MAX1326ECM

19-3157; Rev 4; 10/08 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges General Description The MAX1316–MAX1318/MAX1320–MAX1322/MAX1324– MAX1326 14-bit, analog-to-digital converters (ADCs) offer two, four, or eight independent input channels. Independent track/hold (T/H) circuitry provides simultaneous sampling for each channel. The MAX1316/ MAX1317/MAX1318 have a 0 to +5V input range with ±6.0V fault-tolerant inputs. The MAX1320/MAX1321/ MAX1322 have a ±5V input range with ±16.5V fault-tolerant inputs. The MAX1324/MAX1325/MAX1326 have a ±10V input range with ±16.5V fault-tolerant inputs. These ADCs convert two channels in 2µs, and up to eight channels in 3.8µs, and have an 8-channel throughput of 250ksps per channel. Other features include a 10MHz T/H input bandwidth, internal clock, internal (+2.5V) or external (+2.0V to +3.0V) reference, and powersaving modes. A 16.6MHz, 14-bit, bidirectional, parallel interface provides the conversion results and accepts digital configuration inputs. These devices operate from a +4.75V to +5.25V analog supply and a separate +2.7V to +5.25V digital supply, and consume less than 50mA total supply current. These devices come in a 48-pin LQFP package and operate over the extended -40°C to +85°C temperature range. Features ♦ 8-/4-/2-Channel, 14-Bit ADCs ±1.5 LSB INL, ±1 LSB DNL, No Missing Codes 90dBc SFDR, -86dBc THD, 76.5dB SINAD, 77dB SNR at 100kHz Input ♦ On-Chip T/H Circuit for Each Channel 10ns Aperture Delay 50ps Channel-to-Channel T/H Matching ♦ Fast Conversion Time One Channel in 1.6µs Two Channels in 1.9µs Four Channels in 2.5µs Eight Channels in 3.7µs ♦ High Throughput 526ksps/ch for One Channel 455ksps/ch for Two Channels 357ksps/ch for Four Channels 250ksps/ch for Eight Channels ♦ Flexible Input Ranges 0 to +5V (MAX1316/MAX1317/MAX1318) ±5V (MAX1320/MAX1321/MAX1322) ±10V (MAX1324/MAX1325/MAX1326) ♦ No Calibration Needed ♦ 14-Bit, High-Speed, Parallel Interface ♦ Internal or External Clock ♦ +2.5V Internal Reference or +2.0V to +3.0V External Reference ♦ +5V Analog Supply, +3V to +5V Digital Supply 46mA Analog Supply Current (typ) 1.6mA Digital Supply Current (max) Shutdown and Power-Saving Modes ♦ 48-Pin LQFP Package (7mm x 7mm Footprint) MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Applications Multiphase Motor Control Power-Grid Synchronization Power-Factor Monitoring and Correction Vibration and Waveform Analysis Selector Guide PART MAX1316ECM MAX1317ECM MAX1318ECM MAX1320ECM MAX1321ECM MAX1322ECM MAX1324ECM MAX1325ECM MAX1326ECM INPUT RANGE (V) 0 to +5 0 to +5 0 to +5 ±5 ±5 ±5 ±10 ±10 ±10 CHANNEL COUNT 8 4 2 8 4 2 8 4 2 Ordering Information PART MAX1316ECM MAX1317ECM MAX1318ECM MAX1320ECM MAX1321ECM MAX1322ECM MAX1324ECM MAX1325ECM MAX1326ECM TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 48 LQFP 48 LQFP 48 LQFP 48 LQFP 48 LQFP 48 LQFP 48 LQFP 48 LQFP 48 LQFP Pin Configurations and Typical Operating Circuits appear at end of data sheet. ________________________________________________________________ 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. 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 ABSOLUTE MAXIMUM RATINGS AVDD to AGND .........................................................-0.3V to +6V DVDD to DGND.........................................................-0.3V to +6V AGND to DGND.....................................................-0.3V to +0.3V CH0–CH7, I.C. to AGND (MAX1316/MAX1317/MAX1318)...±6.0V CH0–CH7, I.C. to AGND (MAX1320/MAX1321/MAX1322).±16.5V CH0–CH7, I.C. to AGND (MAX1324/MAX1325/MAX1326).±16.5V INTCLK/EXTCLK to AGND .......................-0.3V to (AVDD + 0.3V) EOC, EOLC, WR, RD, CS to DGND .........-0.3V to (DVDD + 0.3V) CONVST, CLK, SHDN, ALLON to DGND..................................-0.3V to (DVDD + 0.3V) MSV, REFMS, REF to AGND.....................-0.3V to (AVDD + 0.3V) REF+, COM, REF- to AGND.....................-0.3V to (AVDD + 0.3V) D0–D13 to DGND ....................................-0.3V to (DVDD + 0.3V) Maximum Current into Any Pin Except AVDD, DVDD, AGND, DGND...............................................................±50mA Continuous Power Dissipation LQFP (derate 22.7mW/°C above +70°C) ...................1818mW Operating Temperature Range ...........................-40°C to +85°C 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 (VAVDD = +5V, VDVDD = +3V, VAGND = VDGND = 0, VREF = VREFMS = +2.5V (external reference), CREF = CREFMS = 0.1µF, CREF+ = CREF- = 0.1µF, CREF+-to-REF- = 2.2µF || 0.1µF, C COM = 2.2µF || 0.1µF, C MSV = 2.2µF || 0.1µF (unipolar devices, MAX1316/ MAX1317/MAX1318), MSV = AGND (bipolar devices, MAX1320/MAX1321/MAX1322/MAX1324/MAX1325/MAX1326), fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER STATIC PERFORMANCE (Note 1) Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Offset Drift Channel Offset Matching Gain Error Channel Gain-Error Matching Gain Temperature Coefficient DYNAMIC PERFORMANCE (at fIN = 100kHz, -0.4dB FS) Signal-to-Noise Ratio Signal-to-Noise and Distortion Ratio Spurious-Free Dynamic Range Total Harmonic Distortion Channel-to-Channel Isolation ANALOG INPUTS (CH0–CH7) MAX1316/MAX1317/MAX1318 Input Voltage Range MAX1320/MAX1321/MAX1322 MAX1324/MAX1325/MAX1326 0 -5 -10 +5 +5 +10 V SNR SINAD SFDR THD 83 Unipolar Bipolar Unipolar Bipolar 74.5 75 74.5 75 83 76 76.5 76 76.5 93 -90 -83 dB dB dBc dBc dB N INL DNL (Note 2) No missing codes (Note 2) Unipolar devices Bipolar devices Unipolar devices Bipolar devices Unipolar devices between all channels Bipolar devices between all channels (Note 3) Between all channels 3 -4 -4 35 25 ±8 80 60 ±40 25 14 ±0.8 ±0.5 ±2.0 ±1 ±40 ±40 Bits LSB LSB LSB ppm/°C LSB LSB LSB ppm/°C SYMBOL CONDITIONS MIN TYP MAX UNITS 2 _______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges ELECTRICAL CHARACTERISTICS (continued) (VAVDD = +5V, VDVDD = +3V, VAGND = VDGND = 0, VREF = VREFMS = +2.5V (external reference), CREF = CREFMS = 0.1µF, CREF+ = CREF- = 0.1µF, CREF+-to-REF- = 2.2µF || 0.1µF, C COM = 2.2µF || 0.1µF, C MSV = 2.2µF || 0.1µF (unipolar devices, MAX1316/ MAX1317/MAX1318), MSV = AGND (bipolar devices, MAX1320/MAX1321/MAX1322/MAX1324/MAX1325/MAX1326), fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MAX1316/MAX1317/MAX1318 Input Current (Note 4) MAX1320/MAX1321/MAX1322 MAX1324/MAX1325/MAX1326 MAX1316/MAX1317/MAX1318 Input Resistance (Note 4) Input Capacitance TRACK/HOLD One channel External-Clock Throughput Rate (Note 5) Two channels Four channels Eight channels One channel (INTCLK/EXTCLK = AVDD) Internal-Clock Throughput Rate (Note 5) Small-Signal Bandwidth Full-Power Bandwidth Aperture Delay Aperture Jitter Aperture-Delay Matching INTERNAL REFERENCE REFMS Voltage REF Voltage REF Temperature Coefficient EXTERNAL REFERENCE (REFMS AND REF EXTERNALLY DRIVEN) Input Current REFMS Input Voltage Range REF Voltage Input Range REF Input Capacitance REFMS Input Capacitance DIGITAL INPUTS (D0–D7, RD, WR, CS, CLK, SHDN, ALLON, CONVST) Input-Voltage High VIH 0.7 x DVDD VREFMS VREF Unipolar devices -250 2.0 2.0 2.5 2.5 15 15 +250 3.0 3.0 µA V V pF pF VREFMS VREF 2.475 2.475 2.500 2.500 30 2.525 2.525 V V ppm/°C Two channels (INTCLK/EXTCLK = AVDD) Four channels (INTCLK/EXTCLK = AVDD) Eight channels (INTCLK/EXTCLK = AVDD) 526 455 357 250 526 455 357 250 10 10 16 50 100 MHz MHz ns psRMS ps ksps ksps MAX1320/MAX1321/MAX1322 MAX1324/MAX1325/MAX1326 VIN = +5V VIN = 0V VIN = +5V VIN = -5V VIN = +10V VIN = -10V -1.13 -1.16 -0.157 MIN TYP 0.54 -0.12 0.29 -0.87 0.56 -0.85 7.58 8.66 14.26 15 pF kΩ 0.74 0.39 mA MAX 0.72 UNITS MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 V _______________________________________________________________________________________ 3 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 ELECTRICAL CHARACTERISTICS (continued) (VAVDD = +5V, VDVDD = +3V, VAGND = VDGND = 0, VREF = VREFMS = +2.5V (external reference), CREF = CREFMS = 0.1µF, CREF+ = CREF- = 0.1µF, CREF+-to-REF- = 2.2µF || 0.1µF, C COM = 2.2µF || 0.1µF, C MSV = 2.2µF || 0.1µF (unipolar devices, MAX1316/ MAX1317/MAX1318), MSV = AGND (bipolar devices, MAX1320/MAX1321/MAX1322/MAX1324/MAX1325/MAX1326), fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Input-Voltage Low Input Hysteresis Input Capacitance Input Current CIN IIN VIN = 0V or DVDD 0.7 x AVDD 0.3 x AVDD DVDD 0.6 0.4 0.06 15 4.75 2.70 All channels selected CLOAD = 100pF, all channels selected (Note 6) VSHDN = DVDD, VCH = float V RD = V WR = DVDD, VSHDN = DVDD AVDD = +4.75V to +5.75V (Note 8) 0.1 50 46 1 5.25 5.25 56 1.6 10 2 1 SYMBOL VIL 15 15 ±1 CONDITIONS MIN TYP MAX 0.3 x DVDD UNITS V mV pF µA CLOCK-SELECT INPUT (INTCLK/EXTCLK) Input-Voltage High Input-Voltage Low DIGITAL OUTPUTS (D0–D13, EOC, EOLC) Output-Voltage High Output-Voltage Low Tri-State Leakage Current Tri-State Output Capacitance POWER SUPPLIES Analog-Supply Voltage Digital-Supply Voltage Analog-Supply Current Digital-Supply Current Shutdown Current (Note 7) Power-Supply Rejection Ratio AVDD DVDD IAVDD IDVDD IAVDD IDVDD PSRR V V mA mA µA dB VOH VOL ISOURCE = 0.8mA ISINK = 1.6mA RD ≥ VIH or CS ≥ VIH RD ≥ VIH or CS ≥ VIH V V µA pF V V 4 _______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges TIMING CHARACTERISTICS (Figures 3, 4, 5, 6 and 7) (Tables 1, 3) PARAMETER Time-to-First-Conversion Result SYMBOL tCONV CONDITIONS Internal clock External clock, Figure 6 Internal clock Time-to-Next-Conversion Result CONVST Pulse-Width Low (Acquisition Time) CS Pulse Width RD Pulse-Width Low RD Pulse-Width High WR Pulse-Width Low CS to WR WR to CS CS to RD RD to CS Data-Access Time (RD Low to Valid Data) Bus-Relinquish Time (RD High) EOC Pulse Width Input-Data Setup Time Input-Data Hold Time External-Clock Period External-Clock High Period External-Clock Low Period External-Clock Frequency Internal-Clock Frequency CONVST High to CLK Edge EOC Low to RD t19 t20 20 tNEXT External clock, Figure 6 (Note 9) 0.16 30 30 30 30 (Note 10) (Note 10) (Note 10) (Note 10) 30 30 Internal clock t12 t14 t15 t16 t17 t18 Logic sensitive to rising edges Logic sensitive to rising edges (Note 11) External clock, Figure 6 10 10 0.08 20 20 0.1 10 (Note 12) 0 12.5 10.00 80 1 MIN TYP 1.6 16 0.3 3 100 0.36 MAX 1.8 UNITS µs Clock cycles µs Clock cycles µs ns ns ns ns ns ns ns ns ns ns ns Clock cycles ns ns µs ns ns MHz MHz ns ns MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 tACQ t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 Note 1: Note 2: Note 3: Note 4: For the MAX1316/MAX1317/MAX1318, VIN = 0 to +5V. For the MAX1320/MAX1321/MAX1322, VIN = -5V to +5V. For the MAX1324/MAX1325/MAX1326, VIN = -10V to +10V. All channel performance is guaranteed by correlation to a single channel test. Offset nulled. The analog input resistance is terminated to an internal bias point. Calculate the analog input current using: ICH _ = VCH _ − VBIAS RCH _ for VCH within the input voltage range. Note 5: Note 6: Throughput rate is given per channel. Throughput rate is a function of clock frequency (fCLK = 10MHz). See the Data Throughput section for more information. All analog inputs are driven with an FS 100kHz sine wave. _______________________________________________________________________________________ 5 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 TIMING CHARACTERISTICS (Figures 3, 4, 5, 6 and 7) (Tables 1, 3) (continued) Shutdown current is measured with analog input floating. The large amplitude of the maximum shutdown current specification is due to automatic test equipment limitations. Note 8: Defined as the change in positive full scale caused by ±5% variation in the nominal supply voltage. Note 9: CONVST must remain low for at least the acquisition period. The maximum acquisition time is limited by internal capacitor droop. Note 10: CS-to-WR and CS-to-RD pins are internally AND together. Setup and hold times do not apply. Note 11: Minimum clock frequency is limited only by the internal T/H droop rate. Limit the time between the falling edge of CONVST to the falling edge of EOLC to a maximum of 0.25ms. Note 12: To avoid T/H droop degrading the sampled analog input signals, the first clock pulse should occur within 10µs of the rising edge of CONVST, and have a minimum clock frequency of 100kHz. Note 7: Typical Operating Characteristics (AVDD = +5V, DVDD = +3V, AGND = DGND = 0V, VREF = VREFMS = +2.5V (external reference), see the Typical Operating Circuits section, fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = +25°C, unless otherwise noted.) INTEGRAL NONLINEARITY vs. DIGITAL OUTPUT CODE MAX1316 toc01 DIFFERENTIAL NONLINEARITY vs. DIGITAL OUTPUT CODE 0.75 0.50 DNL (LSB) 0.25 0 -0.25 -0.50 -0.75 -1.00 30 0 4096 8192 12288 16384 4.75 MAX1316 toc02 ANALOG SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX1316 toc03 1.00 0.75 0.50 INL (LSB) 0.25 0 -0.25 -0.50 -0.75 -1.00 0 4096 8192 12288 1.00 50 SUPPLY CURRENT (mA) 45 40 35 fSAMPLE = 250ksps ALL 8 CHANNELS DRIVEN WITH FULLSCALE SINE WAVES 4.87 5.00 5.12 5.25 16384 DIGITAL OUTPUT CODE DIGITAL OUTPUT CODE SUPPLY VOLTAGE (V) ANALOG SUPPLY CURRENT vs. TEMPERATURE MAX1316 toc04 SHUTDOWN CURRENT vs. SUPPLY VOLTAGE MAX1316 toc05 SHUTDOWN CURRENT vs. TEMPERATURE MAX1316 toc06 50 0.8 0.8 SHUTDOWN CURRENT (µA) SUPPLY CURRENT (mA) 45 0.6 ANALOG SHUTDOWN CURRENT SHUTDOWN CURRENT (µA) 0.6 ANALOG SHUTDOWN CURRENT 40 fSAMPLE = 250ksps ALL 8 CHANNELS DRIVEN WITH FULLSCALE SINE WAVES 0.4 DIGITAL SHUTDOWN CURRENT 0.4 DIGITAL SHUTDOWN CURRENT 35 0.2 0.2 30 -40 -15 10 35 60 85 TEMPERATURE (°C) 0 2.5 3.5 4.5 5.5 SUPPLY VOLTAGE (V) 0 -40 -15 10 35 60 85 TEMPERATURE (°C) 6 _______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges Typical Operating Characteristics (continued) (AVDD = +5V, DVDD = +3V, AGND = DGND = 0V, VREF = VREFMS = +2.5V (external reference), see the Typical Operating Circuits section, fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = +25°C, unless otherwise noted.) INTERNAL REFERENCE VOLTAGE vs. ANALOG SUPPLY VOLTAGE MAX1316 toc07 MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 INTERNAL REFERENCE VOLTAGE vs. TEMPERATURE MAX1316 toc08 OFFSET ERROR vs. SUPPLY VOLTAGE MAX1316 toc09 2.5004 2.5003 2.5002 VREF (V) 2.504 2.503 2.502 VREF (V) 2.501 2.500 2.499 2.498 2.497 2.496 1.5 1.0 OFFSET ERROR (LSB) 0.5 0 -0.5 -1.0 -1.5 -2.0 NORMALIZED AT TA = +25°C 4.75 4.85 4.95 5.05 5.15 2.5001 2.5000 2.4999 2.4998 2.4997 2.4996 4.7 4.8 4.9 5.0 AVDD (V) 5.1 5.2 5.3 -40 -15 10 35 60 85 5.25 TEMPERATURE (°C) AVDD (V) OFFSET ERROR vs. TEMPERATURE MAX1316 toc10 GAIN ERROR vs. SUPPLY VOLTAGE MAX1316 toc11 GAIN ERROR vs. TEMPERATURE 0.08 GAIN ERROR (%FSR) 0.07 0.06 0.05 0.04 0.03 0.02 0.01 MAX1316 toc12 0.04 0.03 OFFSET ERROR (%FSR) 0.02 0.01 0 -0.01 -0.02 -0.03 -0.04 NORMALIZED AT TA = +25°C -40 -15 10 35 60 16 15 GAIN ERROR (LSB) 14 13 12 11 10 9 0.09 85 4.75 4.85 4.95 5.05 5.15 5.25 -40 -15 10 35 60 85 TEMPERATURE (°C) AVDD (V) TEMPERATURE (°C) _______________________________________________________________________________________ 7 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Typical Operating Characteristics (continued) (AVDD = +5V, DVDD = +3V, AGND = DGND = 0V, VREF = VREFMS = +2.5V (external reference), see the Typical Operating Circuits section, fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = +25°C, unless otherwise noted.) SIGNAL-TO-NOISE RATIO vs. CLOCK FREQUENCY fANALOG_IN = 103kHz fSAMPLE = 490kHz fCLK = 10MHz SINAD = 76.7dB SNR = 77.0dB THD = -88.3dB SFDR = 91.0dB MAX1316 toc13 MAX1316 toc14 FFT 0 -20 -40 -60 -80 -100 -120 -140 0 0.05 0.10 0.15 0.20 0.25 FREQUENCY (MHz) 80 79 78 77 SIGNAL-TO-NOISE PLUS DISTORTION vs. CLOCK FREQUENCY 79 78 77 SINAD (dB) 76 75 74 73 72 71 70 fIN = 100kHz MAX1316 toc15 80 fIN = 100kHz AMPLITUDE (dB) SNR (dB) 76 75 74 73 72 71 70 8 10 12 14 fCLK (MHz) 16 18 20 8 10 12 14 fCLK (MHz) 16 18 20 EFFECTIVE NUMBER OF BITS vs. CLOCK FREQUENCY MAX1316 toc16 TOTAL HARMONIC DISTORTION vs. CLOCK FREQUENCY MAX1316 toc17 SPURIOUS-FREE DYNAMIC RANGE vs. CLOCK FREQUENCY 95 90 MAX1316 toc17b 13.5 fIN = 100kHz 13.0 12.5 -70 -75 -80 -85 -90 -95 -100 100 ENOB (BITS) SFDR (dB) THD (dB) 85 80 75 70 12.0 11.5 11.0 10.5 8 10 12 14 fCLK (MHz) 16 18 20 65 60 8 10 12 14 fCLK (MHz) 16 18 20 8 10 12 14 fCLK (MHz) 16 18 20 8 _______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Typical Operating Characteristics (continued) (AVDD = +5V, DVDD = +3V, AGND = DGND = 0V, VREF = VREFMS = +2.5V (external reference), see the Typical Operating Circuits section, fCLK = 10MHz, 50% duty cycle, INTCLK/EXTCLK = AGND (external clock), SHDN = DGND, TA = +25°C, unless otherwise noted.) CONVERSION TIME vs. ANALOG SUPPLY VOLTAGE MAX1316 toc18 CONVERSION TIME vs. TEMPERATURE MAX1316 toc19 OUTPUT HISTOGRAM (DC INPUT) 4000 3500 3000 COUNTS 2500 2000 1500 1000 500 0 0 13 341 154 1 0 1562 2306 3815 MAX1316 toc20 2.0 1.8 1.6 CONVERSION TIME (µs) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 4.750 4.875 5.000 tNEXT tCONV 2.0 1.8 1.6 CONVERSION TIME (µs) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 tNEXT tCONV INTERNAL CLOCK INTERNAL CLOCK 4500 5.125 5.250 -40 -15 10 35 60 85 8209 8210 8211 8212 8213 8214 8215 8216 8217 DIGITAL OUTPUT CODE ANALOG SUPPLY VOLTAGE (V) TEMPERATURE (°C) Pin Description PIN MAX1316 MAX1320 MAX1324 MAX1317 MAX1321 MAX1325 MAX1318 MAX1322 MAX1326 NAME FUNCTION 1, 15, 17 1, 15, 17 1, 15, 17 AVDD Analog Supply Input. AVDD is the power input for the analog section of the converter. Apply 4.75V to 5.25V to AVDD. Bypass AVDD to AGND (pin 14 to pin 15, pin 16 to pin 17, pin 1 to pin 2) with a 0.1µF capacitor at each AVDD input. Analog Ground. AGND is the power return for AVDD. Connect all AGNDs together. Channel 0 Analog Input Channel 1 Analog Input Midscale Voltage Bypass. For the MAX1316/MAX1317/MAX1318, connect a 2.2µF and a 0.1µF capacitor from MSV to AGND. For the MAX1320/MAX1321/MAX1322/MAX1324/MAX1325/MAX1326, connect MSV directly to AGND. Channel 2 Analog Input Channel 3 Analog Input Channel 4 Analog Input 2, 3, 14, 16, 23 2, 3, 14, 16, 23 2, 3, 14, 16, 23 4 5 4 5 4 5 AGND CH0 CH1 6 6 6 MSV 7 8 9 7 8 — — — — CH2 CH3 CH4 _______________________________________________________________________________________ 9 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Pin Description (continued) PIN MAX1316 MAX1320 MAX1324 10 11 12 MAX1317 MAX1321 MAX1325 — — — MAX1318 MAX1322 MAX1326 — — — NAME FUNCTION CH5 CH6 CH7 INTCLK/ EXTCLK Channel 5 Analog Input Channel 6 Analog Input Channel 7 Analog Input Clock-Mode Select Input. Use INTCLK/EXTCLK to select the internal or external conversion clock. Connect INTCLK/EXTCLK to AVDD to select the internal clock. Connect INTCLK/EXTCLK to AGND to use an external clock connected to CLK. Midscale Reference Bypass or Input. REFMS is the bypass point for an internally generated reference voltage. For the MAX1316/ MAX1317/MAX1318, connect a 0.1µF capacitor from REFMS to AGND. For the MAX1320/MAX1321/MAX1322/MAX1324/ MAX1325/MAX1326, connect REFMS directly to REF and bypass with a 0.1µF capacitor from REFMS to AGND. ADC Reference Bypass or Input. REF is the bypass point for an internally generated reference voltage. Bypass REF with a 0.01µF capacitor to AGND. REF can be driven externally by a precision external voltage reference. Positive Reference Bypass. REF+ is the bypass point for an internally generated reference voltage. Bypass REF+ with a 0.1µF capacitor to AGND. Also bypass REF+ to REF- with a 2.2µF and a 0.1µF capacitor. Reference Common Bypass. COM is the bypass point for an internally generated reference voltage. Bypass COM to AGND with a 2.2µF and a 0.1µF capacitor. Negative Reference Bypass. REF- is the bypass point for an internally generated reference voltage. Bypass REF- with a 0.1µF capacitor to AGND. Also bypass REF- to REF+ with a 2.2µF and a 0.1µF capacitor. Digital I/O Bit 0 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital I/O Bit 1 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital I/O Bit 2 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. 13 13 13 18 18 18 REFMS 19 19 19 REF 20 20 20 REF+ 21 21 21 COM 22 22 22 REF- 24 25 26 24 25 26 24 25 26 D0 D1 D2 10 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges Pin Description (continued) PIN MAX1316 MAX1320 MAX1324 27 28 29 30 31 32 33 34 35 36 37 38 MAX1317 MAX1321 MAX1325 27 28 29 30 31 32 33 34 35 36 37 38 MAX1318 MAX1322 MAX1326 27 28 29 30 31 32 33 34 35 36 37 38 NAME FUNCTION MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 DVDD Digital I/O Bit 3 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital I/O Bit 4 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital I/O Bit 5 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital I/O Bit 6 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital I/O Bit 7 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital Out Bit 8 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital Out Bit 9 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital Out Bit 10 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital Out Bit 11 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital Out Bit 12 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital Out Bit 13 of 14-Bit Parallel Data Bus. High impedance when RD = 1 or CS = 1. Digital-Supply Input. Apply +2.7V to +5.25V to DVDD. Bypass DVDD to DGND with a 0.1µF capacitor. Digital-Supply GND. DGND is the power return for DVDD. Connect DGND to AGND at only one point (see the Layout, Grounding, and Bypassing section). End-of-Conversion Output. EOC goes low to indicate the end of a conversion. EOC returns high after one clock period. 39 39 39 DGND 40 40 40 EOC ______________________________________________________________________________________ 11 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Pin Description (continued) PIN MAX1316 MAX1320 MAX1324 MAX1317 MAX1321 MAX1325 MAX1318 MAX1322 MAX1326 NAME FUNCTION 41 41 41 EOLC End-of-Last-Conversion Output. EOLC goes low to indicate the end of the last conversion. EOLC returns high when CONVST goes low for the next conversion sequence. Read Input. When RD and CS go low, the device initiates a read command of the parallel data buses, D0–D13. D0–D13 are high impedance while either RD or CS is high. Write Input. The write command initiates when WR and CS go low. A write command loads the configuration byte on D0–D7. Chip-Select Input. Pulling CS low activates the digital interface. D0–D13 are high impedance while either CS or RD is high. Convert-Start Input. Driving CONVST high places the device in hold mode and initiates the conversion process. The analog inputs are sampled on the rising edge of CONVST. When CONVST is low, the analog inputs are tracked. External-Clock Input. CLK accepts an external-clock signal up to 15MHz. Connect CLK to DGND for internally clocked conversions. To select external-clock mode, set INTCLK/EXTCLK = 0. Shutdown Input. Set SHDN = 0 for normal operation. Set SHDN = 1 for shutdown mode. Enable-All-Channels Input. Drive ALLON high to enable all input channels. When ALLON is low, only input channels selected as active are powered. Select channels as active using the configuration register. Internally Connected. Connect I.C. to AGND. For factory use only. 42 42 42 RD 43 44 43 44 43 44 WR CS 45 45 45 CONVST 46 46 46 CLK 47 47 47 SHDN 48 48 48 ALLON — 9–12 7–12 I.C. 12 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 MAX1316–MAX1318 MAX1320–MAX1322 MAX1324–MAX1326 S/H 8x1 MUX CH7 S/H 14-BIT ADC AVDD CH0 DVDD D13 8 x 14 SRAM OUTPUT DRIVERS D8 D7 D0 MSV CONFIGURATION REGISTER REF+ COM REF* INTERFACE AND CONTROL 5kΩ REF 5kΩ REFMS 2.500V INTCLK/EXTCLK AGND WR CS RD CONVST SHDN CLK ALLON EOC EOLC DGND *SWITCH CLOSED ON UNIPOLAR DEVICES, OPEN ON BIPOLAR DEVICES Figure 1. Functional Diagram Detailed Description The MAX1316–MAX1318/MAX1320–MAX1322/MAX1324MAX1326 are 14-bit ADCs. They offer two, four, or eight (independently selectable) input channels, each with its own T/H circuitry. Simultaneous sampling of all active channels preserves relative phase information, making these devices ideal for motor control and power monitoring. These devices are available with 0 to +5V, ±5V, and ±10V input ranges. The 0 to +5V devices feature ±6V fault-tolerant inputs. The ±5V and ±10V devices feature ±16.5V fault-tolerant inputs. Two channels convert in 2µs; all eight channels convert in 3.8µs, with a maximum 8channel throughput of 263ksps per channel. Internal or external reference and internal- or external-clock capability offer great flexibility and ease of use. A write-only configuration register can mask out unused channels, and a shutdown feature reduces power. A 16.6MHz, 14-bit, parallel data bus outputs the conversion result. Figure 1 shows the functional diagram of these devices. Analog Inputs T/H To preserve phase information across these multichannel devices, each input channel has a dedicated T/H amplifier. Use a low-input source impedance to minimize gainerror harmonic distortion. The time required for the T/H to acquire an input signal depends on the input source impedance. If the input signal’s source impedance is high, the acquisition time lengthens and more time must be allowed between conversions. The acquisition time (t 1 ) is the maximum time the device takes to acquire the signal. Use the following formula to calculate acquisition time: t1 = 10 (RS + RIN) x 6pF where R IN = 2.2k Ω , R S = the input signal’s source impedance, and t1 is never less than 180ns. A source impedance of less than 100Ω does not significantly affect the ADC’s performance. ______________________________________________________________________________________ 13 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 To improve the input-signal bandwidth under AC conditions, drive the input with a wideband buffer (>50MHz) that can drive the ADC’s input capacitance and settle quickly. For example, the MAX4265 can be used for +5V unipolar devices, or the MAX4350 can be used for ±5V bipolar inputs. The T/H aperture delay is typically 13ns. The aperturedelay mismatch between T/Hs of 50ps allows the relative phase information of up to eight different inputs to be preserved. Figure 2 shows a simplified equivalent input circuit, illustrating the ADC’s sampling architecture. Power-Saving Modes Shutdown Mode During shutdown, the analog and digital circuits in the device power down and the device draws less than 100µA from AVDD, and less than 100µA from DVDD. Select shutdown mode using the SHDN input. Set SHDN high to enter shutdown mode. After coming out of shutdown, allow a 1ms wake-up time before making the first conversion. When using an external clock, apply at least 20 clock cycles with CONVST high before making the first conversion. When using internal-clock mode, wait at least 2µs before making the first conversion. ALLON ALLON is useful when some of the analog input channels are selected (see the Configuration Register section). Drive ALLON high to power up all input channel circuits, regardless of whether they are selected as active by the configuration register. Drive ALLON low or connect to ground to power only the input channels selected as active by the configuration register, saving 2mA per channel (typ). The wake-up time for any channel turned on with the configuration register is 2µs (typ) when ALLON is low. The wake-up time with ALLON high is only 0.01µs. New configuration-register information does not become active until the next CONVST falling edge. Therefore, when using software to control power states (ALLON = 0), pulse CONVST low once before applying the actual CONVST signal (Figure 3). With an external clock, apply at least 15 clock cycles before the second CONVST. If using internal-clock mode, wait at least 1.5µs or until the first EOC before generating the second CONVST. Input Bandwidth The input tracking circuitry has a 12MHz small-signal bandwidth, making it is possible to digitize high-speed transient events and measure periodic signals with bandwidths exceeding the ADC’s sampling rate by using undersampling techniques. To avoid high-frequency signals being aliased into the frequency band of interest, anti-alias filtering is recommended. Input Range and Protection These devices provide ±10V, ±5V, or 0 to +5V analog input voltage ranges. Figure 2 shows the equivalent input circuit. Overvoltage protection circuitry at the analog input provides ±16.5V fault protection for the bipolar input devices and ±6.0V fault protection for the unipolar input devices. This fault-protection circuit limits the current going into or out of the device to less than 50mA, providing an added layer of protection from momentary overvoltage or undervoltage conditions at the analog input. MAX1316–MAX1318 MAX1320–MAX1322 MAX1324–MAX1326 R1 CH_ R2 CPAR 1pF Table 1. Conversion Times Using the Internal Clock NUMBER OF CHANNELS 5pF INTERNAL-CLOCK CONVERSION TIME 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 1 2 3 4 VBIAS INPUT RANGE (V) R1 (kΩ) R2 (kΩ) VBIAS (V) 0 TO +5 ±5 ±10 3.33 6.67 13.33 5.00 2.86 2.35 0.90 2.50 2.06 5 6 7 8 Figure 2. Typical Input Circuit 14 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 tACQ CONVST DUMMY CONVERSION START ACTUAL CONVERSION START tACQ SAMPLE WR LATCH DATA-IN CHANGES ONE OR MORE CHANNELS FROM POWER-DOWN TO ACTIVE MODE D0–D7 DATA-IN 1 CLK >14 CYCLES EOC 2 3 4 5 14 15 1 EOLC Figure 3. Software Channel Wake-Up Timing (ALLON = 0) Clock Modes These devices provide an internal clock of 10MHz (typ). Alternatively, an external clock can be used. MAX4265), which settles quickly and is stable with the ADC’s capacitive load (in parallel with any bypass capacitors on the analog inputs). Internal Clock Internal-clock mode frees the microprocessor from the burden of running the ADC conversion clock. For internalclock operation, connect INTCLK/EXTCLK to AVDD and connect CLK to DGND. Table 1 illustrates the total conversion time using internal-clock mode. External Clock For external-clock operation, connect INTCLK/EXTCLK to AGND and connect an external-clock source to CLK. Note that INTCLK/EXTCLK is referenced to the analog power supply, AVDD. The external-clock frequency can be up to 15MHz, with a duty cycle between 30% and 70%. Clock frequencies of 100kHz and lower can be used, but the droop in the T/H circuits reduce linearity. Applications Section Digital Interface The bidirectional, parallel, digital interface sets the 8-bit configuration register (see the Configuration Register section) and outputs the 14-bit conversion result. The interface includes the following control signals: chip select (CS), read (RD), write (WR), end of conversion (EOC), end of last conversion ( EOLC), convert start (CONVST), shutdown (SHDN), all on (ALLON), internalclock select (INTCLK /EXTCLK), and external-clock input (CLK). Figures 4, 5, 6, 7, Table 4, and the T iming Characteristics section show the operation of the interface. D0–D7 are bidirectional, and D8–D13 are output only. All bits are high impedance when RD = 1 or CS = 1. Selecting an Input Buffer Most applications require an input buffer to achieve 14bit accuracy. Although slew-rate and bandwidth are important, the most critical specification is settling time. The sampling requires a relatively brief sampling interval of 150ns. At the beginning of the acquisition, the internal sampling capacitor array connects to CH_ (the amplifier output), causing some output disturbance. Ensure the amplifier is capable of settling to at least 14bit accuracy during this interval. Use a low-noise, lowdistortion, wideband amplifier (such as the MAX4350 or Configuration Register Enable channels as active by writing to the configuration register through I/O lines D0–D7 (Table 2). The bits in the configuration register map directly to the channels, with D0 controlling channel zero, and D7 controlling channel seven. Setting any bit high activates the corresponding input channel, while resetting any bit low deactivates the corresponding channel. Devices with fewer than eight channels contain some bits that have no function. ______________________________________________________________________________________ 15 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Table 2. Configuration Register PART NO. MAX1316 MAX1320 MAX1324 MAX1317 MAX1321 MAX1325 MAX1318 MAX1322 MAX1326 STATE ON OFF ON OFF ON OFF BIT/CHANNEL D0/CH0 1 0 1 0 1 0 D1/CH1 1 0 1 0 1 0 D2/CH2 1 0 1 0 NA NA D3/CH3 1 0 1 0 NA NA D4/CH4 1 0 NA NA NA NA D5/CH5 1 0 NA NA NA NA D6/CH6 1 0 NA NA NA NA D7/CH7 1 0 NA NA NA NA NA = Not applicable. To write to the configuration register, pull CS and WR low, load bits D0–D7 onto the parallel bus, and force WR high. The data are latched on the rising edge of WR (Figure 4). It is possible to write to the configuration register at any point during the conversion sequence; however, it is not active until the next convert-start signal. At power-up, write to the configuration register to select the active channels before beginning a conversion. Shutdown does not change the configuration register. See the Shutdown Mode and the ALLON sections for information about using the configuration register for power saving. RD t2 CS t6 WR t14 D0–D7 t15 DATA-IN t5 t7 Starting a Conversion To start a conversion using internal-clock mode, pull CONVST low for at least the acquisition time (t1). The T/H acquires the signal while CONVST is low, and conversion begins on the rising edge of CONVST. An endof-conversion signal (EOC) pulses low when the first result becomes available, and for each subsequent result until the end of the conversion cycle. The end-oflast-conversion signal (EOLC) goes low when the last conversion result is available (Figures 5, 6, and 7). To start a conversion using external-clock mode, pull CONVST low for at least the acquisition time (t1). The T/H acquires the signal while CONVST is low, and conversion begins on the rising edge of CONVST. Apply an external clock to CLK. To avoid T/H droop degrading the sampled analog input signals, the first clock pulse should occur within 10µs from the rising edge of CONVST, and have a minimum clock frequency of 100kHz. The first conversion result is available for read on the rising edge of the 17th clock cycle, and subsequent conversions after every third clock cycle thereafter (Figures 5, 6, and 7). Figure 4. Write Timing In both internal- and external-clock modes, CONVST must be held high until the last conversion result is read. For best operation, the rising edge of CONVST must be a clean, high-speed, low-jitter digital signal. Table 3 shows the total throughput as a function of the clock frequency and the number of channels selected for conversion. The calculations use the nominal speed of the internal clock (10MHz) and a 200ns CONVST pulse width. 16 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges Data Throughput The data throughput (fTH) of the MAX1316–MAX1318/ MAX1320–MAX1322/MAX1324–MAX1326 is a function of the clock speed (fCLK). In internal-clock mode, fCLK = 10MHz. In external-clock mode, 100kHz ≤ f CLK ≤ 12.5MHz. When reading during conversion (Figures 5 and 6), calculate fTH as follows: 1 fTH = 16 + 3 x (N − 1) + 1 tQUIET + fCLK where N is the number of active channels and tQUIET includes acquistion time tACQ. tQUIET is the period of bus inactivity before the rising edge of CONVST. Typically use tQUIET = tACQ + 50ns, and prevent disturbance on the output bus from corrupting signal acquistion. See the Starting a Conversion section for more information. Reading a Conversion Result Reading During a Conversion Figures 5 and 6 show the interface signals for initiating a read operation during a conversion cycle. These figures show two channels selected for conversion. If more channels are selected, the results are available successively every third clock cycle. CS can be low at all times; it can be low during the RD cycles, or it can be the same as RD. After initiating a conversion by bringing CONVST high, wait for EOC to go low (about 1.6µs in internal-clock mode or 17 clock cycles in external-clock mode) before reading the first conversion result. Read the conversion result by bringing RD low, thus latching the data to the parallel digital-output bus. Bring RD high to release the digital bus. Wait for the next falling edge of EOC (about 300ns in internal-clock mode or three clock cycles in external-clock mode) before reading the next result. When the last result is available, EOLC goes low. MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Table 3. Throughput vs. Channels Sampled (tQUIET = tACQ = 200ns, fCLK = 10MHz) CHANNELS SAMPLED (N) 1 2 3 4 5 6 7 8 CLOCK CYCLES UNTIL LAST RESULT 16 19 22 25 28 31 34 37 SAMPLE t1 CONVST TRACK tCONV t12 EOC t20 RD t10 D0–D13 CH0 t11 CH1 t3 t13 HOLD tNEXT TRACK CLOCK CYCLE FOR READING LAST CONVERSION 1 1 1 1 1 1 1 1 TOTAL CONVERSION TIME (ns) 1900 2200 2500 2800 3100 3400 3700 4000 SAMPLES PER SECOND (ksps) 526 909 1200 1429 1613 1765 1892 2000 THROUGHPUT PER CHANNEL (ksps) 526 455 400 357 323 294 270 250 Figure 5. Read During Conversion—Two Channels Selected, Internal Clock ______________________________________________________________________________________ 17 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 SAMPLE tACQ CONVST TRACK t19 CLK 1 2 3 16 t16 17 t13 HOLD t17 18 19 20 t18 21 22 23 1 TRACK EOC t12 RD t10 D0–D13 CH0 t11 CH1 t3 tQUIET Figure 6. Read During Conversion—Two Channels Selected, External Clock SAMPLE tACQ t13 HOLD t19 t17 2 t16 38 39 40 t18 41 42 43 CONVST TRACK CLK 1 EOC ONLY LAST PULSE SHOWN t12 EOLC CS t8 RD t3 t4 t9 tQUIET D0–D13 CH0 t10 t11 CH1 CH2 CH3 CH4 CH5 CH6 CH7 Figure 7. Reading After Conversion—Eight Channels Selected, External Clock 18 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges Reading After Conversion Figure 7 shows the interface signals for a read operation after a conversion with all eight channels enabled. At the falling edge of EOLC, on the 38th clock pulse after the initiation of a conversion, driving CS and RD low places the first conversion result onto the parallel bus, which can be latched on the rising edge of RD. Successive low pulses of RD place the successive conversion results onto the bus. Pulse CONVST low to initiate a new conversion. Layout, Grounding, and Bypassing For best performance use PC boards with ground planes. Board layout should ensure that digital and analog signal lines are separated from each other. Do not run analog and digital lines parallel to one another (especially clock lines), or do not run digital lines underneath the ADC package. Figure 8 shows the recommended system ground connections when not using a ground plane. A single-point analog ground (star ground point) should be established at AGND, separate from the logic ground. All other analog grounds and DGND should be connected to this ground. MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Power-Up Reset At power-up, all channels are selected for conversion (see the Configuration Register section). After applying power, allow a 1.0ms wake-up time to elapse before initiating the first conversion. Then, hold CONVST high for at least 2.0µs after the wake-up time is complete. If using an external clock, apply 20 clock pulses to CLK with CONVST high before initiating the first conversion. SUPPLIES +5V RETURN OPTIONAL FERRITE BEAD +3V TO +5V RETURN Reference Internal Reference The internal-reference circuits provide for analog input voltages of 0 to +5V unipolar (MAX1316/MAX1317/ MAX1318), ±5V bipolar (MAX1320/MAX1321/MAX1322), or ±10V bipolar (MAX1324/MAX1325/MAX1326). Install external capacitors for reference stability, as indicated in Table 4, and as shown in the Typical Operating Circuits. External Reference Connect a +2.0V to +3.0V external reference at REFMS and/or REF. When connecting an external reference, the input impedance is typically 5kΩ. The external reference must be able to drive 200µA of current and have a low output impedance. For more information about using external references see the Transfer Functions section. AVDD AGND DVDD DGND VDD GND MAX1316–MAX1318 MAX1320–MAX1322 MAX1324–MAX1326 DIGITAL CIRCUITRY Figure 8. Power-Supply Grounding and Bypassing Table 4. Reference Bypass Capacitors LOCATION MSV bypass capacitor to AGND REFMS bypass capacitor to AGND REF bypass capacitor to AGND REF+ bypass capacitor to AGND REF+ to REF- capacitor REF- bypass capacitor to AGND COM bypass capacitor to AGND INPUT VOLTAGE RANGE UNIPOLAR (µF) 2.2 || 0.1 0.01 0.01 0.1 2.2 || 0.1 0.1 2.2 || 0.1 BIPOLAR (µF) NA 0.01 (connect REFMS to REF) 0.01 (connect REFMS to REF) 0.1 2.2 || 0.1 0.1 2.2 || 0.1 NA = Not applicable (connect MSV directly to AGND). ______________________________________________________________________________________ 19 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 No other digital system ground should be connected to this single-point analog ground. The ground return to the power supply for this ground should be low impedance and as short as possible for noise-free operation. High-frequency noise in the VDD power supply may affect the high-speed comparator in the ADC. Bypass these supplies to the single-point analog ground with 0.1µF and 2.2µF bypass capacitors close to the device. If the +5V power supply is very noisy, a ferrite bead can be connected as a lowpass filter, as shown in Figure 8. The input range is centered about V MSV. Normally, MSV = AGND, and the input is symmetrical about zero. For a custom midscale voltage, drive MSV with an external voltage source. Noise present on MSV directly couples into the ADC result. Use a precision, low-drift voltage reference with adequate bypassing to prevent MSV from degrading ADC performance. For maximum FSR, be careful not to violate the absolute maximum voltage ratings of the analog inputs when choosing VMSV. Determine the input voltage as a function of V REF , VMSV, and the output code in decimal using the following equation: VCH _ = LSB × CODE10 + VMSV Transfer Functions Bipolar ±10V Devices Table 5 and Figure 9 show the two’s complement transfer function for the MAX1324/MAX1325/MAX1326 with a ±10V input range. The full-scale input range (FSR) is eight times the voltage at REF. The internal +2.500V reference gives a +20V FSR, while an external +2V to +3V reference allows an FSR of +16V to +24V, respectively. Calculate the LSB size using the following equation: LSB = 8 × VREF 214 This equals 1.2207mV with a +2.5V internal reference. Bipolar ±5V Devices Table 6 and Figure 10 show the two’s complement transfer function for the MAX1320/MAX1321/MAX1322 with a ±5V input range. The FSR is four times the voltage at REF. The internal +2.500V reference gives a +10V FSR, while an external +2V to +3V reference allows an FSR of +8V to +12V, respectively. Calculate the LSB size using the following equation: LSB = 4 × VREF 214 This equals 0.6104mV when using the internal reference. Table 5. ±10V Bipolar Code Table TWO’S COMPLEMENT BINARY OUTPUT CODE DECIMAL EQUIVALENT OUTPUT (CODE10) 8191 8190 1 0 -1 -8191 -8192 INPUT VOLTAGE (V) (VREF = 2.5V, VMSV = 0V) 9.9994 ±0.5 LSB 9.9982 ±0.5 LSB 0.0018 ±0.5 LSB 0.0006 ±0.5 LSB -0.0006 ±0.5 LSB -9.9982 ±0.5 LSB -9.9994 ±0.5 LSB 8 x VREF 0x1FFF 0x1FFE 0x1FFD 0x1FFC 01 1111 1111 1111 0x1FFF 01 1111 1111 1110 0x1FFE 00 0000 0000 0001 0x0001 00 0000 0000 0000 0x0000 11 1111 1111 1111 0x3FFF 10 0000 0000 0001 0x2001 10 0000 0000 0000 0x2000 TWO'S COMPLEMENT BINARY OUTPUT CODE 0x0001 0x0000 0x3FFF 8 x VREF 0x2003 0x2002 0x2001 0x2000 -8192 -8190 -1 0 +1 (MSV) 1 LSB = 8 x VREF 214 +8189 +8191 INPUT VOLTAGE (VCH_ - VMSV IN LSBs) Figure 9. ±10V Bipolar Transfer Function 20 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Table 6. ±5V Bipolar Code Table 4 x VREF 0x1FFF 0x1FFE 0x1FFD 0x1FFC TWO'S COMPLEMENT BINARY OUTPUT CODE TWO’S COMPLEMENT BINARY OUTPUT CODE DECIMAL EQUIVALENT OUTPUT (CODE10) 8191 8190 1 0 -1 -8191 -8192 INPUT VOLTAGE (V) (VREF = 2.5V, VMSV = 0V) 4.9997 ±0.5 LSB 4.9991 ±0.5 LSB 0.0009 ±0.5 LSB 0.0003 ±0.5 LSB -0.0003 ±0.5 LSB -4.9991 ±0.5 LSB -4.9997 ±0.5 LSB 0x0001 0x0000 0x3FFF 01 1111 1111 1111 0x1FFF 4 x VREF 01 1111 1111 1110 0x1FFE 00 0000 0000 0001 0x0001 0x2003 0x2002 0x2001 0x2000 -8192 -8190 -1 0 +1 (MSV) 1 LSB = 4 x VREF 2 14 00 0000 0000 0000 0x0000 11 1111 1111 1111 0x3FFF 10 0000 0000 0001 0x2001 10 0000 0000 0000 0x2000 +8189 +8191 INPUT VOLTAGE (VCH_ - VMSV IN LSBs) Figure 10. ±5V Bipolar Transfer Function The input range is centered about V MSV. Normally, MSV = AGND, and the input is symmetrical about zero. For a custom midscale voltage, drive MSV with an external voltage source. Noise present on MSV directly couples into the ADC result. Use a precision, low-drift voltage reference with adequate bypassing to prevent MSV from degrading ADC performance. For maximum FSR, be careful not to violate the absolute maximum voltage ratings of the analog inputs when choosing V MSV . Determine the input voltage as a function of VREF, VMSV, and the output code in decimal using the following equation: VCH _ = LSB × CODE10 + VMSV Table 7. 0 to +5V Unipolar Code Table BINARY OUTPUT CODE DECIMAL EQUIVALENT OUTPUT (CODE10) 16383 16382 8193 8192 8191 1 0 INPUT VOLTAGE (V) (VREF = VREFMS = 2.5V) 4.9998 ±0.5 LSB 4.9995 ±0.5 LSB 2.5005 ±0.5 LSB 2.5002 ±0.5 LSB 2.4998 ±0.5 LSB 0.0005 ±0.5 LSB 0.0002 ±0.5 LSB 11 1111 1111 1111 0x3FFF 11 1111 1111 1110 0x3FFE 10 0000 0000 0001 0x2001 10 0000 0000 0000 0x2000 01 1111 1111 1111 0x1FFF 00 0000 0000 0001 0x0001 00 0000 0000 0000 0x0000 Unipolar 0 to +5V Devices Table 7 and Figure 11 show the offset binary transfer function for the MAX1316/MAX1317/MAX1318 with a 0 to +5V input range. The FSR is two times the voltage at REF. The internal +2.500V reference gives a +5V FSR, while an external +2V to +3V reference allows an FSR of +4V to +6V, respectively. Calculate the LSB size using the following equation: LSB = 2 × VREF 214 This equals 0.3052mV when using the internal reference. ______________________________________________________________________________________ 21 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Differential Nonlinearity 2 x VREF 0x3FFF 0x3FFE 0x3FFD 0x3FFC BINARY OUTPUT CODE Differential nonlinearity (DNL) is the difference between an actual step width and the ideal value of 1 LSB. For these devices, the DNL of each digital output code is measured and the worst-case value is reported in the Electrical Characteristics table. A DNL error specification of less than ±1 LSB guarantees no missing codes and a monotonic transfer function. 2 x VREF 0x2001 0x2000 0x1FFF Unipolar Offset Error For the unipolar MAX1316/MAX1317/MAX1318, the ideal zero-scale transition from 0x0000 to 0x0001 occurs at 1 LSB (see Figure 11). The unipolar offset error is the amount of deviation between the measured zero-scale transition point and the ideal zero-scale transition point. 0x0003 0x0002 0x0001 0x0000 0 2 8192 8190 8194 (MSV) 1 LSB = 2 x VREF 214 Bipolar Offset Error For the bipolar MAX1320/MAX1321/MAX1322/ MAX1324/MAX1325/MAX1326, the ideal zero-point transition from 0x3FFF to 0x0000 occurs at MSV, which is usually connected to ground (see Figures 9 and 10). The bipolar offset error is the amount of deviation between the measured zero-point transition and the ideal zero-point transition. 16,381 16,383 INPUT VOLTAGE (LSBs) Figure 11. 0 to +5V Unipolar Transfer Function Gain Error The input range is centered about VMSV, which is internally set to +2.500V. For a custom midscale voltage, drive REFMS with an external voltage source and MSV will follow REF MS. Noise present on MSV or REFMS directly couples into the ADC result. Use a precision, low-drift voltage reference with adequate bypassing to prevent MSV from degrading ADC performance. For maximum FSR, be careful not to violate the absolute maximum voltage ratings of the analog inputs when choosing VMSV. Determine the input voltage as a function of VREF, VMSV, and the output code in decimal using the following equation: VCH _ = LSB × CODE10 + (VMSV - 2.500V) The ideal full-scale transition from 0x1FFE to 0x1FFF occurs at 1 LSB below full scale (see the T ransfer Functions section). The gain error is the amount of deviation between the measured full-scale transition point and the ideal full-scale transition point, once offset error has been nullified. 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 where N = 14 bits. 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. Definitions Integral Nonlinearity Integral nonlinearity (INL) is the deviation of the values on an actual transfer function from a straight line. For these devices, this straight line is a line drawn between the end points of the transfer function, once offset and gain errors have been nullified. 22 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges 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: ⎡ ⎤ SignalRMS SINAD(dB) = 20 × log ⎢ ⎥ ⎣ (Noise + Distortion)RMS ⎦ Aperture Delay Aperture delay (tAD) is the time delay from the sampling clock edge to the instant when an actual sample is taken. MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Aperture Jitter Aperture Jitter (tAJ) is the sample-to-sample variation in aperture delay. Channel-to-Channel Isolation Channel-to-channel isolation indicates how well each analog input is isolated from the other channels. Channelto-channel isolation is measured by applying DC to channels 1 to 7, while a -0.5dBFS sine wave is applied to channel 0. A 100kHz FFT is taken for channel 0 and channel 1. Channel-to-channel isolation is expressed in dB as the power ratio of the two 100kHz magnitudes. Effective Number of Bits The 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 Small-Signal Bandwidth A small -20dBFS analog input signal is applied to an ADC in a manner that ensures that the signal’s slew rate does not limit the ADC’s performance. The input frequency is then swept up to the point where the amplitude of the digitized conversion result has decreased 3dB. 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 ⎢ ⎥ ⎣ ⎦ where V1 is the fundamental amplitude and V2 through V5 are the 2nd- through 5th-order harmonics. Full-Power Bandwidth A large -0.5dBFS analog input signal is applied to an ADC, and the input frequency is swept up to the point where the amplitude of the digitized conversion result has decreased by 3dB. This point is defined as fullpower input bandwidth frequency. Spurious-Free Dynamic Range 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. Chip Information TRANSISTOR COUNT: 80,000 PROCESS: BiCMOS 0.6µm ______________________________________________________________________________________ 23 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Typical Operating Circuits 13 INTCLK/EXTCLK DVDD 38 +3V 0.1µF 0.1µF 0.1µF 0.1µF 1 15 17 AVDD AVDD AVDD CS RD 6 MSV 0.01µF 0.01µF WR CONVST SHDN 18 REFMS 19 REF ALLON CLK EOC 20 REF+ EOLC 44 42 43 45 47 48 46 40 41 DIGITAL INTERFACE AND CONTROL +5V MAX1316 MAX1317 MAX1318 DGND 39 GND 2.2µF 0.1µF UNIPOLAR CONFIGURATION 0.1µF 2.2µF 0.1µF 22 REFD13 D12 2.2µF D11 21 COM 2, 3, 14, 16, 23 AGND 12 CH7 11 10 CH6 CH5 CH4 CH3 CH2 CH1 CH0 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 37 36 35 34 33 32 31 30 29 28 27 26 25 24 PARALLEL DIGITAL I/O PARALLEL DIGITAL OUTPUT 0.1µF 0.1µF GND ANALOG INPUTS 0 TO +5V MAX1316 9 8 7 MAX1317 MAX1318 5 4 24 ______________________________________________________________________________________ 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges Typical Operating Circuits (continued) MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 13 INTCLK/EXTCLK DVDD 38 +3V 0.1µF +5V 0.1µF 0.1µF 0.1µF 1 15 17 AVDD AVDD AVDD MAX1320 MAX1321 MAX1322 MAX1324 MAX1325 MAX1326 DGND CS RD WR 39 44 42 43 45 47 48 46 40 41 GND 6 BIPOLAR CONFIGURATION 0.01µF 18 19 MSV REFMS REF CONVST SHDN ALLON CLK DIGITAL INTERFACE AND CONTROL 0.1µF 20 REF+ EOC EOLC 2.2µF 0.1µF 22 REFD13 D12 2.2µF D11 21 COM 2, 3, 14, 16, 23 AGND 12 CH7 11 10 CH6 CH5 CH4 CH3 CH2 CH1 CH0 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 37 36 35 34 33 32 31 30 29 28 27 26 25 24 PARALLEL DIGITAL I/O PARALLEL DIGITAL OUTPUT 0.1µF 0.1µF GND BIPOLAR ANALOG INPUTS MAX1322 MAX1324 9 8 7 MAX1320 MAX1325 MAX1321 MAX1326 5 4 ______________________________________________________________________________________ 25 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 Pin Configurations ALLON SHDN CLK CONVST CS WR RD EOLC EOC DGND DVDD CLK CONVST CS ALLON SHDN TOP VIEW EOLC EOC DGND 41 40 39 48 47 46 45 44 43 42 41 40 39 38 37 48 47 46 45 44 43 42 38 AVDD AGND AGND CH0 CH1 MSV CH2 CH3 CH4 CH5 CH6 CH7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 36 35 34 33 32 31 30 29 28 27 26 25 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 AVDD AGND AGND CH0 CH1 MSV CH2 CH3 I.C. I.C. I.C. I.C. 37 DVDD D13 D13 WR RD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 36 35 34 33 32 31 30 29 28 27 26 25 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 MAX1316 MAX1320 MAX1324 MAX1317 MAX1321 MAX1325 INTCLK/EXTCLK AGND AVDD INTCLK/EXTCLK AGND AGND AVDD REFMS REF REF+ COM REFAGND D0 REFMS REF REF+ AVDD AGND AVDD COM REFAGND 8-CHANNEL LQFP ALLON SHDN CLK CONVST EOLC EOC DGND DVDD D13 CS WR RD 4-CHANNEL LQFP 48 47 46 45 44 43 42 41 40 39 38 AVDD AGND AGND CH0 CH1 MSV I.C. I.C. I.C. I.C. I.C. I.C. 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 36 35 34 33 32 31 30 29 28 27 26 25 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 MAX1318 MAX1322 MAX1326 INTCLK/EXTCLK AGND AVDD AGND AVDD REFMS REF REF+ COM REFAGND 2-CHANNEL LQFP Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 48 LQFP 26 PACKAGE CODE C48-6 DOCUMENT NO. 21-0054 ______________________________________________________________________________________ D0 D0 8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs with ±10V, ±5V, and 0 to +5V Analog Input Ranges Revision History REVISION NUMBER 3 4 REVISION DATE 2/07 10/08 DESCRIPTION Corrected units for input resistance in EC table Changed specs for analog and digital supply current in EC table PAGES CHANGED 3 4 MAX1316–MAX1318/MAX1320–MAX1322/MAX1324–MAX1326 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 ____________________ 27 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.