MAX132CNG ,18-Bit ADC with Serial InterfaceApplicationsMAX132C/D 0°C to +70°C Dice*Remote Data AcquisitionMAX132ENG -40°C to +85°C 24 Narrow P ..
MAX132CNG+ ,±18-Bit ADC with Serial InterfaceFeaturesThe MAX132 is a CMOS, 18-bit plus sign, serial-output,♦ Low Supply Current:analog-to-digita ..
MAX132CWG ,18-Bit ADC with Serial InterfaceELECTRICAL CHARACTERISTICS(V+ = 5V, V- = -5V, DGND = AGND = IN LO = REF- = 0V, REF+ = 545mV, R = 60 ..
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 ..
MAX395EAG ,Serially Controlled, Low-Voltage, 8-Channel SPST SwitchFeaturesThe MAX395 8-channel, serially controlled, single-pole/sin-♦ SPI™/QSPI™, Microwire™-Compati ..
MAX3964AETP ,+3 V to +5.5 V, 125 Mbps to 155 Mbps limiting amplifier with loss-of-signal detectorApplicationso oMAX3968CEP 0 C to +70 C 20 QSOP125Mbps FDDI Receiverso oMAX3968C/D 0 C to +70 C Dice ..
MAX3964ETP ,+3.0 to +5.5 V, 124 to 266 Mbps limiting amplifier with loss-of-signal detectorApplicationso oMAX3968CEP 0 C to +70 C 20 QSOP125Mbps FDDI Receiverso oMAX3968C/D 0 C to +70 C Dice ..
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 ..
MAX132CNG-MAX132CWG-MAX132ENG-MAX132EWG
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
____________________________FeaturesLow 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 Rejection
MAX132
±18-Bit ADC with Serial Interface
__________________Pin Configuration
________________Functional Diagram
MAX132
±18-Bit ADC with Serial Interface
ABSOLUTE 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
MAX132
±18-Bit ADC with Serial Interface
ELECTRICAL 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.
MAX132
±18-Bit ADC with Serial Interface
__________________________________________Typical Operating CharacteristicsERROR vs. COMMON-MODE
INPUT VOLTAGE (VIN LO–AGND)
MAX132-01
COMMON-MODE VOLTAGE (V)-2-101234-4
ERROR (% OF FSR)0.51.5
50Hz/60Hz READ-ZERO OFFSET
vs. VREFMAX132-02
VREF (V)
READ-ZERO OFFSET (% OF FSR)
50Hz/60Hz READ-ZERO OFFSET
vs. TEMPERATURE
MAX132-03
TEMPERATURE (°C)406080100
READ-ZERO OFFSET (% OF FSR)
SUPPLY CURRENT
vs. CRYSTAL FREQUENCY
MAX132-04
CRYSTAL FREQUENCY (kHz)
SUPPLY CURRENT (
FULL-SCALE ROLLOVER ERROR
vs. VREF
MAX132-05
VREF (V)0.51.01.52.52.0
ROLLOVER ERROR (% OF FSA)
NOISE vs. NUMBER
OF SAMPLES AVERAGEDMAX132-06
NUMBER OF SAMPLES AVERAGED
NOISE (
RMS
______________________________________________________________Pin Description
MAX132
±18-Bit ADC with Serial InterfaceFigure 1. Test and Typical Application Circuit
_________________________________________________Pin Description (continued)
____________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 is
±512mV. 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
MAX132
±18-Bit ADC with Serial InterfaceFigure 3. Load Circuits for Access Time
Figure 4. Load Circuits for Disable Time to Three-State
Figure 2. Serial-Mode Timing
MAX132
±18-Bit ADC with Serial Interface±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
±18-Bit ADC with Serial Interface
Differential 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.
