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Details, datasheet, quote on part number:ZMD31020AF-R
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Datasheet text preview:
ZMD31020
Differential Sensor Signal Conditioner 1. General Description
ZMD31020 is a signal conditioner for sensors (sensor elements; transducers) with differential output signal, e.g. for Wheatstone-bridge-type sensors. The device provides digital correction and compensation of sensor offset, gain, temperature sensitivity and non-linearity through an on-chip RISC-Microcontroller running a correction algorithm. A bidirectional digital serial interface allows for a simple PC-controlled calibration procedure, encompassing reading of non-corrected sensor signal and temperature values and writing and programming of a resulting calculated set of calibration coefficients into an on-chip parameter EEPROM. Thus a specific sensor and a ZMD31020 conditioner device are mated digitally: fast, precise and without cost overhead for trimming components and equipment. ZMD31020 has been designed in 0.8µm EEPROM-CMOS for a typical supply voltage of 5V and an operating temperature range 40°C ... +125°C, covering commercial, industrial and automobile applications. The device is available both unpackaged as tested die or as finished product in 5.3mm width SSOP14. A demokit including samples, documentation and PC-compatible hardware and software for emulation and calibration is available.
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Features
Optimized for ratiometric differential sensors Cost-effective: a single 12-bit input ADC, 16-bit RISC-µC, 11-bit output DAC; no adjustment DACs needed Minimum number of external components required: supply capacitor; sensor; analog output load capacitor Temperature sensing optionally through off-chip or on-chip diode Analog input multiplexer for differential sensor signal and temperature Chopper-stabilized PGA, programmable to 3 differential gains (15.66, 24 and 42) ADC resolves sensor signal with 12 bits, temperature with 10 bits ADC's output programmable to 4 zero-input bias values: 1/16, 1/8, ¼, ½ of conversion range Analog input stage measures sensor signal ratiometrically, however temperature BG-related Correction Processor: 16-bit ALU & (16 x 16 bit ) RAM; (1k x 16)-bit instruction ROM; (12 x 16)-bit parameter EEPROM Cancellation of chip-related offset in sensor and temperature signal through short-circuit input switch and subtraction routine Correction formula based on 7 calibration coefficients Parameter EEPROM stores: configuration word, calibration coefficients, upper and lower output signal limits, customer specific identifiers Corrected sensor signal available both as 12-bit digital word at the I2C interface and as ratiometric analog voltage from an 11-bit output DAC Cycle time: 10ms. Response time: 11ms Calibration of a sensor element / ZMD31020 combination to a desired output characteristic through measurement of 7 uncorrected sensor and temperature value pairs These values are read over the I2C interface and processed to calculate the 7 calibration coefficients. Mating is completed by programming the calibration coefficients into the EEPROM over the I2C interface PC-compatible hardware and software supporting the calibration procedure is available and included in the demokit ZMD31020DK Accuracy: ± 0.25% FSO typically
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Datasheet, Rev. 1.4, March 27th, 2002
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ZMD31020
Differential Sensor Signal Conditioner 3. Application Circuit
220nF +5V typ.
VDDA VTN Temperature Sensing Diode VDDB1 (*) Differential Sensor VDDB2 (*)
VDD VPP
SCL SDA
VBP
VOUT 10 to 25nF
VBN VSSB VSSA VSS 0V
(*) either pin/pad may be chosen, whichever is more favourable layoutwise
Datasheet, Rev. 1.4, March 27th, 2002
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ZMD31020
Differential Sensor Signal Conditioner 4. Pin Description
PIN Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 (*) (**) Name VOUT VDDA (*) VDD VSS SCL SDA VPP VBN VDDB2 (*) VTN VDDB1 (*) VBP VSSB (**) VSSA (**) Description analog conditioned sensor signal output analog device functions positive supply digital device functions positive supply digital device functions negative supply I²C clock input, on-chip pull-up resistor I²C data input / output, on-chip pull-up resistor positive EEPROM programming voltage differential sensor signal negative input positive supply for sensor and temperature sensing diode input for temperature sensing diode positive supply for sensor and temperature sensing diode differential sensor signal positive input sensor negative supply analog device functions negative supply
VDDA, VDDB1 and VDDB2 tied to common on-chip positive supply rail VSSA and VSSB tied to common on-chip negative supply rail
Datasheet, Rev. 1.4, March 27th, 2002
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