Analog Devices

The AD680 is a bandgap voltage reference which provides a 2.5 V output from inputs between 4.5 V and 36 V. The architecture of the AD680 enables the reference to be operated at a very low quiescent current while still realizing excellent dc characteristics and noise performance. Trimming of the high stability thin-film resistors is performed for initial accuracy and temperature coefficient, resulting in low errors over temperature. The precision dc characteristics of the AD680 make it ideal for use as a reference for D/A converters which require an external precision reference. The device is also ideal for A/D converters and, in general, can offer better performance than the standard on-chip references.Based upon the low quiescent current of the AD680, which that of many incomplete two-terminal references, the AD680 is recommended for low power applications such as hand-held battery equipment.A temperature output pin is provided on the 8-pin package versions of the AD680. The temperature output pin provides an output voltage that varies linearly with temperature and allows the AD680 to be configured as a temperature transducer while providing a stable 2.5 V output.The AD680 is available in five grades. The AD680AN is specified for operation from -40°C to +85°C, while the AD680JN is specified for 0°C to +70°C operation. Both the AD680AN and AD680JN are available in 8-pin plastic DIP packages. The AD680AR is specified for operation from -40°C to +85°C, while the AD680JR is specified for 0°C to +70°C operation. Both are available in an 8-pin Small Outline IC (SOIC) package. The AD680JT is specified for 0°C to +70°C operation and is available in a 3-pin TO-92 package.

The AD684 is a monolithic quad sample-and-hold amplifier (SHA). It features four complete sampling channels, each controlled by an independent hold command. Each SHA is complete with an internal hold capacitor. The high accuracy SHA channels are self-contained and require no external components or adjustments. The AD684 is manufactured on a BiMOS process which provides a merger of high performance bipolar circuitry and low power CMOS logic.The AD684 is ideal for high performance, multichannel data acquisition systems. Each SHA channel can acquire a signal in less than 1 µs and retain the held value with a droop rate of less than 0.01 µV/µs. Excellent linearity and ac performance make the AD684 an ideal front end for high speed 12- and 14-bit ADCs.The AD684 has a self-correcting architecture that minimizes hold mode errors and insures accuracy over temperature. Each channel of the AD684 is capable of sourcing 5 mA and incorporates output short circuit protection.The AD684 is specified for three temperature ranges. The J grade device is specified for operation from 0 to +70°C, the A grade from -40°C to +85°C and the S grade from -55°C to +125°C.

The AD693 is a monolithic signal conditioning circuit which accepts low-level inputs from a variety of transducers to control a standard 4-20 mA, two-wire current loop. An on-chip voltage reference and auxiliary amplifier are provided for transducer excitation; up to 3.5 mA of excitation current is available when the device is operated in the loop-powered mode. Alternatively, the device may be locally powered for three-wire applications when 0-20 mA operation is desired.Precalibrated 30 mV and 60 mV input spans may be set by simple pin strapping. Other spans from 1 mV to 100 mV may be realized with the addition of external resistors. The auxiliary amplifier may be used in combination with on-chip voltages to provide six precalibrated ranges for 100 (ohm) RTDs. Output span and zero are also determined by pin strapping to obtain the standard ranges: 4-20mA, 12 ± 8 mA and 0-20 mA.Active laser trimming of the AD693's thin-film resistors result in high levels of accuracy without the need for additional adjustments and calibration. Total unadjusted error is tested on every device to be less than 0.5% of full scale at +25°C, and less than 0.75% over the industrial temperature range. Residual nonlinearity is under 0.05%. The AD693 also allows for the use of an external pass transistor to further reduce errors caused by self-heating.For transmission of low-level signals from RTDs, bridges and pressure transducers, the AD693 offers a cost-effective signal conditioning solution. It is recommended as a replacement for discrete designs in a variety of applications in process control, factory automation and system monitoring.The AD693 is packaged in a 20-pin ceramic side-brazed DIP, 20-pin Cerdip, and 20-pin LCCC and is specified over the -40°C to +85°C industrial temperature range.

The AD698 is a complete, monolithic Linear Variable Differential Transformer (LVDT) signal conditioning subsystem. It is used in conjunction with LVDTs to convert transducer mechanical position to a unipolar or bipolar dc voltage with a high degree of accuracy and repeatability. All circuit functions are included on the chip. With the addition of a few external passive components to set frequency and gain, the AD698 converts the raw LVDT output to a scaled dc signal. The device will operate with half-bridge LVDTs, LVDTs connected in the series opposed configuration (4-wire), and RVDTs.The AD698 contains a low distortion sine wave oscillator to drive the LVDT primary. Two synchronous demodulation channels of the AD698 are used to detect primary and secondary amplitude. The part divides the output of the secondary by the amplitude of the primary and multiplies by a scale factor. This eliminates scale factor errors due to drift in the amplitude of the primary drive, improving temperature performance and stability.The AD698 uses a unique ratiometric architecture to eliminate several of the disadvantages associated with traditional approaches to LVDT interfacing. The benefits of this new circuit are: no adjustments are necessary; temperature stability is improved; and transducer interchangeability is improved.

The AD706 is a dual, low power, bipolar op amp that has the low input bias current of a JFET amplifier, but which offers a significantly lower IBdrift over temperature. It utilizes superbeta bipolar input transistors to achieve picoampere input bias current levels (similar to FET input amplifiers at room temperature), while its IB typically only increases by 5 at 125°C (unlike a JFET amp, for which IB doubles every 10°C for a 1000× increase at 125°C). The AD706 also achieves the microvolt offset voltage and low noise characteristics of a precision bipolar input amplifier.Since it has < 200 pA of bias current, the AD706 does not require the commonly used "balancing" resistor. Furthermore, the current noise is only 50 fA/√Hz, which makes this amplifier usable with very high source impedances. At 600 A max supply current (per amplifier), the AD706 is well suited for today’s high density boards.The AD706 is an excellent choice for use in low frequency active filters in 12-bit and 14-bit data acquisition systems, in precision instrumentation, and as a high quality integrator. The AD706 is internally compensated for unity gain and is available in five performance grades. The AD706J is rated over the commercial temperature range of 0°C to +70°C. The AD706A is rated for the extended industrial temperature range of −40°C to +85°C.The AD706 is offered in two varieties of an 8-lead package: PDIP and surface-mount (SOIC).PRODUCT HIGHLIGHTSThe AD706 is a dual low drift op amp that offers JFET level input bias currents, yet has the low IBdrift of a bipolar amplifier. It may be used in circuits using dual op amps such as the LT1024.The AD706 provides both low drift and high dc precision.The AD706 can be used in applications where a chopper amplifier would normally be required but without the chopper’s inherent noise.APPLICATIONSLow Frequency Active FiltersPrecision InstrumentationPrecision Integrators

The AD708 is a high precision, dual monolithic operational amplifier. Each amplifier individually offers excellent dc precision with maximum offset voltage and offset voltage drift of any dual bipolar op amp.The matching specifications are among the best available in any dual op amp. In addition, the AD708 provides 5 V/μV mini-mum open-loop gain and guaranteed maximum input voltage noise of 350 nV p-p (0.1 Hz to 10 Hz). All dc specifications show excellent stability over temperature, with offset voltage drift typically 0.1 μV/°C and input bias current drift of 25 pA/°C maximum.The AD708 is available in four performance grades. The AD708J is rated over the commercial temperature range of 0°C to 70°C and is available in a narrow body, PDIP. The AD708A and AD708B are rated over the industrial temperature range of −40°C to +85°C and are available in a CERDIP.The AD708S is rated over the military temperature range of −55°C to +125°C and is available in a CERDIP military version processed to MIL-STD-883B.PRODUCT HIGHLIGHTSThe combination of outstanding matching and individual specifications make the AD708 ideal for constructing high gain, precision instrumentation amplifiers.The low offset voltage drift and low noise of the AD708 allow the designer to amplify very small signals without sacrificing overall system performance.The AD708 10 V/μV typical open-loop gain and 140 dB common-mode rejection make it ideal for precision applications.

TheAD7091R-2/AD7091R-4/ AD7091R-8 family is a multichannel 12-bit, ultralow power, successive approximation analog-to-digital converter (ADC) that is available in two, four, or eight analog input channel options. The AD7091R-2 / AD7091R-4 / AD7091R-8 operate from a single 2.7 V to 5.25 V power supply and are capable of achieving a sampling rate of 1 MSPS.The AD7091R-2 / AD7091R-4 / AD7091R-8 family offers up to eight single-ended analog input channels with a channel sequencer that allows a preprogrammed selection of channels to be converted sequentially. The AD7091R-2 / AD7091R-4 / AD7091R-8 also feature an on-chip conversion clock, an on-chip accurate 2.5 V reference, and a high speed serial interface.The AD7091R-2 / AD7091R-4 / AD7091R-8 have a serial port interface (SPI) that allows data to be read after the conversion while achieving a 1 MSPS throughput rate. The conversion process and data acquisition are controlled using theCONVSTpin.The AD7091R-2 / AD7091R-4 / AD7091R-8 use advanced design techniques to achieve ultralow power dissipation at high throughput rates. They also feature flexible power management options. An on-chip configuration register allows the user to set up different operating conditions. These include power management, alert functionality, busy indication, channel sequencing, and general-purpose output pins. The MUXOUTand ADCINpins allow signal conditioning of the multiplexer output prior to acquisition by the ADC.ApplicationsBattery powered systemsPersonal digital assistantsMedical instrumentsMobile communicationsInstrumentation and control systemsData acquisition systemsOptical sensorsDiagnostic/monitoring functions