MAX132CWG+ ,±18-Bit ADC with Serial InterfaceMAX13219-0009; Rev 2; 8/95±18-Bit ADC w ith Serial Interface_______________
MAX132CWG+T ,±18-Bit ADC with Serial InterfaceApplicationsMAX132C/D 0°C to +70°C Dice*Remote Data AcquisitionMAX132ENG -40°C to +85°C 24 Narrow P ..
MAX132ENG ,18-Bit ADC with Serial InterfaceFeaturesThe MAX132 is a CMOS, 18-bit plus sign, serial-output,' Low Supply Current:analog-to-digita ..
MAX132EWG ,18-Bit ADC with Serial InterfaceMAX13219-0009; Rev 2; 8/95±18-Bit ADC with Serial Interface_______________
MAX132EWG ,18-Bit ADC with Serial InterfaceGeneral Description ________
MAX132EWG+ ,±18-Bit ADC with Serial InterfaceGeneral Description ________
MAX3967AETG+T ,270Mbps SFP LED DriverELECTRICAL CHARACTERISTICS(Load as specified in Figure 1; V = +2.97V to +5.5V (at the V pins); V V ..
MAX3969ETP ,200Mbps SFP Limiting AmplifierApplicationsMAX3969E/D** — Dice* —SFP/SFF Transceivers*Dice are designed to operate over a -40°C to ..
MAX396CAI+ ,Precision, 16-Channel/Dual 8-Channel, Low-Voltage, CMOS Analog MultiplexersFeaturesThe MAX396/MAX397 low-voltage, CMOS analog ● Pin-Compatible with MAX306/MAX307, DG406/DG4 ..
MAX396CPI ,Precision, 16-Channel/Dual 8-Channel, Low-Voltage, CMOS Analog MultiplexersFeaturesThe MAX396/MAX397 low-voltage, CMOS analog multi- ' Pin Compatible with MAX306/MAX307,plexe ..
MAX396CQI ,Precision, 16-Channel/Dual 8-Channel, Low-Voltage, CMOS Analog MultiplexersFeaturesThe MAX396/MAX397 low-voltage, CMOS analog multi- ' Pin Compatible with MAX306/MAX307,plexe ..
MAX396CWI ,Precision, 16-Channel/Dual 8-Channel, Low-Voltage, CMOS Analog MultiplexersFeaturesThe MAX396/MAX397 low-voltage, CMOS analog multi- ' Pin Compatible with MAX306/MAX307,plexe ..
MAX132CNG+-MAX132CWG+-MAX132CWG+T-MAX132EWG+-MAX132EWG+T
±18-Bit ADC with Serial Interface
_______________General DescriptionThe MAX132 is a CMOS, 18-bit plus sign, serial-output,
analog-to-digital converter (ADC). Multi-slope integra-
tion provides high-resolution conversions in less time
than standard integrating ADCs, allowing operation up
to 100 conversions per second. Low conversion noise
provides guaranteed operation with ±512mV full-scale
input range (2μV/LSB). A simple 4-wire serial interface
connects easily to all common microprocessors, and
twos-complement output coding simplifies bipolar mea-
surements. Typical supply current is only 60μA and is
reduced to 1μA in sleep mode. Four serially pro-
grammed digital outputs can be used to control an
external multiplexer or programmable-gain amplifier.
The MAX132 comes in 24-pin narrow DIP and wide SO
packages, and is available in commercial and extend-
ed temperature grades.
High resolution, compact size, and low power make this
device ideal for data loggers, weigh scales, data-acqui-
sition systems, and panel meters.
________________________ApplicationsRemote Data Acquisition
Battery-Powered Instruments
Industrial Process Control
Transducer-Signal Measurement
Pressure, Flow, Temperature, Voltage
Current, Resistance, Weight
____________________________FeatureLow Supply Current:
60μA (Normal Operation)
1μA (Sleep-Mode Operation)±0.006% FSR Accuracy at 16 Conv/secLow Noise: 15μVRMSSerial I/O Interface with Programmed Output for
Mux and PGAPerforms up to 100 Conv/sec±2pA Input Current50Hz/60Hz Rejection18-Bit ADC with Serial InterfacBUF OUT
INT OUT
INT INSCLK
DOUT
DIN
TOP VIEW
CREF-
CREF+
REF+
REF-P1
OSC1
OSC2
AGND
IN LO
IN HIDGND
EOC
DIP/SOMAX132
__________________Pin ConfigurationMAX132
CREF-CREF+602k
SCLK
DOUT
DIN
EOC
-5V
±512mV INPUT
BUF OUT
INT OUT
INT IN4.7nF
REF+
REF-
AGND
IN LO
IN HI
DGND
OSC2OSC1
+5V
________________Functional Diagram19-0009; Rev 2; 8/95
PARTMAX132CNG
MAX132CWG
MAX132C/D0°C to +70°C
0°C to +70°C
0°C to +70°C
TEMP. RANGEPIN-PACKAGE24 Narrow Plastic DIP
24 Wide SO
Dice*
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
______________Ordering Information* Contact factory for dice specifications.
** Contact factory for availability and processing to MIL-STD-883.
MAX132ENG
MAX132EWG
MAX132MRG-55°C to +125°C
-40°C to +85°C
-40°C to +85°C24 Narrow Plastic DIP
24 Wide SO
24 Narrow CERDIP**
18-Bit ADC with Serial InterfaceABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(V+ = 5V, V- = -5V, DGND = AGND = IN LO = REF- = 0V, REF+ = 545mV, RINT= 602kΩ, CINT= 0.0047μF, CREF= 0.1μF,
fCLK= 32,768Hz, 60Hz mode, TA= TMINto TMAX, unless otherwise noted.)
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.
Supply Voltage
V+ to DGND..............................................-0.3V < V+ < +6.0V
V- to DGND................................................+0.3V < V- < -9.0V
V+ to V-............................................................................+15V
Analog Input Voltage (any input).....................................V+ to V-
Digital Input Voltage .....................(DGND - 0.3V) to (V+ + 0.3V)
Continuous Power Dissipation
Narrow Plastic DIP (derate 8.70mW/°C above +70°C)....478mW
Wide SO (derate 11.76mW/°C above +70°C)..............647mW
Narrow CERDIP (derate 12.50mW/°C above +70°C)..688mW
Operating Temperature Ranges
MAX132C_ _.......................................................0°C to +70°C
MAX132E_ _....................................................-40°C to +85°C
MAX132MRG.................................................-55°C to +125°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
Bits±18Resolution
UNITSMINTYPMAXPARAMETER(Note 1)
CONDITIONSVINHI = 0V% of FSR±0.0168±0.0076Zero Error
fCLK= 32.768Hz
(Note 4)63
±0.032Rollover Error
(Notes 2, 3)
% of FSR0±0.010
% of FSR±0.0015±0.006Integral Nonlinearity
IN HI = IN LOV±3.0
Input Voltage Range
Common-Mode Range
(Note 3)ppm/°C±5Scale Factor Temp. Coefficient
(Note 3)ppm/°C±0.15±1.515RMS Noise
Zero-Reading Drift±512
Conversion Time
VINHI = 400mV, V- = -5.0V,
4.5V ≤V+ ≤5.5V±0.003±0.0168% of FSR±0.003±0.0061Positive Supply Rejection
Digital input = 0V or V+
Digital input = 0V or V+110-25-60Digital Ground Supply Current
Positive Sleep-Mode Current
Digital input = 0V or V+
Digital input = 0V or V+-35-6560125Positive Supply Current
Negative Supply Current
Digital input = 0V or V+μA-1-10Negative Sleep-Mode Current-5.5-4.54.55.5Positive Supply Voltage
Negative Supply Voltage= +25°C= TMINto TMAX= +25°C= +25°C= TMINto TMAX
IN HI to IN LO, for specified accuracy
% of FSR±0.25±0.50Common-Mode Rejection RatioIN HI = IN LO±0.009±0.032VCM= ±500mV
VCM= ±3.0V±12±250Leakage CurrentIN HI, IN LO±2±10TA= +25°C= TMINto TMAX= +25°C= TMINto TMAX= TMINto TMAX= +25°CVINHI = 400mV, V- = 5.0V,
-5.5V ≤V- ≤-4.5V±0.003±0.0168% of FSR±0.003±0.0061Negative Supply Rejection
Digital input = 0V or V+μA0±2Digital Ground Sleep-Mode
Current= +25°C
% of FSR±3.1Read-Zero 50Hz/60Hz Range
ACCURACY
POWER REQUIREMENTS
18-Bit ADC with Serial InterfacELECTRICAL CHARACTERISTICS (continued)(V+ = 5V, V- = -5V, DGND = AGND = IN LO = REF- = 0V, REF+ = 545mV, RINT= 602kΩ, CINT= 0.0047μF, CREF= 0.1μF,
fCLK= 32,768Hz, 60Hz mode, TA= TMINto TMAX, unless otherwise noted.)
INTERFACE TIMING(Test Circuit of Figure 1, Figure 2, V+ = 5V, V- = -5V, DGND = AGND = 0V, TA= +25°C, unless otherwise noted.) (Note 3)
Note 1:±18-bit accuracy achieved by averaging multiple conversions.
Note 2:Maximum deviation from best straight-line fit.
Note 3:Guaranteed by design, not tested.
Note 4:Difference in reading for equal positive and negative inputs near full scale.
DOUT, IOUT= -100μA
DOUT, IOUT= -1mA
CS, DIN, SCLK, and DOUT when three-stated
CS, DIN, SCLK, and DOUT when three-stated
Referred to DGND, 4.5V ≤V+ ≤5.5V, CS, DIN, SCLK
EOC, P0–P3, IOUT= -100μA
DOUT, IOUT= 1.6mA
EOC, P0–P3, IOUT= 100μA
Referred to DGND, 4.5V ≤V+ ≤5.5V, CS, DIN, SCLK
CONDITIONS3.54.35CINInput Capacitance±10±500IINInput Current0.8VILInput Low
VOHOutput High
0.10.4V0.10.4VOLOutput Low2.4VIHInput High
UNITSMINTYPMAXSYMBOLPARAMETER
CONDITIONS500t1CSLead Time1t5CSHigh Pulse Width300t4SCLKLow Time400t3SCLKHigh Time400t2CSLag Time
UNITSMINTYPMAXSYMBOLPARAMETERSee Figure 4
See Figure 30t6DIN to SCLK Setup Time320t10DOUT Disable Time to Three-State60t9Data Valid320t8DOUT Access Time from Three-State200t7DIN to SCLK Hold Time230350t12Delay to P0–P3 Low230350t11Delay to P0–P3 High
DIGITAL SECTION
18-Bit ADC with Serial Interface__________________________________________Typical Operating CharacteristicsERROR vs. COMMON-MODE
INPUT VOLTAGE (VIN LO–AGND)
AX132-01
COMMON-MODE VOLTAGE (V)-2-101234-4
(%
IN HI = IN LO0.51.5
50Hz/60Hz READ-ZERO OFFSET
vs. VREFAX132-02
VREF (V)
(%
60Hz MODE
50Hz MODE
50Hz/60Hz READ-ZERO OFFSET
vs. TEMPERATURE
MAX132-03
TEMPERATURE (°C)406080100
(%
60Hz MODE, VREF = 545mV
50Hz MODE, VREF = 655mV
SUPPLY CURRENT
vs. CRYSTAL FREQUENCY
MAX132-04
CRYSTAL FREQUENCY (kHz)
(m
FULL-SCALE ROLLOVER ERROR
vs. VREF
AX132-05
VREF (V)0.51.01.52.52.0
NOISE vs. NUMBER
OF SAMPLES AVERAGEDAX132-06
NUMBER OF SAMPLES AVERAGED1020305040
______________________________________________________________Pin DescriptionOscillator Output 2 is normally connected to a 32,768Hz crystal. Do not connect with external clock source.OSC25
Serial Clock Input. On SCLK’s rising edge, data is shifted into the internal shift register through DIN. On
SCLK’s falling edge, data is clocked out of DOUT.SCLK4
Serial Data Out, D7 first bit out. Data is clocked out at the falling edge of SCLK. High impedance when CSis high.DOUT3
User-programmable output bit 1—programmed through the serial port.P18
User-programmable output bit 0—programmed through the serial port.P07
Oscillator Input 1 is normally connected to a 32,768Hz crystal, or may be connected to an external clock.OSC16
Serial Data In, D7 first bit in. Data is clocked into the register on the rising edge of SCLK.DIN2
PINCHIP SELECTInput has 3 functions: 1) When low, selects IC for communication; 2) on rising edge, loads
input shift register data into one of the command registers; 3) on falling edge, loads data from one of the
output registers into the output shift register. When CSis high, DOUT is high impedance.1
FUNCTIONNAME
18-Bit ADC with Serial InterfacMAX132
CREF-CREF+602kSCLKDOUTDINEOCP0P1P2P3
-5V
512mV INPUT5
15pF15pF
BUF OUT
INT OUT
INT IN4.7nF
32,768Hz
REF+
REF-
AGND
IN LOIN HIV+
DGND
OSC2OSC1
0.1mF
120k
100k
40.2k
2.5VMAX872
+5V
Figure 1. Test and Typical Application Circuit
_________________________________________________Pin Description (continued)End of Conversion Output goes high at end of conversion.EOC11
Positive Supply, nominally +5VV+24
User-programmable output bit 3—programmed through the serial port.P310
Negative Reference Capacitor connectionCREF-20
Positive Reference Capacitor connectionCREF+19
Positive Reference InputREF+18
Negative Reference InputREF-17
Analog GroundAGND16
Negative Analog InputIN LO15
Buffer-Amplifier Output drives the integrator resistor.BUF OUT23
User-programmable output bit 2—programmed through the serial port.P29
PINIntegrator Output. To minimize noise, this pin should drive the capacitor’s outside foil (negative end).INT OUT22
Integrator Input. Connect the integration capacitor between INT IN and INT OUT.INT IN21
FUNCTIONNAMEPositive Analog InputIN HI14
Negative Supply, nominally -5VV-13
Digital Ground—power-supply returnDGND12
____________Functional DescriptionThe MAX132 integrates the input voltage for a fixed
period of time, then deintegrates a known reference
voltage and measures the time required to reach zero.
Good line rejection is achieved by setting the (input)
integration time equal to one 50Hz or 60Hz period. The
MAX132 has a 50Hz/60Hz mode selection bit that sets
the integration time to 655/545 clock periods, respec-
tively, so that 50Hz/60Hz rejection is obtained with a
32,768Hz crystal. The MAX132 is tested and guaran-
teed at a 16 conv/sec throughput rate. Figure 1 shows
the basic MAX132 application circuit, with component
values selected for 16 conv/sec .
For applications that don’t require 50Hz/60Hz rejection,
the MAX132 will operate up to 100 conv/sec at reduced
accuracy (typically 0.012% FSR nonlinearity, or ±13
bits). In these applications, the 50Hz mode is recom-
mended because of its longer (655 count) integration
time. See Increased Speedsection.
__________Analog Design Procedure
Input Voltage Rangeand Input ProtectionThe recommended analog full-scale input range is512mV. Performance is tested and guaranteed at
±512mV full scale, corresponding to a 2μV/LSB resolu-
tion at 18 bits. Resolution is defined as follows:
which corresponds to 2μV/LSB resolution at 18 bits.
Consult the Typical Operating Characteristicsfor Noise
vs. Number of Samples Averaged and other important
operating parameters. Note how accuracy depends on
common-mode input voltage (common mode is defined
here as |VINLO - AGND|). For optimum performance,
set the analog input full-scale between ±470mV and
18-Bit ADC with Serial Interface / () / ,solutionVoltsLSBVFSIN[]=262144
DOUTDOUT
a. High-Z to VOH (t8)b. High-Z to VOL (t8)
DGNDDGND
+5VCL
Figure 3. Load Circuits for Access Time
DOUTDOUT
a. VOH to High-Z (t10)b. VOL to High-Z (t10)
DGNDDGND
+5V
10pF10pF
Figure 4. Load Circuits for Disable Time to Three-State
DINt4t1t10
t11, t12
SCLK
DOUT
P0–P3
MSB INB6–B1LSB IN
LSB OUTB6–B1MSB OUT
Figure 2. Serial-Mode Timing
18-Bit ADC with Serial Interfac±660mV for 60Hz mode operation or between ±390mV
and ±550mV for 50Hz mode operation. The pseudo-
differential input voltage is applied across pins 14 and
15 (IN HI, IN LO), and can range to within 2V of either
supply rail.
The inputs IN HI and IN LO lead directly to CMOS tran-
sistor gates, yielding extremely high input impedances
that are useful when converting signals from a high
input source impedance, such as a sensor. Input cur-
rents are only 2pA typical at +25°C. Figure 6 shows an
RC filter at the input to optimize noise performance.
Fault protection is accomplished by the 100kΩseries
resistance. Internal protection diodes, which clamp the
analog inputs from V+ to V-, allow the channel input
pins to swing from (V- - 0.3V) to (V+ + 0.3V) without
damage. However, if the analog input voltage at the
pins IN HI or IN LO exceed the supplies, limit the cur-
rent into the device to less than 1mA, as excessive cur-
rent will damage the device.
Reference Voltage Selection The reference voltage sets the analog input voltage
range. For the nominal ±512mV full-scale input range, a
545mV reference voltage is used for the 60Hz mode
and a 655mV reference voltage is used in the 50Hz mode.
The reference voltage can be calculated as follows:
The recommended reference voltage range is 500mV
to 700mV. The MAX132 is tested with the nominal
545mV reference voltage in 60Hz mode. Use amplifiers
or attenuators (resistor dividers) to scale other full-scale
input signal ranges to the recommended ±512mV full-
scale range.
References outside the recommended range may be
used with a degradation of linearity. A reference volt-
age from 200mV to 500mV will result in a lower signal-
to-noise ratio; a reference voltage from 700mV to 2V will
increase the rollover error.
The MAX872 2.50V reference, with its 10μA supply cur-
rent, is ideally suited for the MAX132. Figure 7 shows
how 2.50V can be divided to obtain the desired refer-
ence voltage. The reference input accepts voltages
anywhere within the converter’s power-supply range;
however, for best performance, neither REF+ nor REF-
should come within 2V of the supplies.
MAX132
IN LO
AGND
IN HI
DE+
DE+
REF+CREF+CREFREF-CREF-INT ININT OUT
INTEGRATOR
COMPARATOR 1
COMPARATOR 2
DE-
BUFFER
8pF
64pF
Z1+ x 8
CINTRINT
BUFFER
DE-
TO
DIGITAL
SECTION
INT
REST
INT
INTDE
Figure 5. Analog Section Block Diagram
262144ModeV
countsVModeVcountsV
REFFS
REFFS: ) () : ( ) () )))
18-Bit ADC with Serial InterfaceDifferential Reference Inputs
and Rollover ErrorThe main source of rollover voltage error is due to
common-mode voltages. This error is caused by the
reference capacitor losing or gaining charge to stray
capacitance. A positive signal with a large common-
mode voltage can cause the reference capacitor to
gain charge (increase voltage). In contrast, the refer-
ence capacitor will lose charge (decrease voltage)
when deintegrating a negative input signal. Rollover
error is a direct result of the difference in reference to
positive or negative input voltages. With the recom-
mended reference capacitor types, the worst-case
rollover error is 0.01% of full-scale. Connect REF- to
AGND to minimize rollover error. As outlined in the ref-
erence section, reference voltages below 500mV also
contribute to rollover errors.
Oscillator Circuit The internal oscillator is typically driven by a crystal, as
shown in Figure 8, or by an external clock. If an exter-
nal clock is used, connect the clock to OSC1 and leave
OSC2 floating. The duty-cycle can vary from 20% to
80%. The typical threshold voltage is approximately 2V.
For proper start-up, a full +5V CMOS-logic swing is
required.
The oscillator frequency sets the conversion rate. Use
32,768Hz for applications that require 50Hz or 60Hz
line rejection. This frequency yields 16 conv/sec. The
same clock frequency can be used to reject both line
frequencies because the MAX132 integrates for a dif-
ferent number of clock cycles in its 50Hz and 60Hz
modes. In each case, the MAX132 integrates for a sin-
gle complete line cycle (20ms for the 50Hz mode,
16.67ms for the 60Hz mode). Refer to the Increased
Speedsection for operation at higher conversion rates.
External ComponentsThe MAX132 requires an integrator resistor (RINT) and
capacitor (CINT), a reference capacitor (CREF), and a
crystal. All MAX132 tests are performed with a
32,768Hz crystal frequency. The crystal frequency, ref-
erence voltage, and integrator current determine the
values of RINTand CINT.
CrystalFigure 8 shows the internal oscillator drive circuitry used
with external crystals. The two external capacitors provide
DC bias at start-up. The 15pF capacitors shown are typical
values. The actual capacitance will vary, depending on the
crystal manufacturer’s recommendation and board layout.
150k
15pF15pF
5pF5pF1M
+5V5
OSC1OSC2
MAX132
Figure 8. MAX132 Internal Oscillator Drive Circuitry
MAX132
+5V
-5V
IN HI
IN LO15
+545mV
100k
0.1mF±512mV17
AGND
REF-REF+
Figure 6. MAX132 Input Circuit
REF+
REF-F
120k
100k
40.2k
2.5V
MAX872
+5V
Figure 7. Dividing MAX872 to Generate the MAX132’s
Reference Voltage
