MAX1166

19-2551; Rev 2; 8/08 Low-Power, 16-Bit Analog-to-Digital Converters with Parallel Interface General Description The MAX1165/MAX1166 16-bit, low-power, successiveapproximation analog-to-digital converters (ADCs) feature automatic power-down, factory-trimmed internal clock, and a 16-bit wide (MAX1165) or byte wide (MAX1166) parallel interface. The devices operate from a single +4.75V to +5.25V analog supply and a +2.7V to +5.25V digital supply. The MAX1165/MAX1166 use an internal 4.096V reference or an external reference. The MAX1165/MAX1166 consume only 1.8mA at a sampling rate of 165ksps with external reference and 2.7mA with internal reference. AutoShutdown™ reduces supply current to 0.1mA at 10ksps. The MAX1165/MAX1166 are ideal for high-performance, battery-powered, data-acquisition applications. Excellent dynamic performance and low power consumption in a small package make the MAX1165/ MAX1166 ideal for circuits with demanding power consumption and space requirements. The 16-bit wide MAX1165 is available in a 28-pin TSSOP package and the byte wide MAX1166 is available in a 20-pin TSSOP package. Both devices are available in either the 0°C to +70°C commercial, or the -40°C to +85°C extended temperature range. AutoShutdown is a trademark of Maxim Integrated Products, Inc. Features ♦ 16-Bit Wide (MAX1165) and Byte Wide (MAX1166) Parallel Interface ♦ High Speed: 165ksps Sample Rate ♦ Accurate: ±2.5 LSB INL, 16 Bit No Missing Codes ♦ 4.096V, 25ppm/°C Internal Reference ♦ External Reference Range: +3.8V to +5.25V ♦ Single +4.75V to +5.25V Analog Supply Voltage ♦ +2.7V to +5.25V Digital Supply Voltage ♦ Low Supply Current 1.8mA (External Reference) 2.7mA (Internal Reference) 0.1µA (10ksps, External Reference) ♦ Small Footprint 28-Pin TSSOP Package (16-Bit Wide) 20-Pin TSSOP Package (Byte Wide) MAX1165/MAX1166 Ordering Information PART MAX1165ACUI MAX1165BCUI MAX1165CCUI MAX1165AEUI MAX1165BEUI MAX1165CEUI TEMP RANGE 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PINPACKAGE 28 TSSOP 28 TSSOP 28 TSSOP 28 TSSOP 28 TSSOP 28 TSSOP INL ±2 ±2 ±4 ±2.5 ±2.5 ±4 Applications Temperature Sensor/Monitor Industrial Process Control I/O Boards Data-Acquisition Systems Cable/Harness Tester Accelerometer Measurements Digital Signal Processing Ordering Information continued at end of data sheet. Typical Operating Circuit +5V ANALOG +5V DIGITAL 0.1µF 0.1µF µP DATA BUS Pin Configurations and Functional Diagram appear at end of data sheet. ANALOG INPUT AIN AVDD DVDD D0–D15 MAX1165 R/C CS RESET EOC REF REFADJ AGND DGND 0.1µF 4.7µF ________________________________________________________________ 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. Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface MAX1165/MAX1166 ABSOLUTE MAXIMUM RATINGS AVDD to AGND .........................................................-0.3V to +6V DVDD to DGND ........................................-0.3V to (AVDD + 0.3V) AGND to DGND.....................................................-0.3V to +0.3V AIN, REF, REFADJ to AGND....................-0.3V to (AVDD + 0.3V) CS, HBEN, R/C, RESET to DGND ............................-0.3V to +6V Digital Output (D15–D0, EOC) to DGND ..............................................-0.3V to (DVDD + 0.3V) Maximum Continuous Current Into Any Pin ........................50mA Continuous Power Dissipation (TA = +70°C) 20-Pin TSSOP (derate 10.9mW/°C above+70°C) ........879mW 28-Pin TSSOP (derate 12.8mW/°C above +70°C) .....1026mW Operating Temperature Ranges MAX116_ _CU_ ...................................................0°C to +70°C MAX116_ _EU_ ................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (AVDD = DVDD = +5V, external reference = +4.096V, CREF = 4.7µF, CREFADJ = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER DC ACCURACY Resolution N MAX116_A TA = -40°C MAX116_B MAX116_C MAX116_A Relative Accuracy (Note 1) INL TA = 0°C MAX116_B MAX116_C MAX116_A TA = +85°C MAX116_B MAX116_C TA = -40°C No missing codes MAX116_C Differential Nonlinearity DNL TA = 0°C No missing codes MAX116_C TA = +85°C No missing codes MAX116_C Transition Noise Offset Error Gain Error Offset Drift Gain Drift DYNAMIC PERFORMANCE (fIN(SINE-WAVE) = 1kHz, VIN = 4.096VP-P, 165ksps) Signal-to-Noise Plus Distortion SINAD 86 90 dB (Note 2) RMS noise, external reference, includes quantization noise Internal reference MAX116_A MAX116_B MAX116_A MAX116_B MAX116_A MAX116_B 16 -2.5 -2.5 -4 -2 -2 -4 -2 -2 -4 -1 -1 -2 -1 -1 -2 -1 -1 -2 0.65 0.7 0.05 ±0.002 0.6 0.2 1 ±0.02 +2.5 +2.5 +4 +2 +2 +4 +2 +2 +4 +2 +2 +2 +1.5 +1.5 +2 +1 +1.5 +2 LSBRMS LSBRMS mV %FSR ppm/°C ppm/°C LSB LSB Bits SYMBOL CONDITIONS MIN TYP MAX UNITS 2 _______________________________________________________________________________________ Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface ELECTRICAL CHARACTERISTICS (continued) (AVDD = DVDD = +5V, external reference = +4.096V, CREF = 4.7µF, CREFADJ = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Signal-to-Noise Ratio Total Harmonic Distortion Spurious-Free Dynamic Range Full-Power Bandwidth Full-Linear Bandwidth CONVERSION RATE Sample Rate Aperture Delay Aperture Jitter ANALOG INPUT Input Range Input Capacitance INTERNAL REFERENCE REF Output Voltage REF Output Tempco REF Short-Circuit Current Capacitive Bypass at REFADJ Capacitive Bypass at REF REFADJ Input Leakage Current EXTERNAL REFERENCE REFADJ Buffer Disable Threshold REF Input Voltage Range REF Input Current DIGITAL INPUTS/OUTPUTS Input High Voltage Input Low Voltage Input Leakage Current Input Hysteresis Input Capacitance Output High Voltage Output Low Voltage Three-State Leakage Current VIH VIL IIN VHYST CIN VOH VOL IOZ VIH = 0 or DVDD ±0.1 0.1 15 DVDD 0.4 0.4 ±0.1 ±10 0.7 × DVDD 0.3 × DVDD ±1 V V µA V pF V V µA IREF SYMBOL SNR THD SFDR -3dB point SINAD > 81dB fSAMPLE 27 4MHz) that can drive the ADC’s input capacitance and settle quickly. Internal Clock The MAX1165/MAX1166 generate an internal conversion clock. This frees the microprocessor from the burden of running the SAR conversion clock. Total conversion time after entering hold mode (second falling edge of CS) to end of conversion (EOC) falling is 4.7µs (max). Applications Information Starting a Conversion CS and R/C control acquisition and conversion in the MAX1165/MAX1166 (Figure 2). The first falling edge of CS powers up the device and puts it in acquire mode if R/C is low. The convert start is ignored if R/C is high. The MAX1165/MAX1166 need at least 10ms (CREFADJ = 0.1µF, CREF = 4.7µF) for the internal reference to wake up and settle before starting the conversion if powering up from shutdown. The ADC can wake up, from shutdown, to an unknown state. Put the ADC in a known state by completing one “dummy” conversion. The MAX1165/MAX1166 are in a known state, ready for actual data acquisition, after the completion of the dummy conversion. A dummy conversion consists of one full conversion cycle. The MAX1165 provides an alternative reset function to reset the device (see the RESET section). _______________________________________________________________________________________ 9 Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface MAX1165/MAX1166 ACQUISITION CONVERSION DATA OUT ACQUISITION CONVERSION DATA OUT CS REF POWERDOWN BIT CS REF POWERDOWN BIT R/C R/C EOC REF AND BUFFER EOC REF AND BUFFER Figure 5. Selecting Standby Mode Figure 6. Selecting Shutdown Mode Selecting Standby or Shutdown Mode The MAX1165/MAX1166 have a selectable standby or low-power shutdown mode. In standby mode, the ADC’s internal reference and reference buffer do not power down between conversions, eliminating the need to wait for the reference to power up before performing the next conversion. Shutdown mode powers down the reference and reference buffer after completing a conversion. The reference and reference buffer require a minimum of 10ms (CREFADJ = 0.1µF, CREF = 4.7µF) to power up and settle from shutdown. The state of R/ C at the second falling edge of C S selects which power-down mode the MAX1165/ MAX1166 enter upon conversion completion. Holding R/C low causes the MAX1165/MAX1166 to enter standby mode. The reference and buffer are left on after the conversion completes. R/C high causes the MAX1165/ MAX1166 to enter shutdown mode and shut down the reference and buffer after conversion (Figures 5 and 6). When using an external reference, set the REF powerdown bit high for lowest current operation. causes the reference and buffer to wake up and enter acquisition mode. To achieve 16-bit accuracy, allow 10ms (CREFADJ = 0.1µF, CREF = 4.7µF) for the internal reference to wake up. Internal and External Reference Internal Reference The internal reference of the MAX1165/MAX1166 is internally buffered to provide +4.096V output at REF. Bypass REF to AGND and REFADJ to AGND with 4.7µF and 0.1µF, respectively. Fine adjustments can be made to the internal reference voltage by sinking or sourcing current at REFADJ. The input impedance of REFADJ is nominally 5k Ω . The internal reference voltage is adjustable to ±1.5% with the circuit of Figure 7. +5V 68kΩ 100kΩ 0.1µF 150kΩ MAX1165 MAX1166 REFADJ Standby Mode While in standby mode, the supply current is reduced to less than 1mA (typ). The next falling edge of CS with R/C low causes the MAX1165/MAX1166 to exit standby mode and begin acquisition. The reference and reference buffer remain active to allow quick turn-on time. Standby mode allows significant power savings while running at the maximum sample rate. Figure 7. MAX1165/MAX1166 Reference Adjust Circuit Shutdown Mode In shutdown mode, the reference and reference buffer are shut down between conversions. Shutdown mode reduces supply current to 0.5µA (typ) immediately after the conversion. The falling edge of CS with R/C low 10 External Reference An external reference can be placed at either the input (REFADJ) or the output (REF) of the MAX1165/ MAX1166s’ internal buffer amplifier. When connecting an ______________________________________________________________________________________ Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface external reference to REFADJ, the input impedance is typically 5kΩ. Using the buffered REFADJ input makes buffering the external reference unnecessary; however, the internal buffer output must be bypassed at REF with a 1µF capacitor. Connect REFADJ to AVDD to disable the internal buffer. Directly drive REF using an external reference. During conversion the external reference must be able to drive 100µA of DC load current and have an output impedance of 10Ω or less. REFADJ’s impedance is typically 5kΩ. The DC input impedance of REF is a minimum 40kΩ. For optimal performance, buffer the reference through an op amp and bypass REF with a 1µF capacitor. Consider the MAX1165/MAX1166s’ equivalent input noise (38µVRMS) when choosing a reference. MAX1165/MAX1166 OUTPUT CODE FULL-SCALE TRANSITION 11...111 11...110 11...101 FS = VREF 1 LSB = VREF 65536 00...011 00...010 00...001 00...000 0 1 2 3 FS INPUT VOLTAGE (LSB) FS - 3/2LSB Figure 8. MAX1165/MAX1166 Transfer Function Reading a Conversion Result EOC is provided to flag the microprocessor when a conversion is complete. The falling edge of EOC signals that the data is valid and ready to be output to the bus. D0–D15 are the parallel outputs of the MAX1165/ MAX1166. These three-state outputs allow for direct connection to a microcontroller I/O bus. The outputs remain high-impedance during acquisition and conversion. Data is loaded onto the bus with the third falling edge of CS with R/C high after tDO. Bringing CS high forces the output bus back to high impedance. The MAX1165/MAX1166 then wait for the next falling edge of CS to start the next conversion cycle (Figure 2). The MAX1165 loads the conversion result onto a 16-bit wide data bus while the MAX1166 has a byte-wide output format. HBEN toggles the output between the most/least significant byte. The least significant byte is loaded onto the output bus when HBEN is low and the most significant byte is on the bus when HBEN is high (Figure 2). plexed, the input channel should be switched immediately after acquisition, rather than near the end of or after a conversion. This allows more time for the input buffer amplifier to respond to a large step change in input signal. The input amplifier must have a high enough slew rate to complete the required output voltage change before the beginning of the acquisition time. At the beginning of acquisition, the internal sampling capacitor array connects to AIN (the amplifier output), causing some output disturbance. Ensure that the sampled voltage has settled to within the required limits before the end of the acquisition time. If the frequency of interest is low, AIN can be bypassed with a large enough capacitor to charge the internal sampling capacitor with very little ripple. However, for AC use, AIN must be driven by a wideband buffer (at least 10MHz), which must be stable with the ADC’s capacitive load (in parallel with any AIN bypass capacitor used) and also settle quickly. An example of this circuit using the MAX4434 is given in Figure 9. RESET Toggle RESET with CS high. The next falling edge of CS begins acquisition. This reset is an alternative to the dummy conversion explained in the Starting a Conversion section. MAX1165 MAX1166 AIN ANALOG INPUT 40pF 10Ω Transfer Function Figure 8 shows the MAX1165/MAX1166 output transfer function. The output is coded in standard binary. MAX4434 Input Buffer Most applications require an input buffer amplifier to achieve 16-bit accuracy. If the input signal is multiFigure 9. MAX1165/MAX1166 Fast Settling Input Buffer ______________________________________________________________________________________ 11 Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface MAX1165/MAX1166 Layout, Grounding, and Bypassing For best performance, use printed circuit boards. Do not run analog and digital lines parallel to each other, and do not lay out digital signal paths underneath the ADC package. Use separate analog and digital ground planes with only one point connecting the two ground systems (analog and digital) as close to the device as possible. Route digital signals far away from sensitive analog and reference inputs. If digital lines must cross analog lines, do so at right angles to minimize coupling digital noise onto the analog lines. If the analog and digital sections share the same supply, then isolate the digital and analog supply by connecting them with a low-value (10Ω) resistor or ferrite bead. The ADC is sensitive to high-frequency noise on the AV DD supply. Bypass AV DD to AGND with a 0.1µF capacitor in parallel with a 1µF to 10µF low-ESR capacitor with the smallest capacitor closest to the device. Keep capacitor leads short to minimize stray inductance. noise error only and results directly from the ADC’s resolution (N bits): SNR = (6.02 ✕ N + 1.76)dB where N = 16 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. 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 ⎦ Definitions Integral Nonlinearity Integral nonlinearity (INL) is the deviation of the values on an actual transfer function from a straight line. This straight line can be either a best-straight-line fit or a line drawn between the end points of the transfer function, once offset and gain errors have been nullified. The static linearity parameters for the MAX1165/MAX1166 are measured using the end-point method. Effective Number of Bits Effective number of bits (ENOB) indicates the global accuracy of an ADC at a specific input frequency and sampling rate. An ideal ADC’s error consists of quantization noise only. With an input range equal to the fullscale range of the ADC, calculate the effective number of bits as follows: ENOB = SINAD − 1.76 6.02 Differential Nonlinearity Differential nonlinearity (DNL) is the difference between an actual step width and the ideal value of 1 LSB. A DNL error specification of ±1 LSB guarantees no missing codes and a monotonic transfer function. 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. Aperture Jitter and Delay Aperture jitter is the sample-to-sample variation in the time between samples. Aperture delay is the time between the rising edge of the sampling clock and the instant when the actual sample is taken. Signal-to-Noise Ratio For a waveform perfectly reconstructed from digital samples, signal-to-noise ratio (SNR) is the ratio of the full-scale analog input (RMS value) to the RMS quantization error (residual error). The ideal, theoretical minimum analog-to-digital noise is caused by quantization 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. 12 ______________________________________________________________________________________ Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface Functional Diagram REFADJ HBEN* AVDD AGND DVDD DGND MAX1165/MAX1166 5kΩ REFERENCE OUTPUT REGISTERS REF 16 OR 8* 16 OR 8* D0–D15 OR D0/D7–D8/D15* AIN CAPACITIVE DAC AGND MAX1165 MAX1166 RESET** CLOCK CS R/C * BYTE WIDE (MAX1166 ONLY) **16-BIT WIDE (MAX1165 ONLY) SUCCESSIVEAPPROXIMATION REGISTER AND CONTROL LOGIC EOC Ordering Information (continued) PART MAX1166ACUP MAX1166BCUP MAX1166CCUP MAX1166AEUP MAX1166BEUP MAX1166CEUP TEMP RANGE 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C -40°C to +85°C PINPACKAGE 20 TSSOP 20 TSSOP 20 TSSOP 20 TSSOP 20 TSSOP 20 TSSOP INL ±2 ±2 ±4 ±2.5 ±2.5 ±4 Chip Information TRANSISTOR COUNT: 15,140 PROCESS: BiCMOS ______________________________________________________________________________________ 13 Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface MAX1165/MAX1166 Pin Configurations TOP VIEW D8 1 D9 2 D10 3 D11 4 D12 5 D13 6 D14 7 D15 8 R/C 9 EOC 10 AVDD 11 AGND 12 AIN 13 AGND 14 28 D7 27 D6 26 D5 25 D4 24 D3 D4/D12 1 D5/D13 2 D6/D14 3 D7/D15 4 R/C 5 EOC 6 AVDD 7 AGND 8 AIN 9 AGND 10 20 D3/D11 19 D2/D10 18 D1/D9 17 D0/D8 MAX1166 16 DVDD 15 DGND 14 CS 13 HBEN 12 REF 11 REFADJ MAX1165 23 D2 22 D1 21 D0 20 DVDD 19 DGND 18 CS 17 RESET 16 REF 15 REFADJ TSSOP TSSOP Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 28 TSSOP 20 TSSOP PACKAGE CODE U28-1 U20-2 DOCUMENT NO. 21-0066 21-0066 14 ______________________________________________________________________________________ Low-Power, 16-Bit Analog-to-Digital Converter with Parallel Interface Revision History REVISION NUMBER 0 1 2 REVISION DATE 7/02 2/07 8/08 Initial release Modified specifications due to inclusion of reference buffer Modified specifications for GBD at -40°C DESCRIPTION PAGES CHANGED — 1–4, 13, 15 1, 2, 3, 13 MAX1165/MAX1166 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 ____________________ 15 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.