Industrial and Instrumentation ICs

4.8 kHz, Ultralow Noise, 24-Bit Σ-Δ ADC with PGA Enables Faster Precision Measurement

Σ-Δ ADCs are traditionally used to accurately process very small real-world signals from high sensitivity sensors measuring parameters like temperature, weight, pressure, and flow. Featuring high resolution with low offset and drift, the Σ-Δ ADC has long fulfilled these requirements. However, designers increasingly demand faster speeds to meet market requirements for boosted throughput or an increased number of sensor channels that must be processed in the same amount of time. This requirement must be achieved without sacrificing resolution or dc accuracy.

The new AD7190 Σ-Δ ADC from ADI features an advanced on-chip PGA with ultralow noise and drift from dc to 4.8 kHz. The innovative design of this integrated PGA allows the AD7190 to realize an ultralow noise of only 8.5 nV rms at 4.7 Hz data rate with a gain setting of 128. This performance translates to 20.5 bits of noise-free resolution on an input signal of only ±40 mV. However, unlike other devices on the market, the AD7190 is able to extend this performance into higher speeds. It is the first Σ-Δ ADC to achieve greater than 16-bit noise-free resolution on a ±40 mV input signal beyond 1 kHz data rates. Furthermore, it achieves 16 bits of noise-free resolution at a data rate of 2.4 kHz. Delivering superior noise-free resolution across the widest data rate and input signal range of any Σ-Δ ADC available, the AD7190 offers designers the flexibility to use a single data converter solution in multiple lines of end equipment.

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Application Focus: Weigh Scale

Weigh scale applications require very precise measurement. The typical linear range of the load cell bridge sensor is only 6 mV. Even at such extremely small full-scale input voltages, the AD7190 can still yield greater than 100,000 noise-free counts. The AD7190 also features a switch to power down the bridge during idle time in order to save system power.

"Design Considerations for Industrial Instrumentation and Process Control Systems"

New Family of Precision Analog Microcontrollers Delivers Unequaled Data Acquisition and Processing Performance

The ADuC706x family of ARM7TDMI® microcontrollers, integrated with best-in-class data conversion performance, is ideal for industrial systems engineers designing smart sensing, factory automation, and instrumentation equipment. The ADuC7060 (48-lead, dual ADC), ADuC7061 (32-lead, dual ADC), and ADuC7062 (32-lead, single ADC) incorporate two 24-bit Σ-Δ ADCs and a host of analog peripherals with the ARM7TDMI core to create a solution for precision sensing applications. The integration of a 32-bit RISC MCU, flash memory, and high resolution data converters in a small footprint, combined with low power operation, eliminates the complexity, cost, and performance degradation issues associated with discrete mixed-signal solutions.

Designed to support 4 mA to 20 mA loop-powered applications and precision instrumentation, these 24-bit Σ-Δ ADCs provide the resolution required by high performance industrial and instrumentation equipment, while keeping the noise low at just 60 nV. This performance, combined with an ARM7TDMI core, provides a single-chip solution that can handle all data acquisition, processing, and communications functions at the sensor node. In addition, the ADuC706x products integrate 32 kB flash memory and 4 kB SRAM, a 14-bit DAC, multiplexers, buffers, an 8-channel auxiliary ADC, and a 24-bit ADC for cold junction compensation and interfacing to thermocoupler applications. Also integrated are SPI, UART, and I2C® ports. Operating current is just 2.6 mA with all peripherals activated.

ADuC7061 ADuC7060


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