19-2955; Rev 1; 8/07 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters The MAX1067/MAX1068 low-power, multichannel, 14bit analog-to-digital converters (ADCs) feature a successive-approximation ADC, integrated +4.096V reference, a reference buffer, an internal oscillator, automatic power-down, and a high-speed SPI™/ QSPI™/MICROWIRE™-compatible interface. The MAX1067/MAX1068 operate with a single +5V analog supply and feature a separate digital supply, allowing direct interfacing with +2.7V to +5.5V digital logic. The MAX1067/MAX1068 consume only 3.6mA (AVDD = DVDD = +5V) at 200ksps when using an external reference. AutoShutdown™ reduces the supply current to 185µA at 10ksps and to less than 10µA at reduced sampling rates. The MAX1067 includes a 4-channel input multiplexer, and the MAX1068 accepts up to eight analog inputs. In addition, digital signal processor (DSP)-initiated conversions are simplified with the DSP frame-sync input and output featured in the MAX1068. The MAX1068 includes a data-bit transfer input to select between 8-bit-wide or 16bit-wide data-transfer modes. Both devices feature a scan mode that converts each channel sequentially or one channel continuously. Excellent dynamic performance and low power, combined with ease of use and an integrated reference, make the MAX1067/MAX1068 ideal for control and dataacquisition operations or for other applications with demanding power consumption and space requirements. The MAX1067 is available in a 16-pin QSOP package, and the MAX1068 is available in a 24-pin QSOP package. Both devices are guaranteed over the commercial (0°C to +70°C) and extended (-40°C to +85°C) temperature ranges. Use the MAX1168 evaluation kit to evaluate the MAX1068. Features ♦ 14-Bit Resolution, ±0.5 LSB INL and ±1 LSB DNL (max) ♦ +5V Single-Supply Operation ♦ Adjustable Logic Level (+2.7V to +5.25V) ♦ Input Voltage Range: 0 to VREF ♦ Internal (+4.096V) or External (+3.8V to AVDD) Reference ♦ Internal Track/Hold, 4MHz Input Bandwidth ♦ Internal or External Clock ♦ SPI/QSPI/MICROWIRE-Compatible Serial Interface, MAX1068 Performs DSP-Initiated Conversions ♦ 8-Bit-Wide or 16-Bit-Wide Data-Transfer Mode (MAX1068 Only) ♦ 4-Channel (MAX1067) or 8-Channel (MAX1068) Input Mux Scan Mode Sequentially Converts Multiple Channels or One Channel Continuously ♦ Low Power 3.6mA at 200ksps 1.85mA at 100ksps 185µA at 10ksps 0.6µA in Full Power-Down Mode ♦ Small Package Size 16-Pin QSOP (MAX1067) 24-Pin QSOP (MAX1068) Ordering Information Applications Motor Control PART Industrial Process Control MAX1067ACEE Industrial I/O Modules TEMP RANGE PINPACKAGE INL (LSB) 0°C to +70°C 16 QSOP ±0.5 MAX1067BCEE 0°C to +70°C 16 QSOP ±1 Data-Acquisition Systems MAX1067CCEE 0°C to +70°C 16 QSOP ±2 Thermocouple Measurements MAX1067AEEE -40°C to +85°C 16 QSOP ±0.5 MAX1067BEEE -40°C to +85°C 16 QSOP ±1 MAX1067CEEE -40°C to +85°C 16 QSOP ±2 Accelerometer Measurements Ordering Information continued at end of data sheet. SPI/QSPI are trademarks of Motorola, Inc. Pin Configurations appear at end of data sheet. MICROWIRE is a trademark of National Semiconductor Corp. AutoShutdown is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1 For pricing delivery, and ordering information please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX1067/MAX1068 General Description MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters ABSOLUTE MAXIMUM RATINGS AVDD to AGND .........................................................-0.3V to +6V DVDD to DGND.........................................................-0.3V to +6V DGND to AGND.....................................................-0.3V to +0.3V AIN_, REF, REFCAP to AGND..................-0.3V to (AVDD + 0.3V) SCLK, CS, DSEL, DSPR, DIN to DGND ...................-0.3V to +6V DOUT, DSPX, EOC to DGND...................-0.3V to (DVDD + 0.3V) Maximum Current into Any Pin............................................50mA Continuous Power Dissipation (TA = +70°C) 16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW 24-Pin QSOP (derate 9.5mW/°C above +70°C)...........762mW Operating Temperature Ranges MAX106_ _ CE_ ..................................................0°C to +70°C MAX106_ _ EE_ ...............................................-40°C to +85°C Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 (AVDD = DVDD = +4.75V to +5.25V, fSCLK = 4.8MHz external clock (50% duty cycle), 24 clocks/conversion (200ksps), external VREF = +4.096V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC ACCURACY (Note 1) Resolution Relative Accuracy (Note 2) Differential Nonlinearity 14 INL DNL Transition Noise MAX106_A ±0.5 ±1 MAX106_B ±1.0 ±2 MAX106_C ±1.5 ±3 No missing codes over temperature RMS noise MAX106_A ±1 MAX106_B +1.5 -1.0 MAX106_C +1.5 -1.0 External reference 0.33 Internal reference 0.35 Offset Error Gain Error (Note 3) Offset Drift Gain Drift Bits (Note 3) LSB LSB LSBRMS ±0.1 ±10 ±0.01 ±0.2 mV %FSR 1 ppm/°C ±1.2 ppm/°C DYNAMIC SPECIFICATIONS (1kHz sine wave, 4.096VP-P) (Note 1) Signal-to-Noise Plus Distortion Signal-to-Noise Ratio SINAD 81 84 dB SNR 82 84 dB Total Harmonic Distortion THD Spurious-Free Dynamic Range SFDR -98 86 -86 dB 99 dB Full-Power Bandwidth -3dB point 4 MHz Full-Linear Bandwidth SINAD > 81dB 10 kHz Channel-to-Channel Isolation (Note 4) 85 dB CONVERSION RATE Conversion Time 2 tCONV Internal clock, no data transfer, single conversion (Note 5) 5.52 External clock 3.75 _______________________________________________________________________________________ 7.07 µs Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters (AVDD = DVDD = +4.75V to +5.25V, fSCLK = 4.8MHz external clock (50% duty cycle), 24 clocks/conversion (200ksps), external VREF = +4.096V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Acquisition Time SYMBOL tACQ Serial Clock Frequency Internal Clock Frequency fSCLK fINTCLK Aperture Delay tAD Aperture Jitter tAJ Sample Rate (Note 7) fS CONDITIONS MIN (Note 6) 729 External clock, data transfer and conversion 0.1 TYP MAX ns 4.8 External clock, data transfer only Internal clock 9 3.2 MHz 4.0 MHz 15 ns <50 ps 8-bit-wide data-transfer mode 4.17 200.00 16-bit-wide data-transfer mode 3.125 150.000 Internal clock, single conversion, 8-bit-wide data-transfer mode 89 Internal clock, single conversion, 16-bitwide data-transfer mode 68 Internal clock, scan mode, 8-bit-wide datatransfer mode (four conversions) 103 External clock, scan mode, 16-bit-wide data-transfer mode (four conversions) 82 Duty Cycle UNITS ksps 45 55 % 0 VREF V ANALOG INPUT (AIN_) Input Range VAIN_ Input Capacitance CAIN_ 45 pF EXTERNAL REFERENCE Input Voltage Range VREF Input Current IREF (Note 8) 3.8 AVDD – 0.2 VAIN_ = 0 34 SCLK idle 0.1 CS = DVDD, SCLK idle 0.1 V µA INTERNAL REFERENCE Reference Voltage VREFIN Reference Short-Circuit Current IREFSC 4.042 Reference Temperature Coefficient Reference Wake-Up Time tRWAKE VREF = 0 4.096 4.136 V 13 mA ±25 ppm/°C 5 ms _______________________________________________________________________________________ 3 MAX1067/MAX1068 ELECTRICAL CHARACTERISTICS (continued) MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters ELECTRICAL CHARACTERISTICS (continued) (AVDD = DVDD = +4.75V to +5.25V, fSCLK = 4.8MHz external clock (50% duty cycle), 24 clocks/conversion (200ksps), external VREF = +4.096V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DIGITAL INPUTS (SCLK, CS, DSEL, DSPR, DIN) (DVDD = +2.7V to +5.25V) Input High Voltage VIH Input Low Voltage VIL Input Leakage Current Input Hysteresis Input Capacitance IIN 0.7 × DVDD Digital inputs = 0 to DVDD V ±0.1 0.3 × DVDD V ±1 µA VHYST 0.2 V CIN 15 pF DIGITAL OUTPUT (DOUT, DSPX, EOC) (DVDD = +2.7V to +5.25V) Output High Voltage VOH Output Low Voltage VOL Tri-State Output Leakage Current Tri-State Output Capacitance DVDD 0.4 ISOURCE = 0.5mA V ISINK = 10mA, DVDD = +4.75V to +5.25V 0.8 ISINK = 1.6mA, DVDD = +2.7V to +5.25V 0.4 IL CS = DVDD ±0.1 COUT CS = DVDD 15 ±10 V µA pF POWER SUPPLIES Analog Supply AVDD 4.75 5.25 V Digital Supply DVDD 2.70 5.25 V 200ksps 100ksps Analog Supply Current (Note 9) IAVDD 10ksps 1ksps Digital Supply Current Power-Down Supply Current 4 IDVDD IAVDD + IDVDD DOUT = all zeros CS = DVDD, SCLK = 0, DIN = 0, DSPR = DVDD External reference 2.7 3.3 4.2 Internal reference 3.6 External reference 1.4 Internal reference 2.7 External reference 0.14 Internal reference 1.8 External reference 0.014 Internal reference 1.7 200ksps 0.87 100ksps 0.45 10ksps 0.045 1ksps 0.005 Internal reference and reference buffer on between conversions 0.66 mA 1.3 mA mA Internal reference on, reference buffer off between conversions 0.20 _______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters (AVDD = DVDD = +4.75V to +5.25V, fSCLK = 4.8MHz external clock (50% duty cycle), 24 clocks/conversion (200ksps), external VREF = +4.096V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Shutdown Supply Current Power-Supply Rejection Ratio SYMBOL IAVDD + IDVDD PSRR TYP MAX UNITS CS = DVDD, SCLK = 0, DIN = 0, DSPR = DVDD, full power-down CONDITIONS MIN 0.6 10 µA AVDD = DVDD = 4.75V to 5.25V, full-scale input (Note 10) 63 dB TIMING CHARACTERISTICS (Figures 1, 2, 8, and 16) (AVDD = DVDD = +4.75V to +5.25V, fSCLK = 4.8MHz external clock (50% duty cycle), 24 clocks/conversion (200ksps), external VREF = +4.096V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX tACQ External clock (Note 6) SCLK to DOUT Valid tDO CDOUT = 30pF 50 ns CS Fall to DOUT Enable tDV CDOUT = 30pF 80 ns CS Rise to DOUT Disable tTR CDOUT = 30pF 80 CS Pulse Width tCSW CS to SCLK Setup tCSS CS to SCLK Hold tCSH SCLK High Pulse Width tCH Duty cycle 45% to 55% SCLK Low Pulse Width tCL Duty cycle 45% to 55% SCLK Period tCP DIN to SCLK Setup tDS DIN to SCLK Hold tDH CS Falling to DSPR Rising 729 UNITS Acquisition Time SCLK rise SCLK fall (DSP) SCLK rise SCLK fall (DSP) ns ns 100 ns 100 ns 0 ns Conversion 93 Data transfer 50 Conversion 93 Data transfer 50 ns ns 209 ns 50 ns 0 ns tDF 100 ns DSPR to SCLK Falling Setup tFSS 100 ns DSPR to SCLK Falling Hold tFSH 0 ns SCLK rise SCLK fall (DSP) SCLK rise SCLK fall (DSP) _______________________________________________________________________________________ 5 MAX1067/MAX1068 ELECTRICAL CHARACTERISTICS (continued) MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters TIMING CHARACTERISTICS (Figures 1, 2, 8, and 16) (AVDD = +4.75V to +5.25V, DVDD = +2.7V to +5.25V, fSCLK = 4.8MHz external clock (50% duty cycle), 24 clocks/conversion (200ksps), external VREF = +4.096V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Acquisition Time tACQ External clock (Note 6) SCLK to DOUT Valid tDO CDOUT = 30pF 100 ns CS Fall to DOUT Enable tDV CDOUT = 30pF 100 ns tTR CDOUT = 30pF 80 ns CS Rise to DOUT Disable CS Pulse Width tCSW CS to SCLK Setup tCSS CS to SCLK Hold tCSH SCLK High Pulse Width tCH Duty cycle 45% to 55% SCLK Low Pulse Width tCL Duty cycle 45% to 55% SCLK Period tCP DIN to SCLK Setup tDS DIN to SCLK Hold tDH 729 SCLK rise SCLK fall (DSP) SCLK rise SCLK fall (DSP) SCLK rise SCLK fall (DSP) SCLK rise SCLK fall (DSP) ns 100 ns 100 ns 0 ns Conversion 93 Data transfer 93 Conversion 93 Data transfer 93 ns ns 209 ns 100 ns 0 ns CS Falling to DSPR Rising tDF 100 ns DSPR to SCLK Falling Setup tFSS 100 ns DSPR to SCLK Falling Hold tFSH 0 ns Note 1: AVDD = DVDD = +5.0V. Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after full-scale range has been calibrated. Note 3: Offset and reference errors nulled. Note 4: DC voltage applied to on channel, and a full-scale 1kHz sine wave applied to off channels. Note 5: Conversion time is measured from the rising edge of the 8th external SCLK pulse to EOC transition minus tACQ in 8-bit data-transfer mode. Note 6: See Figures 10 and 17. Note 7: fSCLK = 4.8MHz, fINTCLK = 4.0MHz. Sample rate is calculated with the formula fs = n1 (n2 / fSCLK + n3 / fINTCLK)-1 where: n1 = number of scans, n2 = number of SCLK cycles, and n3 = number of internal clock cycles (see Figures 11–14). Note 8: Guaranteed by design, not production tested. Note 9: Internal reference and buffer are left on between conversions. Note 10: Defined as the change in the positive full scale caused by a ±5% variation in the nominal supply voltage. 6 _______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters DNL vs. CODE 0.8 0.4 0.2 0.2 0 -0.2 0 -0.2 -80 -0.4 -100 -0.6 -0.6 -120 -0.8 -0.8 -140 -1.0 0 4096 8192 12,288 -160 16,384 0 4096 8192 CODE 12,288 0 16,384 SINAD vs. FREQUENCY SFDR vs. FREQUENCY 100 60 fSAMPLE = 200kbps -20 30 60 20 fSAMPLE = 200ksps 20 -100 0 0 1 10 -120 0.1 100 -60 -80 40 fSAMPLE = 200kbps 1 100 10 0.1 1 100 10 FREQUENCY (kHz) FREQUENCY (kHz) FREQUENCY (kHz) SUPPLY CURRENT vs. CONVERSION RATE (EXTERNAL CLOCK) ANALOG SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE (INTERNAL REFERENCE) ANALOG SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE (EXTERNAL REFERENCE) 1.5 1.0 TA = +85°C TA = +70°C 2.00 2.85 2.80 TA = +85°C DVDD = +5V fS = 200ksps 1.95 TA = +70°C 1.90 1.85 TA = +25°C 0.5 IAVDD, INT REF IAVDD, EXT REF 0 -0.5 TA = +25°C TA = 0°C 2.75 IDVDD 20 40 60 80 100 120 140 160 180 200 CONVERSION RATE (ksps) TA = 0°C 1.80 TA = -40°C TA = -40°C 2.70 0 MAX1067/68 toc09 2.90 IAVDD (mA) 2.0 DVDD = +5V fS = 200ksps IAVDD (mA) 2.5 2.95 MAX1067/68 toc08 DVDD = AVDD = +5V DOUT = ALL ZEROS EXTERNAL CLOCK SPI MODE MAX1067/68 toc07 3.0 100 -40 THD (dB) SFDR (dB) 40 80 THD vs. FREQUENCY 80 50 60 0 MAX1067/68 toc05 70 0.1 40 FREQUENCY (kHz) 120 MAX1067/68 toc04 80 10 20 CODE 90 SINAD (dB) -60 -0.4 -1.0 SUPPLY CURRENT (mA) -40 MAX1067/68 toc06 0.4 0 -20 AMPLITUDE (dB) 0.6 DNL (LSB) INL (LSB) 0.6 20 MAX1067/68 toc02 MAX1067/68 toc01 0.8 FFT AT fAIN = 1kHz 1.0 MAX1067/68 toc03 INL vs. CODE 1.0 1.75 4.75 4.85 4.95 5.05 AVDD (V) 5.15 5.25 4.75 4.85 4.95 5.05 5.15 5.25 AVDD (V) _______________________________________________________________________________________ 7 MAX1067/MAX1068 Typical Operating Characteristics (AVDD = DVDD = +5V, fSCLK = 4.8MHz, CDOUT = 30pF, external VREF = +4.096V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (AVDD = DVDD = +5V, fSCLK = 4.8MHz, CDOUT = 30pF, external VREF = +4.096V, TA = +25°C, unless otherwise noted.) 0.57 IDVDD (µA) 1.4 1.03 0.6 1.02 0.5 1.02 0.56 DOUT = 1010...1010 DOUT = 0000...0000 IAVDD 1.01 0.55 1.0 0.54 0.6 0.53 IDVDD 0.4 1.00 0.3 0.99 0.2 0.98 5.25 0.1 1.01 IAVDD IDVDD 0.52 0.2 2.70 3.21 3.72 4.23 4.75 5.25 4.74 4.85 4.95 5.05 5.15 1.00 0.99 3.21 2.70 3.72 4.74 SHUTDOWN SUPPLY CURRENT vs. DVDD SUPPLY VOLTAGE (EXTERNAL REFERENCE) SHUTDOWN SUPPLY CURRENT vs. AVDD SUPPLY VOLTAGE (EXTERNAL REFERENCE) MAX1067/68 toc13 0.58 4.23 DVDD (V) AVDD (V) DVDD (V) MAX1067/68 toc14 0.7 0.54 0.43 DVDD = +5V AV DVDD = +5V 0.57 0.50 0.6 0.42 0.46 0.5 0.41 0.4 0.54 0.38 0.3 0.53 0.34 0.2 0.30 5.25 0.1 0.52 4.85 4.95 5.05 5.15 0.39 IDVDD 0.38 0.37 2.70 3.21 3.72 4.23 DVDD (V) POWER-DOWN SUPPLY CURRENT vs. TEMPERATURE (INTERNAL REFERENCE) SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE (EXTERNAL REFERENCE) MAX1067/68 toc15 MAX1067/68 toc16 0.58 1.04 DVDD = AVDD = +5V 0.57 1.03 0.55 1.01 IDVDD 0.56 IDVDD (µA) 1.02 IAVDD (mA) 0.56 0.41 0.55 0.54 1.00 0.54 0.53 0.99 0.53 0.98 0.52 0.52 -15 10 35 TEMPERATURE (°C) 60 0.43 IAVDD IAVDD -40 0.45 DVDD = AVDD = +5V 0.57 IDVDD (µA) 5.25 AVDD (V) 0.58 8 4.74 85 IDVDD 0.39 0.37 0.35 -40 -15 10 35 60 TEMPERATURE (°C) _______________________________________________________________________________________ 85 IAVDD (nA) 4.75 0.40 IAVDD IAVDD (nA) 0.42 IDVDD (µA) IDVDD (µA) IDVDD IAVDD (nA) IAVDD 0.56 0.55 1.03 DVDD = +5V AV 5.25 IAVDD (mA) 1.8 DVDD = +5V IDVDD (µA) 2.2 MAX1067/68 toc12 0.7 1.04 IAVDD (mA) AVDD = +5V VIL = 0 fS = 200ksps MAX1067/68 toc11 0.58 MAX1067/68 toc10 2.6 POWER-DOWN SUPPLY CURRENT vs. DVDD SUPPLY VOLTAGE (INTERNAL REFERENCE) POWER-DOWN SUPPLY CURRENT vs. AVDD SUPPLY VOLTAGE (INTERNAL REFERENCE) DIGITAL SUPPLY CURRENT vs. DIGITAL SUPPLY VOLTAGE IDVDD (mA) MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters -50 0 -0.005 -0.010 -0.015 200 100 0 -100 -200 -0.020 -300 -150 -0.025 -400 -200 -0.030 4.85 4.95 5.05 5.15 5.25 4.85 4.95 5.05 5.15 -40 5.25 -15 10 35 AVDD (V) TEMPERATURE (°C) GAIN ERROR vs. TEMPERATURE CHANNEL-TO-CHANNEL ISOLATION vs. FREQUENCY INTERNAL +4.096V REFERENCE VOLTAGE vs. ANALOG SUPPLY VOLTAGE 0.005 -10 VREF = +4.096V -20 4.104 DVDD = +5V -0.010 TA = +70°C -40 VREF (V) ISOLATION (dB) -0.005 -50 -60 4.096 TA = +25°C -70 -80 -0.015 TA = +85°C 4.100 -30 0 4.092 TA = 0°C -90 -0.020 TA = -40°C -100 -110 -0.025 -40 -15 10 35 60 0 85 10 20 30 40 50 60 70 80 90 100 TEMPERATURE (°C) FREQUENCY (kHz) EXTERNAL REFERENCE INPUT CURRENT vs. EXTERNAL REFERENCE VOLTAGE INTERNAL REFERENCE VOLTAGE vs. REF LOAD 120 4.0 3.5 60 tCONV(ms) VREF (V) 80 2.5 2.0 1.5 87.19ksps, INTERNAL CLOCK 40 1.0 20 0.5 0 2.5 3.0 3.5 4.0 VREF (V) 4.5 5.0 5.5 5.15 fSCLK = 4.8MHz 5.25 40 24 22 10 6 44 38 33 31 30 60 53 46 39 20 fSCLK = 0 INTERNAL REFERENCE MODE LOAD APPLIED TO REF CREF = 1µF 28 17 17 10 12 0 0 2.0 5.05 8-BIT DATA-TRANSFER MODE 16-BIT DATA-TRANSFER MODE 60 50 199ksps, EXTERNAL CLOCK 4.95 70 3.0 100 4.85 INTERNAL CLOCK CONVERSION TIME (8th RISING SCLK TO FALLING EOC) MAX1067/68 toc24 VAIN = 0 fSCLK = 4.8MHz AVDD = DVDD = +5V 4.088 4.75 AVDD (V) 4.5 MAX1067/68 toc23 160 MAX1067/68 toc22 0 MAX1067/68 toc20 VREF = +4.096V 140 85 60 AVDD (V) 0.015 0.010 -500 4.75 MAX1067/68 toc21 4.75 IREF (µA) 300 MAX1067/68 toc25 0 0.005 VREF = +4.096V 400 OFFSET ERROR (µV) 50 -100 GAIN ERROR (%FSR) 0.010 GAIN ERROR (%FSR) OFFSET ERROR (µV) 100 VREF = +4.096V 0.015 500 MAX1067/68 toc18 MAX1067/68 toc17 VREF = +4.096V 150 OFFSET ERROR vs. TEMPERATURE GAIN ERROR vs. SUPPLY VOLTAGE 0.020 MAX1067/68 toc19 OFFSET ERROR vs. SUPPLY VOLTAGE 200 0 2 4 6 8 IREF (mA) 10 12 14 1 2 3 4 5 6 7 8 NUMBER OF SCAN-MODE CONVERSIONS _______________________________________________________________________________________ 9 MAX1067/MAX1068 Typical Operating Characteristics (continued) (AVDD = DVDD = +5V, fSCLK = 4.8MHz, CDOUT = 30pF, external VREF = +4.096V, TA = +25°C, unless otherwise noted.) MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Pin Description PIN NAME FUNCTION MAX1067 MAX1068 1 3 DOUT Serial Data Output. Data changes state on SCLK’s falling edge in SPI/QSPI/MICROWIRE mode and on SCLK’s rising edge in DSP mode (MAX1068 only). DOUT is high impedance when CS is high. 2 4 SCLK Serial Clock Input. SCLK drives the conversion process in external clock mode and clocks data out. 3 5 DIN Serial Data Input. Use DIN to communicate with the command/configuration/control register. In SPI/QSPI/MICROWIRE mode, the rising edge of SCLK clocks in data at DIN. In DSP mode, the falling edge of SCLK clocks in data at DIN. 4 6 EOC End-of-Conversion Output. In internal clock mode, a logic low at EOC signals the end of a conversion with the result available at DOUT. In external clock mode, EOC remains high. 5 7 AIN0 Analog Input 0 6 8 AIN1 Analog Input 1 7 9 AIN2 Analog Input 2 8 10 AIN3 Analog Input 3 9 15 REF Reference Voltage Input/Output. VREF sets the analog voltage range. Bypass to AGND with a 10µF capacitor. Bypass with a 1µF (min) capacitor when using the internal reference. 10 16 REFCAP Reference Bypass Capacitor Connection. Bypass to AGND with a 0.1µF capacitor when using internal reference. Internal reference and buffer shut down in external reference mode. 11 17 AGND Analog Ground. Connect to pin 18 (MAX1068) or pin 12 (MAX1067). 12 18 AGND Primary Analog Ground (Star Ground). Power return for AVDD. 13 19 AVDD Analog Supply Voltage. Bypass to AGND with a 0.1µF capacitor. 10 Active-Low Chip-Select Input. Forcing CS high places the MAX1067/MAX1068 in shutdown with a typical supply current of 0.6µA. In SPI/QSPI/MICROWIRE mode, a high-to-low transition on CS activates normal operating mode. In DSP mode, after the initial CS transition from high to low, CS can remain low for the entire conversion process (see the Operating Modes section). 14 20 CS 15 21 DGND Digital Ground 16 22 DVDD Digital Supply Voltage. Bypass to DGND with a 0.1µF capacitor. — 1 DSPR DSP Frame-Sync Receive Input. A frame-sync pulse received at DSPR initiates a conversion. Connect to logic high when using SPI/QSPI/MICROWIRE mode. — 2 DSEL Data-Bit Transfer-Select Input. Logic low on DSEL places the device in 8-bit-wide datatransfer mode. Logic high places the device in 16-bit-wide data-transfer mode. Do not leave DSEL unconnected. — 11 AIN4 Analog Input 4 — 12 AIN5 Analog Input 5 ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters PIN NAME FUNCTION MAX1067 MAX1068 — 13 AIN6 Analog Input 6 — 14 AIN7 Analog Input 7 — 23 DSPX DSP Frame-Sync Transmit Output. A frame-sync pulse at DSPX notifies the DSP that the MSB data is available at DOUT. Leave DSPX unconnected when not in DSP mode. — 24 N.C. No Connection. Not internally connected. DVDD DVDD 1mA DOUT 1mA DOUT CLOAD = 30pF 1mA DOUT CLOAD = 30pF DGND DGND a) VOL TO VOH b) HIGH-Z TO VOL AND VOH TO VOL Figure 1. Load Circuits for DOUT Enable Time and SCLK-toDOUT Delay Time Detailed Description The MAX1067/MAX1068 low-power, multichannel, 14bit ADCs feature a successive-approximation ADC, automatic power-down, integrated +4.096V reference, and a high-speed SPI/QSPI/MICROWIRE-compatible interface. A DSPR input and DSPX output allow the MAX1068 to communicate with DSPs with no external glue logic. The MAX1067/MAX1068 operate with a single +5V analog supply and feature a separate digital supply allowing direct interfacing with +2.7V to +5.5V digital logic. Figures 3 and 4 show the functional diagrams of the MAX1067/MAX1068, and Figures 5 and 6 show the MAX1067/MAX1068 in a typical operating circuit. The serial interface simplifies communication with microprocessors (µPs). In external reference mode, the MAX1067/MAX1068 have two power modes: normal mode and shutdown mode. Driving CS high places the MAX1067/MAX1068 in shutdown mode, reducing the supply current to 0.6µA (typ). Pull CS low to place the MAX1067/ MAX1068 in normal operating mode. The internal reference mode offers software-programmable, power-down options as shown in Table 5. In SPI/QSPI/MICROWIRE mode, a falling edge on CS wakes the analog circuitry and allows SCLK to clock in DOUT CLOAD = 30pF CLOAD = 30pF 1mA DGND DGND a) VOH TO HIGH-Z b) VOL TO HIGH-Z Figure 2. Load Circuits for DOUT Disable Time data. Acquisition and conversion are initiated by SCLK. The conversion result is available at DOUT in unipolar serial format. DOUT is held low until data becomes available (MSB first) on the 8th falling edge of SCLK when in 8-bit transfer mode, and on the 16th falling edge when in 16-bit transfer mode. See the Operating Modes section. Figure 8 shows the detailed SPI/QSPI/ MICROWIRE serial-interface timing diagram. In external clock mode, the MAX1068 also interfaces with DSPs. In DSP mode, a frame-sync pulse from the DSP initiates a conversion that is driven by SCLK. The MAX1068 formats a frame-sync pulse to notify the DSP that the conversion results are available at DOUT in MSB-first, unipolar, serial-data format. Figure 16 shows the detailed DSP serial-interface timing diagram (see the Operating Modes section). Analog Input Figure 7 illustrates the input-sampling architecture of the ADC. The voltage applied at REF or the internal +4.096V reference sets the full-scale input voltage. Track/Hold (T/H) In track mode, the analog signal is acquired on the internal hold capacitor. In hold mode, the T/H switches open and the capacitive digital-to-analog converter (DAC) samples the analog input. ______________________________________________________________________________________ 11 MAX1067/MAX1068 Pin Description (continued) MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters AVDD REFCAP DVDD BUFFER REFERENCE REF AGND MAX1067 AIN0 AIN1 ANALOG-INPUT MULTIPLEXER DAC COMPARATOR AIN2 AZ RAIL AIN3 ANALOG-SWITCH FINE TIMING BIAS SCLK MULTIPLEXER SUCCESSIVE-APPROXIMATION REGISTER OUTPUT DOUT OSCILLATOR ACCUMULATOR CONTROL CS EOC MEMORY INPUT REGISTER DIN AGND DGND Figure 3. MAX1067 Functional Diagram During the acquisition, the analog input (AIN_) charges capacitor CDAC. At the end of the acquisition interval the T/H switches open. The retained charge on CDAC represents a sample of the input. In hold mode, the capacitive DAC adjusts during the remainder of the conversion cycle to restore node ZERO to zero within the limits of 14-bit resolution. At the end of the conversion, force CS high and then low to reset the T/H switches back to track mode (AIN_), where CDAC charges to the input signal again. The time required for the T/H to acquire an input signal is a function of how quickly its input capacitance is 12 charged. If the input signal’s source impedance is high, the acquisition time lengthens and more time must be allowed between conversions. The acquisition time (tACQ) is the maximum time the device takes to acquire the signal. Use the following formula to calculate acquisition time: tACQ = 11(RS + RIN + RDS(ON)) ✕ 45pF + 0.3µs where R IN = 340Ω, R S = the input signal’s source impedance, RDS(ON) = 60Ω, and tACQ is never less than 729ns. A source impedance less than 200Ω does not significantly affect the ADC’s performance. The MAX1068 features a 16-bit-wide data-transfer mode ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters MAX1067/MAX1068 AVDD REFCAP DVDD BUFFER REFERENCE REF AGND MAX1068 AIN0 AIN1 AIN2 AIN3 AIN4 ANALOG-INPUT MULTIPLEXER DAC COMPARATOR AIN5 AIN6 AZ RAIL AIN7 ANALOG-SWITCH FINE TIMING BIAS SCLK SUCCESSIVE-APPROXIMATION REGISTER MULTIPLEXER OUTPUT DOUT OSCILLATOR ACCUMULATOR CS EOC DSPX CONTROL DSEL DSPR MEMORY INPUT REGISTER DIN AGND DGND Figure 4. MAX1068 Functional Diagram that includes a longer acquisition time (11.5 clock cycles). Longer acquisition times are useful in applications with input source resistances greater than 1kΩ. Noise increases when using large source resistances. To improve the input signal bandwidth under AC conditions, drive AIN_ with a wideband buffer (>10MHz) that can drive the ADC’s input capacitance and settle quickly. Input Bandwidth The ADC’s input-tracking circuitry has a 4MHz smallsignal bandwidth, making possible the digitization of high-speed transient events and the measurement of periodic signals with bandwidths exceeding the ADC’s sampling rate by using undersampling techniques. To avoid aliasing of unwanted, high-frequency signals into the frequency band of interest, use anti-alias filtering. Analog Input Protection Internal protection diodes, which clamp the analog input to AVDD or AGND, allow the input to swing from (AGND - 0.3V) to (AVDD + 0.3V) without damaging the device. If the analog input exceeds 300mV beyond the supplies, limit the input current to 10mA. ______________________________________________________________________________________ 13 MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters CS AIN0 AIN1 AIN2 AIN3 ANALOG INPUTS DIN SCLK DOUT EOC SCLK DOUT EOC ANALOG INPUTS MAX1067 REF AGND AGND DGND AVDD +5V 0.1µF DVDD +5V AIN7 DIN DSEL DSPR REF DIN 16 8 DOUT EOC AGND AGND DGND AVDD DVDD +5V DOUT MAX1068 0.1µF 0.1µF 0.1µF SCLK DSPX EOC 1µF +5V REFCAP CS DSPX SCLK AIN4 AIN5 AIN6 DIN 1µF CS AIN0 AIN1 AIN2 AIN3 CS REFCAP 0.1µF 0.1µF GND GND Figure 5. MAX1067 Typical Operating Circuit In addition to the standard 3-wire serial interface modes, the MAX1068 includes a DSPR input and a DSPX output for communicating with DSPs in external clock mode and a DSEL input to determine 8-bit-wide or 16-bit-wide data-transfer mode. When not using the MAX1068 in the DSP interface mode, connect DSPR to DVDD and leave DSPX unconnected. REF MUX RDSON Figure 6. MAX1068 Typical Operating Circuit TRACK AIN_ CAPACITIVE DAC ZERO CMUX HOLD CSWITCH CDAC RIN AGND HOLD TRACK Command/Configuration/Control Register AUTO-ZERO RAIL Figure 7. Equivalent Input Circuit Digital Interface The MAX1067/MAX1068 feature an SPI/QSPI/ MICROWIRE-compatible 3-wire serial interface. The MAX1067 digital interface consists of digital inputs CS, SCLK, and DIN; and outputs DOUT and EOC. The MAX1067 operates in the following modes: • SPI interface with external clock • SPI interface with internal clock • SPI interface with internal clock and scan mode Table 1 shows the contents of the command/configuration/control register and the state of each bit after initial power-up. Tables 2–6 define the control and configuration of the device for each bit. Cycling the power supplies resets the command/configuration/control register to the power-on-reset default state. Initialization After Power-Up A logic high on CS places the MAX1067/MAX1068 in the shutdown mode chosen by the power-down bits, and places DOUT in a high-impedance state. Drive CS low to power-up and enable the MAX1067/MAX1068 before starting a conversion. In internal reference mode, allow 5ms for the shutdown internal reference and/or buffer to wake and stabilize before starting a conversion. In external reference mode (or if the internal reference is already on), no reference settling time is needed after power-up. Table 1. Command/Configuration/Control Register COMMAND POWER-UP STATE 14 BIT7 (MSB) BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0 (LSB) CH SEL2 CH SEL1 CH SEL0 SCAN1 SCAN0 REF/PD_SEL1 REF/PD SEL0 INT/EXT CLK 0 0 0 0 0 1 1 0 ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Table 3. MAX1067 Scan Mode, Internal Clock Only BIT7 BIT6 BIT5 CH SEL2 CH SEL1 CH SEL0 CHANNEL AIN_ 0 0 0 0 0 0 1 1 Single channel, no scan 0 1 0 2 0 1 1 3 1 0 0 4 1 0 1 1 1 1 1 BIT4 BIT3 SCAN1 SCAN0 0 0 Sequentially scan channels 0 through N (N ≤ 3) 0 1 5 Sequentially scan channels 2 through N (2 ≤ N ≤ 3) 1 0 0 6 Scan channel N 4 times 1 1 1 7 ACTION Table 4. MAX1068 Scan Mode, Internal Clock Only (Not for DSP Mode) ACTION BIT4 BIT3 SCAN1 SCAN0 Single channel, no scan 0 0 Sequentially scan channels 0 through N (N ≤ 7) 0 1 Sequentially scan channels 4 through N (4 ≤ N ≤ 7) 1 0 Scan channel N 8 times 1 1 Table 5. Power-Down Modes BIT2 BIT1 REF/PD_ SEL1 REF/PD SEL0 REFERENCE 0 0 Internal 0 1 1 1 TYPICAL SUPPLY CURRENT TYPICAL WAKEUP TIME (CREF = 1µF) Internal reference and reference buffer stay on between conversions 1mA NA Internal Internal reference and reference buffer off between conversions 0.6µA 5ms 0 Internal Internal reference on, reference buffer off between conversions 0.43mA 5ms 1 External Internal reference and buffer always off 0.6µA NA REFERENCE MODE (INTERNAL REFERENCE) Table 6. Clock Modes BIT0 INT/EXT CLK CLOCK MODE 0 External clock 1 Internal clock ______________________________________________________________________________________ 15 MAX1067/MAX1068 Table 2. Channel Select MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters tCSW ••• CS tCSS tCP tCL tCSH tCH ••• SCLK tDS tDH ••• DIN tDO tTR tDV DOUT ••• Figure 8. Detailed SPI Interface Timing ence and buffer wake up on the falling edge of CS when in SPI/QSPI/MICROWIRE mode and on the falling edge of DSPR when in DSP mode. Allow 5ms for the internal reference to rise and settle when powering up from a complete shutdown (VREF = 0, CREF = 1µF). CS COMPLETE CONVERSION SEQUENCE DOUT CONVERSION 0 CONVERSION 1 POWERED UP POWERED DOWN POWERED UP Figure 9. Shutdown Sequence Power-Down Modes Table 5 shows the MAX1067/MAX1068 power-down modes. Three internal reference modes and one external reference mode are available. Select power-down modes by writing to bits 2 and 1 in the command/configuration/control register. The MAX1067/MAX1068 enter the selected power-down mode on the rising edge of CS. The internal reference stays on when CS is pulled high, if bits 2 and 1 are set to zero. This mode allows for the fastest turn-on time. Setting bit 2 = 0 and bit 1 = 1 turns both the reference and reference buffer off when CS is brought high. This mode achieves the lowest supply current. The refer- 16 The internal reference stays on and the buffer is shut off on the rising edge of CS when bit 2 = 1 and bit 1 = 0. The MAX1067/MAX1068 enter this mode on the rising edge of CS. The buffer wakes up on the falling edge of CS when in SPI/QSPI/MICROWIRE mode and on the falling edge of DSPR when in DSP mode. Allow 5ms for VREF to settle when powering up from a complete shutdown (VREF = 0, CREF = 1µF). VREFCAP is always equal to +4.096V in this mode. Set both bit 2 and bit 1 to 1 to turn off the reference and reference buffer to allow connection of an external reference. Using an external reference requires no extra wake-up time. Operating Modes External Clock 8-Bit-Wide Data-Transfer Mode (MAX1067 and MAX1068) Force DSPR high and DSEL low (MAX1068) for SPI/ QSPI/MICROWIRE-interface mode. The falling edge of CS wakes the analog circuitry and allows SCLK to clock in data. Ensure the duty cycle on SCLK is between 45% and 55% when operating at 4.8MHz (the maximum clock frequency). For lower clock frequencies, ensure the ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters MAX1067/MAX1068 CS 1 16 8 24 SCLK MSB LSB DIN 0 MSB LSB S1 DOUT S0 DSPR* DSEL* ADC STATE tACQ tCONV IDLE *MAX1068 ONLY Figure 10. SPI External Clock Mode, 8-Bit Data-Transfer Mode, Conversion Timing minimum high and low times are at least 93ns. External clock-mode conversions with SCLK rates less than 125kHz can reduce accuracy due to leakage of the sampling capacitor. DOUT changes from high-Z to logic low after CS is brought low. Input data latches on the rising edge of SCLK. The first SCLK rising edge begins loading data into the command/configuration/control register from DIN. The devices select the proper channel for conversion on the rising edge of the 3rd SCLK cycle. Acquisition begins immediately thereafter and ends on the falling edge of the 6th clock cycle. The MAX1067/MAX1068 sample the input and begin conversion on the falling edge of the 6th clock cycle. Setup and configuration of the MAX1067/MAX1068 complete on the rising edge of the 8th clock cycle. The conversion result is available (MSB first) at DOUT on the falling edge of the 8th SCLK cycle. To read the entire conversion result, 16 SCLK cycles are needed. Extra clock pulses, occurring after the conversion result has been clocked out and prior to the rising edge of CS, cause zeros to be clocked out of DOUT. The MAX1067/MAX1068 external clock 8-bit-wide data-transfer mode requires 24 SCLK cycles for completion (Figure 10). Force CS high after the conversion result is read. For maximum throughput, force CS low again to initiate the next conversion immediately after the specified minimum time (tCSW). Forcing CS high in the middle of a conversion immediately aborts the conversion and places the MAX1067/MAX1068 in shutdown. External Clock 16-Bit-Wide Data-Transfer Mode (MAX1068 Only) Force DSPR high and DSEL high for SPI/QSPI/ MICROWIRE-interface mode. Logic high at DSEL allows the MAX1068 to transfer data in 16-bit-wide words. The acquisition time is extended an extra eight SCLK cycles in the 16-bit-wide data-transfer mode. The falling edge of CS wakes the analog circuitry and allows SCLK to clock in data. Ensure the duty cycle on SCLK is between 45% and 55% when operating at 4.8MHz (the maximum clock frequency). For lower clock frequencies, ensure that the minimum high and low times are at least 93ns. External-clock-mode conversions with SCLK rates less than 125kHz can reduce accuracy due to leakage of the sampling capacitor. DOUT changes from high-Z to logic low after CS is brought low. Input data latches on the rising edge of SCLK. The first SCLK rising edge begins loading data into the command/configuration/control register from DIN. The devices select the proper channel for conversion and begin acquisition on the rising edge of the 3rd SCLK cycle. Setup and configuration of the MAX1068 completes on the rising edge of the 8th clock cycle. Acquisition ends on the falling edge of the 14th SCLK cycle. The MAX1068 samples the input and begins conversion on the falling edge of the 14th clock cycle. The conversion result is available (MSB first) at DOUT on the falling edge of the 16th SCLK cycle. To read the entire conversion result, 16 SCLK cycles are needed. Extra clock pulses, occurring after the conversion result has been clocked out and ______________________________________________________________________________________ 17 MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters CS 1 16 8 24 32 SCLK MSB LSB 0 X DIN X X X X X X X MSB LSB S1 S0 DOUT DSPR DSEL ADC STATE IDLE tCONV tACQ , X = DON T CARE Figure 11. SPI External Clock Mode, 16-Bit Data-Transfer Mode, Conversion Timing (MAX1068 Only) CS 1 9 8 16 24 SCLK 2 INTERNAL CLK 25 ••• MSB DIN 6 LSB 1 MSB LSB DOUT S1 S0 X EOC ADC STATE , X = DON T CARE DSPR = DVDD, DSEL = GND (MAX1068 ONLY) tACQ tCONV IDLE POWER-DOWN Figure 12. SPI Internal Clock Mode, 8-Bit Data-Transfer Mode, Conversion Timing prior to the rising edge of CS, cause zeros to be clocked out of DOUT. The MAX1068 external clock 16bit-wide data-transfer mode requires 32 SCLK cycles for completion (Figure 11). Force CS high after the conversion result is read. For maximum throughput, force CS low again to initiate the next conversion immediately after the specified minimum time (tCSW). Forcing CS high in the middle of a conversion immediately aborts the conversion and places the MAX1068 in shutdown. Internal Clock 8-Bit-Wide Data-Transfer and Scan Mode (MAX1067 and MAX1068) Force DSPR high and DSEL low (MAX1068) for the SPI/ QSPI/MICROWIRE-interface mode. The falling edge of CS wakes the analog circuitry and allows SCLK to clock in data (Figure 12). DOUT changes from high-Z 18 to logic low after CS is brought low. Input data latches on the rising edge of SCLK. The command/configuration/control register begins reading DIN on the first SCLK rising edge and ends on the rising edge of the 8th SCLK cycle. The MAX1067/MAX1068 select the proper channel for conversion on the rising edge of the 3rd SCLK cycle. The internal oscillator activates 125ns after the rising edge of the 8th SCLK cycle. Turn off the external clock while the internal clock is on. Turning off SCLK ensures the lowest noise performance during acquisition. Acquisition begins on the 2nd rising edge of the internal clock and ends on the falling edge of the 6th internal clock cycle. Each bit of the conversion result shifts into memory as it becomes available. The conversion result is available (MSB first) at DOUT on the falling edge of EOC. The internal oscillator and analog circuitry are shut down on the high-to-low EOC tran- ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters MAX1067/MAX1068 CS 1 8 ••• SCLK 9 16 17 2 13 INTERNAL CLK ••• DIN DATA 24 32 ••• 32 ••• XXXXXXXX MSB LSB DOUT S1 S0 X EOC ADC STATE CONFIGURATION , X = DON T CARE DSPR = DSEL = DVDD tACQ tCONV POWER-DOWN Figure 13. SPI Internal Clock Mode,16-Bit Data-Transfer Mode, Conversion Timing (MAX1068 Only) CS 1 8 9 2 INTERNAL CLK 24 6 26 30 ••• MSB DIN 40 ••• SCLK 48 ••• LSB 1 MSB LSB ••• DOUT S1 S0 X EOC ADC STATE CONFIGURATION , X = DON T CARE DSPR = DVDD, DSEL = GND (MAX1068 ONLY) tACQ tCONV tACQ tCONV POWER-DOWN Figure 14. SPI Internal Clock Mode, 8-Bit Data-Transfer Mode, Scan Mode for Two Conversions, Conversion Timing sition. Use the EOC high-to-low transition as the signal to restart the external clock (SCLK). To read the entire conversion result, 16 SCLK cycles are needed. Extra clock pulses, occurring after the conversion result has been clocked out and prior to the rising edge of CS, cause the conversion result to be shifted out again. The MAX1067/MAX1068 internal clock 8-bit-wide datatransfer mode requires 24 external clock cycles and 25 internal clock cycles for completion. Force CS high after the conversion result is read. For maximum throughput, force CS low again to initiate the next conversion immediately after the specified minimum time (tCSW). Forcing CS high in the middle of a conversion immediately aborts the conversion and places the MAX1067/MAX1068 in shutdown. Scan mode allows multiple channels to be scanned consecutively or one channel to be scanned eight times. Scan mode can only be enabled when using the MAX1067/MAX1068 in the internal clock mode. Enable scanning by setting bits 4 and 3 in the command/configuration/control register (see Tables 3 and 4). In scan mode, conversion results are stored in memory until the completion of the last conversion in the sequence. Upon completion of the last conversion in the sequence, EOC transitions from high to low to indicate the end of the conversion and shuts down the internal oscillator. Use the EOC high-to-low transition as the signal to restart the external clock (SCLK). DOUT provides the conversion results in the same order as the channel conversion process. The MSB of the first conversion is available at DOUT on the falling edge of EOC (Figure 14). ______________________________________________________________________________________ 19 MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Internal Clock 16-Bit-Wide Data-Transfer and Scan Mode (MAX1068 Only) Force DSPR high and DSEL low for the SPI/QSPI/ MICROWIRE-interface mode. The falling edge of CS wakes the analog circuitry and allows SCLK to clock in data (see Figure 13). DOUT changes from high-Z to logic low after CS is brought low. Input data latches on the rising edge of SCLK. The command/configuration/control register begins reading DIN on the first SCLK rising edge and ends on the rising edge of the 8th SCLK cycle. The MAX1068 selects the proper channel for conversion on the rising edge of the 3rd SCLK cycle. The internal oscillator activates 125ns after the rising edge of the 16th SCLK cycle. Turn off the external clock while the internal clock is on. Turning off SCLK ensures lowest noise performance during acquisition. Acquisition begins on the 2nd rising edge of the internal clock and ends on the falling edge of the 18th internal clock cycle. Each bit of the conversion result shifts into memory as it becomes available. The conversion result is available (MSB first) at DOUT on the falling edge of EOC. The internal oscillator and analog circuitry are shut down on the EOC high-to-low transition. Use the EOC high-to-low transition as the signal to restart the external clock (SCLK). To read the entire conversion result, 16 SCLK cycles are needed. Extra clock pulses, occurring after the conversion result has been clocked out and prior to the rising edge of CS, cause the conversion result to be shifted out again. The MAX1068 internal-clock 16-bit-wide data-transfer mode requires 32 external clock cycles and 32 internal clock cycles for completion. Force CS high after the conversion result is read. For maximum throughput, force CS low again to initiate the next conversion immediately after the specified minimum time (tCSW). Forcing CS high in the middle of a conversion immediately aborts the conversion and places the MAX1068 in shutdown. Scan mode allows multiple channels to be scanned consecutively or one channel to be scanned eight times. Scan mode can only be enabled when using the MAX1068 in internal clock mode. Enable scanning by setting bits 4 and 3 in the command/configuration/control register (see Tables 3 and 4). In scan mode, conversion results are stored in memory until the completion of the last conversion in the sequence. Upon completion of the last conversion in the sequence, EOC transitions from high to low to indicate the end of the conversion and shuts down the internal oscillator. Use the EOC high-to-low transition as the signal to restart the external clock (SCLK). DOUT provides the conversion results in the same order as the channel conversion process. The MSB of the first conversion is available at DOUT on the falling edge of EOC. Figure 15 shows the timing diagram for 16-bit-wide data transfer in scan mode. CS 1 SCLK 8 ••• 9 ••• DIN ••• DATA 32 13 2 INTERNAL CLK 48 17 16 ••• ••• 34 45 ••• 64 ••• XXXXXXXX LSB MSB ••• DOUT S1 S0 X EOC ADC STATE , X = DON T CARE tACQ tCONV tACQ tCONV POWER-DOWN Figure 15. SPI Internal Clock Mode, 16-Bit Data-Transfer Mode, Scan Mode for Two Conversions, Conversion Timing (MAX1068 Only) 20 ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters rising edge of the 9th clock pulse. To read the entire conversion results, 16 SCLK cycles are needed. Extra clock pulses, occuring after the conversion result has been clocked out, and prior to the next rising edge of DSPR, cause zeros to be clocked out of DOUT. The MAX1068 external-clock, DSP 8-bit-wide data-transfer mode requires 24 clock cycles to complete. Begin a new conversion by sending a new frame sync pulse to DSPR followed by new configuration data. Send the new DSPR pulse immediately after reading the conversion result to realize maximum throughput. Sending a new frame sync pulse in the middle of a conversion immediately aborts the current conversion and begins a new one. A rising edge on CS in the middle of a conversion aborts the current conversion and places the MAX1068 in shutdown. DSP 16-Bit-Wide Data-Transfer Mode (External Clock Mode, MAX1068 Only) Figure 16 shows the DSP-interface timing diagram. Logic low at DSPR on the falling edge of CS enables DSP interface mode. After the MAX1068 enters DSP mode, CS can remain low for the duration of the conversion process and each subsequent conversion. The acquisition time is extended an extra eight SCLK cycles in the 16-bit-wide data-transfer mode. Drive DSEL high to select the 16-bit-wide data-transfer mode. A sync pulse from the DSP at DSPR wakes the analog circuitry and allows SCLK to clock in data (Figure 18). The frame sync pulse also alerts the MAX1068 that incoming data is about to be sent to DIN. Ensure the duty cycle on SCLK is between 45% and 55% when operating at tCSW ... CS tDF tFSS ... DSPR tFSH tCSS tCL tCSH tCH ... SCLK tCP tDS tDH ... DIN tDO tDV DOUT tTR ... Figure 16. Detailed DSP-Interface Timing (MAX1068 Only) ______________________________________________________________________________________ 21 MAX1067/MAX1068 DSP 8-Bit-Wide Data-Transfer Mode (External Clock Mode, MAX1068 Only) Figure 16 shows the DSP-interface timing diagram. Logic low at DSPR on the falling edge of CS enables DSP interface mode. After the MAX1068 enters DSP mode, CS can remain low for the duration of the conversion process and each subsequent conversion. Drive DSEL low to select the 8-bit data-transfer mode. A sync pulse from the DSP at DSPR wakes the analog circuitry and allows SCLK to clock in data (Figure 17). The frame sync pulse alerts the MAX1068 that incoming data is about to be sent to DIN. Ensure the duty cycle on SCLK is between 45% and 55% when operating at 4.8MHz (the maximum clock frequency). For lower clock frequencies, ensure the minimum high and low times are at least 93ns. External clock mode conversions with SCLK rates less than 125kHz can reduce accuracy due to leakage of the sampling capacitor. The input data latches on the falling edge of SCLK. The command/configuration/control register starts reading data in on the falling edge of the first SCLK cycle immediately following the falling edge of the frame sync pulse and ends on the falling edge of the 8th SCLK cycle. The MAX1068 selects the proper channel for conversion on the falling edge of the 3rd clock cycle and begins acquisition. Acquisition continues until the rising edge of the 7th clock cycle. The MAX1068 samples the input on the rising edge of the 7th clock cycle. On the rising edge of the 8th clock cycle, the MAX1068 outputs a frame sync pulse at DSPX. The frame sync pulse alerts the DSP that the conversion results are about to be output at DOUT (MSB first) starting on the MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters 4.8MHz (the maximum clock frequency). For lower clock frequencies, ensure the minimum high and low times are at least 93ns. External-clock-mode conversions with SCLK rates less than 125kHz can reduce accuracy due to leakage of the sampling capacitor. The input data latches on the falling edge of SCLK. The command/configuration/control register starts reading data in on the falling edge of the first SCLK cycle immediately following the falling edge of the frame sync pulse and ends on the falling edge of the 16th SCLK cycle. The MAX1068 selects the proper channel for conversion on the falling edge of the 3rd clock cycle and begins acquisition. Acquisition continues until the rising edge of the 15th clock cycle. The MAX1068 samples the input on the rising edge of the 15th clock cycle. On the rising edge of the 16th clock cycle, the MAX1068 outputs a frame sync pulse at DSPX. The frame sync pulse alerts the DSP that the conversion results are about to be output at DOUT (MSB first) starting on the rising edge of the 17th clock pulse. To read the entire conversion result, 16 SCLK cycles are needed. Extra clock pulses, occuring after the conversion result has been clocked out and prior to the next rising edge of DSPR, cause zeros to be clocked out of DOUT. The MAX1068 external clock, DSP 16-bit-wide data-transfer mode requires 32 clock cycles to complete. Begin a new conversion by sending a new frame sync pulse to DSPR followed by new configuration data. Send the new DSPR pulse immediately after reading the conversion result to realize maximum throughput. Sending a new frame sync pulse in the middle of a conversion immediately aborts the current conversion and begins a new one. A rising edge on CS in the middle of a conversion aborts the current conversion and places the MAX1068 in shutdown. CS DSPR 16 1 8 MSB LSB 24 SCLK DIN 0 MSB LSB S1 DOUT S0 DSPX ADC STATE tACQ IDLE tCONV Figure 17. DSP External Clock Mode, 8-Bit Data-Transfer Mode, Conversion Timing (MAX1068 Only) CS DSPR 1 8 MSB LSB 0 X 16 24 32 SCLK DIN X X X X X X X LSB MSB S1 S0 DOUT DSPX ADC STATE , X = DON T CARE tACQ tCONV Figure 18. DSP External Clock Mode, 16-Bit Data-Transfer Mode, Conversion Timing (MAX1068 Only) 22 ______________________________________________________________________________________ IDLE Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Applications Information MAX1067/MAX1068 Output Coding and Transfer Function The data output from the MAX1067/MAX1068 is straight binary. Figure 19 shows the nominal transfer function. Code transitions occur halfway between successive integer LSB values (V REF = +4.096V, and 1 LSB = +250µV or 4.096V / 16,384V). OUTPUT CODE FULL-SCALE TRANSITION 11...111 11...110 11...101 Internal Reference The internal bandgap reference provides a buffered +4.096V. Bypass REFCAP with a 0.1µF capacitor to AGND and REF with a 1µF capacitor to AGND. For best results, use low-ESR, X5R/X7R ceramic capacitors. Allow 5ms for the reference and buffer to wake up from full power-down (see Table 5). External Reference The MAX1067/MAX1068 accept an external reference with a voltage range between +3.8V and AV DD . Connect the external reference directly to REF. Bypass REF to AGND with a 10µF capacitor. When not using a low-ESR bypass capacitor, use a 0.1µF ceramic capacitor in parallel with the 10µF capacitor. Noise on the reference degrades conversion accuracy. The input impedance at REF is 37kΩ for DC currents. During a conversion, the external reference at REF must deliver 118µA of DC load current and have an output impedance of 10Ω or less. For optimal performance, buffer the reference through an op amp and bypass the REF input. Consider the equivalent input noise (82µV RMS ) of the MAX1067/ MAX1068 when choosing a reference. Internal/External Oscillator Select either an external (0.1MHz to 4.8MHz) or the internal 4MHz (typ) clock to perform conversions (Table 6). The external clock shifts data in and out of the MAX1067/MAX1068 in either clock mode. When using the internal clock mode, the internal oscillator controls the acquisition and conversion processes, while the external oscillator shifts data in and out of the MAX1067/MAX1068. Turn off the external clock (SCLK) when the internal clock is on to realize lowest noise performance. The internal clock remains off in external clock mode. FS = VREF V 1 LSB = REF 16,384 00...011 00...010 00...001 00...000 0 1 2 3 INPUT VOLTAGE (LSB) FS FS - 3/2 LSB Figure 19. Unipolar Transfer Function, Full Scale (FS) = VREF, Zero Scale (ZS) = GND Input Buffer Most applications require an input-buffer amplifier to achieve 14-bit accuracy. The input amplifier must have a slew rate of at least 2V/µs and a unity-gain bandwidth of at least 10MHz to complete the required output-voltage change before the end of the acquisition time. At the beginning of the acquisition, the internal sampling capacitor array connects to AIN_ (the amplifier input), causing some disturbance on the output of the buffer. Ensure the sampled voltage has settled before the end of the acquisition time. Digital Noise Digital noise can couple to AIN_ and REF. The conversion clock (SCLK) and other digital signals active during input acquisition contribute noise to the conversion result. Noise signals, synchronous with the sampling interval, result in an effective input offset. Asynchronous signals produce random noise on the input, whose highfrequency components can be aliased into the frequency band of interest. Minimize noise by presenting a low impedance (at the frequencies contained in the noise signal) at the inputs. This requires bypassing AIN_ to AGND, or buffering the input with an amplifier that has a small-signal bandwidth of several megahertz (doing both is preferable). AIN has a typical bandwidth of 4MHz. ______________________________________________________________________________________ 23 MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Distortion Avoid degrading dynamic performance by choosing an amplifier with distortion much less than the total harmonic distortion of the MAX1067/MAX1068 at the frequencies of interest (THD = -98db at 1kHz). If the chosen amplifier has insufficient common-mode rejection, which results in degraded THD performance, use the inverting configuration (positive input grounded) to eliminate errors from this source. Low-temperature-coefficient, gain-setting resistors reduce linearity errors caused by resistance changes due to self-heating. To reduce linearity errors due to finite amplifier gain, use amplifier circuits with sufficient loop gain at the frequencies of interest.. max for +5V supply), or whose offset can be trimmed while maintaining stability over the required temperature range. Serial Interfaces SPI and MICROWIRE Interfaces When using the SPI (Figure 20a) or MICROWIRE (Figure 20b) interfaces, set CPOL = 0 and CPHA = 0. Drive CS low to power on the MAX1067/MAX1068 before starting a conversion (Figure 20c). Three consecutive 8-bit-wide readings are necessary to obtain the entire 14-bit result from the ADC. DOUT data transitions on the serial clock’s falling edge. The first 8-bit-wide data stream contains all leading zeros. The 2nd 8-bit-wide data stream contains the MSB through D6. The 3rd 8-bit-wide data stream contains D5 through D0 followed by S1 and S0. DC Accuracy To improve DC accuracy, choose a buffer with an offset much less than the MAX1067/MAX1068s’ offset (±10mV CS I/O CS SCK SCLK SK SCLK MISO DOUT SI DOUT I/O VDD SPI MICROWIRE MAX1067 MAX1068 SS MAX1067 MAX1068 Figure 20a. SPI Connections Figure 20b. MICROWIRE Connections 1ST BYTE READ 1 SCLK 2ND BYTE READ 4 6 12 8 16 CS DOUT* 0 0 0 0 0 0 0 0 D13 D12 D11 D10 D9 D8 MSB *WHEN CS IS HIGH, DOUT = HIGH-Z 3RD BYTE READ 20 24 HIGH-Z D5 D4 D3 D2 D1 D0 S1 S0 LSB Figure 20c. SPI/MICROWIRE Interface Timing Sequence (CPOL = CPHA = 0) 24 ______________________________________________________________________________________ D7 D6 D5 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters PIC16 with SSP Module and PIC17 Interface The MAX1067/MAX1068 are compatible with a PIC16/ PIC17 controller (µC), using the synchronous serial-port (SSP) module. To establish SPI communication, connect the controller as shown in Figure 22a and configure the PIC16/PIC17 as system master by initializing its synchronous serialport control register (SSPCON) and synchronous serialport status register (SSPSTAT) to the bit patterns shown in Tables 7 and 8. In SPI mode, the PIC16/PIC17 µCs allow 8 bits of data to be synchronously transmitted and received simultaneously. Three consecutive 8-bit-wide readings (Figure 22b) are necessary to obtain the entire 14-bit result from the ADC. DOUT data transitions on the serial clock’s falling edge and is clocked into the µC on SCLK’s rising edge. The first 8-bit-wide data stream contains all zeros. The 2nd 8-bit-wide data stream contains the MSB through D6. The 3rd 8-bit-wide data stream contains bits D5 through D0 followed by S1 and S0. CS CS SCK SCLK MISO DOUT VDD QSPI MAX1067 MAX1068 SS Figure 21a. QSPI Connections 1 SCLK 4 6 8 12 16 24 20 CS DOUT* D13 SAMPLING INSTANT D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 MSB D1 D0 S1 S0 HIGH-Z LSB *WHEN CS IS HIGH, DOUT = HIGH-Z Figure 21b. QSPI Interface Timing Sequence (External Clock, 8-Bit Data Transfer, CPOL = CPHA = 0) Table 7. Detailed SSPCON Register Contents CONTROL BIT SETTINGS SYNCHRONOUS SERIAL-PORT CONTROL REGISTER (SSPCON) WCOL BIT7 X Write Collision Detection Bit SSPOV BIT6 X Receive Overflow Detection Bit SSPEN BIT5 1 Synchronous Serial-Port Enable Bit: 0: Disables serial port and configures these pins as I/O port pins. 1: Enables serial port and configures SCK, SDO, and SCI pins as serial port pins. CKP BIT4 0 Clock Polarity Select Bit. CKP = 0 for SPI master-mode selection. SSPM3 BIT3 0 SSPM2 BIT2 0 SSPM1 BIT1 0 SSPM0 BIT0 1 Synchronous Serial-Port Mode Select Bit. Sets SPI master-mode and selects fCLK = fOSC / 16. X = Don’t care. ______________________________________________________________________________________ 25 MAX1067/MAX1068 QSPI Interface Using the high-speed QSPI interface with CPOL = 0 and CPHA = 0, the MAX1067/MAX1068 support a maximum f SCLK of 4.8MHz. Figure 21a shows the MAX1067/MAX1068 connected to a QSPI master and Figure 21b shows the associated interface timing. MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Table 8. Detailed SSPSTAT Register Contents CONTROL BIT SETTINGS SYNCHRONOUS SERIAL-PORT STATUS REGISTER (SSPSTAT) SMP BIT7 0 SPI Data-Input Sample Phase. Input data is sampled at the middle of the data output time. CKE BIT6 1 SPI Clock Edge-Select Bit. Data is transmitted on the rising edge of the serial clock. D/A BIT5 X Data Address Bit P BIT4 X Stop Bit S BIT3 X Start Bit R/W BIT2 X Read/Write Bit Information UA BIT1 X Update Address BF BIT0 X Buffer-Full Status Bit X = Don’t care. DSP Interface VDD VDD SCLK SCK DOUT SDI CS I/O The DSP mode of the MAX1068 only operates in external clock mode. Figure 23 shows a typical DSP interface connection to the MAX1068. Use the same oscillator as the DSP to provide the clock signal for the MAX1068. The DSP provides the falling edge at CS to wake the MAX1068. The MAX1068 detects the state of DSPR on the falling edge of CS (Figure 17). Logic low at DSPR places the MAX1068 in DSP mode. After the MAX1068 enters DSP mode, CS can be left low. A frame sync pulse from the DSP to DSPR initiates a conversion. The MAX1068 sends a frame sync pulse from DSPX to the DSP signaling that the MSB is available at DOUT. Send another frame sync pulse from the DSP to DSPR to begin the next conversion. The MAX1068 does not operate in scan mode when using DSP mode. PIC16/17 MAX1067 MAX1068 GND Figure 22a. SPI Interface Connection for a PIC16/PIC17 1ST BYTE READ 1 SCLK 2ND BYTE READ 4 6 8 12 16 CS DOUT* 0 0 0 0 0 0 0 0 D13 *WHEN CS IS HIGH, DOUT = HIGH-Z D12 D11 D10 D9 D8 D7 D6 MSB 3RD BYTE READ 24 20 HIGH-Z D5 D4 D3 D2 D1 D0 S1 S0 LSB Figure 22b. SPI Interface Timing with PIC16/PIC17 in Master Mode (CKE = 1, CKP = 0, SMP = 0, SSPM3 - SSPM0 = 0001) 26 ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters 14 DSP SCLK SCLK TFS DSPR RFS DSPX EFFECTIVE BITS 12 MAX1068 10 8 6 DT DIN DR DOUT 2 FL1 CS 0 4 fSAMPLE = 200ksps 0.1 1 10 100 FREQUENCY (kHz) Figure 23. DSP Interface Connection Figure 24. Effective Bits vs. Frequency Definitions Integral Nonlinearity Integral nonlinearity (INL) is the deviation of the values on an actual transfer function from a straight line. This straight line can be either a best-straight-line fit or a line drawn between the end points of the transfer function, once offset and gain errors have been nullified. The static linearity parameters for the MAX1067/MAX1068 are measured using the end-point method. Differential Nonlinearity Differential nonlinearity (DNL) is the difference between an actual step-width and the ideal value of ±1 LSB. A DNL error specification of ±1 LSB guarantees no missing codes and a monotonic transfer function. Aperture Definitions Aperture jitter (tAJ) is the sample-to-sample variation in the time between samples. Aperture delay (tAD) is the time between the falling edge of the sampling clock and the instant when the actual sample is taken. Signal-to-Noise Ratio For a waveform perfectly reconstructed from digital samples, signal-to-noise ratio (SNR) is the ratio of the full-scale analog input (RMS value) to the RMS quantization error (residual error). The ideal, theoretical minimum analog-to-digital noise is caused by quantization noise error only and results directly from the ADC’s resolution (N bits): SNR = (6.02 ✕ N + 1.76)dB In reality, there are other noise sources besides quantization noise: thermal noise, reference noise, clock jitter, etc. SNR is computed by taking the ratio of the RMS signal to the RMS noise, which includes all spectral components minus the fundamental, the first five harmonics, and the DC offset. Signal-to-Noise Plus Distortion Signal-to-noise plus distortion (SINAD) is the ratio of the fundamental input frequency’s RMS amplitude to the RMS equivalent of all the other ADC output signals: SINAD (dB) = 20 ✕ log [SignalRMS / (Noise + Distortion)RMS] Effective Number of Bits Effective number of bits (ENOB) indicates the global accuracy of an ADC at a specific input frequency and sampling rate. An ideal ADC’s error consists of quantization noise only. With an input range equal to the fullscale range of the ADC, calculate the ENOB as follows: ENOB = (SINAD - 1.76) / 6.02 Figure 24 shows the ENOB as a function of the MAX1067/ MAX1068s’ input frequency. ______________________________________________________________________________________ 27 MAX1067/MAX1068 EFFECTIVE NUMBER OF BITS (ENOB) 16 EXTERNAL CLOCK MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters Total Harmonic Distortion Total harmonic distortion (THD) is the ratio of the RMS sum of the first five harmonics of the input signal to the fundamental itself. This is expressed as: ⎡ ⎛ 2 2 2 2 ⎢ ⎝ V2 + V3 + V4 + V5 ⎞⎠ ⎢ THD = 20 × log V1 ⎢ ⎢ ⎣ ⎤ ⎥ ⎥ ⎥ ⎥ ⎦ AIN_ SCLK DOUT 1µF AVDD +5V 0.1µF MAX1067 MAX1068 DVDD 0.1µF Spurious-free dynamic range (SFDR) is the ratio of the RMS amplitude of the fundamental (maximum signal component) to the RMS value of the next-largest frequency component. Supplies, Layout, Grounding, and Bypassing Use printed circuit (PC) boards with separate analog and digital ground planes. Do not use wire-wrap boards. Connect the two ground planes together at the MAX1067/MAX1068 AGND terminal. Isolate the digital supply from the analog with a low-value resistor (10Ω) or ferrite bead when the analog and digital supplies come from the same source (Figure 25). Constraints on sequencing the power supplies and inputs are as follows: • Apply AGND before DGND. • Apply AIN_ and REF after AV DD and AGND are present. • DVDD is independent of the supply sequencing. Ensure that digital return currents do not pass through the analog ground and that return-current paths are low 28 CS SCLK DOUT 10Ω where V1 is the fundamental amplitude and V2 through V5 are the 2nd- through 5th-order harmonics. Spurious-Free Dynamic Range CS AIN_ REF AGND AGND DGND GND Figure 25. Powering AVDD and DVDD from a Single Supply impedance. A 5mA current flowing through a PC board ground trace impedance of only 0.05Ω creates an error voltage of about 250µV and a 1 LSB error with a +4.096V full-scale system. The board layout should ensure that digital and analog signal lines are kept separate. Do not run analog and digital lines (especially the SCLK and DOUT) parallel to one another. If one must cross another, do so at right angles. The ADC’s high-speed comparator is sensitive to highfrequency noise on the AVDD power supply. Bypass an excessively noisy supply to the analog ground plane with a 0.1µF capacitor in parallel with a 1µF to 10µF low-ESR capacitor. Keep capacitor leads short for best supply-noise rejection. ______________________________________________________________________________________ Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters PART TEMP RANGE PINPACKAGE INL (LSB) MAX1068ACEG 0°C to +70°C 24 QSOP ±0.5 MAX1068BCEG 0°C to +70°C 24 QSOP ±1 MAX1068CCEG 0°C to +70°C 24 QSOP ±2 MAX1068AEEG* -40°C to +85°C 24 QSOP ±0.5 MAX1068BEEG* -40°C to +85°C 24 QSOP ±1 MAX1068CEEG* -40°C to +85°C 24 QSOP *Future product—contact factory for availability. ±2 Chip Information TRANSISTOR COUNT: 20,760 PROCESS: BiCMOS Pin Configurations TOP VIEW DOUT 1 16 DVDD DSPR 1 24 N.C. 15 DGND DSEL 2 23 DSPX 14 CS DOUT 3 22 DVDD 13 AVDD SCLK 4 AIN0 5 12 AGND DIN 5 AIN1 6 11 AGND EOC 6 19 AVDD AIN2 7 10 REFCAP AIN0 7 18 AGND AIN3 8 9 REF AIN1 8 17 AGND AIN2 9 16 REFCAP AIN3 10 15 REF AIN4 11 14 AIN7 AIN5 12 13 AIN6 SCLK 2 DIN 3 EOC 4 MAX1067 QSOP 21 DGND MAX1068 20 CS QSOP ______________________________________________________________________________________ 29 MAX1067/MAX1068 Ordering Information (continued) 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.) QSOP.EPS MAX1067/MAX1068 Multichannel, 14-Bit, 200ksps Analog-to-Digital Converters PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 F 1 1 Revision History Pages changed at Rev 1: 1–6, 30 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. 30 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.