also allows system configurations with more than four ADC channels as shown in Figure 19 (using 8 ADCs) and Figure 20 (using 16 ADCs). Due to the high ABCLK frequency, this mode is available only in the 48 kHz/44.1 kHz/ 32 kHz sample rates. Combining the TDM/AUX ADC and DAC modes results in a system configuration of 8 ADCs and 12 DACs. The system, then consists of two external stereo ADCs, two external stereo DACs, and one AD1937. This mode is shown in Figure 21 (combined TDM/AUX DAC and ADC modes). In the TDM/AUX mode, the frame sync (ALRCLK) triggers the TDM word by crossing the high frequency TDM BCLK (ABCLK) to 0, similar to the single-line TDM modes (see Figure 16 and Figure 17). The AUX LRCLK (DLRCLK) runs at the much slower fS of the AUX port; the AUX BCLK (DBCLK) runs at 64 x fS. This is shown in the TDM/AUX figures (see Figure 18 to Figure 21).
DSDATA
LRCLK BCLK MSB MSB - 1 MSB - 2 DATA
07414-014
Figure 16. Single-Line TDM Mode 8-Channel DAC Configuration
ALRCLK 256 BCLKs ABCLK 32 BCLKs SLOT 1 LEFT 1 SLOT 2 RIGHT 1 SLOT 3 LEFT 2 SLOT 4 SLOT 5 SLOT 6 SLOT 7 SLOT 8 RIGHT 2
ASDATA
LRCLK BCLK MSB MSB - 1 MSB - 2 DATA
07414-013
Figure 17. Single-Line TDM Mode 8-Channel ADC Configuration
Table 18. Pin Function Changes in TDM and TDM/AUX Modes
Mnemonic ASDATA1 ASDATA2 DSDATA1 DSDATA2 DSDATA3 DSDATA4 ALRCLK ABCLK DLRCLK DBCLK Stereo Modes ADC1 data out ADC2 data out DAC1 data in DAC2 data in DAC3 data in DAC4 data in ADC LRCLK in/out ADC BCLK in/out DAC LRCLK in/out DAC BCLK in/out TDM Modes TDM ADC data out TDM ADC data in TDM DAC data in TDM DAC data out TDM DAC2 data in (dual-line mode) TDM DAC2 data out (dual-line mode) TDM ADC frame sync in/out TDM ADC BCLK in/out TDM DAC frame sync in/out TDM DAC BCLK in/out TDM/AUX Modes TDM data out AUX DAC1 data out (to external DAC1) TDM data in AUX ADC1 data in (from external ADC1) AUX ADC2 data in (from external ADC2) AUX DAC2 data out (to external DAC2) TDM frame sync in/out TDM BCLK in/out AUX LRCLK in/out AUX BCLK in/out
Rev. 0 | Page 20 of 36
AD1937
ALRCLK
ABCLK AUX DAC CHANNELS APPEAR AT AUX DAC PORTS
DAC4L DAC4R AUX1L AUX1R AUX2L AUX2R
DSDATA1 (TDM DATA IN)
UNUSED SLOTS
EMPTY EMPTY EMPTY EMPTY DAC1L DAC1R
8 ON-CHIP DAC CHANNELS
DAC2L DAC2R DAC3L DAC3R
32 BITS
MSB
DLRCLK (AUX LRCLK IN/OUT) DBCLK (AUX BCLK IN/OUT) ASDATA2 (AUX DAC1 DATA OUT) DSDATA4 (AUX DAC2 DATA OUT)
LEFT
RIGHT
MSB
MSB
07414-015
MSB
MSB
Figure 18. TDM/AUX Mode 16-Channel DAC configuration
ALRCLK
ABCLK 8 ON-CHIP DAC CHANNELS DSDATA1 (TDM DATA IN) DACL1 DACR1 DACL2 DACR2 DACL3 DACR3 DACL4 DACR4
4 ON-CHIP ADC CHANNELS ASDATA1 (TDM DATA OUT) ADCL1 ADCR1 ADCL2 ADCR2 AUXL1
4 AUX ADC CHANNELS AUXR1 AUXL2 AUXR2
32 BITS
MSB
DLRCLK (AUX LRCLK IN/OUT) DBCLK (AUX BCLK IN/OUT) DSDATA2 (AUX ADC1 DATA IN) DSDATA3 (AUX ADC2 DATA IN)
LEFT
RIGHT
MSB
MSB
07414-016
MSB
MSB
Figure 19. TDM/AUX Mode 8-Channel ADC Configuration
Rev. 0 | Page 21 of 36
AD1937
ALRCLK ABCLK
ASDATA1 (TDM DATA OUT)
4 ON-CHIP ADC CHANNELS
ADCL1 ADCR1 ADCL2 ADCR2
AUXILIARY ADC CHANNELS
AUXL1 AUXR1 AUXL2
UNUSED SLOTS
AUXR2 UNUSED UNUSED UNUSED UNUSED UNUSED UNUSED UNUSED UNUSED
32 BITS
MSB
DLRCLK (AUX LRCLK IN/OUT) DBCLK (AUX BCLK IN/OUT) DSDATA2 (AUX ADC1 DATA IN) DSDATA3 (AUX ADC2 DATA IN)
LEFT
RIGHT
MSB
MSB
07414-017
MSB
MSB
Figure 20. TDM/AUX Mode 16-Channel ADC Configuration
ALRCLK
ABCLK AUXILIARY DAC CHANNELS APPEAR AT AUX DAC PORTS
DACL4 DACR4 AUXL1 AUXR1 AUXL2 AUXR2
DSDATA1 (TDM DATA IN)
UNUSED SLOTS
EMPTY EMPTY EMPTY EMPTY DACL1 DACR1
8 ON-CHIP DAC CHANNELS
DACL2 DACR2 DACL3 DACR3
ASDATA1 (TDM DATA OUT) DLRCLK (AUX LRCLK IN/OUT) DBCLK (AUX BCLK IN/OUT) DSDATA2 (AUX ADC1 DATA IN) DSDATA3 (AUX ADC2 DATA IN) ASDATA2 (AUX ADC1 DATA OUT) DSDATA4 (AUX DAC2 DATA OUT)
4 ON-CHIP ADC CHANNELS
ADCL1 ADCR1 ADCL2 ADCR2
AUXILIARY ADC CHANNELS
AUXL1 AUXR1 AUXL2
UNUSED SLOTS
AUX R2 UNUSED UNUSED UNUSED UNUSED UNUSED UNUSED UNUSED UNUSED
LEFT
RIGHT
MSB
MSB
MSB
MSB
MSB
MSB
07414-018
MSB
MSB
Figure 21. Combined TDM/AUX Mode DAC and ADC Configuration
Rev. 0 | Page 22 of 36
AD1937
DAISY-CHAIN MODE
The AD1937 also allows a daisy-chain configuration to expand the system to 16 DACs and 8 ADCs (see Figure 22 to Figure 26). In this mode, the DBCLK frequency is 512 x fS. The first eight slots of the TDM DAC data stream belong to the first AD1937 in the chain and the last eight slots belong to the second AD1937. The second AD1937 is the device attached to the DSP TDM port. To accommodate 16 channels at a 96 kHz sample rate, the AD1937 can be configured into a dual-line, TDM mode as shown in Figure 23. This mode allows a slower DBCLK than normally required by the one-line TDM mode. The first four channels of each TDM input belong to the first AD1937 in the chain and the last four channels belong to the second AD1937. The dual-line TDM mode can also be used to send data at a 192 kHz sample rate into the AD1937, as shown in Figure 24.
DLRCLK
There are two configurations for the ADC port to work in daisy-chain mode. The first configuration is with an ABCLK at 256 x fS, see Figure 25. The second configuration is with an ABCLK at 512 x fS, see Figure 26. Note that in the 512 x fS ABCLK mode, the ADC channels occupy the first eight slots; the second eight slots are empty. The TDM ADC data in (ASDATA2) port of the first AD1937 must be grounded in all modes of operation. The I/O pins of the serial ports are defined according to the serial mode selected. See Table 19 for a detailed description of the function of each pin. See Figure 27 for a typical AD1937 configuration with two external stereo DACs and two external stereo ADCs.
DBCLK 8 DAC CHANNELS OF THE FIRST IC IN THE CHAIN DSDATA1 (TDM ADC DATA IN) OF THE SECOND AD1937
DAC1L DAC1R DAC2L DAC2R DAC3L DAC3R DAC4L DAC4R
8 DAC CHANNELS OF THE SECOND IC IN THE CHAIN
DAC1L DAC1R DAC2L DAC2R DAC3L DAC3R DAC4L DAC4R
DSDATA2 (TDM DAC DATA OUT) OF THE SECOND AD1937; THIS IS THE TDM TO THE FIRST AD1937
DAC1L
DAC1R
DAC2L
DAC2R
DAC3L
DAC3R
DAC4L
DAC4R
8 UNUSED SLOTS 32 BITS
FIRST AD1937
SECOND AD1937
DSP
MSB
Figure 22. Single-Line Daisy-Chain TDM Mode 16-Channel 48 kHz DAC Configuration
DLRCLK
DBCLK 8 DAC CHANNELS OF THE FIRST IC IN THE CHAIN DSDATA1 (TDM DAC DATA IN) DSDATA2 (TDM DAC DATA OUT) DSDATA3 (TDM DAC2 DATA IN) DSDATA4 (TDM DAC2 DATA OUT) 32 BITS DAC3L DAC3R DAC4L DAC4R DAC1L DAC1R DAC2L DAC2R 8 DAC CHANNELS OF THE SECOND IC IN THE CHAIN DAC1L DAC1R DAC2L DAC2R
DAC1L
DAC1R
DAC2L
DAC2R
DAC3L
DAC3R
DAC4L
DAC4R
DAC3L
DAC3R
DAC4L
DAC4R
MSB
FIRST AD1937
SECOND AD1937
DSP
Figure 23. Dual-Line Daisy-Chain TDM Mode16-Channel 96 kHz DAC Configuration
Rev. 0 | Page 23 of 36
07414-020
07414-019
AD1937
DLRCLK
DBCLK
DSDATA1
DAC1L
DAC1R
DAC2L
DAC2R
DSDATA2
DAC3L
DAC3R
DAC4L
DAC4L
32 BITS
MSB
Figure 24. Dual-Line Daisy-Chain TDM Mode 8-Channel 192 kHz DAC Configuration
ALRCLK
ABCLK 4 ADC CHANNELS OF SECOND IC IN THE CHAIN ADC1L ADC1R ADC2L ADC2R 4 ADC CHANNELS OF FIRST IC IN THE CHAIN ADC1L ADC1R ADC2L ADC2R
ASDATA1 (TDM ADC DATA OUT) OF THE SECOND AD1937 IN THE CHAIN ASDATA2 (TDM ADC DATA IN) OF THE SECOND AD1937 IN THE CHAIN
ADC1L
ADC1R
ADC2L
ADC2R
32 BITS FIRST AD1937 SECOND AD1937 DSP
07414-022 07414-023
MSB
Figure 25. Single-Line Daisy-Chain TDM Mode 256 x fS ADC Configuration
ALRCLK
ABCLK
ASDATA1 (TDM ADC DATA OUT) OF THE SECOND AD1937 IN THE CHAIN
4 ADC CHANNELS OF SECOND IC IN THE CHAIN
ADCL1 ADCR1 ADCL2 ADCR2
4 ADC CHANNELS OF FIRST IC IN THE CHAIN
ADCL1 ADCR1 ADCL2 ADCR2
ASDATA2 (TDM ADC DATA IN) OF THE SECOND AD1937 IN THE CHAIN
ADCL1
ADCR1
ADCL2
ADCR2
32 BITS
FIRST AD1937
SECOND AD1937
DSP
MSB
Figure 26. Single-Line Daisy-Chain TDM Mode 512 x fS ADC Configuration
Rev. 0 | Page 24 of 36
07414-021
AD1937
Table 19. Pin Function Changes in TDM and TDM/AUX Modes (Replication of Table 18)
Mnemonic ASDATA1 ASDATA2 DSDATA1 DSDATA2 DSDATA3 DSDATA4 ALRCLK ABCLK DLRCLK DBCLK Stereo Modes ADC1 data out ADC2 data out DAC1 data in DAC2 data in DAC3 data in DAC4 data in ADC LRCLK in/out ADC BCLK in/out DAC LRCLK in/out DAC BCLK in/out TDM Modes TDM ADC data out TDM ADC data in TDM DAC data in TDM DAC data out TDM DAC2 data in (dual-line mode) TDM DAC2 data out (dual-line mode) TDM ADC frame sync in/out TDM ADC BCLK in/out TDM DAC frame sync in/out TDM DAC BCLK in/out TDM/AUX Modes TDM data out AUX DAC1 data out (to external DAC1) TDM data in AUX ADC1 data in (from external ADC1) AUX ADC2 data in (from external ADC2) AUX DAC2 data out (to external DAC2) TDM frame sync in/out TDM BCLK in/out AUX LRCLK in/out AUX BCLK in/out
30MHz
FSYNC-TDM (RFS)
SHARC
SHARC IS RUNNING IN SLAVE MODE (INTERRUPT-DRIVEN)
RxDATA
LRCLK AUX ADC 1 BCLK DATA MCLK ASDATA1 ALRCLK ABCLK DSDATA1 DBCLK DLRCLK LRCLK AUX ADC 2 BCLK DATA MCLK DSDATA2 DSDATA3 MCLKI/MCLKXI
TxDATA
RxCLK
TxCLK
12.288MHz
TFS (NC)
LRCLK BCLK AUX DATA DAC 1 MCLK
AD1937
TDM MASTER AUX MASTER ASDATA2 DSDATA4
LRCLK BCLK AUX DATA DAC 2 MCLK
07414-027
Figure 27. Example of TDM/AUX Mode Connection to SHARC(R) (AD1937 as TDM Master/AUX Master Shown)
Rev. 0 | Page 25 of 36
AD1937
ADDITIONAL MODES
The AD1937 offers several additional modes for board level design enhancements. To reduce the EMI in board level design, serial data can be transmitted without an explicit BCLK. See Figure 28 and Figure 29 for an example of a DAC TDM data transmission mode that does not require high speed DBCLK. This configuration is applicable when the AD1937 master clock is generated by the PLL with the DLRCLK as the PLL reference frequency. To relax the requirement for the setup time of the AD1937 in cases of high speed TDM data transmission, the AD1937 can latch in the data using the falling edge of DBCLK. This effectively dedicates the entire BCLK period to the setup time. This mode is useful in cases where the source has a large delay time in the serial data driver. Figure 30 shows this pipeline mode of data transmission. Both the BCLK-less and pipeline modes are available on the ADC serial data port.
DLRCLK 32 BITS INTERNAL DBCLK
07414-028
DSDATAx
Figure 28. Serial DAC Data Transmission in TDM Format Without DBCLK; 2-Channel 64 BCLKs per Frame Mode (Applicable Only If PLL Locks to DLRCLK; This Mode Is Also Available in the ADC Serial Data Port)
DLRCLK
DBCLK DATA MUST BE VALID AT THIS BCLK EDGE DSDATAn MSB
07414-029
Figure 29. Serial DAC Data Transmission in TDM Format Without DBCLK; 128 to 512 BCLKs per Frame TDM Mode (Applicable Only If PLL Locks to DLRCLK; This Mode Is Also Available in the ADC Serial Data Port)
DLRCLK
INTERNAL DBCLK
07414-128
TDM DSDATAn
Figure 30. I2S Pipeline Mode in DAC Serial Data Transmission (Applicable in Stereo and TDM, Useful for High Frequency TDM Transmission; This Mode Is Also Available in the ADC Serial Data Port)
Rev. 0 | Page 26 of 36
AD1937 CONTROL REGISTERS
DEFINITIONS
The global address for the AD1937 is 0x08 OR'ed with ADDR1 and ADDR0 and one R/W bit; see Figure 13 and Figure 14. The address bits (Bits[18:17]) setting must correspond to the low/high state of Pin 30 and Pin 35. All registers are reset to 0, except for the DAC volume registers that are set to full volume. Note that the first setting in each control register parameter is the default setting. Table 20. Register Format
Global Address Bit 23:17 R/W 16 Register Address 15:8 Data 7:0
Table 21. Register Addresses and Functions
Hexadecimal 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F 0x10 Address 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Function PLL and Clock Control 0 PLL and Clock Control 1 DAC Control 0 DAC Control 1 DAC Control 2 DAC individual channel mutes DAC1L volume control DAC1R volume control DAC2L volume control DAC2R volume control DAC3L volume control DAC3R volume control DAC4L volume control DAC4R volume control ADC Control 0 ADC Control 1 ADC Control 2
PLL AND CLOCK CONTROL REGISTERS
Table 22. PLL and Clock Control 0 Register (Address 0, 0x00)
Bit 0 2:1 Value 0 1 00 01 10 11 00 01 10 11 00 01 10 11 0 1 Function Normal operation Power-down Input 256 (x 44.1 kHz or 48 kHz) Input 384 (x 44.1 kHz or 48 kHz) Input 512 (x 44.1 kHz or 48 kHz) Input 768 (x 44.1 kHz or 48 kHz) XTAL oscillator enabled 256 x fS VCO output 512 x fS VCO output Off MCLKI/MCLKXI DLRCLK ALRCLK Reserved Disable: ADC and DAC idle Enable: ADC and DAC active Description PLL power-down MCLKI/MCLKXI pin functionality (PLL active), master clock rate setting
4:3
MCLKO/MCLKXO pin, master clock rate setting
6:5
PLL input
7
Internal master clock enable
Rev. 0 | Page 27 of 36
AD1937
Table 23. PLL and Clock Control 1 Register (Address 1, 0x01)
Bit 0 1 2 3 7:4 Value 0 1 0 1 0 1 0 1 0000 Function PLL clock MCLK PLL clock MCLK Enabled Disabled Not locked Locked Reserved Description DAC clock source select ADC clock source select On-chip voltage reference PLL lock indicator (read-only)
DAC CONTROL REGISTERS
Table 24. DAC Control 0 Register (Address 2, 0x02)
Bit 0 2:1 Value 0 1 00 01 10 11 000 001 010 011 100 101 110 111 00 01 10 11 Function Normal Power-down 32 kHz/44.1 kHz/48 kHz 64 kHz/88.2 kHz/96 kHz 128 kHz/176.4 kHz/192 kHz Reserved 1 cycle (I2S mode) 0 (left-justified mode) 8 cycles (right-justified 24-bit mode) 12 cycles (right-justified 20-bit mode) 16 cycles (right-justified 16-bit mode) Reserved Reserved Reserved Stereo (normal) TDM single-line, standalone, and daisy-chain modes TDM/AUX mode (ADC-, DAC-, TDM-coupled) TDM dual-line daisy-chain mode Description Power-down Sample rate
5:3
DSDATA delay (BCLK periods)
7:6
Serial format
Rev. 0 | Page 28 of 36
AD1937
Table 25. DAC Control 1 Register (Address 3, 0x03)
Bit 0 2:1 Value 0 1 00 01 10 11 0 1 0 1 0 1 0 1 0 1 Function Latch in midcycle (normal) Latch in at end of cycle (pipeline) 64 (2 channels) 128 (4 channels) 256 (8 channels) 512 (16 channels) Left low Left high Slave Master Slave Master DBCLK pin Internally generated Normal Inverted Description DBCLK active edge (TDM_IN) DBCLKs per frame
3 4 5 6 7
DLRCLK polarity DLRCLK master/slave DBCLK master/slave DBCLK source DBCLK polarity
Table 26. DAC Control 2 Register (Address 4, 0x04)
Bit 0 2:1 Value 0 1 00 01 10 11 00 01 10 11 0 1 00 Function Unmute Mute Flat 48 kHz curve 44.1 kHz curve 32 kHz curve 24 bits 20 bits Reserved 16 bits Noninverted Inverted Reserved Description Master mute De-emphasis (32 kHz/44.1 kHz/48 kHz mode only)
4:3
Word width
5 7:6
DAC output polarity
Table 27. DAC Individual Channel Mutes Register (Address 5, 0x05)
Bit 0 1 2 3 4 5 6 7 Value 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Function Unmute Mute Unmute Mute Unmute Mute Unmute Mute Unmute Mute Unmute Mute Unmute Mute Unmute Mute Description DAC1L mute DAC1R mute DAC2L mute DAC2R mute DAC3L mute DAC3R mute DAC4L mute DAC4R mute
Rev. 0 | Page 29 of 36
AD1937
Table 28. DACxx Volume Controls Registers (Address 6 to Address 13, 0x06 to 0x0D)
Bit 7:0 Value 0 1 to 254 255 Function No attenuation -0.375 dB per step Full attenuation Description DAC volume control
ADC CONTROL REGISTERS
Table 29. ADC Control 0 Register (Address 14, 0x0E)
Bit 0 1 2 3 4 5 7:6 Value 0 1 0 1 0 1 0 1 0 1 0 1 00 01 10 11 Function Normal Power down Off On Unmute Mute Unmute Mute Unmute Mute Unmute Mute 32 kHz/44.1 kHz/48 kHz 64 kHz/88.2 kHz/96 kHz 128 kHz/176.4 kHz/192 kHz Reserved Description Power-down High-pass filter ADC1L mute ADC1R mute ADC2L mute ADC2R mute Output sample rate
Table 30. ADC Control 1 Register (Address 15, 0x0F)
Bit 1:0 Value 00 01 10 11 000 001 010 011 100 101 110 111 00 01 10 11 0 1 Function 24 bits 20 bits Reserved 16 bits 1 cycle (I2S mode) 0 (left-justified mode) 8 cycles (right-justified 24-bit mode) 12 cycles (right-justified 20-bit mode) 16 cycles (right-justified 16-bit mode) Reserved Reserved Reserved Stereo TDM single-line, standalone, and daisy-chain modes TDM/AUX mode (ADC-, DAC-, TDM-coupled) Reserved Latch in midcycle (normal) Latch in at end of cycle (pipeline) Description Word width
4:2
ASDATA delay (BCLK periods)
6:5
Serial format
7
ABCLK active edge (TDM_IN)
Rev. 0 | Page 30 of 36
AD1937
Table 31. ADC Control 2 Register (Address 16, 0x10)
Bit 0 1 2 3 5:4 Value 0 1 0 1 0 1 0 1 00 01 10 11 0 1 0 1 Function 50/50 (allows 32, 24, 20, or 16 BCLKs per channel) Pulse (32 BCLKs per channel) Drive out on falling edge (DEF) Drive out on rising edge Left low Left high Slave Master 64 cycles 128 cycles 256 cycles 512 cycles Slave Master ABCLK pin Internally generated Description ALRCLK format ABCLK polarity ALRCLK polarity ALRCLK master/slave ABCLKs per frame
6 7
ABCLK master/slave ABCLK source
Rev. 0 | Page 31 of 36
AD1937 APPLICATIONS CIRCUITS
Typical application circuits are shown in Figure 31 through Figure 34. Figure 31 shows a typical ADC input filter circuit. Recommended loop filters for LRCLK and MCLK as the PLL reference are shown in Figure 32. Output filters for the DAC outputs are shown in Figure 33 and a regulator circuit is shown in Figure 34.
120pF 600Z 100pF 5.76k 2 3 - OP275 + 5.76k 1
AUDIO INPUT
11k
5.76k 120pF 4.7F 237 + 1nF NPO
ADCxxN
DAC OUTN
11k
3.01k 270pF NPO 560pF NPO
68pF NPO 2 3
- OP275 +
1
604 2.2nF NPO
100pF 6 5 5.76k - OP275 + 7 1nF NPO 4.7F 237 +
AUDIO OUTPUT
DAC OUTP
07414-030
ADCxxP
5.62k 5.62k
1.50k
Figure 31. Typical ADC Input Filter Circuit
Figure 33. Typical DAC Output Filter Circuit (Differential)
100nF VSUPPLY 1k
+
10F 5V
LF
LRCLK 39nF 2.2nF 3.32k
LF
MCLK 5.6nF 390pF
07414-031
VDRIVE VSENSE 100nF
B
E FZT953 C 3.3V
+
AVDD2
AVDD2
Figure 32. Recommended Loop Filters for LRCLK or MCLK as PLL Reference
Figure 34. Recommended 3.3 V Regulator Circuit
Rev. 0 | Page 32 of 36
07414-033
562
10F
07414-032
150pF NPO
AD1937 OUTLINE DIMENSIONS
0.75 0.60 0.45 1.60 MAX
1 PIN 1
12.20 12.00 SQ 11.80
64 49 48
TOP VIEW
(PINS DOWN)
10.20 10.00 SQ 9.80
1.45 1.40 1.35
0.15 0.05
SEATING PLANE
0.20 0.09 7 3.5 0
0.08 COPLANARITY
16 17 32
33
VIEW A
COMPLIANT TO JEDEC STANDARDS MS-026-BCD
Figure 35. 64-Lead Low Profile Quad Flat Package [LQFP] (ST-64-2) Dimensions shown in millimeters
ORDERING GUIDE
Model AD1937WBSTZ 1 AD1937WBSTZ-RL1 EVAL-AD1937EBZ1
1
Temperature Range -40C to +125C -40C to +125C
Package Description 64-Lead LQFP 64-Lead LQFP, 13" Tape and Reel Evaluation Board
Package Option ST-64-2 ST-64-2
Z = RoHS Compliant Part.
Rev. 0 | Page 33 of 36
051706-A
ROTATED 90 CCW
VIEW A
0.50 BSC LEAD PITCH
0.27 0.22 0.17
AD1937 NOTES
Rev. 0 | Page 34 of 36
AD1937 NOTES
Rev. 0 | Page 35 of 36
AD1937 NOTES
Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips.
(c)2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07414-0-9/08(0)
Rev. 0 | Page 36 of 36

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