Precision Measurement

The ADA4523-1 is a high voltage, low noise, zero drift op amp that offers precision dc performance over a wide supply range of 4.5 V to 36 V. Offset voltage and 1/f noise are suppressed, allowing this op amp to achieve a maximum offset voltage of ±4 µV and a 0.1 Hz to 10 Hz input noise voltage of 88 nV p-p typical.The self calibrating circuitry of the ADA4523-1 results in low offset voltage drift with temperature (0.01 µV/°C maximum) and zero drift over time. Additionally, the ADA4523-1 uses on-chip filtering to achieve high immunity to electromagnetic interference (EMI).

Wide supply range, combined with low noise, low offset, 168 dB power supply rejection ratio (PSRR), and 160 dB common-mode rejection ratio (CMRR), make the ADA4523-1 well suited for high dynamic range test, measurement, and instrumentation systems. 

Applications

• High resolution data acquisition
• Reference buffering
• Test and measurement
• Electronic scales
• Thermocouple amplifiers
• Strain gages
• Low-side current sense

The AD3552R is a low drift, ultra-fast, 16-bit accuracy, current output digital-to-analog converter (DAC) that can be configured in multiple voltage span ranges. The AD3552R operates with a fixed 2.5 V reference.

The device incorporates three drift compensating feedback resistors for the required external transimpedance amplifier (TIA) that scales the output voltage. Offset and gain scaling registers allow for generation of multiple output span ranges, such as 0 V to 2.5 V, 0 V to 5 V, 0 V to 10 V, −5 V to +5 V, and −10 V to +10 V, and custom intermediate ranges with full 16-bit resolution.

The DAC can operate in fast mode for maximum speed or precision mode for maximum accuracy.

The SPI interface can be configured in single SPI (classic SPI) mode, dual SPI mode, synchronous dual SPI mode, and quad SPI mode with single date rate (SDR) or double data rate (DDR), with logical levels from 1.2 V to 1.8 V.

To improve device robustness, cyclic redundancy check (CRC) can be enabled. Multiple error checkers have also been integrated to detect V_REF failures or memory map corruption.

The AD3552R is specified over the extended industrial temperature range (–40°C to +105°C).

APPLICATIONS

• Instrumentation
• Hardware in the loop
• Process control equipment
• Medical devices
• Automatic test equipment
• Data acquisition system
• Programmable voltage sources
• Optical communications

The AD4134 is a quad channel, low noise, simultaneous sampling, precision analog-to-digital converter (ADC) that delivers on functionality, performance, and ease of use.

Based on the continuous time sigma-delta (CTSD) modulation scheme, the AD4134 removes the traditionally required switched capacitor circuitry sampling preceding the Σ-Δ modulator, which leads to a relaxation of the ADC input driving requirement. The CTSD architecture also inherently rejects signals around the ADC aliasing frequency band, giving the device its inherent antialiasing capability, and removes the need for a complex external antialiasing filter.

The AD4134 has four independent converter channels in parallel, each with a CTSD modulator and a digital decimation and filtering path. The AD4134 enables simultaneous sampling of four separate signal sources, each supporting a maximum input bandwidth of 391.5 kHz and achieving tight phase matching between these four signal measurements. The high level of channel integration, together with its simplified analog front-end requirement, enables the AD4134 to provide a high density multichannel data acquisition solution in a small form factor.

The signal chain simplification property of the AD4134 also improves the system level performance through the reduction of noise, error, mismatch, and distortion that is normally introduced by the analog front-end circuitry.

The AD4134 offers excellent dc and ac performance. The bandwidth of each ADC channel ranges from dc to 391.5 kHz, making the device an ideal candidate for universal precision data acquisition solutions supporting a breadth of sensor types, from temperature and pressure to vibration and shock.

The AD4134 offers a large number of features and configuration options, giving the user the flexibility to achieve the optimal balance between bandwidth, noise, accuracy, and power for a given application.

An integrated asynchronous sample rate converter (ASRC) allows the AD4134 to precisely control the decimation ratio and, in turn, the output data rate (ODR) using interpolation and resampling techniques. The AD4134 supports a wide range of ODR frequencies, from 0.01 kSPS to 1496 kSPS with less than 0.01 SPS adjustment resolution, allowing the user to granularly vary sampling speed to achieve coherent sampling. The ODR value can be controlled through the ODR_VAL_INT_× and ODR_VAL_FLT_× registers (Register 0×16 to Register 0×1C, ASRC master mode), or using an external clock source (ASRC slave mode). The ASRC slave mode operation enables synchronous sampling between multiple AD4134 devices to a single system clock. The ASRC simplifies the clock distribution requirement within a medium bandwidth data acquisition system because it no longer requires a high frequency, low jitter master clock from the digital back end to be routed to each ADC.

The ASRC acts as a digital filter and decimates the oversampled data from the Σ-Δ modulator to a lower rate to favor higher precision. The ADC data is then further processed by one of the AD4134 user-selectable digital filter profiles to further reject the out of band signals and noises, and reduce the data rate to the final desired ODR value.

The AD4134 offers three main digital filter profile options: a wideband low ripple filter with a brick wall frequency profile and an ODR range from 2.5 kSPS to 374 kSPS that is suitable for frequency domain analysis, a fast responding sinc3 filter with an ODR range from 0.01 kSPS to 1496 kSPS that is suitable for low latency time domain analysis and low frequency high dynamic range input types, and a balanced sinc6 filter with an ODR range from 2.5 kSPS to 1.496 MSPS, offering optimal noise performance and response time.

The AD4134 is also capable of performing on-board averaging between two or four of its input channels. The result is a near 3 dB, if two channels are combined, or 6 dB, if all four channels are combined, improvement in dynamic range while maintaining the bandwidth.

The AD4134 supports two device configuration schemes: serial peripheral interface (SPI) and hardware pin configuration (pin control mode). The SPI control mode offers access to all the features and configuration options available on the AD4134. SPI control mode also enables access to the on-board diagnostic features designed to enable a robust system design. Pin control mode offers the benefit of simplifying the device configuration, enabling the device to operate autonomously after power-up operating in a standalone mode.

In addition to the optional SPI, the AD4134 has a flexible and independent data interface for transmitting the ADC output data. The data interface can act as either a bus master or a slave with various clocking options to support multiple communication bus protocols. The data interface also supports daisy-chaining and an optional minimum input/output (I/O) mode designed to minimize the number of digital isolator channels required in isolated applications.

The AD4134 has an operating ambient temperature range from -40°C to 105°C. The device is housed in an 8 mm × 8 mm, 56-lead lead frame chip scale package (LFCSP).

APPLICATIONS

• Electrical test and measurement
• Audio test
• 3-phase power quality analysis
• Control and hardware in loop verification
• Sonars
• Condition monitoring for predictive maintenance
• Acoustic and material science research and development

The AD4630-24/AD4632-24 are two-channel, simultaneous sampling, Easy Drive^™, 2 MSPS or 500 kSPS successive approximation register (SAR) analog-to-digital converters (ADCs). With a guaranteed maximum ±0.9 ppm INL and no missing codes at 24 bits, the AD4630-24/AD4632-24 achieve unparalleled precision from −40°C to +125°C. Figure 1 in the data sheet shows the functional architecture of the AD4630-24/AD4632-24.

A low drift, internal precision reference buffer eases voltage reference sharing with other system circuitry. The AD4630-24/ AD4632-24 offer a typical dynamic range of 106 dB when using a 5 V reference. The low noise floor enables signal chains requiring less gain and lower power. A block averaging filter with programmable decimation ratio can increase dynamic range up to 153 dB. The wide differential input and common-mode ranges allow inputs to use the full voltage reference (±V_REF) range without saturating, simplifying signal conditioning requirements and system calibration. The improved settling of the Easy Drive analog inputs broadens the selection of analog front-end components compatible with the AD4630-24/AD4632-24. Both single-ended and differential signals are supported.

The versatile Flexi-SPI serial peripheral interface (SPI) eases host processor and ADC integration. A wide data clocking window, multiple SDO lanes, and optional dual data rate (DDR) data clocking can reduce the serial clock to 10 MHz while operating at a sample rate of 2 MSPS or 500 kSPS. Echo clock mode and ADC host clock mode relax the timing requirements and simplify the use of digital isolators.

The 64-ball chip scale package ball grid array (CSP_BGA) of the AD4630-24/AD4632-24 integrates all critical power supply and reference bypass capacitors, reducing the footprint and system component count, and lessening sensitivity to board layout.

APPLICATIONS

• Automatic test equipment
• Digital control loops
• Medical instrumentation
• Seismology
• Semiconductor manufacturing
• Scientific instrumentation

The AD7606C-18 is an 18-bit, simultaneous sampling, analog-to-digital data acquisition system (DAS) with eight channels. Each channel contains analog input clamp protection, a programmable gain amplifier (PGA), a low-pass filter (LPF), and an 18-bit successive approximation register (SAR) analog-to-digital converter (ADC). The AD7606C-18 also contains a flexible digital filter, a low drift, 2.5 V precision reference, a reference buffer to drive the ADC, and flexible parallel and serial interfaces.

The AD7606C-18 operates from a single 5 V supply and accommodates the following input ranges when sampling at throughput rates of 1 MSPS for all channels:

• Bipolar single-ended: ±12.5 V, ±10 V, ±6.25 V, ±5 V, and ±2.5 V
• Unipolar single-ended: 0 V to 12.5 V, 0 V to 10 V, and 0 V to 5 V
• Bipolar differential: ±20 V, ±12.5 V, ±10 V, and ±5 V

The input clamp protection tolerates voltages up to ±21 V. The single supply operation, on-chip filtering, and high input impedance eliminate the need for external driver op amps, which require bipolar supplies. For applications with lower throughput rates, the AD7606C-18 flexible digital filter can be used to improve noise performance.

In hardware mode, the AD7606C-18 is fully compatible with the AD7608 and AD7609. In software mode, the following advanced features are available:

• Analog input range selectable per channel with added ranges available
• High bandwidth mode (220 kHz) selectable per channel
• Additional oversampling options with an oversampling ratio up to 256
• System gain, system offset, and system phase calibration, per channel
• Analog input open circuit detector
• Diagnostic multiplexer
• Monitoring functions (serial peripheral interface (SPI) invalid read and write, cyclic redundancy check (CRC), busy stuck monitor, and reset detection)

Note that throughout the data sheet, multifunction pins, such as the RD/SCLK pin, are referred to either by the entire pin name or by a single function of the pin, for example, the SCLK pin, when only that function is relevant.

APPLICATIONS

• Power line monitoring
• Protective relays
• Multiphase motor control
• Instrumentation and control systems
• Data acquisition systems

The ADR1000 is a 6.62 V, output highly stable, oven-controlled, buried Zener reference component built on an Analog Devices, Inc., proprietary bipolar process and is a pin-compatible replacement for the LTZ1000. Included on the chip is a buried Zener reference, a heater resistor for temperature stabilization, and a temperature sensing transistor. External circuitry is used to set the operating currents and the temperature of the reference, allowing the maximum flexibility to achieve maximum long-term stability and minimum noise.

The ADR1000 application circuit can achieve a temperature coefficient of <0.2 ppm/°C and a long-term drift of 0.5 ppm per year (typical) after the first 3000 hours when properly implemented with the recommended external circuitry shown in Figure 9 in the data sheet and with the recommended layout.

The low long-term drift of the ADR1000 is well suited for any application that must maintain accuracy over long calibration intervals or product lifetime. The low thermal drift ensures the output is constant with temperature variation because the on‑chip heater of the ADR1000 maintains a constant temperature higher than the expected ambient range.

The ADR1000 is specified for operation over the extended industrial temperature range of −40°C to +125°C. To obtain the optimal thermal drift performance, the temperature set point of the heater needs to be 10°C higher than the maximum ambient temperature to provide optimum stability of the buried Zener reference.

The ADR1000 comes packaged in an industry-standard, 8-pin TO-99 metal can package that is hermetically sealed to resist the effects of humidity.

APPLICATIONS

• High accuracy instrumentation
• Multimeters
• Weigh scales
• Electric balance
• Automatic test equipment
• Metrology equipment
• Standard cells
• Calibrators

The ADR1399 precision shunt reference features excellent temperature stability over a wide range of voltage, temperature, and quiescent current conditions. A temperature stabilizing loop is incorporated with the active Zener on a monolithic  substrate, which nearly eliminates changes in voltage with temperature. The subsurface Zener circuit is fully specified at a quiescent current I_REF of 3 mA and offers minimal noise (1.44 μV p-p, 0.1 Hz to 10 Hz) and excellent long-term stability (7 ppm/√kHr). The ADR1399 offers a lower output dynamic impedance (0.08 Ω) than the LM399, reducing the effects of shunt resistor (R_SHUNT) and the supply voltage variation on the reference output.

Ideal applications for the ADR1399 include ultrastable digital voltmeters, precision calibration equipment, and ultrarepeatable analog-to-digital converters (ADCs). The simplicity of the basic pin configurations is shown in Figure 1. The 8-terminal LCC version offers force and sense pins for lower dynamic impedance and for Kelvin sensing.

APPLICATIONS

• Precision voltage reference for multimeters
• Calibration equipment voltage standards
• Laboratory measurement equipment
• Industrial monitor and control instrumentation
• Ultrastable data convertors

The LTC2688 is a 16-channel,16-bit, ±15 V digital-to-analog converter (DAC) with an integrated precision reference. The LTC2688 is guaranteed monotonic and has built in rail-to-rail output buffers that can source or sink up to 20 mA. This SoftSpan^™ DAC offers five output ranges up to ±15 V. The range of each channel is independently programmable.

The internal 4.096 V precision reference sets the accuracy of the output voltage. An external reference can be used for additional range options. Three toggle pins support Input Register A and Input Register B toggle or sinusoidal dither at multiple frequencies. An analog multiplexer simplifies measurement of pin voltages, load currents, and junction temperature.

Programmable offset and gain registers improve the accuracy of the DAC outputs.

The serial peripheral interface (SPI) and MICROWIRE^™-compatible, 3-wire serial interface operates on logic levels as low as 1.71 V and clock rates up to 50 MHz.

APPLICATIONS

• Optical networking
• Instrumentation
• Data acquisition
• Automatic test equipment
• Process control and industrial automation

The LTC6373 is a precision instrumentation amplifier with fully differential outputs which includes a closely matched internal resistor network to achieve excellent CMRR, offset voltage, gain error, gain drift, and gain nonlinearity. The user can easily program the gain to one of seven available settings through a 3-bit parallel interface (A2 to A0). The 8th state puts the part in shutdown which reduces the current consumption to 220μA. Unlike a conventional voltage feedback amplifier, the LTC6373 maintains nearly the same bandwidth across all its gain settings.

The LTC6373 features fully differential outputs to drive high performance, differential-input ADCs. The output common mode voltage is independently adjustable via the V_OCM pin. The combination of high impedance inputs, DC precision, low noise, low distortion, and high-speed differential ADC drive makes the LTC6373 an ideal candidate for optimizing data acquisition systems.

The LTC6373 is available in a 12-lead 4mm × 4mm DFN (LFCSP) package and is fully specified over the −40°C to 125°C temperature range.

Applications

• Data Acquisition Systems
• Biomedical Instrumentation
• Test and Measurement Equipment
• Differential ADC Drivers
• Single-Ended-to-Differential Conversion
• Multiplexed Applications