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19-0550; Rev 0; 5/06
Low-Cost Stereo Audio DACs
General Description
The MAX5556-MAX5559 stereo audio sigma-delta digital-to-analog converters (DACs) offer a simple and complete stereo digital-to-analog solution for media servers, set-top boxes, video-game hardware, automotive rear-seat entertainment and other general consumer audio applications. These DACs feature built-in digital interpolation/filtering, sigma-delta digital-to-analog conversion and analog output filtering. Control logic and mute circuitry minimize audible pops and clicks during power-up, power-down, clock changes, or when invalid clock conditions occur. The MAX5556-MAX5559 receive input data over a flexible 3-wire interface, supporting I2S-compatible, left-justified, right-justified 16-bit, and right-justified 18-bit audio data. Data can be clocked by either an external or internal serial clock. The internal serial clock frequency is programmable by selection of a master clock (MCLK) and sample clock (LRCLK) ratio. Sampling rates from 2kHz to 50kHz are supported. The MAX5556-MAX5559 operate from a single +4.75V to +5.5V analog supply with total harmonic distortion plus noise below -87dB. These devices are available in 8-pin SO packages and are specified over the -40C to +85C industrial temperature range.
Features
Simple and Complete Stereo Audio DAC Solutions, No Controls to Set Sigma-Delta Stereo DACs with Built-In Interpolation and Analog Output Filters I2S-Compatible Digital Audio Interface (MAX5556) Clickless/Popless Operation Output Voltage Swing: 3.5VP-P -87dB THD+N +87dB Dynamic Range Sample Frequencies (fS) from 2kHz to 50kHz Master Clock (MCLK) up to 25MHz Automatic Detection of Clock Ratio (MCLK/ LRCLK)
MAX5556-MAX5559
Applications
Digital Video Recorders and Media Servers Set-Top Boxes Video-Game Hardware Automotive Rear-Seat Entertainment
PART
Ordering Information
PINPKG DATA FORMAT PACKAGE CODE MAX5556ESA 8 SO S8-5 Left-justified I2S data MAX5557ESA* 8 SO S8-5 Left-justified data MAX5558ESA* 8 SO S8-5 Right-justified 16-Bit data MAX5559ESA* 8 SO S8-5 Right-justified 18-Bit data
Typical Operating Circuit
+5V
Note: All devices are specified over the -40C to +85C operating temperature range. Contact factory for +105C operation. *Future product--contact factory for availability.
Pin Configuration
VDD LEFT OUTPUT SDATA AUDIO DECOMPRESSION SCLK LRCLK SERIAL INTERFACE DAC OUTL LINE-LEVEL BUFFER
TOP VIEW
SDATA 1 SCLK 2
8 7
OUTL VDD GND OUTR
MAX5556-MAX5559
RIGHT OUTPUT
LRCLK
3
MAX5556- MAX5559
6 5
CLOCK
MCLK
DAC
OUTR LINE-LEVEL BUFFER
MCLK 4
GND
SO
________________________________________________________________ Maxim Integrated Products
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
ABSOLUTE MAXIMUM RATINGS
VDD to GND ...........................................................-0.3V to +6.0V OUTL, OUTR, SDATA to GND................... -0.3V to (VDD + 0.3V) Current Into Any Pin (excluding VDD and GND)...............10mA OUTL, OUTR Shorted to GND....................................Continuous SCLK, LRCLK, MCLK to GND ...............................-0.3V to +6.0V Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.88mW above +70C)....................471mW Package Thermal Resistance (JA) ...............................170C/W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDD = +4.75V to +5.5V, GND = 0V, ROUT_ = 10k, COUT_ = 10pF, 0dBFS sine-wave signal at 997Hz, fLRCLK (fS) = 48kHz, fMCLK = 12.288MHz, measurement bandwidth 10Hz to 20kHz, unless otherwise specified. TA = -40C to +85C, unless otherwise noted. Outputs are unloaded, unless otherwise noted. Typical values at VDD = +5V, TA = +25C.) (Note 1)
PARAMETER POWER SUPPLY Supply Voltage Supply Current Power Dissipation DYNAMIC PERFORMANCE (Note 2) Dynamic Range, 16-Bit Dynamic Range, 18-Bit to 24-Bit Total Harmonic Distortion Plus Noise, 16-Bit Unweighted A-weighted Unweighted A-weighted 0dBFS THD+N -20dBFS -60dBFS 0dBFS Total Harmonic Distortion Plus Noise, 18-Bit to 24-Bit Interchannel Isolation THD+N -20dBFS -60dBFS 1kHz full-scale output (crosstalk) -0.5dB corner Passband -3dB corner -6dB corner Frequency Response/Passband Ripple Stopband Stopband Attenuation Group Delay Passband Group-Delay Variation tgd tgd 20Hz to 20kHz 52 20 / fS 0.4 / fS 10Hz to 20kHz (fS = 48kHz) 10Hz to 20kHz (fS = 44.1kHz) 10Hz to 16kHz (fS = 32kHz) -0.025 -0.025 -6.000 0.46 0.49 0.50 +0.08 +0.08 +0.073 0.5465 fS dB s s dB fS COMBINED DIGITAL AND INTEGRATED ANALOG FILTER FREQUENCY RESPONSE (Note 3) 84 86 86 90 87 91 -86 -67 -26 -87 -68 -27 94 dB dB -24 -81 dB dB dB VDD IDD Up to 48ksps Static digital Up to 48ksps Static digital 4.75 5.0 13 6 65 30 5.50 15 8.5 82.5 44 V mA mW SYMBOL CONDITIONS MIN TYP MAX UNITS
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +4.75V to +5.5V, GND = 0V, ROUT_ = 10k, COUT_ = 10pF, 0dBFS sine-wave signal at 997Hz, fLRCLK (fS) = 48kHz, fMCLK = 12.288MHz, measurement bandwidth 10Hz to 20kHz, unless otherwise specified. TA = -40C to +85C, unless otherwise noted. Outputs are unloaded, unless otherwise noted. Typical values at VDD = +5V, TA = +25C.) (Note 1)
PARAMETER DC CHARACTERISTICS Interchannel Gain Mismatch Gain Error Gain Drift ANALOG OUTPUTS Full-Scale Output Voltage DC Quiescent Output Voltage Minimum Load Resistance Maximum Load Capacitance Power-Supply Rejection Ratio POP AND CLICK SUPPRESSION Mute Attenuation Power-Up Until Bias Established Valid Clock to Normal Operation Input-Voltage High Input-Voltage Low Input Leakage Current Input Capacitance TIMING CHARACTERISTICS Input Sample Rate MCLK Pulse-Width Low fS MCLK/LRCLK = 512 tMCLKL MCLK/LRCLK = 384 MCLK/LRCLK = 256 MCLK/LRCLK = 512 MCLK Pulse-Width High EXTERNAL SCLK MODE LRCLK Duty Cycle SCLK Pulse-Width Low SCLK Pulse-Width High SCLK Period LRCLK Edge to SCLK Rising LRCLK Edge to SCLK Rising SDATA Valid to SCLK Rising SCLK Rising to SDATA Hold Time tSCLKL tSCLKH tSCLK tSLRS tSLRH tSDS tSDH (Note 6) 25 20 20 1 / (128 x fS) 20 20 20 20 75 % ns ns ns ns ns ns ns tMCLKH MCLK/LRCLK = 384 MCLK/LRCLK = 256 2 10 20 20 10 20 20 ns ns 50 kHz VIH VIL IIN -10 8 Figure 14 Soft-start ramp time, Figure 15 (Note 5) 2.0 0.8 +10 100 360 20 dB ms ms V V A pF VOUTR, VOUTL VQ RL CL PSRR VRIPPLE = 100mVP-P, frequency = 1kHz Input code = 0 3.25 3.5 2.4 3 100 66 3.75 VP-P V k pF dB -5 100 0.1 0.4 +5 dB % ppm/C SYMBOL CONDITIONS MIN TYP MAX UNITS
DIGITAL AUDIO INTERFACE (SCLK, SDATA, MCLK, LRCLK)
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +4.75V to +5.5V, GND = 0V, ROUT_ = 10k, COUT_ = 10pF, 0dBFS sine-wave signal at 997Hz, fLRCLK (fS) = 48kHz, fMCLK = 12.288MHz, measurement bandwidth 10Hz to 20kHz, unless otherwise specified. TA = -40C to +85C, unless otherwise noted. Outputs are unloaded, unless otherwise noted. Typical values at VDD = +5V, TA = +25C.) (Note 1)
PARAMETER INTERNAL SCLK MODE LRCLK Duty Cycle Internal SCLK Period LRCLK Edge to Internal SCLK SDATA Valid to Internal SCLK SDATA Valid to Internal SCLK tISCLK tISCLKR tISDS tISDH MCLK period = tMCLK MCLK period = tMCLK tMCLK + 10 tMCLK (Note 7) (Note 8) 1 / fSCLK tISCLK / 2 50 % ns ns ns ns SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: 100% production tested at TA = +85C. Limits to -40C are guaranteed by design. Note 2: 0.5 LSB of triangular PDF dither added to data. Note 3: Guaranteed by design, not production tested. Note 4: PSRR test block diagram shown in Figure 1 denotes the test setup used to measure PSRR. Note 5: Volume ramping interval starts from establishment of a valid MCLK to LRCLK ratio. Total time is proportional to the sample rate (fS). 20ms based on 48ksps operation. Note 6: In external SCLK mode, LRCLK duty cycles are not limited, provided all data formatting requirements are met. See Figures 4-7. Note 7: The LRCLK duty cycle must be 50% 1/2 MCLK period in internal SCLK mode. Note 8: The SCLK/LRCLK ratio can be set to 32, 48, or 64, depending on the device and the MCLK/LRCLK ratio selected. See Figures 4-7.
VDD
ACTIVE CLOCKS
AUDIO SIGNAL GENERATOR (100mVP-P AT 1kHz)
ZG SCLK LRCLK MCLK
LOUT, ROUT
MAX5556-MAX5559
SPECTRUM ANALYZER SDATA
-
DC POWER SUPPLY (5VDC)
+
GND
Figure 1. PSRR Test Block Diagram
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Low-Cost Stereo Audio DACs
Typical Operating Characteristics
(VDD = +5V, GND = 0V, ROUT_ = 10k, COUT_ = 10pF, TA = +25C, unless otherwise noted.)
STOPBAND REJECTION
MAX5556 toc01
MAX5556-MAX5559
TRANSITION BAND
MAX5556 toc02
TRANSITION BAND DETAIL
-1 -2 AMPLITUDE (dB) -3 -4 -5 -6 -7 -8 -9 -10
MAX5556 toc03
0 -10 -20 AMPLITUDE (dB) -30 -40 -50 -60 -70 -80 -90 -100 0
0 -10 -20 AMPLITUDE (dB) -30 -40 -50 -60 -70 -80 -90 -100
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 FREQUENCY (NORMALIZED TO fS)
0.40
0.44
0.48
0.52
0.56
0.60
0.40
0.42
0.44
0.46
0.48
0.50
0.52
FREQUENCY (NORMALIZED TO fS)
FREQUENCY (NORMALIZED TO fS)
PASSBAND RIPPLE
0.20 0.15 AMPLITUDE (dB) 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -0.25 0 0.1 0.2 0.3 0.4 0.5 FREQUENCY (NORMALIZED TO fS)
MAX5556 toc04
0dBFS FFT
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 0 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 0 2
MAX5556 toc05
-60dBFS FFT
MAX5556 toc06
0.25
AMPLITUDE (dBr)
AMPLITUDE (dBr)
16,000-SAMPLE FFT USING 1kHz INPUT
16,000-SAMPLE FFT USING 1kHz INPUT
2
4
6
8
10 12 14 16 18 20
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
FREQUENCY (kHz)
IDLE-CHANNEL NOISE FFT
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 0 2 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 0
MAX5556 toc07
TWIN-TONE IMD FFT
MAX5556 toc08
THD+N vs. AMPLITUDE
MAX5556 toc09
-60
-70 THD+N (dBr) UNWEIGHTED
AMPLITUDE (dBr)
AMPLITUDE (dBr)
16,000-SAMPLE FFT WITH NO INPUT
16,000-SAMPLE FFT WITH 13kHz AND 14kHz INPUT SIGNALS
-80
-90 INPUT = 1kHz 18-BIT SIGNAL -100 A-WEIGHTED INTEGRATION BANDWIDTH = 20Hz TO 20kHz -60 -50 -40 -30 -20 -10 0
-110 2 4 6 8 10 12 14 16 18 20 FREQUENCY (kHz)
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
AMPLITUDE (dBFS)
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
Typical Operating Characteristics (continued)
(VDD = +5V, GND = 0V, ROUT_ = 10k, COUT_ = 10pF, TA = +25C, unless otherwise noted.)
UNWEIGHTED THD+N vs. FREQUENCY
MAX5556 toc10
POWER DISSIPATION vs. SAMPLE FREQUENCY
MAX5556 toc11
SUPPLY CURRENT vs. SUPPLY VOLTAGE
14 13 SUPPLY CURRENT (mA) 12 11 10 9 8 7 STATIC DIGITAL INPUT MUTE OPERATION INPUT = 1kHz, 0dBFS SIGNAL NORMAL OPERATION
MAX5556 toc12
-60 INPUT = 1kHz 18-BIT SIGNAL, INTEGRATION BANDWIDTH = 20Hz TO 20kHz -70 THD+N (dBr)
70 60 POWER DISSIPATION (mW) 50 40 30 20 10 VDD = +5V INPUT = 1kHz, 0dBFS SIGNAL 0 10 20 30 40
15
-80
-90
-100
6 5 50 4.75 4.90 5.05 5.20 5.35 5.50
-110 0 2 4 6 8 10 12 14 16 18 20 FREQUENCY (kHz)
0 SAMPLE FREQUENCY (kHz)
SUPPLY VOLTAGE (V)
SUPPLY CURRENT vs. DIGITAL INPUT VOLTAGE (VDIG)
14 13 SUPPLY CURRENT (mA) 12 11 10 9 8 7 6 5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 DIGITAL INPUT VOLTAGE (VDIG) (V) VDD = +5.5V DC OUTPUT VIH 2.4V VDIG < VIH MUTE ENGAGED VDIG < VIH NORMAL OPERATION
MAX5556 toc13
CLOCK-LOSS MUTE RECOVERY
MAX5556 toc14
POWER-UP RESPONSE
MAX5556 toc15
15
CLOCK RESTORED VOUT 1V/div VOUT 1V/div
LOSS OF CLOCK
0V
5ms/div
100ms/div
6
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Low-Cost Stereo Audio DACs
Pin Description
PIN 1 2 3 4 5 6 7 8 NAME SDATA SCLK LRCLK MCLK OUTR GND VDD OUTL FUNCTION Serial Audio Data Input. Data is clocked into the MAX5556-MAX5559 on the rising edge of the internal or external SCLK. Data is input in two's complement format, MSB first. The state of LRCLK determines whether data is directed to OUTL or OUTR. External Serial Clock Input. Data is strobed on the rising edge of SCLK. Left-/Right-Channel Select Clock. For the MAX5556, drive LRCLK low to direct data to OUTL or LRCLK high to direct data to OUTR. For the MAX5557/MAX5558/MAX5559, drive LRCLK high to direct data to OUTL or LRCLK low to direct data to OUTR. Master Clock Input. The MCLK/LRCLK ratio must equal to 256, 384, or 512. Right-Channel Analog Output Ground Power-Supply Input. Bypass VDD to GND with a 0.1F capacitor in parallel with a 4.7F capacitor as close to VDD as possible. Place the 0.1F capacitor closest to VDD. Left-Channel Analog Output
MAX5556-MAX5559
Detailed Description
The MAX5556-MAX5559 stereo audio sigma-delta DACs offer a complete stereo digital-to-analog system for consumer audio applications. The MAX5556-MAX5559 feature built-in digital interpolation/filtering, sigma-delta digital-to-analog conversion and analog output filters (Figure 2). Control logic and mute circuitry minimize audible pops and clicks during power-up, power-down, and whenever invalid clock conditions occur. These stereo audio DACs receive input data over a 3wire interface that supports up to 24 bits of left-justified, right-justified, or I 2 S-compatible audio data. The MAX5556 accepts left-justified I2S data, up to 24 bits. The MAX5557 accepts left-justified data, up to 24 bits. The MAX5558 accepts right-justified 16-bit data. The MAX5559 accepts right-justified 18-bit data. These DACs also support a wide range of sample rates from 2kHz to 48kHz. Direct analog output data is routed to the right or left output by driving LRCLK high or low. See the Clock and Data Interface section. The MAX5556-MAX5559 support MCLK/LRCLK ratios of 256, 384, or 512. These devices allow a change to the clock speed ratio without causing glitches on the analog outputs by internally muting the audio during invalid clock conditions. The internal mute function ramps down the audio amplitude and forces the analog
outputs to a 2.4V quiescent voltage immediately upon clock loss or change of ratio. A soft-start routine is then engaged when a valid clock ratio is re-established, producing clickless and popless continuous operation. The MAX5556-MAX5559 operate from a +4.75V to +5.5V analog supply and feature +87dB dynamic range with total harmonic distortion typically below -87dB.
Interpolator
The digital interpolation filter eliminates images of the baseband audio signal that exist at multiples of the input sample rate (fS). The resulting upsampled frequency spectrum has images of the input signal at multiples of 8 x fS. An additional upsampling sinc filter further reduces upsampling images up to 64 x fS. These images are ultimately removed through the internal analog lowpass filter and the external analog output filter.
Sigma-Delta Modulator/DAC
The MAX5556-MAX5559 use a multibit sigma-delta DAC with an oversampling ratio (OSR) of 64 to achieve a wide dynamic range. The sigma-delta modulator accepts a 3bit data stream from the interpolation filter at a rate of 64 x fS (fS = LRCLK frequency) and provides an analog voltage representation of that data stream.
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
VDD
INTERPOLATOR SDATA
SIGMA-DELTA MODULATOR
DAC
ANALOG LOWPASS FILTER BUFFER
OUTL
SCLK SERIAL INTERFACE LRCLK INTERNAL REFERENCE
MCLK INTERPOLATOR SIGMA-DELTA MODULATOR DAC ANALOG LOWPASS FILTER BUFFER OUTR
MAX5556-MAX5559
GND
Figure 2. Functional Diagram
125
100 LOAD CAPACITANCE CL (pF)
75
50 SAFE OPERATING REGION
25
3 5 10 15 20 25
LOAD RESISTANCE RL (k)
Figure 3. Load-Impedance Operating Region
Integrated Analog Lowpass Filter
The DAC output of the sigma-delta modulator is followed by an analog smoothing filter that attenuates high-frequency quantization noise. The corner frequency of the filter is approximately 2 x fS.
8
Integrated Analog Output Buffer
Following the analog lowpass filter, the analog signal is routed through internal buffers to OUTR and OUTL. The buffer can directly drive load resistances larger than 3k and load capacitances up to 100pF (Figure 3).
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Low-Cost Stereo Audio DACs
Clock and Data Interface
The MAX5556-MAX5559 strobe serial data (SDATA) in on the rising edge of SCLK. LRCLK routes data to the left or right outputs and, along with SCLK, defines the number of bits per sample transferred. The digital interpolators filter data at internal clock rates derived from the MCLK frequency. Each device supports both internal and external serial clock (SCLK) modes.
SDATA Input The serial interface strobes data (SDATA) in on the rising edge of SCLK, MSB first. The MAX5556-MAX5559 support four different data formats, as detailed in Figures 4-7.
MAX5556-MAX5559
LRCLK
DATA DIRECTED TO OUTL
DATA DIRECTED TO OUTR
SCLK
SDATA
MSB -1
-2
-3
-4 -5
+5
+4
+3
+2
+1 LSB
MSB -1
-2
-3 -4
+5
+4
+3
+2
+1 LSB
INTERNAL SERIAL CLOCK MODE * I2S, 16-BIT DATA AND INTERNAL SCLK = 32 x fS IF MCLK/ LRCLK = 256 OR 512 * I2S, UP TO 24 BITS OF DATA AND INTERNAL SCLK = 48 X fS IF MCLK/ LRCLK = 384
EXTERNAL SERIAL CLOCK MODE
* I2S, UP TO 24 BITS OF DATA * DATA VALID ON RISING EDGE OF SCLK
Figure 4. MAX5556 Data Format Timing
LRCLK
DATA DIRECTED TO OUTR DATA DIRECTED TO OUTL
SCLK
SDATA
MSB -1
-2
-3
-4 -5
+5
+4
+3
+2
+1 LSB
MSB -1
-2
-3 -4
+5
+4
+3
+2
+1 LSB
INTERNAL SERIAL CLOCK MODE
EXTERNAL SERIAL CLOCK MODE
* LEFT-JUSTIFIED, UP TO 24 BITS OF DATA * INTERNAL SCLK = 64 x fS IF MCLK / LRCLK = 256 OR 512 * INTERNAL SCLK = 48 x fS IF MCLK / LRCLK = 384
* LEFT-JUSTIFIED, UP TO 24 BITS OF DATA * DATA VALID ON RISING EDGE OF SCLK
Figure 5. MAX5557 Data Format Timing
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
LRCLK
DATA DIRECTED TO OUTL
DATA DIRECTED TO OUTR
SCLK
SDATA
15 MSB
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0 LSB
15 MSB
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0 LSB
INTERNAL SERIAL CLOCK MODE
EXTERNAL SERIAL CLOCK MODE
* RIGHT-JUSTIFIED, 16-BIT DATA * INTERNAL SCLK = 32 x fS IF MCLK / LRCLK = 256 OR 512 * INTERNAL SCLK = 48 x fS IF MCLK / LRCLK = 384
* RIGHT-JUSTIFIED, 16-BIT DATA * DATA VALID ON RISING EDGE OF SCLK * SCLK MUST HAVE AT LEAST 32 CYCLES PER LRCLK PERIOD
Figure 6. MAX5558 Data Format Timing
LRCLK
DATA DIRECTED TO OUTL
DATA DIRECTED TO OUTR
SCLK
SDATA
17 MSB
16 15
14
13
12
11 10
9
8
7
6
5
4
3
2
1
0 LSB
17 MSB
16
15
14
13
12 11
10
9
8
7
6
5
4
3
2
1
0 LSB
INTERNAL SERIAL CLOCK MODE
EXTERNAL SERIAL CLOCK MODE
* RIGHT-JUSTIFIED, 18-BIT DATA * INTERNAL SCLK = 64 x fS IF MCLK / LRCLK = 256 OR 512 * INTERNAL SCLK = 48 x fS IF MCLK / LRCLK = 384
* RIGHT-JUSTIFIED, 18-BIT DATA * DATA VALID ON RISING EDGE OF SCLK * SCLK MUST HAVE AT LEAST 36 CYCLES PER LRCLK PERIOD
Figure 7. MAX5559 Data Format Timing
Serial Clock (SCLK) SCLK strobes the individual data bits at SDATA into the DAC. The MAX5556-MAX5559 operate in one of two modes: internal serial clock mode or external serial clock mode. External SCLK Mode The MAX5556-MAX5559 operate in external serial clock mode when SCLK activity is detected. All four devices return to internal serial clock mode if no SCLK signal is detected for one LRCLK period. Figure 8 details the external serial clock mode timing parameters.
Internal SCLK Mode The MAX5556-MAX5559 transition from external serial clock mode to internal serial clock mode if no SCLK signal is detected for one LRCLK period. In internal clock mode, SCLK is derived from and is synchronous with MCLK and LRCLK (operation in internal clock mode is identical to an external clock mode when LRCLK is synchronized with MCLK). Figure 9 details the internal serial clock mode timing parameters. Figure 10 details the generation of the internal clock.
10
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
LRCLK tSLRH tSCLK tSLRS tSCLKL tSCLKH
SCLK
tSDS
tSDH
SDATA
Figure 8. External SCLK Serial Timing Diagram
LRCLK tISCLKR
SDATA tISDS tISCLK
tISDH
INTERNAL SCLK
Figure 9. Internal SCLK Serial Timing Diagram
LRCLK
MCLK
1 INTERNAL SCLK
N / 2*
N*
SDATA
*N = MCLK / SCLK.
Figure 10. Internal Serial Clock Generation ______________________________________________________________________________________
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
Left/Right Clock Input (LRCLK) LRCLK is the left/right clock input signal for the 3-wire interface and sets the sample frequency (fS). On the MAX5556, drive LRCLK low to direct data to OUTL or LRCLK high to direct data to OUTR (Figure 4). On the MAX5557/MAX5558/MAX5559, drive LRCLK high to direct data to OUTL or LRCLK low to direct data to OUTR (Figures 5, 6, 7). LRCLK is internally resampled on each SCLK rising edge. The MAX5556-MAX5559 accept data at LRCLK audio sample rates from 2kHz to 50kHz. Master Clock (MCLK) MCLK accepts the master clock signal from an external clocking device and is used to derive internal clock frequencies. Set the MCLK/LRCLK ratio to 256, 384, or 512 to achieve the internal serial clock frequencies listed in Table 1. Table 2 details the MCLK/LRCLK ratios for three sample audio rates. The MAX5556-MAX5559 detect the MCLK/LRCLK ratio during the initialization sequence by counting the number of MCLK transitions during a single LRCLK period. MCLK, SCLK, and LRCLK must be synchronous signals.
Data Formats
MAX5556 I2S Left-Justified Data Format The MAX5556 accepts data with an I2S left-justified data format, accepting up to 24 bits of data. SDATA accepts data in two's complement format with the MSB first. The MSB is valid on the second SCLK rising edge after LRCLK transitions low to high or high to low (Figure 4). Drive LRCLK low to direct data to OUTL. Drive LRCLK high to direct data to OUTR. The number of SCLK pulses with LRCLK high or low determines the number of bits transferred per sample. If fewer than 24 bits of data are written, the remaining LSBs are set to 0. If more than 24 bits are written, any bits after the LSB are ignored. The MAX5556 accepts up to 24 bits of data in external serial clock mode or when the MCLK/LRCLK ratio is 384 (internal serial clock = 48 x fS) in internal serial clock mode. The DAC also accepts 16 bits of data in internal serial clock mode when the MCLK/LRCLK ratio is 256 or 512 (internal serial clock = 32 x fS). MAX5557 Left-Justified Data Format The MAX5557 accepts data with a left-justified data format, allowing for up to 24 bits of data. SDATA accepts data in two's complement format with the MSB first. The MSB is valid on the first SCLK rising edge after LRCLK transitions low to high or high to low (Figure 5). Drive LRCLK high to direct data to OUTL. Drive LRCLK low to direct data to OUTR. The number of SCLK pulses with LRCLK high or low determines the number of bits transferred per sample. If fewer than 24 bits of data are written, the remaining LSBs are set to 0. If more than 24 bits are written, the bits after the LSB are ignored. The MAX5557 accepts up to 24 bits of data in external serial clock mode and internal serial clock mode. Program the MCLK/LRCLK ratio to 384 to operate the internal serial clock at 48 x f S . Program the MCLK/LRCLK ratio to 256 or 512 to operate the internal serial clock at 64 x fS. MAX5558 16-Bit Right-Justified Data Format The MAX5558 operates from a 16-bit right-justified data format. The LSB is valid on the final SCLK rising edge prior to LRCLK transitioning low to high or high to low (Figure 6). In external serial clock mode, the MAX5558 requires a minimum of 32 SCLK cycles per LRCLK period (16 SCLK cycles with LRCLK low and 16 SCLK cycles with LRCLK high). Drive LRCLK high to direct data to OUTL. Drive LRCLK low to direct data to OUTR. Any additional SDATA bits prior to the MSB are ignored.
Table 1. Internal and External Clock Frequencies
INTERNAL SERIAL CLOCK FREQUENCY PART MCLK/LRCLK = 256 OR 512 MAX5556 MAX5557 MAX5558 MAX5559 32 x fS 64 x fS 32 x fS 64 x fS MCLK/LRCLK = 384 48 x fS 48 x fS 48 x fS 48 x fS EXTERNAL SERIAL CLOCK FREQUENCY User defined (Figure 4) User defined (Figure 5) User defined (Figure 6) User defined (Figure 7)
Table 2. MCLK/LRCLK Ratios
MCLK (MHz) LRCLK (kHz) 32 44.1 48 MCLK/LRCLK = 256 8.1920 11.2896 12.2880 MCLK/LRCLK = 384 12.2880 16.9344 18.4320 MCLK/LRCLK = 512 16.3840 22.5792 24.5760
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Low-Cost Stereo Audio DACs
The MAX5558 accepts 16 bits of data in external serial clock mode and internal serial clock mode. Program the MCLK/LRCLK ratio to 384 to operate the internal serial clock at 48 x fS. Program the MCLK/LRCLK ratio to 256 or 512 to operate the internal serial clock at 32 x fS. The MAX5559 accepts 18 bits of data in external serial clock mode and internal serial clock mode. Program the MCLK/LRCLK ratio to 384 to operate the internal serial clock at 48 x fS. Program the MCLK/LRCLK ratio to 256 or 512 to operate the internal serial clock at 64 x fS.
MAX5556-MAX5559
MAX5559 18-Bit Right-Justified Data Format The MAX5559 accepts data with an 18-bit right-justified data format. The LSB is valid on the final SCLK rising edge prior to LRCLK transitioning low to high or high to low (Figure 7). In external serial clock mode, the MAX5559 requires a minimum of 36 SCLK cycles per LRCLK period (18 SCLK cycles with LRCLK low and 18 SCLK cycles with LRCLK high). Drive LRCLK high to direct data to OUTL. Drive LRCLK low to direct data to OUTR. Any additional SDATA bits prior to the MSB are ignored.
External Analog Filter
Use an external lowpass analog filter to further reduce harmonic images, noise, and spurs. The external analog filter can be either active or passive depending upon performance and design requirements. For example filters, see Figures 11 and 12 and the Applications Information section. Careful attention should be paid when selecting capacitors for audio signal path applications. NPO and C0G types are recommended as are aluminum electrolytics and some tantalum varieties. Use of generic ceramic types is not recommended and may result in degraded THD performance. Always consult manufacturers' data sheets and applications information.
R = 560 OUTL 100k C = 1.5nF
MAX5556-MAX5559
R = 560 OUTR 100k C = 1.5nF
Figure 11. Passive Component Analog Output Filter
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
56pF
+5V 5.23k OUTR 24.3k
33pF
10k VBIAS
59k
MAX5556-MAX5559
56pF
+5V 5.23k OUTL 24.3k
33pF
10k VBIAS
59k
Figure 12. Active Component Analog Output Filter
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
NO POWER APPLIED
POWER-UP
OUTPUTS HELD AT GROUND OUTPUTS HELD AT CURRENT LEVELS VALID CLOCK RATIO ESTABLISHED
LofC OUTPUTS LINEARLY RAMPED TO DC QUIESCENT LEVELS (< 1 SECOND) VALID CLOCK RATIO RE-ESTABLISHED
VALID CLOCK RATIO RE-ESTABLISHED LofC INTERNAL REGISTERS INITIALIZED (MUTE) LOSSOFPOWER EVENT OUTPUTS IMMEDIATELY RETURNED TO DC QUIESCENT LEVELS LofC SOFT-START VOLUME RAMPING
LofC
NORMAL OPERATION (FULL VOLUME)
LofC = LOSS OF CLOCK EVENT
INVALID RATIO DETECTED MCLK TIME OUT SCLK INT/EXT MODE CHANGED LRCLK LOSS
OUTPUTS IMMEDIATELY RETURNED TO GROUND
Figure 13. Internal State Diagram ______________________________________________________________________________________
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
Pop and Click Suppression
The MAX5556-MAX5559 feature a pop and click supression routine to reduce the unwanted audible effects of system transients. This routine produces glitch-free operation at the outputs during power-on, loss of clock, or invalid clock conditions. See Figure 13 for a detailed state diagram during transient conditions.
Power-Down
When the positive supply is removed from the MAX5556-MAX5559, the outputs discharge to ground. When power is restored, the power-up ramp routine engages once a valid clock ratio is established (see the Power-Up section). Avoid violating absolute maximum conditions by supplying digital inputs to the part or forcing voltages on the analog outputs during a loss-of-power event.
Power-Up Once the MAX5556-MAX5559 recognize a valid MCLK/LRCLK ratio (256, 384, or 512), the analog outputs (OUTR and OUTL) are enabled in stages using a glitchless ramping routine. First, the outputs ramp up to the quiescent output voltage at a rate of 5V/s typ (see Figure 14). After the outputs reach the quiescent voltage, the converted data stream begins soft-start ramping, achieving the full-scale operation over a 20ms period. If invalid clock signals are detected while the outputs are DC ramping to their quiescent state, the outputs stop ramping and hold their preset values until valid clock signals are restored (Figure 15). Loss of Clock and Invalid Clock Conditions The MAX5556-MAX5559 mute both outputs after detecting one of four invalid clock conditions. All four devices mute their outputs to prevent propagation of pops, clicks, or corrupted data through the signal path. The MAX5556-MAX5559 force the outputs to the quiescent DC voltage (2.4V) to prevent clicks in capacitivecoupled systems. Invalid clock conditions include: 1. MCLK/LRCLK ratio changes between 256, 384, and 512
2. Transition between internal and external serialclock mode 3. Invalid MCLK/LRCLK ratio 4. MCLK falls below the minimum operating frequency 2kHz When the MCLK/LRCLK ratio returns to 256, 384, or 512 and MCLK is equal or greater than its minimum operating frequency, the MAX5556-MAX5559 outputs return to their full-scale setting over a soft-start mute time of 20ms (Figure 15).
Applications Information
Low-Cost Line-Level Solution
Connect the MAX5556-MAX5559 outputs through a passive output filter as detailed in Figure 11 for a low-cost solution. This lowpass filter yields single-pole (20dB/decade) roll-off at a corner frequency (f C ) determined by: fC = 1 2RC
In the case of Figure 11, fC is approximately 190kHz.
High-Performance Line-Level Solution
For enhanced performance, connect the MAX5556- MAX5559 outputs to an active filter by using an operational amplifier as shown in Figure 12. The use of an active filter allows for steeper roll-off, more efficient filtering, and also adds the capability of a programmable output gain.
Power-Supply Sequencing
For correct power-up sequencing, apply VDD and then connect the input digital signals. Do not apply digital signals before VDD is applied. Do not violate any of the absolute maximum ratings by removing power with the digital inputs still connected. To correctly power down the device, first disconnect the digital input signals, and then remove VDD.
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
VOUT_ SETTLES AT QUIESCENT VOLTAGE (2.4V) VOUT_ RAMPS UP TO QUIESCENT VOLTAGE AT 5V/s (TYP)
OUTPUT VOLTAGE (OUTR OR OUTL)
VALID MCLK/LRCLK RATIO DETECTED VOUT_ BEGINS TO FOLLOW THE DATA. THE AMPLITUDE IS RAMPED TO FULL SCALE (20ms TYP)
TIME
Figure 14. Power-Up Sequence
INVALID CLOCK CONDITION
MUTE: VOUT_ IMMEDIATELY FORCED TO DC QUIESCENT LEVEL (2.4V)
OUTPUT VOLTAGE (OUTR OR OUTL)
VALID MCLK/LRCLK RE-ESTABLISHED AND MCLK EQUAL OR GREATER THAN MINIMUM OPERATING FREQUENCY
VOUT_ SOFT START RAMPING (20ms TYP) TIME
Figure 15. Invalid Clock Output Response
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Low-Cost Stereo Audio DACs MAX5556-MAX5559
Power-Supply Connections and Ground Management
Proper layout and grounding are essential for optimum performance. Use large traces for the power-supply inputs and analog outputs to minimize losses due to parasitic trace resistance. Large traces also aid in moving heat away from the package. Proper grounding improves audio performance, minimizes crosstalk between channels, and prevents any switching noise from coupling into the audio signal. Route the analog paths (GND, VDD, OUTL, and OUTR) away from the digital signals. Connect a 0.1F capacitor in parallel with a 4.7F capacitor as close to VDD as possible. Low ESR-type capacitors are recommended for supply decoupling applications. A small value C0G-type bypass capacitor located as close to the device as possible is recommended in parallel with larger values.
Chip Information
PROCESS: BiCMOS
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Low-Cost Stereo Audio DACs
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
SOICN .EPS
MAX5556-MAX5559
INCHES DIM A A1 B C e E H L MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050
MILLIMETERS MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D A e B A1 L C
0-8
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL DOCUMENT CONTROL NO. REV.
21-0041
B
1 1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19
(c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
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