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19-2854; Rev 3; 3/09
KIT ATION EVALU BLE AVAILA
10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
General Description Features
o Internal Temperature Sensor (1C Accuracy) o 16-Entry First-In/First-Out (FIFO) o Analog Multiplexer with True Differential Track/Hold 16-, 12-, 8-Channel Single Ended 8-, 6-, 4-Channel True Differential (Unipolar or Bipolar) o Accuracy: 1 LSB INL, 1 LSB DNL, No Missing Codes Over Temperature o Scan Mode, Internal Averaging, and Internal Clock o Low-Power Single +3V Operation 1mA at 300ksps o Internal 2.5V Reference or External Differential Reference o 10MHz 3-Wire SPI/QSPI/MICROWIRE-Compatible Interface o Space-Saving 28-Pin 5mm x 5mm TQFN Package
MAX1027/MAX1029/MAX1031
The MAX1027/MAX1029/MAX1031 are serial 10-bit analog-to-digital converters (ADCs) with an internal reference and an internal temperature sensor. These devices feature on-chip FIFO, scan mode, internal clock mode, internal averaging, and AutoShutdownTM. The maximum sampling rate is 300ksps using an external clock. The MAX1031 has 16 input channels, the MAX1029 has 12 input channels, and the MAX1027 has 8 input channels. All input channels are configurable for single-ended or differential inputs in unipolar or bipolar mode. All three devices operate from a +3V supply and contain a 10MHz SPITM/QSPITM/MICROWIRETM-compatible serial port. The MAX1031 is available in 28-pin 5mm x 5mm TQFN with exposed pad and 24-pin QSOP packages. The MAX1027/MAX1029 are only available in QSOP packages. All three devices are specified over the extended -40C to +85C temperature range.
________________________Applications
System Supervision Data-Acquisition Systems Industrial Control Systems Patient Monitoring Data Logging Instrumentation
Ordering Information
PART MAX1027ACEE-T MAX1027AEEE-T TEMP RANGE 0C to +70C -40C to +85C PIN-PACKAGE 16 QSOP 16 QSOP
Ordering Information continued at end of data sheet. AutoShutdown is a trademark of Maxim Integrated Products, Inc. SPI/QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.
Pin Configurations
TOP VIEW
AIN0 1 AIN1 2 AIN2 3 AIN3 4 AIN4 5 AIN5 6 REF-/AIN6 7 CNVST/AIN7 8 16 EOC 15 DOUT 14 DIN AIN0 1 AIN1 2 AIN2 3 AIN3 4 AIN4 5 AIN5 6 AIN6 7 AIN7 8 AIN8 9 AIN9 10 20 EOC 19 DOUT 18 DIN 17 CS
MAX1027
13 CS 12 SCLK 11 VDD 10 GND 9 REF+
MAX1029
16 SCLK 15 VDD 14 GND 13 REF+ 12 CNVST/AIN11 11 REF-/AIN10
QSOP
Pin Configurations continued at end of data sheet.
QSOP
________________________________________________________________ Maxim Integrated Products
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
ABSOLUTE MAXIMUM RATINGS
VDD to GND ..............................................................-0.3V to +6V CS, SCLK, DIN, EOC, DOUT to GND.........-0.3V to (VDD + 0.3V) AIN0-AIN13, REF-/AIN_, CNVST/AIN_, REF+ to GND.........................................-0.3V to (VDD + 0.3V) Maximum Current into Any Pin............................................50mA Continuous Power Dissipation (TA = +70C) 16-Pin QSOP (derate 8.3mW/C above +70C)...........667mW 20-Pin QSOP (derate 9.1mW/C above +70C)...........727mW 24-Pin QSOP (derate 9.5mW/C above +70C)...........762mW 28-Pin TQFN 5mm x 5mm (derate 20.8mW/C above +70C) ........................1667mW Operating Temperature Ranges MAX10__C__.......................................................0C to +70C MAX10__E__ ....................................................-40C to +85C Storage Temperature Range .............................-60C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDD = +2.7V to +3.6V, fSAMPLE = 300kHz, fSCLK = 4.8MHz (50% duty cycle), VREF = 2.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER DC ACCURACY (Note 1) Resolution Integral Nonlinearity Differential Nonlinearity Offset Error Gain Error Offset Error Temperature Coefficient Gain Temperature Coefficient Channel-to-Channel Offset Matching DYNAMIC SPECIFICATIONS (10kHz sine wave input, 2.5VP-P, 300ksps, fSCLK = 4.8MHz) Signal-to-Noise Plus Distortion Total Harmonic Distortion Spurious-Free Dynamic Range Intermodulation Distortion Full-Power Bandwidth Full-Linear Bandwidth SINAD THD SFDR IMD fin1 = 9.9kHz, fin2 = 10.2kHz -3dB point S / (N + D) > 68dB Up to the 5th harmonic 70 -82 80 76 1 25 dB dBc dBc dBc MHz kHz (Note 2) RES INL DNL No missing codes over temperature 0.5 0.5 2 0.8 0.1 10 1.0 1.0 2.0 2.0 Bits LSB LSB LSB LSB ppm/C FSR ppm/C LSB SYMBOL CONDITIONS MIN TYP MAX UNITS
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +3.6V, fSAMPLE = 300kHz, fSCLK = 4.8MHz (50% duty cycle), VREF = 2.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER CONVERSION RATE Power-Up Time Acquisition Time Conversion Time External Clock Frequency SCLK Duty Cycle Aperture Delay Aperture Jitter ANALOG INPUT Input Voltage Range Input Leakage Current Input Capacitance INTERNAL TEMPERATURE SENSOR Grade A, TA = +25C Grade A, TA = -20C to +85C Measurement Error (Note 7) Grade A, TA = TMIN to TMAX Grade B, TA = +25C Grade B, TA = TMIN to TMAX Temperature Measurement Noise Temperature Resolution Power-Supply Rejection INTERNAL REFERENCE REF Output Voltage REF Temperature Coefficient Output Resistance REF Output Noise REF Power-Supply Rejection EXTERNAL REFERENCE INPUT REF- Input Voltage Range REF+ Input Voltage Range REF+ Input Current VREFVREF+ IREF+ VREF+ = 2.5V, fSAMPLE = 300ksps VREF+ = 2.5V, fSAMPLE = 0 0 1.0 40 0.1 500 VDD + 50mV 100 5 mV V A PSRR TCREF Grade A Grade B 2.48 2.50 8 30 6.5 200 -70 2.52 V ppm/C k VRMS dB 0.3 0.5 0.75 0.7 1.2 0.1 1/8 0.3 2.5 CRMS C C/V 1 1.5 C Unipolar Bipolar (Note 5) VIN = VDD During acquisition time (Note 6) 0 -VREF / 2 0.01 24 VREF VREF / 2 1 V A pF tPU tACQ tCONV fSCLK Internally clocked Externally clocked (Note 4) Externally clocked conversion Data I/O 40 30 <50 2.7 0.1 4.8 10 60 3.5 External reference Internal reference (Note 3) 0.8 65 0.6 s s s MHz % ns ps SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX1027/MAX1029/MAX1031
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +2.7V to +3.6V, fSAMPLE = 300kHz, fSCLK = 4.8MHz (50% duty cycle), VREF = 2.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Input Voltage Low Input Voltage High Input Hysteresis Input Leakage Current Input Capacitance DIGITAL OUTPUTS (DOUT, EOC) Output Voltage Low Output Voltage High Tri-State Leakage Current Tri-State Output Capacitance POWER REQUIREMENTS Supply Voltage VDD During temp sense Internal reference Supply Current (Note 8) IDD External reference Power-Supply Rejection PSR fSAMPLE = 300ksps fSAMPLE = 0, REF on Shutdown During temp sense fSAMPLE = 300ksps Shutdown VDD = 2.7V to 3.6V; full-scale input 2.7 2200 1550 1000 0.2 1550 880 0.2 0.2 3.6 2700 1800 1200 5 2000 1100 5 1 mV A V VOL VOH IL COUT ISINK = 2mA ISINK = 4mA ISOURCE = 1.5mA CS = VDD CS = VDD VDD - 0.5 0.05 15 1 0.4 0.8 V V A pF SYMBOL VIL VIH VHYST IIN CIN VIN = 0 or VDD VDD x 0.7 200 0.01 15 1.0 CONDITIONS MIN TYP MAX VDD x 0.3 UNITS V V mV A pF
DIGITAL INPUTS (SCLK, DIN, CS, CNVST)
Note 1: Note 2: Note 3: Note 4: Note 5:
Tested at VDD = +2.7V, unipolar input mode. Offset nulled. Time for reference to power up and settle to within 1 LSB. Conversion time is defined as the number of clock cycles multiplied by the clock period; clock has 50% duty cycle. The operational input voltage range for each individual input of a differentially configured pair is from GND to VDD. The operational input voltage difference is from -VREF / 2 to +VREF / 2. Note 6: See Figure 3 (Input Equivalent Circuit) and the Sampling Error vs. Source Impedance curve in the Typical Operating Characteristics section. Note 7: Fast automated test, excludes self-heating effects. Note 8: Supply current is specified depending on whether an internal or external reference is used for voltage conversions. Temperature measurements always use the internal reference.
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
TIMING CHARACTERISTICS (Figure 1)
PARAMETER SCLK Clock Period SCLK Duty Cycle SCLK Fall to DOUT Transition CS Rise to DOUT Disable CS Fall to DOUT Enable DIN to SCLK Rise Setup SCLK Rise to DIN Hold CS to SCLK Rise Setup SCLK Rise to CS Hold CNVST Pulse Width CS or CNVST Rise to EOC Low (Note 9) SYMBOL tCP tCH tDOT tDOD tDOE tDS tDH tCSS tCSH tCSW tTS tRP CKSEL = 00, CKSEL = 01 (temp sense) CKSEL = 01 (voltage conversion) Temp sense Voltage conversion Reference power-up 0 40 1.4 56 7 65 s 0 40 CLOAD = 30pF CLOAD = 30pF CLOAD = 30pF Data I/O CONDITIONS Externally clocked conversion MIN 208 100 40 60 40 40 40 40 TYP MAX UNITS ns % ns ns ns ns ns ns ns ns s
Note 9: This time is defined as the number of clock cycles needed for conversion multiplied by the clock period. If the internal reference needs to be powered up, the total time is additive. The internal reference is always used for temperature measurements.
Typical Operating Characteristics
(VDD = +3V, VREF = +2.5V, fSCLK = 4.8MHz, CLOAD = 30pF, TA = +25C, unless otherwise noted.)
INTEGRAL NONLINEARITY vs. OUTPUT CODE
MAX1027/29/31 toc01
DIFFERENTIAL NONLINEARITY vs. OUTPUT CODE
MAX1027/29/31 toc02
SINAD vs. FREQUENCY
90 80 SINAD AMPLITUDE (dB) 70 60 50 40 30 20 10 0
MAX1027/29/31 toc03
0.4 0.3 INTEGRAL NONLINEARITY (LSB) 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 0 256 512 OUTPUT CODE 768
0.4 DIFFERENTIAL NONLINEARITY (LSB) 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4
100
1024
0
256
512 OUTPUT CODE
768
1024
0.1
1
10 FREQUENCY (kHz)
100
1000
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
Typical Operating Characteristics (continued)
(VDD = +3V, VREF = +2.5V, fSCLK = 4.8MHz, CLOAD = 30pF, TA = +25C, unless otherwise noted.)
SFDR vs. FREQUENCY
MAX1027/29/31 toc04
SUPPLY CURRENT vs. SAMPLING RATE
MAX1027/29/31 toc05
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1027/29/31 toc06
120 100 SFDR AMPLITUDE (dB) 80 60 40 20 0 0.1 1 10 FREQUENCY (kHz) 100
700
700
600 SUPPLY CURRENT (A)
500
SUPPLY CURRENT (A)
650
600
400
300
550
200 1000 1 10 100 1000 SAMPLING RATE (ksps)
500 2.7 3.0 3.3 3.6 SUPPLY VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1027/29/31 toc07
SUPPLY CURRENT vs. TEMPERATURE
fS = 300ksps SUPPLY CURRENT (A) 620
MAX1027/29/31 toc08
0.5 SHUTDOWN SUPPLY CURRENT (A)
625
0.4
0.3
615
0.2
610 0.1
0 2.7 3.0 3.3 3.6 SUPPLY VOLTAGE (V)
605 -40 -15 10 35 60 85 TEMPERATURE (C)
SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
MAX1027/29/31 toc09
INTERNAL REFERENCE VOLTAGE vs. SUPPLY VOLTAGE
MAX1027/29/31 toc10
0.5 SHUTDOWN SUPPLY CURRENT (A)
2.4990 INTERNAL REFERENCE VOLTAGE (V)
0.4
2.4986
0.3
2.4982
0.2
2.4978
0.1
2.4974
0 -40 -15 10 35 60 85 TEMPERATURE (C)
2.4970 2.7 3.0 3.3 3.6 SUPPLY VOLTAGE (V)
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
Typical Operating Characteristics (continued)
(VDD = +3V, VREF = +2.5V, fSCLK = 4.8MHz, CLOAD = 30pF, TA = +25C, unless otherwise noted.)
INTERNAL REFERENCE VOLTAGE vs. TEMPERATURE
MAX1027/29/31 toc11
MAX1027/MAX1029/MAX1031
OFFSET ERROR vs. SUPPLY VOLTAGE
MAX1027/29/31 toc12
OFFSET ERROR vs. TEMPERATURE
MAX1027/29/31 toc13
2.510 INTERNAL REFERENCE VOLTAGE (V)
0.6 0.5 OFFSET ERROR (LSB) 0.4 0.3 0.2 0.1 0
0.6 0.5 OFFSET ERROR (LSB) 0.4 0.3 0.2 0.1 0
2.506
2.502
2.498
2.494
2.490 -40 -15 10 35 60 85 TEMPERATURE (C)
2.7
3.0
3.3
3.6
-40
-15
10
35
60
85
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
GAIN ERROR vs. SUPPLY VOLTAGE
MAX1027/29/31 toc14
GAIN ERROR vs. TEMPERATURE
MAX1027/29/31 toc15
0.6
0.5
0.4 GAIN ERROR (LSB)
0.4 GAIN ERROR (LSB)
0.3
0.2
0.2
0
0.1
-0.2 2.7 3.0 3.3 3.6 SUPPLY VOLTAGE (V)
0 -40 -15 10 35 60 85 TEMPERATURE (C)
TEMPERATURE SENSOR ERROR vs. TEMPERATURE
MAX1027/29/31 toc16
SAMPLING ERROR vs. SOURCE IMPEDANCE
MAX1027/29/31 toc17
1.00 TEMPERATURE SENSOR ERROR (LSB) 0.75 0.50 0.25 0 -0.25 -0.50 -0.75 -1.00 -40 -15 10 35 60 GRADE B GRADE A
1.0
SAMPLING ERROR (LSB)
0.5
0
-0.5
-1.0 85 0 2 4 6 8 10 TEMPERATURE (C) SOURCE IMPEDANCE (k)
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
Pin Description
MAX1031 TQFN 2-12, 26, 27, 28 -- -- 13 -- -- 14 -- -- 15 16 18 20 MAX1031 QSOP 1-14 -- -- 15 -- -- 16 -- -- 17 18 19 20 MAX1029 -- 1-10 -- -- 11 -- -- 12 -- 13 14 15 16 MAX1027 -- -- 1-6 -- -- 7 -- -- 8 9 10 11 12 NAME AIN0-13 AIN0-9 AIN0-5 REF-/AIN14 REF-/AIN10 REF-/AIN6 CNVST/ AIN15 CNVST/ AIN11 CNVST/ AIN7 REF+ GND VDD SCLK Analog Inputs Analog Inputs Analog Inputs Negative Input for External Differential Reference/Analog Input 14. See Table 3 for details on programming the setup register. Negative Input for External Differential Reference/Analog Input 10. See Table 3 for details on programming the setup register. Negative Input for External Differential Reference/Analog Input 6. See Table 3 for details on programming the setup register. Active-Low Conversion Start Input/Analog Input 15. See Table 3 for details on programming the setup register. Active-Low Conversion Start Input/Analog Input 11. See Table 3 for details on programming the setup register. Active-Low Conversion Start Input/Analog Input 7. See Table 3 for details on programming the setup register. Positive Reference Input. Bypass to GND with a 0.1F capacitor. Ground Power Input. Bypass to GND with a 0.1F capacitor. Serial Clock Input. Clocks data in and out of the serial interface. (Duty cycle must be 40% to 60%.) See Table 3 for details on programming the clock mode. Active-Low Chip Select Input. When CS is low, the serial interface is enabled. When CS is high, DOUT is high impedance. Serial Data Input. DIN data is latched into the serial interface on the rising edge of SCLK. Serial Data Output. Data is clocked out on the falling edge of SCLK. High impedance when CS is connected to VDD. End of Conversion Output. Data is valid after EOC pulls low. No Connection. Not internally connected. FUNCTION
21 22 23 24 1, 17, 19, 25
21 22 23 24 --
17 18 19 20 --
13 14 15 16 --
CS DIN DOUT EOC N.C.
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
CS
tCSS
tCH
tCP
tCSH
tCSH tCSS
SCLK tDH tDS
DIN tDOT tDOE DOUT tDOD
Figure 1. Detailed Serial-Interface Timing Diagram
CS DIN SCLK
SERIAL INTERFACE
DOUT
OSCILLATOR CNVST
CONTROL
EOC
AIN1 AIN2 AIN15 TEMP SENSE REFREF+ MAX1027 MAX1029 MAX1031 INTERNAL REFERENCE T/H 12-BIT SAR ADC FIFO AND ACCUMULATOR
Figure 2. Functional Diagram
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
Detailed Description
The MAX1027/MAX1029/MAX1031 are low-power, serial-output, multichannel ADCs with temperature-sensing capability for temperature-control, process-control, and monitoring applications. These 10-bit ADCs have internal track and hold (T/H) circuitry that supports singleended and fully differential inputs. Data is converted from an internal temperature sensor or analog voltage sources in a variety of channel and data-acquisition configurations. Microprocessor (P) control is made easy through a 3-wire SPI/QSPI/MICROWIRE-compatible serial interface. Figure 2 shows a simplified functional diagram of the MAX1027/MAX1029/MAX1031 internal architecture. The MAX1027 has eight single-ended analog input channels or four differential channels. The MAX1029 has 12 single-ended analog input channels or six differential channels. The MAX1031 has 16 single-ended analog input channels or eight differential channels. and set clock polarity (CPOL) and phase (CPHA) in the P control registers to the same value. The MAX1027/ MAX1029/MAX1031 operate with SCLK idling high or low, and thus operate with CPOL = CPHA = 0 or CPOL = CPHA = 1. Set CS low to latch input data at DIN on the rising edge of SCLK. Output data at DOUT is updated on the falling edge of SCLK. Bipolar true-differential results and temperature sensor results are available in two's complement format, while all others are in binary. Serial communication always begins with an 8-bit input data byte (MSB first) loaded from DIN. Send a second byte, immediately following the setup byte, to write to the unipolar mode or bipolar mode registers (see Tables 1, 3, 4, and 5). A high-to-low transition on CS initiates the data input operation. The input data byte and the subsequent data bytes are clocked from DIN into the serial interface on the rising edge of SCLK. Tables 1-7 detail the register descriptions. Bits 5 and 4, CKSEL1 and CKSEL0, respectively, control the clock modes in the setup register (see Table 3). Choose between four different clock modes for various ways to start a conversion and determine whether the acquisitions are internally or externally timed. Select clock mode 00 to configure CNVST/AIN_ to act as a conversion start and use it to request the programmed internally timed conversions without tying up the serial bus. In clock mode 01, use CNVST to request conversions one channel at a time, controlling the sampling speed without tying up the serial bus. Request and start internally timed conversions through the serial interface by writing to the conversion register in the default clock mode, 10. Use clock mode 11 with SCLK up to 4.8MHz for externally timed acquisitions to achieve sampling rates up to 300ksps. Clock mode 11 disables scanning and averaging. See Figures 4-7 for timing specifications and how to begin a conversion. These devices feature an active-low, end-of-conversion output. EOC goes low when the ADC completes the last-requested operation and is waiting for the next input data byte (for clock modes 00 and 10). For clock mode 01, EOC goes low after the ADC completes each requested operation. EOC goes high when CS or CNVST goes low. EOC is always high in clock mode 11.
Converter Operation
The MAX1027/MAX1029/MAX1031 ADCs use a fully differential, successive-approximation register (SAR) conversion technique and an on-chip T/H block to convert temperature and voltage signals into a 10-bit digital result. Both single-ended and differential configurations are supported, with a unipolar signal range for singleended mode and bipolar or unipolar ranges for differential mode.
Input Bandwidth
The ADC's input-tracking circuitry has a 1MHz smallsignal bandwidth, so it is possible to digitize highspeed transient events and measure periodic signals with bandwidths exceeding the ADC's sampling rate by using undersampling techniques. Anti-alias prefiltering of the input signals is necessary to avoid high-frequency signals aliasing into the frequency band of interest.
Analog Input Protection
Internal ESD protection diodes clamp all pins to VDD and GND, allowing the inputs to swing from (GND 0.3V) to (VDD + 0.3V) without damage. However, for accurate conversions near full scale, the inputs must not exceed VDD by more than 50mV or be lower than GND by 50mV. If an off-channel analog input voltage exceeds the supplies, limit the input current to 2mA.
Single-Ended/Differential Input
The MAX1027/MAX1029/MAX1031 use a fully differential ADC for all conversions. The analog inputs can be configured for either differential or single-ended conversions by writing to the setup register (see Table 3). Single-ended conversions are internally referenced to GND (Figure 3).
3-Wire Serial Interface
The MAX1027/MAX1029/MAX1031 feature a serial interface compatible with SPI/QSPI and MICROWIRE devices. For SPI/QSPI, ensure the CPU serial interface runs in master mode so it generates the serial clock signal. Select the SCLK frequency of 10MHz or less,
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
True Differential Analog Input T/H
AIN0-AIN15 (SINGLE ENDED); AIN0, AIN2, AIN4...AIN14 (DIFFERENTIAL) HOLD GND (SINGLE ENDED); AIN1, AIN3, AIN5...AIN15 (DIFFERENTIAL) CINREF GND CIN+ DAC
MAX1027/MAX1029/MAX1031
COMPARATOR +
HOLD VDD/2
HOLD
Figure 3. Equivalent Input Circuit
The equivalent circuit of Figure 3 shows the MAX1027/MAX1029/MAX1031s' input architecture. In track mode, a positive input capacitor is connected to AIN0-AIN15 in single-ended mode (and AIN0, AIN2, AIN4...AIN14 in differential mode). A negative input capacitor is connected to GND in single-ended mode (or AIN1, AIN3, AIN5...AIN15 in differential mode). For external track-and-hold timing, use clock mode 01. After the T/H enters hold mode, the difference between the sampled positive and negative input voltages is converted. The time required for the T/H to acquire an input signal is determined by how quickly its input capacitance is charged. If the input signal's source impedance is high, the required acquisition time lengthens. The acquisition time, tACQ, is the maximum time needed for a signal to be acquired, plus the powerup time. It is calculated by the following equation: t AQC = 9 x (RS + RIN ) x 24pF + tPWR where RIN = 1.5k, RS is the source impedance of the input signal, and tPWR = 1s, the power-up time of the device. The varying power-up times are detailed in the explanation of the clock mode conversions. tACQ is never less than 1.4s, and any source impedance below 300 does not significantly affect the ADC's AC performance. A high-impedance source can be accommodated either by lengthening tACQ or by placing a 1F capacitor between the positive and negative analog inputs.
In differential mode, the T/H samples the difference between two analog inputs, eliminating common-mode DC offsets and noise. IN+ and IN- are selected from the following pairs: AIN0/AIN1, AIN2/AIN3, AIN4/AIN5, AIN6/AIN7, AIN8/AIN9, AIN10/AIN11, AIN12/AIN13, and AIN14/AIN15. AIN0-AIN7 are available on the MAX1027, MAX1029, and MAX1031. AIN8-AIN11 are only available on the MAX1029 and MAX1031. AIN12-AIN15 are only available on the MAX1031. See Tables 2-5 for more details on configuring the inputs. For the inputs that can be configured as CNVST or an analog input, only one can be used at a time. For the inputs that can be configured as REF- or an analog input, the REF- configuration excludes the analog input.
Unipolar/Bipolar
Address the unipolar and bipolar registers through the setup register (bits 1 and 0). Program a pair of analog channels for differential operation by writing a 1 to the appropriate bit of the bipolar or unipolar register. Unipolar mode sets the differential input range from 0 to VREF. A negative differential analog input in unipolar mode causes the digital output code to be zero. Selecting bipolar mode sets the differential input range to VREF / 2. The digital output code is binary in unipolar mode and two's complement in bipolar mode (see the transfer function graphs, Figures 8 and 9). In single-ended mode, the MAX1027/MAX1029/ MAX1031 always operate in unipolar mode. The analog inputs are internally referenced to GND with a full-scale input range from 0 to VREF.
Internal FIFO
The MAX1027/MAX1029/MAX1031 contain a FIFO buffer that can hold up to 16 ADC results plus one temperature result. This allows the ADC to handle multiple internally clocked conversions and a temperature measurement, without tying up the serial bus. If the FIFO is filled and further conversions are requested without reading from the FIFO, the oldest ADC results are overwritten by the new ADC results. Each result contains 2 bytes, with the MSB preceded by four leading zeros and the LSB followed by two sub-bits. After each falling edge of CS, the oldest available byte of data is available at DOUT, MSB first. When the FIFO is empty, DOUT is zero. The first 2 bytes of data read out after a temperature measurement always contain the temperature result preceded by four leading zeros, MSB first. If another
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
temperature measurement is performed before the first temperature result is read out, the old measurement is overwritten by the new result. Temperature results are in degrees Celsius (two's complement) at a resolution of 1/8 of a degree. See the Temperature Measurements section for details on converting the digital code to a temperature. total conversion time = tcnv x navg x nresult + tTS + tRP where: tcnv = tacq(max) + tconv(max) navg = samples per result (amount of averaging) nresult = number of FIFO results requested; determined by number of channels being scanned or by NSCAN1, NSCAN0 tTS = time required for temperature measurement; set to zero if temp measurement is not requested tRP = internal reference wake-up; set to zero if the internal reference is already powered up or if the external reference is being used In clock mode 01, the total conversion time depends on how long CNVST is held low or high, including any time required to turn on the internal reference. Conversion time in externally clocked mode (CKSEL1, CKSEL0 = 11) depends on the SCLK period and how long CS is held high between each set of eight SCLK cycles.
Internal Clock
The MAX1027/MAX1029/MAX1031 operate from an internal oscillator, which is accurate within 10% of the 4.4MHz nominal clock rate. The internal oscillator is active in clock modes 00, 01, and 10. Read out the data at clock speeds up to 10MHz. See Figures 4-7 for details on timing specifications and starting a conversion.
Applications Information
Register Descriptions
The MAX1027/MAX1029/MAX1031 communicate between the internal registers and the external circuitry through the SPI/QSPI-compatible serial interface. Table 1 details the registers and the bit names. Tables 2-7 show the various functions within the conversion register, setup register, averaging register, reset register, unipolar register, and bipolar register.
Conversion Time Calculations The conversion time for each scan is based on a number of different factors: conversion time per sample, samples per result, results per scan, if a temperature measurement is requested, and if the external reference is in use.
Use the following formula to calculate the total conversion time for an internally timed conversion in clock modes 00 and 10 (see the Electrical Characteristics section as applicable):
Conversion Register Select active analog input channels, scan modes, and a single temperature measurement per scan by writing to the conversion register. Table 2 details channel selection, the four scan modes, and how to request a temperature measurement. Request a scan by writing to the conversion register when in clock mode 10 or 11, or by applying a low pulse to the CNVST pin when in clock mode 00 or 01.
A conversion is not performed if it is requested on a channel that has been configured as CNVST or REF-. Do not request conversions on channels 8-15 on the MAX1027 and channels 12-15 on the MAX1029. Set CHSEL3:CHSEL0 to the lower channel's binary value. If the last two channels are configured as a differential
Table 1. Input Data Byte (MSB First)
REGISTER NAME Conversion Setup Averaging Reset Unipolar Mode (Setup) Bipolar Mode (Setup) BIT 7 1 0 0 0 UCH0/1 BCH0/1 BIT 6 CHSEL3 1 0 0 UCH2/3 BCH1/2 BIT 5 CHSEL2 CKSEL1 1 0 UCH4/5 BCH4/5 BIT 4 CHSEL1 CKSEL0 AVGON 1 UCH6/7 BCH6/7 BIT 3 CHSEL0 REFSEL1 NAVG1 RESET UCH8/9* BCH8/9* BIT 2 SCAN1 REFSEL0 NAVG0 X BIT 1 SCAN0 DIFFSEL1 NSCAN1 X BIT 0 TEMP DIFFSEL0 NSCAN0 X
UCH10/11* UCH12/13** UCH14/15** BCH10/11* BCH12/13** BCH14/15**
*Unipolar/bipolar channels 8-15 are only valid on the MAX1029 and MAX1031. **Unipolar/bipolar channels 12-15 are only valid on the MAX1031. X = Don't care. 12 ______________________________________________________________________________________
10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
Table 2. Conversion Register*
BIT NAME -- CHSEL3 CHSEL2 CHSEL1 CHSEL0 SCAN1 SCAN0 TEMP BIT FUNCTION
pair and one of them has been reconfigured as CNVST or REF-, the pair is ignored. Select scan mode 00 or 01 to return one result per single-ended channel and one result per differential pair within the requested range, plus one temperature result if selected. Select scan mode 10 to scan a single input channel numerous times, depending on NSCAN1 and NSCAN0 in the averaging register (see Table 6). Select scan mode 11 to return only one result from a single channel.
MAX1027/MAX1029/MAX1031
7 (MSB) Set to 1 to select conversion register. 6 5 4 3 2 1 Analog input channel select. Analog input channel select. Analog input channel select. Analog input channel select. Scan mode select. Scan mode select.
Set to 1 to take a single temperature 0 (LSB) measurement. The first conversion result of a scan contains temperature information.
*See below for bit details.
CHSEL3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 CHSEL2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 CHSEL1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 CHSEL0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 SELECTED CHANNEL (N) AIN0 AIN1 AIN2 AIN3 AIN4 AIN5 AIN6 AIN7 AIN8 AIN9 AIN10 AIN11 AIN12 AIN13 AIN14 AIN15
Setup Register Write a byte to the setup register to configure the clock, reference, and power-down modes. Table 3 details the bits in the setup register. Bits 5 and 4 (CKSEL1 and CKSEL0) control the clock mode, acquisition and sampling, and the conversion start. Bits 3 and 2 (REFSEL1 and REFSEL0) control internal or external reference use. Bits 1 and 0 (DIFFSEL1 and DIFFSEL0) address the unipolar mode and bipolar mode registers and configure the analog input channels for differential operation. Unipolar/Bipolar Registers The final 2 bits (LSBs) of the setup register control the unipolar/bipolar mode address registers. Set bits 1 and 0 (DIFFSEL1 and DIFFSEL0) to 10 to write to the unipolar mode register. Set bits 1 and 0 to 11 to write to the bipolar mode register. In both cases, the setup byte must be followed immediately by 1 byte of data written to the unipolar register or bipolar register. Hold CS low and run 16 SCLK cycles before pulling CS high. If the last 2 bits of the setup register are 00 or 01, neither the unipolar mode register nor the bipolar mode register is written. Any subsequent byte is recognized as a new input data byte. See Tables 4 and 5 to program the unipolar and bipolar mode registers. If a channel is configured as both unipolar and bipolar, the unipolar setting takes precedence. In unipolar mode, AIN+ can exceed AIN- by up to VREF. The output format in unipolar mode is binary. In bipolar mode, either input can exceed the other by up to VREF / 2. The output format in bipolar mode is two's complement. Averaging Register Write to the averaging register to configure the ADC to average up to 32 samples for each requested result, and to independently control the number of results requested for single-channel scans. Table 2 details the four scan modes available in the conversion register. All four scan modes allow averaging as long as the AVGON bit, bit 4 in the averaging register, is
SCAN1 SCAN0 0 0 1 1 0 1 0 1
SCAN MODE (CHANNEL N IS SELECTED BY BITS CHSEL3-CHSEL0) Scans channels 0 through N. Scans channels N through the highest numbered channel. Scans channel N repeatedly. The averaging register sets the number of results. No scan. Converts channel N once only.
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
Table 3. Setup Register*
BIT NAME -- -- CKSEL1 CKSEL0 REFSEL1 REFSEL0 DIFFSEL1 DIFFSEL0 BIT 7 (MSB) 6 5 4 3 2 1 0 (LSB) Set to zero to select setup register. Set to 1 to select setup register. Clock mode and CNVST configuration. Resets to 1 at power-up. Clock mode and CNVST configuration. Reference mode configuration. Reference mode configuration. Unipolar/bipolar mode register configuration for differential mode. Unipolar/bipolar mode register configuration for differential mode. FUNCTION
*See below for bit details.
CKSEL1 0 0 1 1
CKSEL0 0 1 0 1
CONVERSION CLOCK Internal Internal Internal External (4.8MHz max)
ACQUISITION/SAMPLING Internally timed Externally timed through CNVST Internally timed Externally timed through SCLK
CNVST CONFIGURATION CNVST CNVST AIN15/11/7 AIN15/11/7
REFSEL1 0 0 1 1
REFSEL0 0 1 0 1
VOLTAGE REFERENCE Internal External single ended Internal External differential
AutoShutdown Reference off after scan; need wake-up delay. Reference off; no wake-up delay. Reference always on; no wake-up delay. Reference off; no wake-up delay.
REF- CONFIGURATION AIN14/10/6 AIN14/10/6 AIN14/10/6 REF-
DIFFSEL1 0 0 1 1
DIFFSEL0 0 1 0 1
FUNCTION No data follows the setup byte. Unipolar mode and bipolar mode registers remain unchanged. No data follows the setup byte. Unipolar mode and bipolar mode registers remain unchanged. One byte of data follows the setup byte and is written to the unipolar mode register. One byte of data follows the setup byte and is written to the bipolar mode register.
14
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
set to 1. Select scan mode 10 to scan the same channel multiple times. Clock mode 11 disables averaging.
Reset Register Write to the reset register (as shown in Table 7) to clear the FIFO or to reset all registers to their default states. Set the RESET bit to 1 to reset the FIFO. Set the reset bit to zero to return the MAX1027/MAX1029/MAX1031 to its default power-up state.
subtracted from the first at 68A to calculate a digital value that is proportional to absolute temperature. The output data appearing at DOUT is the above digital code minus an offset to adjust from Kelvin to Celsius. The reference voltage used for the temperature measurements is derived from the internal reference source to ensure a resolution of 1/8 of a degree.
MAX1027/MAX1029/MAX1031
Output Data Format
Figures 4-7 illustrate the conversion timing for the MAX1027/MAX1029/MAX1031. The 10-bit conversion result is output in MSB-first format with four leading zeroes and two trailing sub-bits. The 12-bit temperature measurement is output with four leading zeros. DIN data is latched into the serial interface on the rising edge of SCLK. Data on DOUT transitions on the falling edge of SCLK. Conversions in clock modes 00 and 01 are initiated by CNVST. Conversions in clock modes 10 and 11 are initiated by writing an input data byte to the conversion register. Data is binary for unipolar mode and two's complement for bipolar mode.
Power-Up Default State
The MAX1027/MAX1029/MAX1031 power up with all blocks in shutdown, including the reference. All registers power up in state 00000000, except for the setup register, which powers up in clock mode 10 (CKSEL1 = 1).
Temperature Measurements
The MAX1027/MAX1029/MAX1031 perform temperature measurements with an internal diode-connected transistor. The diode bias current changes from 68A to 4A to produce a temperature-dependent bias voltage difference. The second conversion result at 4A is
Table 4. Unipolar Mode Register (Addressed Through Setup Register)
BIT NAME UCH0/1 UCH2/3 UCH4/5 UCH6/7 UCH8/9 UCH10/11 UCH12/13 UCH14/15 BIT 7 (MSB) 6 5 4 3 2 1 0 (LSB) FUNCTION Set to 1 to configure AIN0 and AIN1 for unipolar differential conversion. Set to 1 to configure AIN2 and AIN3 for unipolar differential conversion. Set to 1 to configure AIN4 and AIN5 for unipolar differential conversion. Set to 1 to configure AIN6 and AIN7 for unipolar differential conversion. Set to 1 to configure AIN8 and AIN9 for unipolar differential conversion (MAX1029/MAX1031 only). Set to 1 to configure AIN10 and AIN11 for unipolar differential conversion (MAX1029/MAX1031 only). Set to 1 to configure AIN12 and AIN13 for unipolar differential conversion (MAX1031 only). Set to 1 to configure AIN14 and AIN15 for unipolar differential conversion (MAX1031 only).
Table 5. Bipolar Mode Register (Addressed Through Setup Register)
BIT NAME BCH0/1 BCH2/3 BCH4/5 BCH6/7 BCH8/9 BCH10/11 BCH12/13 BCH14/15 BIT 7 (MSB) 6 5 4 3 2 1 0 (LSB) FUNCTION Set to 1 to configure AIN0 and AIN1 for bipolar differential conversion. Set to 1 to configure AIN2 and AIN3 for bipolar differential conversion. Set to 1 to configure AIN4 and AIN5 for bipolar differential conversion. Set to 1 to configure AIN6 and AIN7 for bipolar differential conversion. Set to 1 to configure AIN8 and AIN9 for bipolar differential conversion (MAX1029/MAX1031 only). Set to 1 to configure AIN10 and AIN11 for bipolar differential conversion (MAX1029/MAX1031 only). Set to 1 to configure AIN12 and AIN13 for bipolar differential conversion (MAX1031 only). Set to 1 to configure AIN14 and AIN15 for bipolar differential conversion (MAX1031 only).
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
Table 6. Averaging Register*
BIT NAME -- -- -- AVGON NAVG1 NAVG0 NSCAN1 NSCAN0 BIT 7 (MSB) 6 5 4 3 2 1 0 (LSB) Set to zero to select averaging register. Set to zero to select averaging register. Set to 1 to select averaging register. Set to 1 to turn averaging on. Set to zero to turn averaging off. Configures the number of conversions for single channel scans. Configures the number of conversions for single channel scans. Single channel scan count. (Scan mode 10 only.) Single channel scan count. (Scan mode 10 only.) FUNCTION
*See below for bit details.
AVGON 0 1 1 1 1
NAVG1 x 0 0 1 1
NAVG0 x 0 1 0 1
FUNCTION Performs 1 conversion for each requested result. Performs 4 conversions and returns the average for each requested result. Performs 8 conversions and returns the average for each requested result. Performs 16 conversions and returns the average for each requested result. Performs 32 conversions and returns the average for each requested result.
NSCAN1 0 0 1 1
NSCAN0 0 1 0 1
FUNCTION (APPLIES ONLY IF SCAN MODE 10 IS SELECTED) Scans channel N and returns 4 results. Scans channel N and returns 8 results. Scans channel N and returns 12 results. Scans channel N and returns 16 results.
Table 7. Reset Register
BIT NAME -- -- -- -- RESET x x x BIT 7 (MSB) 6 5 4 3 2 1 0 (LSB) Set to zero to select reset register. Set to zero to select reset register. Set to zero to select reset register. Set to 1 to select reset register. Set to zero to reset all registers. Set to 1 to clear the FIFO only. Reserved. Don't care. Reserved. Don't care. Reserved. Don't care. FUNCTION
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
Internally Timed Acquisitions and Conversions Using CNVST
Performing Conversions in Clock Mode 00 In clock mode 00, the wake up, acquisition, conversion, and shutdown sequences are initiated through CNVST and performed automatically using the internal oscillator. Results are added to the internal FIFO to be read out later. See Figure 4 for clock mode 00 timing. Initiate a scan by setting CNVST low for at least 40ns before pulling it high again. The MAX1027/MAX1029/ MAX1031 then wake up, scan all requested channels, store the results in the FIFO, and shut down. After the scan is complete, EOC is pulled low and the results are available in the FIFO. Wait until EOC goes low before pulling CS low to communicate with the serial interface. EOC stays low until CS or CNVST is pulled low again. A temperature measurement result, if requested, precedes all other FIFO results.
Do not initiate a second CNVST before EOC goes low; otherwise, the FIFO can become corrupted.
Externally Timed Acquisitions and Internally Timed Conversions with CNVST
Performing Conversions in Clock Mode 01 In clock mode 01, conversions are requested one at a time using CNVST and performed automatically using the internal oscillator. See Figure 5 for clock mode 01 timing. Setting CNVST low begins an acquisition, wakes up the ADC, and places it in track mode. Hold CNVST low for at least 1.4s to complete the acquisition. If the internal reference needs to wake up, an additional 65s is required for the internal reference to power up. If a temperature measurement is being requested, reference power-up and temperature measurement are internally timed. In this case, hold CNVST low for at least 40ns. Set CNVST high to begin a conversion. After the conversion is complete, the ADC shuts down and pulls EOC low. EOC stays low until CS or CNVST is pulled low again. Wait until EOC goes low before pulling CS or CNVST low.
If averaging is turned on, multiple CNVST pulses need to be performed before a result is written to the FIFO. Once the proper number of conversions has been performed to generate an averaged FIFO result, as specified by the averaging register, the scan logic automatically switches the analog input multiplexer to the next-requested channel. If a temperature measurement is programmed, it is performed after the first rising edge of CNVST following the input data byte written to the conversion register. The result is available on DOUT once EOC has been pulled low.
MAX1027/MAX1029/MAX1031
CNVST (UP TO 514 INTERNALLY CLOCKED ACQUISITIONS AND CONVERSIONS) CS SCLK
DOUT MSB1 LSB1 MSB2
EOC SET CNVST LOW FOR AT LEAST 40ns TO BEGIN A CONVERSION. X = DON'T CARE.
Figure 4. Clock Mode 00
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
CNVST (CONVERSION2) (ACQUISITION1) CS (CONVERSION1) SCLK (ACQUISITION2)
DOUT MSB1 LSB1 MSB2
EOC REQUEST MULTIPLE CONVERSIONS BY SETTING CNVST LOW FOR EACH CONVERSION. X = DON'T CARE.
Figure 5. Clock Mode 01
DIN
(CONVERSION BYTE) (UP TO 514 INTERNALLY CLOCKED ACQUISITIONS AND CONVERSIONS)
CS SCLK
DOUT MSB1 LSB1 MSB2
EOC THE CONVERSION BYTE BEGINS THE ACQUISITION. CNVST IS NOT REQUIRED. X = DON'T CARE.
Figure 6. Clock Mode 10
Internally Timed Acquisitions and Conversions Using the Serial Interface
Performing Conversions in Clock Mode 10 In clock mode 10, the wake up, acquisition, conversion, and shutdown sequences are initiated by writing an input data byte to the conversion register, and are performed automatically using the internal oscillator. This is the default clock mode upon power-up. See Figure 6 for clock mode 10 timing. Initiate a scan by writing a byte to the conversion register. The MAX1027/MAX1029/MAX1031 then power up, scan all requested channels, store the results in the
18
FIFO, and shut down. After the scan is complete, EOC is pulled low and the results are available in the FIFO. If a temperature measurement is requested, the temperature result precedes all other FIFO results. EOC stays low until CS is pulled low again.
Externally Clocked Acquisitions and Conversions Using the Serial Interface
Performing Conversions in Clock Mode 11 In clock mode 11, acquisitions and conversions are initiated by writing to the conversion register and are performed one at a time using the SCLK as the conversion
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
DIN (ACQUISITION1) CS SCLK (CONVERSION BYTE) (CONVERSION1) (ACQUISITION2)
DOUT MSB1 LSB1 MSB2
EOC EXTERNALLY TIMED ACQUISITION, SAMPLING AND CONVERSION WITHOUT CNVST. X = DON'T CARE.
Figure 7. Clock Mode 11
clock. Scanning and averaging are disabled, and the conversion result is available at DOUT during the conversion. See Figure 7 for clock mode 11 timing. Initiate a conversion by writing a byte to the conversion register followed by 16 SCLK cycles. If CS is pulsed high between the eighth and ninth cycles, the pulse width must be less than 100s. To continuously convert at 16 cycles per conversion, alternate 1 byte of zeros between each conversion byte. If reference mode 00 is requested, or if an external reference is selected but a temperature measurement is being requested, wait 65s with CS high after writing the conversion byte to extend the acquisition and allow the internal reference to power up. To perform a temperature measurement, write 24 bytes (192 cycles) of zeros after the conversion byte. The temperature result appears on DOUT during the last 2 bytes of the 192 cycles.
partially through the SPI contain new values, starting at the MSB up to the point that the partial write is stopped. The part of the register that is not written contains previously written values. If CS is pulled low before EOC goes low, a conversion cannot be completed and the FIFO is corrupted.
Transfer Function
Figure 8 shows the unipolar transfer function for singleended or differential inputs. Figure 9 shows the bipolar transfer function for differential inputs. Code transitions occur halfway between successive-integer LSB values. Output coding is binary, with 1 LSB = VREF / 1024V for unipolar and bipolar operation, and 1 LSB = 0.125C for temperature measurements.
Layout, Grounding, and Bypassing
For best performance, use PC boards. Do not use wirewrap boards. For the TQFN package, connect its exposed pad to GND. Board layout should ensure that digital and analog signal lines are separated from each other. Do not run analog and digital (especially clock) signals parallel to one another or run digital lines underneath the MAX1027/MAX1029/MAX1031 package. Highfrequency noise in the VDD power supply can affect performance. Bypass the V DD supply with a 0.1F capacitor to GND, close to the VDD pin. Minimize capacitor lead lengths for best supply-noise rejection. If the power supply is very noisy, connect a 10 resistor in series with the supply to improve power-supply filtering.
Partial Reads and Partial Writes
If the first byte of an entry in the FIFO is partially read (CS is pulled high after fewer than 8 SCLK cycles), the second byte of data that is read out contains the next 8 bits (not b7-b0). The remaining bits are lost for that entry. If the first byte of an entry in the FIFO is read out fully, but the second byte is read out partially, the rest of the entry is lost. The remaining data in the FIFO is uncorrupted and can be read out normally after taking CS low again, as long as the 4 leading bits (normally zeros) are ignored. Internal registers that are written
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
OUTPUT CODE FULL-SCALE TRANSITION
OUTPUT CODE V FS = REF + VCOM 2 ZS = COM -FS = -VREF 2 V 1 LSB = REF 1024
11 . . . 111 11 . . . 110 11 . . . 101
011 . . . 111 011 . . . 110
000 . . . 010 000 . . . 001 000 . . . 000 111 . . . 111
FS = VREF + VCOM ZS = VCOM V 1 LSB = REF 1024
111 . . . 110 111 . . . 101
00 . . . 011 00 . . . 010 00 . . . 001 00 . . . 000 01 (COM) 2 3 INPUT VOLTAGE (LSB)
100 . . . 001 100 . . . 000 - FS COM* INPUT VOLTAGE (LSB) *VCOM VREF / 2 +FS - 1 LSB
FS FS - 3/2 LSB
Figure 8. Unipolar Transfer Function, Full Scale (FS) = VREF
Figure 9. Bipolar Transfer Function, Full Scale (FS) = VREF / 2
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. INL for the MAX1027/MAX1029/MAX1031 is measured using the end-point method.
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 error only and results directly from the ADC's resolution (N bits): SNR = (6.02 x N + 1.76)dB In reality, there are other noise sources besides quantization noise, including thermal noise, reference noise, clock jitter, etc. Therefore, SNR is calculated 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.
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 less than 1 LSB guarantees no missing codes and a monotonic transfer function.
Aperture Jitter
Aperture jitter (tAJ) is the sample-to-sample variation in the time between the samples.
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 other ADC output signals: SINAD (dB) = 20 x log (SignalRMS / NoiseRMS)
Aperture Delay
Aperture delay (t AD ) is the time between the rising edge of the sampling clock and the instant when an actual sample is taken.
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
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 error consists of quantization noise only. With an input range equal to the fullscale range of the ADC, calculate the effective number of bits as follows: ENOB = (SINAD - 1.76) / 6.02
Ordering Information (continued)
PART MAX1027BCEE-T MAX1027BEEE-T MAX1029ACEP-T MAX1029AEEP-T MAX1029BCEP-T MAX1029BEEP-T MAX1031ACEG-T MAX1031AEEG-T MAX1031BCEG-T MAX1031BEEG-T MAX1031BCTI-T MAX1031BETI-T TEMP RANGE 0C to +70C -40C to +85C 0C to +70C -40C to +85C 0C to +70C -40C to +85C 0C to +70C -40C to +85C 0C to +70C -40C to +85C 0C to +70C -40C to +85C PIN-PACKAGE 16 QSOP 16 QSOP 20 QSOP 20 QSOP 20 QSOP 20 QSOP 24 QSOP 24 QSOP 24 QSOP 24 QSOP 28 QFN-EP* 28 QFN-EP*
MAX1027/MAX1029/MAX1031
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: THD = 20 x log
(V
2
2
+ V32 + V42 + V52 / V1
)
where V1 is the fundamental amplitude, and V2-V5 are the amplitudes of the first five harmonics.
*EP = Exposed paddle (connect to GND).
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 distortion component.
Chip Information
TRANSISTOR COUNT: 30,889 PROCESS: BiCMOS
Pin Configurations (continued)
TOP VIEW
SCLK
AIN0 1 AIN1 2 AIN2 3 AIN3 4 AIN4 5 AIN5 6 AIN6 7 AIN7 8 AIN8 9 AIN9 10 AIN10 11 AIN11 12
24 EOC 23 DOUT 22 DIN 21 CS
21
20
19
18
VDD
17
16
REF+
15 14 CNVST/AIN15 13 REF-/AIN14 12 AIN13 11 AIN12 10 AIN11 9 8
DIN 22 DOUT 23 EOC 24 N.C. 25 AIN0 26 AIN1 27 AIN2 28
1 2 3 4 5 6 7
MAX1031
20 SCLK 19 VDD 18 GND 17 REF+ 16 CNVST/AIN15 15 REF-/AIN14
MAX1031
GND
N.C.
N.C.
CS
AIN10 AIN9
AIN3
AIN4
AIN5
AIN6
AIN7
13 AIN12
QSOP
TQFN
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AIN8
N.C.
14 AIN13
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference MAX1027/MAX1029/MAX1031
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 16 QSOP 20 QSOP 24 QSOP 28 QSOP-EP PACKAGE CODE E16-1 E20-1 E24-1 T2855-6 DOCUMENT NO. 21-0055 21-0055 21-0055 21-0140
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10-Bit 300ksps ADCs with FIFO, Temp Sensor, Internal Reference
Revision History
REVISION NUMBER 3 REVISION DATE 3/09 Fixed typo on page 1 DESCRIPTION PAGES CHANGED 1
MAX1027/MAX1029/MAX1031
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.
23 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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