19-2654; Rev 0; 10/02
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
General Description
The MAX1169 is a low-power, 16-bit successiveapproximation analog-to-digital converter (ADC). The device features automatic power-down, an on-chip 4MHz clock, a +4.096V internal reference, and an I2C-compatible 2-wire serial interface capable of both fast and high-speed modes. The MAX1169 operates from a single supply and consumes 5mW at the maximum conversion rate of 58.6ksps. AutoShutdown™ powers down the device between conversions, reducing supply current to less than 50µA at a 1ksps throughput rate. The option of a separate digital supply voltage allows direct interfacing with +2.7V to +5.5V digital logic. The MAX1169 performs a unipolar conversion on its single analog input using its internal 4MHz clock. The full-scale analog input range is determined by the internal reference or by an externally applied reference voltage ranging from 1V to AVDD. The four address select inputs (ADD0 to ADD3) allow up to 16 MAX1169 devices on the same bus. The MAX1169 is packaged in a 14-pin TSSOP and offers both commercial and extended temperature ranges. Refer to the MAX1069 data sheet for a 14-bit device in a pin-compatible package. I2C-Compatible
Features
o High-Speed Serial Interface 400kHz Fast Mode 1.7MHz High-Speed Mode o +4.75V to +5.25V Single Supply o +2.7V to +5.5V Adjustable Logic Level o Internal +4.096V Reference o External Reference: 1V to AVDD o Internal 4MHz Conversion Clock o 58.6ksps Sampling Rate o AutoShutdown Between Conversions o Low Power 5.0mW at 58.6ksps 4.2mW at 50ksps 2.0mW at 10ksps 0.23mW at 1ksps 3µW in Shutdown o Small 14-Pin TSSOP Package
MAX1169
Ordering Information
PART MAX1169ACUD* 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 14 TSSOP 14 TSSOP 14 TSSOP 14 TSSOP 14 TSSOP 14 TSSOP INL (LSB) ±2 ±2 ±4 ±2 ±2 ±4
Applications
Hand-Held Portable Applications Medical Instruments Battery-Powered Test Equipment Solar-Powered Remote Systems Received-Signal-Strength Indicators System Supervision
MAX1169BCUD* MAX1169CCUD MAX1169AEUD* MAX1169BEUD* MAX1169CEUD*
*Future product—contact factory for availability.
Pin Configuration
TOP VIEW
DGND 1 SCL SDA 2 3 14 ADD3 13 REF 12 REFADJ
ADD2 4 ADD1 5 ADD0 6 DVDD 7
MAX1169
11 AGNDS 10 AIN 9 8 AGND AVDD
AutoShutdown is a trademark of Maxim Integrated Products, Inc.
TSSOP
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
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 AGNDS to AGND...................................................-0.3V to +0.3V AIN, REF, REFADJ to AGND....................-0.3V to (AVDD + 0.3V) SCL, SDA, ADD_ to DGND.......................................-0.3V to +6V Maximum Current into Any Pin............................................50mA Continuous Power Dissipation (TA = +70°C) 14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW Operating Temperature Ranges MAX1169_CUD ..................................................0°C to +70°C MAX1169_EUD ................................................-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 = +4.75V to +5.25V, DVDD = +2.7V to +5.5V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER DC ACCURACY (Note 1) Resolution MAX1169A Relative Accuracy (Note 2) INL MAX1169B MAX1169C MAX1169A, no missing codes Differential Nonlinearity Offset Error Offset-Error Temperature Coefficient Gain Error Gain Temperature Coefficient DYNAMIC PERFORMANCE (fIN(sine wave) = 1kHz, VIN = VREF(P-P), fSAMPLE = 58.6ksps) Signal-to-Noise Plus Distortion Total Harmonic Distortion Spurious-Free Dynamic Range Signal-to-Noise Ratio Full-Power Bandwidth Full-Linear Bandwidth CONVERSION RATE (Figure 11) Conversion Time (SCL Stretched Low) Throughput Rate (Note 4) Internal Clock Frequency Track/Hold Acquisition Time Aperture Delay, Figure 11c (Note 6) tCONV fSAMPLE fCLK tACQ tAD (Note 5) Fast mode High-speed mode 1100 50 30 Fast mode High-speed mode Fast mode High-speed mode 4 7.1 5.8 7.5 6 19 58.6 µs ksps MHz ns ns SINAD THD SFDR SNR FPBW -3dB point SINAD > 81dB Up to the 5th harmonic 92 87 86 90 -102 105 90 4 33 -90 dB dB dB dB MHz kHz (Note 3) DNL MAX1169B, no missing codes MAX1169C 2 1.0 ±0.25 0.1 ±0.5 -1.0 16 ±2 ±2 ±4 ±1 ±1.5 ±2 5 mV ppm/°C %FSR ppm/°C LSB LSB Bits SYMBOL CONDITIONS MIN TYP MAX UNITS
2
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = +4.75V to +5.25V, DVDD = +2.7V to +5.5V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER Aperture Jitter, Figure 11c ANALOG INPUT (AIN) Input Voltage Range Input Leakage Current Input Capacitance REF Output Voltage Reference Temperature Coefficient Reference Short-Circuit Current REFADJ Output Voltage REFADJ Input Range EXTERNAL REFERENCE (REFADJ = AVDD) REFADJ Buffer Disable Voltage REFADJ Buffer Enable Voltage Reference Input Voltage Range REF Input Current IREF (Note 7) VREF = +4.096V, VIN = VREF(P-P), fIN(sine wave) = 1kHz, fSAMPLE = 58.6ksps VREF = +4.096V, shutdown DIGITAL INPUTS/OUTPUTS (SCL, SDA) Input High Voltage Input Low Voltage Input Hysteresis Input Current Input Capacitance Output Low Voltage VIH VIL VHYST IIN CIN VOL ISINK = 3mA 0.7 × DVDD 0.3 × DVDD 0.1 × DVDD 15 0.4 0.1 × DVDD ±10 0.7 × DVDD 0.3 × DVDD V V V µA pF V 1.0 27 0.1 Pull REFADJ high to disable the internal bandgap reference and reference buffer AVDD - 0.1 AVDD - 0.4 AVDD V V V µA For small adjustments, from 4.096V CIN VREF TCREF IREFSC 4.056 TA = 0°C to +70°C TA = -40°C to +85°C 4.056 VAIN On/off-leakage current, VAIN = 0 or AVDD, no clock, fSCL = 0 0 ±0.01 35 4.096 ±20 ±35 10 4.096 ±60 4.136 4.136 VREF ±10 V µA pF V ppm/°C mA V mV SYMBOL tAJ Fast mode High-speed mode CONDITIONS MIN TYP 100 100 MAX UNITS ps
MAX1169
INTERNAL REFERENCE (bypass REFADJ with 0.1µF to AGND and REF with 10µF to AGND)
ADDRESS SELECT INPUTS (ADD3, ADD2, ADD1, ADD0) Input High Voltage Input Low Voltage Input Hysteresis V V V
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3
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = +4.75V to +5.25V, DVDD = +2.7V to +5.5V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER Input Current Input Capacitance POWER REQUIREMENTS (AVDD, AGND, DVDD, DGND) Analog Supply Voltage Digital Supply Voltage AVDD DVDD Internal reference fSAMPLE = 10ksps (powered down between conversions, fSAMPLE = 1ksps R/W = 0) Shutdown Internal reference (always on, R/W = 1) fSAMPLE = 10ksps fSAMPLE = 1ksps Shutdown fSAMPLE = 58.6ksps External reference (REFADJ = AVDD) fSAMPLE = 58.6ksps Digital Supply Current IDVDD fSAMPLE = 10ksps fSAMPLE = 1ksps Shutdown Power-Supply Rejection Ratio Serial Clock Frequency Bus Free Time Between a STOP and a START Condition Hold Time for Start Condition Low Period of the SCL Clock High Period of the SCL Clock Setup Time for a Repeated START Condition (Sr) Data Hold Time Data Setup Time Rise Time of Both SDA and SCL Signals, Receiving Fall Time of SDA Transmitting Setup Time for STOP Condition Capacitive Load for Each Bus Line Pulse Width of Spike Suppressed PSRR fSCL tBUF tHD, STA tLOW tHIGH tSU, STA tHD, DAT tSU, DAT tR tF tSU, STO CB tSP (Note 10) (Note 10) (Note 9) 1.3 0.6 1.3 0.6 0.6 0 100 20 + 0.1CB 20 + 0.1CB 0.6 400 50 300 300 900 AVDD = 5V ±5%, full-scale input (Note 8) TIMING CHARACTERISTICS FOR 2-WIRE FAST MODE (Figure 1a and Figure 2) 400 kHz µs µs µs µs µs ns ns ns ns µs pF ns fSAMPLE = 10ksps fSAMPLE = 1ksps Shutdown fSAMPLE = 58.6ksps 4.75 2.7 1.8 0.7 40 0.4 1.8 1.4 1.1 0.4 0.90 0.36 40 0.4 260 65 6 0.2 5 5 16 LSB/V 5 400 µA 5 1.8 5 2.5 5.25 5.5 2.5 V V mA µA mA µA mA µA 15 SYMBOL CONDITIONS MIN TYP MAX ±10 UNITS µA pf
fSAMPLE = 58.6ksps Analog Supply Current IAVDD
4
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = +4.75V to +5.25V, DVDD = +2.7V to +5.5V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER Serial Clock Frequency Hold Time (Repeated) Start Condition Low Period of the SCL Clock High Period of the SCL Clock Setup Time for a Repeated START Condition Data Hold Time Data Setup Time Rise Time of SCL Signal (Current Source Enabled) Rise Time of SCL Signal After Acknowledge Bit Fall Time of SCL Signal Rise Time of SDA Signal Fall Time of SDA Signal Setup Time for STOP Condition Capacitive Load for Each Bus Line Pulse Width of Spike Suppressed SYMBOL fSCLH tHD, STA tLOW tHIGH tSU, STA tHD, DAT tSU, DAT tRCL tRCL1 tFCL tRDA tFDA tSU, STO CB tSP (Note 10) (Note 10) (Note 10) (Note 10) (Note 10) (Note 9) (Note 11) 160 320 120 160 0 10 10 20 20 20 20 160 400 10 80 160 80 160 160 150 CONDITIONS MIN TYP MAX 1.7 UNITS MHz ns ns ns ns ns ns ns ns ns ns ns ns pF ns
MAX1169
TIMING CHARACTERISTICS FOR 2-WIRE HIGH-SPEED MODE (Figure 1b and Figure 2)
Note 1: DC accuracy is tested at AVDD = +5.0V and DVDD = +3.0V. Performance at power-supply tolerance limits is guaranteed by power-supply rejection test. Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after the full-scale range and offset have been calibrated. Note 3: Offset nullified. Note 4: One sample is achieved every 18 clocks in continuous conversion mode:
18 clocks fSAMPLE = + t CONV fSCL
-1
Note 5: The track/hold acquisition time is two SCL cycles as illustrated in Figure 11:
1 t ACQ = 2 × fSCL
Note 6: A filter on SDA and SCL delays the sampling instant and suppresses noise spikes less than 10ns in high-speed mode and 50ns in fast mode. Note 7: ADC performance is limited by the converter’s noise floor, typically 225µVP-P. Note 8:
PSRR =
[VFS (5.25V)- VFS (4.75V)] ×
5.25V - 4.75V
2N VREF
where N is the number of bits (16).
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5
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = +4.75V to +5.25V, DVDD = +2.7V to +5.5V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) Note 9: A master device must provide a data hold time for SDA (referred to VIL of SCL) in order to bridge the undefined region of SCL’s falling edge (see Figure 1). Note 10: CB = total capacitance of one bus line in pF. tR and tF measured between 0.3 ✕ DVDD and 0.7 ✕ DVDD. Note 11: fSCL must meet the minimum clock low time plus the rise/fall times.
A. F/S-MODE I2C SERIAL INTERFACE TIMING
tR
tF
SDA tSU,DAT tLOW tHD,DAT tSU,STA tHD,STA tSU,STO tBUF
SCL tHD,STA S B. HS-MODE I2C SERIAL INTERFACE TIMING tHIGH tR tF Sr A tRDA P S tFDA
SDA tSU,DAT tLOW SCL tHD,STA tRCL S HS-MODE PARAMETERS ARE MEASURED FROM 30% TO 70%. tHD,DAT tSU,STA tHD,STA tBUF tSU,STO
tHIGH tFCL Sr A tRCL1 P S F/S-MODE
Figure 1. I2C Serial Interface Timing
VDD
IOL = 3mA
DIGITAL I/O
VOUT 400pF IOH = 0mA
Figure 2. Load Circuit 6 _______________________________________________________________________________________
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
Typical Operating Characteristics
(DVDD = +3.0V, AVDD = +5.0V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = +25°C, unless otherwise noted.)
ANALOG SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE (INTERNAL REFERENCE)
MAX1169 toc01
MAX1169
ANALOG SUPPLY CURRENT vs. ANALOG SUPPLY VOLTAGE (EXTERNAL REFERENCE)
MAX1169 toc02
ANALOG SHUTDOWN CURRENT vs. ANALOG SUPPLY VOLTAGE
DVDD = 3V fSAMPLE = 0 R/W = 0
MAX1169 toc03
1.75 DVDD = 3V 1.73 1.71 IAVDD (mA)
830 DVDD = 3V 820 810 IAVDD (µA) 800 790 780 770 760 TA = +85°C TA = +70°C TA = +25°C TA = 0°C TA = -40°C 4.75 4.85 4.95 5.05 5.15
700 600 500 IAVDD (nA) 400 300 200 100 0
1.69 1.67 1.65 1.63 4.75 4.85 4.95 5.05 5.15 5.25 AVDD (V) TA = +85°C TA = +70°C TA = +25°C TA = 0°C TA = -40°C
TA = +85°C TA = +70°C TA = +25°C TA = 0°C TA = -40°C 4.75 4.85 4.95 5.05 5.15 5.25
5.25
AVDD (V)
AVDD (V)
DIGITAL SUPPLY CURRENT vs. DIGITAL SUPPLY VOLTAGE
MAX1169 toc04
DIGITAL SHUTDOWN CURRENT vs. DIGITAL SUPPLY VOLTAGE
AVDD = 5V fSAMPLE = 0 R/W = 0
MAX1169 toc05
280 260 240 220 IDVDD (µA) 200 180 160 140 120 100 2.7 3.1 3.5 3.9 4.3 4.7 5.1 TA = -40°C TA = +85°C AVDD = 5V
350 300 250 IDVDD (nA)
TA = -40°C TA = 0°C
200 150 100 50 0
TA = +25°C TA = +70°C TA = +85°C
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
DVDD (V)
DVDD (V)
OFFSET ERROR vs. TEMPERATURE
MAX1169 toc06
GAIN ERROR vs. TEMPERATURE
0.006 GAIN ERROR (% FSR) 0.004 0.002 0 -0.002 -0.004 -0.006 -0.008 -40 -15 10 35 60 85
MAX1169 toc07
800 600 OFFSET ERROR (µV) 400 200 0 -200 -400 -600 -800 -40 -15 10 35 60
0.008
85
TEMPERATURE (°C)
TEMPERATURE (°C)
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
Typical Operating Characteristics (continued)
(DVDD = +3.0V, AVDD = +5.0V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. CONVERSION RATE (HIGH-SPEED MODE, INTERNAL REFERENCE)
MAX1169 toc08
SUPPLY CURRENT vs. CONVERSION RATE (HIGH-SPEED MODE, EXTERNAL REFERENCE)
800 SUPPLY CURRENT (µA) 700 600 500 400 300 200 100 0 IDVDD, R/W = 1 OR 0 EXTERNAL REFERENCE, fSCL = 1.7MHz
MAX1169 toc09
2000 1800 1600 SUPPLY CURRENT (µA) 1400 1200 1000 800 600 400 200 0 0 10 20 30 40 50 60 IDVDD, R/W = 1 OR 0 IAVDD, R/W = 0 INTERNAL REFERENCE, fSCL = 1.7MHz IAVDD, R/W = 1
900
IAVDD, R/W = 1 OR 0
70
0
10
20
30
40
50
60
70
CONVERSION RATE (ksps)
CONVERSION RATE (ksps)
SUPPLY CURRENT vs. CONVERSION RATE (FAST MODE, INTERNAL REFERENCE)
MAX1169 toc10
SUPPLY CURRENT vs. CONVERSION RATE (FAST MODE, EXTERNAL REFERENCE)
EXTERNAL REFERENCE, fSCL = 400kHz
MAX1169 toc11
1800 1600 SUPPLY CURRENT (µA) 1400 1200 1000 800 600 400 200 0 0
INTERNAL REFERENCE, fSCL = 400kHz IAVDD, R/W = 1
600 500 SUPPLY CURRENT (µA)
IAVDD, R/W = 1 OR 0 400 300 200 IDVDD, R/W = 1 OR 0 100 0
IAVDD, R/W = 0
IDVDD, R/W = 1 OR 0
5
10
15
20
25
0
5
10
15
20
25
CONVERSION RATE (ksps)
CONVERSION RATE (ksps)
8
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
Typical Operating Characteristics (continued)
(DVDD = +3.0V, AVDD = +5.0V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = +25°C, unless otherwise noted.)
INTERNAL REFERENCE VOLTAGE vs. REF LOAD
fSCL = 0 INTERNAL REFERENCE MODE LOAD APPLIED TO REF
MAX1169 toc13
MAX1169
INTERNAL +4.096V REFERENCE VOLTAGE vs. ANALOG SUPPLY VOLTAGE
DVDD = 3V 4.095 TA = +85°C TA = +70°C TA = +25°C 4.085 TA = 0°C
MAX1169 toc12
4.100
4.20 4.15 4.10
VREF (V)
VREF (V)
4.090
4.05 4.00 3.95
4.080 TA = -40°C 4.075 4.75 4.85 4.95 5.05 5.15 5.25 AVDD (V)
3.90 0 1 2 3 IREF (mA) 4 5 6
EXTERNAL REFERENCE CURRENT vs. EXTERNAL REFERENCE VOLTAGE
MAX1169 toc14
EXTERNAL REFERENCE CURRENT AND REFERENCE VOLTAGE vs. VREFADJ
30 AIN = AGNDS 20 10 0 -10 IREFADJ 4.20 4.15 4.10 4.05 VREF -20 -30 4.00 3.95 3.95 4.00 4.05 4.10 VREFADJ (V) 4.15 4.20 4.25 VREF (V)
MAX1169 toc15
35 AIN = AGNDS 30 25 IREF (µA) 20 15 10 5 0 0 1 2 3 VREF (V) 4 5 6 58.6ksps fSCL = 1.7MHz 19ksps fSCL = 400kHz
4.25
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IREFADJ (µA)
9
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
Typical Operating Characteristics (continued)
(DVDD = +3.0V, AVDD = +5.0V, fSCL = 1.7MHz (33% duty cycle), fSAMPLE = 58.6ksps, VREF = +4.096V, external reference applied to REF, REFADJ = AVDD, CREF = 10µF, TA = +25°C, unless otherwise noted.)
SIGNAL-TO-NOISE RATIO vs. FREQUENCY
MAX1169 toc16
SPURIOUS-FREE DYNAMIC RANGE vs. FREQUENCY
MAX1169 toc17
DIFFERENTIAL NONLINEARITY vs. DIGITAL OUTPUT CODE
1.5 1.0 DNL (LSB) 0.5 0 -0.5 -1.0 -2.0 -2.5 0 16,384 32,768 49,152 65,536
MAX1169 toc18
120 110 100 90 80 SNR (dB)
120 110 100 90 80 SFDR (dB) 70 60 50 40 30 20 10 0 1 10 FREQUENCY (kHz)
2.0
70 60 50 40 30 20 10 0 1 10 FREQUENCY (kHz) 100
100
DIGITAL OUTPUT CODE
TOTAL HARMONIC DISTORTION vs. FREQUENCY
MAX1169 toc19
SINAD vs. FREQUENCY
MAX1169 toc20
INTEGRAL NONLINEARITY vs. DIGITAL OUTPUT CODE
1.5 1.0 INL (LSB) 0.5 0 -0.5 -1.0 -1.5 -2.0
MAX1169 toc21
0 -10 -20 -30 -40 THD (dB) -50 -60 -70 -80 -90 -100 -110 -120 1 10 FREQUENCY (kHz)
120 110 100 90 80 SINAD (dB) 70 60 50 40 30 20 10 0
2.0
100
1
10 FREQUENCY (kHz)
100
0
16,384
32,768
49,152
65,536
DIGITAL OUTPUT CODE
FFT
fSAMPLE = 58.6ksps fIN(SINE WAVE) = 1kHz VIN = VREF(P-P)
MAX1169 toc22
0 -20 MAGNITUDE (dB) -40 -60 -80 -100 -120 -140 0 5.86 11.72 17.56 23.44
29.30
FREQUENCY (kHz)
10
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 NAME DGND SCL SDA ADD2 ADD1 ADD0 DVDD AVDD AGND AIN AGNDS REFADJ REF ADD3 Digital Ground Clock Input Data Input/Output Address Select Input 2 Address Select Input 1 Address Select Input 0 Digital Power Input. Bypass to DGND with a 0.1µF capacitor. Analog Power Input. Bypass to AGND with a 0.1µF capacitor. Analog Ground Analog Input Analog Signal Ground. Negative reference for analog input. Connect to AGND. Internal Reference Output and Reference Buffer Input. Bypass to AGND with a 0.1µF capacitor. Connect REFADJ to AVDD to disable the internal bandgap reference and reference-buffer amplifier. Reference Buffer Output and External Reference Input. Bypass to AGND with a 10µF capacitor when using the internal reference. Address Select Input 3 FUNCTION
MAX1169
Detailed Description
The MAX1169 ADC uses successive-approximation conversion (SAR) techniques and on-chip track-andhold (T/H) circuitry to capture and convert an analog signal to a serial 16-bit digital output. The MAX1169 performs a unipolar conversion on its single analog input using its internal 4MHz clock. The full-scale analog input range is determined by the internal reference or by an externally applied reference voltage ranging from 1V to AVDD. The flexible 2-wire serial interface provides easy connection to microcontrollers (µCs) and supports data rates up to 1.7MHz. Figure 3 shows the simplified functional diagram for the MAX1169 and Figure 4 shows the typical application circuit.
voltage ASICs. The MAX1169 wakes up in shutdown mode when power is applied irrespective of the AVDD and DVDD sequence.
Analog Input and Track/Hold
The MAX1169 analog input contains a T/H capacitor, T/H switches, comparator, and a switched capacitor digital-to-analog converter (DAC) (Figure 5). As shown in Figure 11c, the MAX1169 acquisition period is the two clock cycles prior to the conversion period. The T/H switches are normally in the hold position. During the acquisition period, the T/H switches are in the track position and CT/H charges to the analog input signal. Before a conversion begins, the T/H switches move to the hold position retaining the charge on CT/H as a sample of the analog input signal. During the conversion interval, the switched capacitive DAC adjusts to restore the comparator input voltage to zero within the limits of 16-bit resolution. This is equivalent to transferring a charge of 35pF × (VAIN - VAGNDS) from C T/H to the binary weighted capacitive DAC, forming a digital representation of the analog input signal. During the conversion period, the MAX1169 holds SCL low (clock stretching).
11
Power Supply
To maintain a low-noise environment, the MAX1169 provides separate analog and digital power-supply inputs. The analog circuitry requires a +5V supply and consumes only 900µA at sampling rates up to 58.6ksps. The digital supply voltage accepts voltages from +2.7V to +5.5V to ensure compatibility with low-
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
6 5 4 14 3 2 4MHz INTERNAL OSCILLATOR CLOCK T/H IN SAR ADC OUT REF AV = 1.0 +4.096V REFERENCE 12 REFADJ 13 REF 5kΩ MAX1169 OUTPUT SHIFT REGISTER ADD0 ADD1 ADD2 ADD3 SDA SCL
CONTROL LOGIC
AVDD AGND
8 9
7 DVDD 1 DGND
AIN AGNDS
10 11
Figure 3. MAX1169 Simplified Functional Diagram
5.0V 8 0.1µF 13 10µF 12 0.1µF ANALOG SOURCE 10 11 REFADJ AVDD MAX1169 7 DVDD 6 ADD0 5 ADD1 4 ADD2 SDA 3 2 SCL
3.0V
µC VDD
0.1µF RP RP SDA SCL
REF
AIN AGNDS AGND 9 ADD3 DGND 1 I2C ADDRESS IS 0110111. 14 VSS
Figure 4. Typical Application Circuit
The time required for the T/H to acquire an input signal is a function of the analog input source impedance. If the input signal source impedance is high, lengthen the acquisition time by reducing fSCL. The MAX1169 provides two SCL cycles (tACQ) in which the track-andhold capacitance must acquire a charge representing the input signal. Minimize the input source impedance (RSOURCE) to allow the track-and-hold capacitance to
12
charge within the allotted time. RSOURCE should be less than 11.3kΩ for fSCL = 400kHz and less than 2kΩ for fSCL = 1.7MHz. RSOURCE is calculated with the following equation: RSOURCE ≤ 2 fSCL × In(2 × 2N ) × CIN − RIN
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
where RSOURCE is the analog input source impedance, fSCL is the maximum system SCL frequency, N is 16 (the number of bits of resolution), CIN is 35pF (the sum of CT/H and input stray capacitance), and RIN is 800Ω (the T/H switch resistances). To improve the input-signal bandwidth under AC conditions, drive AIN with a wideband buffer (>4MHz) that can drive the ADC’s input capacitance and settle quickly (see the Input Buffer section). An RC filter at AIN reduces the input track-and-hold switching transient by providing charge for CT/H. data when the conversion is in progress. When the MAX1169 releases SCL, the master reads the conversion results at any clock rate up to 1.7MHz (Figure 11).
MAX1169
Digital Interface
The MAX1169 features an I2C-compatible, 2-wire serial interface consisting of a bidirectional serial data line (SDA) and a serial clock line (SCL). SDA and SCL facilitate bidirectional communication between the MAX1169 and the master at rates up to 1.7MHz. The master (typically a microcontroller) initiates data transfer on the bus and generates SCL. SDA and SCL require pullup resistors (500Ω or greater, Figure 4). Optional resistors (24Ω) in series with SDA and SCL protect the device inputs from high-voltage spikes on the bus lines. Series resistors also minimize crosstalk and undershoot of the bus signals. Bit Transfer One data bit is transferred during each SCL clock cycle. Nine clock cycles are required to transfer the data into or out of the MAX1169. The data on SDA must remain stable during the high period of the SCL clock pulse as changes in SDA while SCL is high are control signals (see the START and STOP Conditions section). Both SDA and SCL idle high. START and STOP Conditions The master initiates a transmission with a START condition (S), a high-to-low transition on SDA with SCL high. The master terminates a transmission with a STOP condition (P), a low-to-high transition on SDA while SCL is high (Figure 7). The STOP condition frees the bus and places all devices in F/S mode (see the Bus Timing section). Use a repeated START condition (Sr) in place of a STOP condition to leave the bus active and in its current timing mode (see the HS Mode section).
Analog Input Bandwidth
The MAX1169 features input-tracking circuitry with a 4MHz small-signal bandwidth. The 4MHz input bandwidth makes it possible to digitize high-speed transient events and measure periodic signals with bandwidths exceeding the ADC’s sampling rate by using undersampling techniques. Use anti-alias filtering to avoid high-frequency signals being aliased into the frequency band of interest.
Analog Input Range and Protection
Internal electrostatic discharge (ESD) protection diodes clamp AIN, REF, and REFADJ to AVDD and AGNDS/ AGND (Figure 6). These diodes allow the analog inputs to swing from (AGND - 0.3V) to (AVDD + 0.3V) without causing damage to the device. For accurate conversions, the inputs must not go more than 50mV beyond their rails. If the analog inputs exceed 300mV beyond their rails, limit the current to 2mA.
Internal Clock
The MAX1169 contains an internal 4MHz oscillator that drives the SAR conversion clock. During conversion, SCL is held low (clock stretching). An internal register stores
*RSOURCE
HOLD AIN TRACK CT/H
REF MAX1169 CAPACITIVE DAC
AVDD AIN MAX1169 REF REFADJ AGNDS AGND
TRACK
ANALOG SIGNAL SOURCE
HOLD TRACK
AGNDS
*MINIMIZE RSOURCE TO ALLOW THE TRACK-AND-HOLD CAPACITANCE (CT/H) TO CHARGE TO THE ANALOG SIGNAL SOURCE VOLTAGE WITHIN THE ALLOTTED TIME (tACQ).
HOLD
Figure 5. Equivalent Input Circuit
Figure 6. Internal Protection Diodes 13
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
S SDA Sr P
SCL
Figure 7. START and STOP Conditions
S SDA
NOT ACKNOWLEDGE
ACKNOWLEDGE SCL 1 2 8 9
Figure 8. Acknowledge Bits
Acknowledge Bits Successful data transfers are acknowledged with an acknowledge bit (A) or a not-acknowledge bit (A). Both the master and the MAX1169 (slave) generate acknowledge bits. To generate an acknowledge, the receiving device must pull SDA low before the rising edge of the acknowledge-related clock pulse (ninth pulse) and keep it low during the high period of the clock pulse (Figure 8). To generate a not acknowledge, the receiver allows SDA to be pulled high before the rising edge of the acknowledge-related clock pulse and leaves it high during the high period of the clock pulse. Monitoring the acknowledge bits allows for detection of unsuccessful data transfers. An unsuccessful data transfer happens if a receiving device is busy or if a system fault has occurred. In the event of an unsuccessful data transfer, the master should reattempt communication at a later time. Slave Address A master initiates communication with a slave device by issuing a START condition followed by a slave address byte. As shown in Figure 9, the slave address byte consists of 7 address bits and a read/write bit (R/W). When idle, the MAX1169 continuously waits for a START condition followed by its slave address. When the MAX1169 recognizes its slave address, it acquires the analog input signal and prepares for conversion. The first 3 bits (MSBs) of the slave address have been factory programmed and are always 0 11 . Connecting
ADD3–ADD0 to DVDD or DGND, programs the last 4 bits (LSBs) of the slave address high or low. Since the MAX1169 does not require setup or configuration, the least significant bit (LSB) of the address byte (R/W) controls power-down. In external reference mode (REFADJ = AVDD), R/W is a don’t care. In internal reference mode, setting R/W = 1 places the device in normal operation and setting R/W = 0 powers down the internal reference following the conversion (see the Internal Reference Shutdown section). After receiving the address, the MAX1169 (slave) issues an acknowledge by pulling SDA low for one clock cycle. Bus Timing At power-up, the MAX1169 bus timing defaults to fast mode (F/S mode), allowing conversion rates up to 19ksps. The MAX1169 must operate in high-speed mode (HS mode) to achieve conversion rates up to 58.6ksps. Figure 1 shows the bus timing for the MAX1169 2-wire interface. HS Mode At power-up, the MAX1169 bus timing is set for F/S mode. The master selects HS mode by addressing all devices on the bus with the HS mode master code 0000 1XXX (X = don’t care). After successfully receiving the HS mode master code, the MAX1169 issues a not acknowledge, allowing SDA to be pulled high for one clock cycle (Figure 10). After the not acknowledge, the
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
S SDA 0 1 1 ADD3 ADD2 ADD1 ADD0 R/W ACKNOWLEDGE SCL 1 2 3 4 5 6 7 8 9 A
Figure 9. MAX1169 Slave Address Byte
S SDA 0 0 0 0 1 X X X A
Sr
1
2
3
4
5
6
7
8
9
F/S MODE
HS MODE
Figure 10. F/S-Mode to HS-Mode Transfer
MAX1169 is in HS mode. The master must then send a repeated START followed by a slave address to initiate HS mode communication. If the master generates a STOP condition, the MAX1169 returns to F/S mode. Data Byte (Read Cycle) Initiate a read cycle to begin a conversion. A read cycle begins with the master issuing a START condition followed by 7 address bits and 1 read bit (R/W). The standard I2C-compatible interface requires that R/W = 1 to read from a device; however, since the MAX1169 does not require setup or configuration, the read mode is inherent and R/ W controls power-down (see the Internal Reference Shutdown section). If the address byte is successfully received, the MAX1169 (slave) issues an acknowledge and begins conversion. As seen in Figure 11, the MAX1169 holds SCL low during conversion. When the conversion is complete, SCL is released and the master can clock data out of the device. The most significant byte of the conversion is available first and contains D15 to D8. The least significant byte contains D7 to D0. Data can be continuously converted as long as the master acknowledges the conversion results. Issuing a not acknowledge frees the bus, allowing the master to generate a STOP or repeated START.
Applications Information
Power-On Reset
When power is first applied, internal power-on reset circuitry activates the MAX1169 in shutdown. When the internal reference is used, allow 12ms for the reference to settle when CREF = 10µF and CREFADJ = 0.1µF.
Automatic Shutdown
The MAX1169 automatic shutdown reduces the supply current to less than 0.6µA between conversions. The MAX1169 I2C-compatible interface is always active. When the MAX1169 receives a valid slave address, the device powers up. The device is then powered down again when the conversion is complete. The automatic shutdown function does not change with internal or external reference. When the internal reference is chosen, the internal reference remains active between conversions unless internal reference shutdown is requested (see the Internal Reference Shutdown section).
Internal Reference Shutdown
The R/W bit of the slave address controls the MAX1169 internal reference shutdown. In external reference mode (REFADJ = AVDD), R/W is a don’t care. In internal reference mode, setting R/W = 1 places the device in normal operation and setting R/W = 0 prepares the internal reference for shutdown.
15
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
MASTER TO SLAVE SLAVE TO MASTER A. SINGLE CONVERSION 1 S 7 SLAVE ADDRESS 11 RA CLOCK STRETCH 8 RESULT 1 A 8 RESULT 1 1 NUMBER OF BITS
A P OR Sr
(MOST SIGNIFICANT BYTE) (LEAST SIGNIFICANT BYTE) tACQ tCONV
B. CONTINUOUS CONVERSIONS 1 7 S SLAVE ADDRESS
11 RA CLOCK STRETCH
8 RESULT #1
1 A
8 RESULT #1
1 A CLOCK STRETCH
8 RESULT #2 (MOST SIGNIFICANT BYTE) tCONV
1 A
NUMBER OF BITS
(MOST SIGNIFICANT BYTE) (LEAST SIGNIFICANT BYTE) tACQ tCONV tACQ
8 RESULT #2 (LEAST SIGNIFICANT BIT) tACQ C. ACQUISITION DETAIL
1 A CLOCK STRETCH
8 RESULT #N
1 A
8 RESULT #N
1
1
NUMBER OF BITS
A P OR Sr
(MOST SIGNIFICANT BYTE) (LEAST SIGNIFICANT BYTE) tCONV
SDA
BIT3
BIT2
BIT1
BIT0
A
D15
D14
D13
D12
SCL
5
6
7
8
9
CLOCK STRETCH tAJ tAD
1
2
3
4
tACQ
tCONV
ANALOG INPUT TRACK AND HOLD
HOLD
TRACK
HOLD
Figure 11. Read Cycle
If the internal reference is used and R/W = 0, shutdown occurs when the master issues a not-acknowledge bit while reading the conversion results. The internal reference and internal reference buffer are disabled during shutdown, reducing the analog supply current to less than 1µA. A dummy conversion is required to power up the internal reference. The MAX1169 internal reference begins
powering up from shutdown on the 9th falling edge of a valid address byte. Allow 12ms for the internal reference to settle before obtaining valid conversion results.
Reference Voltage
The MAX1169 provides an internal or accepts an external reference voltage. The ADC input range is from VAGNDS to VREF. (See the Transfer Function section.)
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
Internal Reference
The MAX1169 contains an internal 4.096V bandgap reference. This bandgap reference is connected to REFADJ through a 5kΩ resistor. Bypass REFADJ with a 0.1µF capacitor to AGND. The MAX1169 reference buffer has a unity gain to provide +4.096V at REF. Bypass REF with a 10µF capacitor to AGND when the internal reference is used (Figure 12). The internal reference is adjustable to ±1.5% using the circuit of Figure 13.
4.096V SAR REF ADC AV = 1.0 REFADJ 12 MAX1169 5kΩ 4.096V BANDGAP REFERENCE DGND 1 AGND 9 0.1µF REF 13 10µF
MAX1169
External Reference
For external reference operation, disable the internal reference by connecting REFADJ to AVDD. During conversion, an external reference at REF must deliver up to 100µA of DC load current and have an output impedance of less than 10Ω. For optimal performance, buffer the reference through an op amp and bypass REF with a 10µF capacitor. Consider the MAX1169 ’ s equivalent input noise (38µVRMS) when choosing a reference.
Figure 12. Internal Reference
Transfer Function
The MAX1169 has a standard unipolar transfer function with a valid analog input voltage range from VAGNDS to V REF . Output data coding is binary with 1LSB = (VREF/2N) where N is the number of bits (16). Code transitions occur halfway between successive-integer
LSB values. Figure 14 shows the MAX1169 input/output (I/O) transfer function.
Input Buffer
Most applications require an input buffer amplifier to achieve 16-bit accuracy. If the input signal is multiplexed, the input channel should be switched immediately after acquisition, rather than near the end of or
5.0V AVDD MAX1169 8 0.1µF
4.096V SAR REF ADC AV = 1.0
REF 13 10µF
REFADJ 12 5kΩ 4.096V BANDGAP REFERENCE DGND 1 AGND 9
68kΩ 0.1µF
100kΩ POTENTIOMETER
150kΩ
Figure 13. Adjusting the Internal Reference ______________________________________________________________________________________ 17
58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
VREF
1...111 1...110 1...101 1...100 V 1LSB = REF 65536
BINARY OUTPUT CODE (LSB)
grounds to the star analog ground. Connect the digital grounds to the star digital ground. Connect the digital ground plane to the analog ground plane at one point. For lowest noise operation, make the ground return to the star ground’s power supply low impedance and as short as possible. High-frequency noise in the AV DD power supply degrades the ADC’s high-speed comparator performance. Bypass AVDD to AGND with a 0.1µF ceramic surface-mount capacitor. Make bypass capacitor connections as short as possible. If the power supply is very noisy, connect a 10Ω resistor in series with AVDD and a 4.7µF capacitor from AVDD to AGND to create a lowpass RC filter.
0...011 0...010 0...001 0...000
VREF
0123 INPUT VOLTAGE (LSB)
65533 65535
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 MAX1169 INL is measured using the end-point method.
AGNDS
Figure 14. Unipolar Transfer Function
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 4MHz), which must be stable with the ADC ’ s capacitive load (in parallel with any AIN bypass capacitor used) and also settle quickly. Refer to Maxim’s website at www.maxim-ic.com for application notes on how to choose the optimum buffer amplifier for your ADC application.
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 (Figure 11).
Aperture Delay
Aperture delay (tAD) is the time from the falling edge of SCL to the instant when an actual sample is taken (Figure 11).
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital samples, signal-to-noise ratio (SNR) is the ratio of full-scale analog input (RMS value) to the RMS quantization error (residual error). The ideal, theoretical minimum analogto-digital noise is caused by quantization error only and results directly from the ADC’s resolution (N bits): SNR = ((6.02 ✕ N) + 1.76) dB In reality, noise sources besides quantization noise exist, including thermal noise, reference noise, clock jitter, etc. Therefore, 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.
Layout, Grounding, and Bypassing
Careful printed circuit (PC) board layout is essential for the best system performance. Boards should have separate analog and digital ground planes and ensure that digital and analog signals are separated from each other. Do not run analog and digital (especially clock) lines parallel to one another, or digital lines underneath the device package. Figure 4 shows the recommended system ground connections. Establish an analog ground point at AGND and a digital ground point at DGND. Connect all analog
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP
Signal-to-Noise Plus Distortion
Signal-to-noise plus distortion (SINAD) is the ratio of the fundamental input frequency’s RMS amplitude to RMS equivalent of all other ADC output signals: SignalRMS SINAD(db) = 20 × log NoiseRMS
MAX1169
V 2 + V32 + V42 + V52 = 20 × log 2 THD V1
where V1 is the fundamental amplitude, and V2 through V5 are the amplitudes of the 2nd- through 5th-order harmonics.
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 ADC’s full-scale range, calculate the ENOB as follows: SINAD - 1.76 ENOB = 6.02
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of RMS amplitude of the fundamental (maximum signal component) to the RMS value of the next-largest distortion component.
Chip Information
TRANSISTOR COUNT: 18,269 PROCESS: BiCMOS
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the RMS sum of the input signal’s first five harmonics to the fundamental itself, expressed as:
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58.6ksps, 16-Bit, 2-Wire Serial ADC in a 14-Pin TSSOP MAX1169
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
TSSOP4.40mm.EPS
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.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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