Analog Devices

This monolithic 3 V CMOS device is a low power, two-channel, input port with signal conditioning. The receive path is composed of two, high-performance sigma-delta ADCs with digital filtering. A common bandgap reference feeds the ADCs. A control DAC is included for such functions as AGC. The auxiliary functions can be accessed via the auxiliary port (ASPORT). The maximum output word rate is 270 kHz.The device is available in a 28-pin TSSOP package and a 28-pin SOIC package.

The AD7730L 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 device 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 110,000 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 AD7730L 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 3 ppm/°C. The part is available in a 24-lead SOIC and 24-lead TSSOP package. It is a lower power version of the AD7730 (approximately 1/3 the power).

The AD7732 is a high precision, high throughput analog front end. True 16-bit peak-to-peak resolution is achievable with total conversion times of 500 µs (2 kHz channel switching) making it ideally suitable for high resolution multiplexing applications.The part can be configured via a simple digital interface, which allows users to balance the noise performance against data throughput up to a 15.4 kHz.The analog front end features two fully differential input channels with unipolar or true bipolar input ranges to ±10 V while operating from a single +5 V analog supply. The part has an overrange and underrange detection capability and accepts an analog input overvoltage to ±16.5 V without degrading the performance of the adjacent channels.The differential reference input features "No-Reference" detect capability. The ADC also supports per channel system calibration options. The digital serial interface can be configured for 3-wire operation and is compatible with microcontrollers and digital signal processors. All interface inputs are Schmitt triggered. The part is specified for operation over the extended industrial temperature range of –40ºC to +105ºC and is available in 28-lead TSSOP package.Other parts in the AD7732 family are theAD7734and theAD7738.The AD7734 is similar to AD7732, but its analog front end features four single-ended input channels.The AD7738 analog front end is configurable for four fully differential or eight single-ended input channels, features 0.625 V to 2.5 V bipolar/unipolar input ranges, and accepts a common-mode input voltage from 200 mV to AVDD – 300 mV. The AD7738 multiplexer output is pinned out externally, allowing the user to implement programmable gain or signal conditioning before being applied to the ADC.APPLICATIONSPLCs/DCSMultiplexing applicationsProcess controlIndustrial instrumentation

The AD7734 is a high precision, high throughput analog front end. True 16-bit p-p resolution is achievable with a total conversion time of 500 μs (2 kHz channel switching), making it ideally suitable for high resolution multiplexing applications.The device can be configured via a simple digital interface, which allows users to balance the noise performance against data throughput up to a 15.4 kHz.The analog front end features four single-ended input channels with unipolar or true bipolar input ranges to ±10 V while operating from a single +5 V analog supply. The device has an overrange and underrange detection capability and accepts an analog input overvoltage to ±16.5 V without degrading the performance of the adjacent channels.The differential reference input features "No-Reference" detect capability. The ADC also supports per channel system calibration options. The digital serial interface can be configured for 3-wire operation and is compatible with microcontrollers and digital signal processors. All interface inputs are Schmitt triggered.The device is specified for operation over the extended industrial temperature range of –40°C to +105°C.Other devices in the AD7734 family are theAD7732and theAD7738.The AD7732 is similar to AD7734, but its analog front end features two fully differential input channels.The AD7738 analog front end is configurable for four fully differential or eight single-ended input channels, features 0.625 V to 2.5 V bipolar/unipolar input ranges, and accepts a common-mode input voltage from 200 mV to AVDD–300 mV. The AD7738 multiplexer output is pinned out externally, allowing the user to implement programmable gain or signal conditioning before being applied to the ADC.APPLICATIONSPLCs/DCSMultiplexing applicationsProcess controlIndustrial instrumentation

The AD7738 is a high precision, high throughput analog front end. True 16-bit peak-to-peak resolution is achievable with a total conversion time of 117 µs (8.5 kHz channel switching) making it ideally suitable for high resolution multiplexing applications.The AD7738 is based on a sigma-delta architecture and features up to 24 bits of no missing codes performance. The part can be configured via a simple digital interface, which allows users to balance the noise performance against data throughput up to a 15.4 kHz conversion rate. The analog front end features 8 single-ended or 4 fully differential input channels with unipolar or bipolar 625 mV, 1.25 V and 2.5V input ranges and accepts a common mode input voltage from 200 mV above AGND to AVDD-300 mV. The multiplexer output is pinned out externally allowing the user to implement programmable gain or signal conditioning before applying the input signal to the ADC. The differential reference input features "No Reference" detect capability. The ADC also supports per channel system calibration options.The digital serial interface can be configured for three-wire operation and is compatible with microcontrollers and digital signal processors. All interface inputs are Schmitt triggered.The part is specified for operation over the extended industrial temperature range of -40ºC to +105ºC and is available in 28-lead TSSOP package.

The AD7740 is a low-cost, ultrasmall synchronous Voltage-to-Frequency Converter (VFC). It works from a single 3.0 V to 3.6 V or 4.75 V to 5.25 V supply consuming 0.9 mA. The AD7740 is available in an 8-lead SOT-23 and also in an 8-lead MSOP package. Small package, low cost and ease of use were major design goals for this product. The part contains an on-chip 2.5 V bandgap reference but the user may overdrive this using an external reference. This external reference range includes VDD.The full-scale output frequency is synchronous with the clock signal on the CLKIN pin. This clock can be generated with the addition of an external crystal (or resonator) or supplied from a CMOS-compatible clock source. The part has a maximum input frequency of 1 MHz.For an analog input signal that goes from 0 V to VREF, the output frequency goes from 10% to 90% of fCLKIN. In buffered mode, the part provides a very high input impedance and accepts a range of 0.1 V to VDD – 0.2 V on the VIN pin. There is also an unbuffered mode of operation that allows VIN to go from –0.15 V to VDD + 0.15 V. The modes are interchangeable using the BUF pin.The AD7740 (Y Grade) is guaranteed over the automotive temperature range of –40°C to +105°C. The AD7740 (K Grade) is guaranteed from 0°C to 85°C.Product HighlightsThe AD7740 is a single channel, single-ended VFC. It is available in 8-lead SOT-23 and 8-lead MSOP packages, and is intended for low-cost applications. The AD7740 offers considerable space saving over alternative solutions.The AD7740 operates from a single 3.0 V to 3.6 V or 4.75 V to 5.25 V supply and consumes typically 0.9 mA when the input is unbuffered. It also contains an automatic power-down function.The AD7740 does not require external resistors and capacitors to set the output frequency. The maximum output frequency is set by a crystal or a clock. No trimming or calibration is required.The analog input can be taken to 150 mV below GND for true bipolar operation.The specified voltage reference range on REFIN is from 2.5 V to the supply voltage, VDD.ApplicationsIsolation of high common-mode voltagesLow-cost analog-to-digital conversionBattery monitoringAutomotive sensing