The AD7703 is a 20-bit ADC that uses a Σ-Δ conversion technique. The analog input is continuously sampled by an analog modulator whose mean output duty cycle is proportional to the input signal. The modulator output is processed by an on-chip digital filter with a six-pole Gaussian response, which updates the output data register with 16-bit binary words at word rates up to 4 kHz. The sampling rate, filter corner frequency, and output word rate are set by a master clock input that may be supplied externally, or by a crystal controlled on-chip clock oscillator. The inherent linearity of the ADC is excellent and endpoint accuracy is ensured by self-calibration of zero and full scale, which may be initiated at any time. The self-calibration scheme can also be extended to null system offset and gain errors in the input channel.The output data is accessed through a flexible serial port, which has an asynchronous mode compatible with UARTs and two synchronous modes suitable for interfacing to shift registers or the serial ports of industry-standard microcontrollers.CMOS construction ensures low power dissipation, and a power-down mode reduces the idle power consumption to only 10 µW.PRODUCT HIGHLIGHTS The AD7703 offers 20-bit resolution coupled with outstanding 0.0003% accuracy. No missing codes ensures true, usable, 20-bit dynamic range, removing the need for programmable gain and level-setting circuitry. The effects of temperature drift are eliminated by on-chip self-calibration, which removes zero and gain error. External circuits can also be included in the calibration loop to remove system offsets and gain errors. Flexible synchronous/asynchronous interface allows the AD7703 to interface directly to the serial ports of industry-standard microcontrollers and DSP processors. Low operating power consumption and an ultralow power standby mode make the AD7703 ideal for loop-powered remote sensing applications, or battery-powered portable instruments.APPLICATIONS Industrial Process Control Weigh Scales Portable Instrumentation Remote Data Acquisition

The AD7703 is a 20-bit ADC that uses a Σ-Δ conversion technique. The analog input is continuously sampled by an analog modulator whose mean output duty cycle is proportional to the input signal. The modulator output is processed by an on-chip digital filter with a six-pole Gaussian response, which updates the output data register with 16-bit binary words at word rates up to 4 kHz. The sampling rate, filter corner frequency, and output word rate are set by a master clock input that may be supplied externally, or by a crystal controlled on-chip clock oscillator. The inherent linearity of the ADC is excellent and endpoint accuracy is ensured by self-calibration of zero and full scale, which may be initiated at any time. The self-calibration scheme can also be extended to null system offset and gain errors in the input channel.The output data is accessed through a flexible serial port, which has an asynchronous mode compatible with UARTs and two synchronous modes suitable for interfacing to shift registers or the serial ports of industry-standard microcontrollers.CMOS construction ensures low power dissipation, and a power-down mode reduces the idle power consumption to only 10 µW.PRODUCT HIGHLIGHTS The AD7703 offers 20-bit resolution coupled with outstanding 0.0003% accuracy. No missing codes ensures true, usable, 20-bit dynamic range, removing the need for programmable gain and level-setting circuitry. The effects of temperature drift are eliminated by on-chip self-calibration, which removes zero and gain error. External circuits can also be included in the calibration loop to remove system offsets and gain errors. Flexible synchronous/asynchronous interface allows the AD7703 to interface directly to the serial ports of industry-standard microcontrollers and DSP processors. Low operating power consumption and an ultralow power standby mode make the AD7703 ideal for loop-powered remote sensing applications, or battery-powered portable instruments.APPLICATIONS Industrial Process Control Weigh Scales Portable Instrumentation Remote Data Acquisition

The AD7709 is a complete analog front-end for low frequency measurement applications. The AD7709 contains a 16-bit sigma delta ADC with PGA and can be configured as 2 fully-differential input channels or 4 pseudo-differential input channels. Inputs signal ranges from 20mV to 2.56V can be directly converted using the AD7709. These signals can be converted directly from a transducer without the need for signal conditioning. Other on-chip features include three software configurable current sources, switchable reference inputs, low side power switches and a 4-bit digital I/O port.

The AD7711 is a complete analog front end for low frequency measurement applications. The device accepts low level signals directly from a transducer and outputs a serial digital word. It employs a sigma-delta conversion technique to realize up to 24 bits of no missing codes performance. The input signal is applied to a proprietary programmable gain front end based around an analog modulator. The modulator output is processed by an on-chip digital filter. The first notch of this digital filter can be programmed via the on-chip control register allowing adjustment of the filter cutoff and settling time.The part features one differential analog input and one single ended analog input as well as a differential reference input. Normally, one of the input channels will be used as the main channel with the second channel used as an auxiliary input to periodically measure a second voltage. It can be operated from a single supply (by tying the VSS pin to AGND) provided that the input signals on the analog inputs are more positive than -30 mV. By taking the VSS pin negative, the part can convert signals down to -VREF on its inputs. The part provides two current sources that can be used to provide excitation in three-wire and four-wire RTD configurations. The AD7711 thus performs all signal conditioning and conversion for a single or dual channel system.The AD7711 is ideal for use in smart, microcontroller based systems. Gain settings, signal polarity, input channel selection and RTD current control can be configured in software using the bidirectional serial port. The AD7711 contains self-measurement calibration, system calibration and background calibration options and also allows the user to read and write the on-chip calibration registers.CMOS construction ensures low power dissipation, and a software programmable power-down mode reduces the standby power consumption to only 7 mW typical. The part is available in a 24-pin, 0.3 inch wide, plastic and hermetic dual-in-line package (DIP) as well as a 24-lead small outline (SOIC) package.

The AD7715 is a complete analog front end for low frequency measurement applications. The part can accept low level input signals directly from a transducer and outputs a serial digital word. It employs a Σ-Δ conversion technique to realize up to 16 bits of no missing codes performance. The input signal is applied to a proprietary programmable gain front end based around an analog modulator. The modulator output is processed by an on-chip digital filter. The first notch of this digital filter can be programmed via the on-chip control register allowing adjustment of the filter cutoff and output update rate.The AD7715 features a differential analog input as well as a differential reference input. It operates from a single supply (3 V or 5 V). It can handle unipolar input signal ranges of 0 mV to 20 mV, 0 mV to 80 mV, 0 V to 1.25 V and 0 V to 2.5 V. It can also handle bipolar input signal ranges of ±20 mV, ±80 mV, ±1.25 V and ±2.5 V. These bipolar ranges are referenced to the negative input of the differential analog input. The AD7715 thus performs all signal conditioning and conversion for a single channel system.The AD7715 is ideal for use in smart, microcontroller, or DSP-based systems. It features a serial interface that can be configured for three-wire operation. Gain settings, signal polarity, and update rate selection can be configured in software using the input serial port. The part contains self-calibration and system calibration options to eliminate gain and offset errors on the part itself or in the system.CMOS construction ensures very low power dissipation, and power-down mode reduces the standby power consumption to 50 μW typical. The part is available in a 16-lead, 0.3 inch-wide, plastic dual-in-line package (PDIP) as well as a 16-lead 0.3 inch wide small outline (SOIC_W) package and a 16-lead TSSOP package.PRODUCT HIGHLIGHTS The AD7715 consumes less than 450 μA in total supply current at 3 V supplies and 1 MHz master clock, making it ideal for use in low-power systems. Standby current is less than 10 μA. The programmable gain input allows the AD7715 to accept input signals directly from a strain gage or transducer removing a considerable amount of signal conditioning. The AD7715 is ideal for microcontroller or DSP processor applications with a three-wire serial interface reducing the number of interconnect lines and reducing the number of optocouplers required in isolated systems. The part contains on-chip registers which allow software control over output update rate, input gain, signal polarity, and calibration modes. The part features excellent static performance specifications with 16-bits no missing codes, ±0.0015% accuracy, and low rms noise (<550 nV). Endpoint errors and the effects of temperature drift are eliminated by on-chip calibration options, which remove zero-scale and full-scale errors.

This device is a 7th order sigma-delta modulator that converts the analog input signal into a high speed 1-bit data stream. The part operates from a +5 V supply and accepts a differential input range of 0 V to +2.5 V or ±1.25 V centered about a common-mode bias. The analog input is continuously sampled by the analog modulator, eliminating the need for external sample and hold circuitry. The input information is contained in the output stream as a density of ones. The original information can be reconstructed with an appropriate digital filter.

The AD7722 is a complete low power, 16-bit, sigma-delta ADC. The part operates from a +5 V supply and accepts a differential input voltage range of 0 V to +2.5 V or ±1.25 V centered around a common-mode bias. The AD7722 provides 16-bit performance for input bandwidths up to 90.625 kHz. The part provides data at an output word rate of 195.3 kHz.The analog input is continuously sampled by an analog modulator eliminating the need for external sample-and-hold circuitry. The modulator output is processed by two Finite Impulse Response (FIR) digital filters in series. The on-chip filtering reduces the external antialias requirements to first order, in most cases. The group delay for the filter is 215.5 µs, while the settling time for a step input is 431 µs. The sample rate, filter corner frequency, and output word rate are set by an external clock that is nominally 12.5 MHz.Use of a single bit DAC in the modulator guarantees excellent linearity and dc accuracy. Endpoint accuracy is ensured by on-chip calibration. This calibration procedure minimizes the zero-scale and full-scale errors.Conversion data is provided at the output register through a flexible serial port or a parallel port. This offers 3-wire, high speed interfacing to digital signal processors. The serial interface operates in an internal clocking (master) mode, whereby an internal serial data clock and framing pulse are device outputs. Additionally, two AD7722s can be configured with the serial data outputs connected together. Each converter alternately transmits its conversion data on a shared serial data line.The part provides an accurate on-chip 2.5 V reference. A reference input/output function is provided to allow either the internal reference or an external system reference to be used as the reference source for the part.The AD7722 is available in a 44-pin PQFP package and is specified over the industrial temperature range from –40°C to +85°C.

The AD7730 is a complete analog front end for weigh-scale and pressure measurement applications. The device accepts low-level signals directly from a transducer and outputs a serial digital word. The input signal is applied to a proprietary programmable gain front end based around an analog modulator.The modulator output is processed by a low pass programmable digital filter, allowing adjustment of filter cutoff, output rate and settling time.The part features two buffered differential programmable gain analog inputs as well as a differential reference input. The part operates from a single +5 V supply. It accepts four unipolar analog input ranges: 0 mV to ±10 mV, +20 mV, +40 mV and +80 mV and four bipolar ranges: ±10 mV, ±20 mV, ±40 mV and ±80 mV. The peak-to-peak resolution achievable directly from the part is 1 in 230,000 counts. An on-chip 6-bit DAC allows the removal of TARE voltages. Clock signals for synchronizing ac excitation of the bridge are also provided.The serial interface on the part can be configured for three-wire operation and is compatible with microcontrollers and digital signal processors. The AD7730 contains self-calibration and system calibration options, and features an offset drift of less than 5 nV/°C and a gain drift of less than 2 ppm/°C.The part is available in a 24-pin plastic DIP, a 24-lead SOIC and 24-lead TSSOP package.APPLICATIONS Weigh Scales Pressure Measurement

The AD7731 is a complete analog front-end for process controlapplications. The device has a proprietary programmable gainfront end that allows it to accept a range of input signal ranges,including low level signals, directly from a transducer. The sigma-deltaarchitecture of the part consists of an analog modulatorand a low pass programmable digital filter, allowing adjustmentof filter cutoff, output rate and settling time.The part features three buffered differential programmable gainanalog inputs (which can be configured as five pseudo-differentialinputs), as well as a differential reference input. The part operatesfrom a single +5 V supply and accepts seven unipolar analoginput ranges: 0 to +20 mV, +40 mV, +80 mV, +160 mV,+320 mV, +640 mV and +1.28 V, and seven bipolar ranges:±20 mV, ±40 mV, ±80 mV, ±160 mV, ±320 mV, ±640 mV and±1.28 V. The peak-to-peak resolution achievable directly fromthe part is 16 bits at an 800 Hz output rate. The part can switchbetween channels with 1 ms settling time and maintain a performancelevel of 13 bits of peak-to-peak resolution.The serial interface on the part can be configured for three-wireoperation and is compatible with microcontrollers and digitalsignal processors. The AD7731 contains self-calibration andsystem calibration options and features an offset drift of lessthan 5 nV/°C and a gain drift of less than 2 ppm/°C.The part is available in a 24-lead plastic DIP, a 24-lead SOICand 24-lead TSSOP package.APPLICATIONS Process Control PLCs/DCS Industrial Instrumentation

The AD7731 is a complete analog front-end for process controlapplications. The device has a proprietary programmable gainfront end that allows it to accept a range of input signal ranges,including low level signals, directly from a transducer. The sigma-deltaarchitecture of the part consists of an analog modulatorand a low pass programmable digital filter, allowing adjustmentof filter cutoff, output rate and settling time.The part features three buffered differential programmable gainanalog inputs (which can be configured as five pseudo-differentialinputs), as well as a differential reference input. The part operatesfrom a single +5 V supply and accepts seven unipolar analoginput ranges: 0 to +20 mV, +40 mV, +80 mV, +160 mV,+320 mV, +640 mV and +1.28 V, and seven bipolar ranges:±20 mV, ±40 mV, ±80 mV, ±160 mV, ±320 mV, ±640 mV and±1.28 V. The peak-to-peak resolution achievable directly fromthe part is 16 bits at an 800 Hz output rate. The part can switchbetween channels with 1 ms settling time and maintain a performancelevel of 13 bits of peak-to-peak resolution.The serial interface on the part can be configured for three-wireoperation and is compatible with microcontrollers and digitalsignal processors. The AD7731 contains self-calibration andsystem calibration options and features an offset drift of lessthan 5 nV/°C and a gain drift of less than 2 ppm/°C.The part is available in a 24-lead plastic DIP, a 24-lead SOICand 24-lead TSSOP package.APPLICATIONS Process Control PLCs/DCS Industrial Instrumentation