The MCP3426A0-E/SN: A Precision 18-Bit Delta-Sigma ADC for High-Resolution Measurement Systems

In the realm of data acquisition, the resolution and accuracy of analog-to-digital conversion are paramount. The MCP3426A0-E/SN from Microchip Technology stands out as a highly integrated, single-channel solution designed to meet the demands of precision measurement applications. This device combines an 18-bit delta-sigma ADC, an I2C interface, and a highly stable on-board reference into a single, compact MSOP-8 package, offering designers a powerful tool for simplifying complex system design.

The core of the device is its high-performance delta-sigma modulator. This architecture is renowned for its exceptional noise rejection and inherent linearity, making it ideal for measuring low-frequency, small-magnitude analog signals commonly found in sensor outputs. The ADC provides differential input sampling, which is critical for rejecting common-mode noise in industrial environments, thereby ensuring the integrity of the measured data. With a maximum conversion rate of 15 samples per second (SPS) at 18-bit resolution, it is perfectly suited for applications where precision outweighs the need for high speed.

A significant advantage of the MCP3426A0-E/SN is its high level of integration. The inclusion of a 2.048V internal voltage reference is a key feature. This precision reference, with a typical drift of just 15 ppm/°C, eliminates the need for an external component, saving board space, reducing the bill of materials (BOM) cost, and simplifying the layout. Furthermore, the device incorporates a programmable gain amplifier (PGA) with gains of 1, 2, 4, or 8. This allows the ADC to effectively measure very small input signals—down to microvolts—maximizing the dynamic range and versatility of the system.

Communication is handled via a standard I2C serial interface, which supports multiple device addressing, allowing up to eight MCP3426/7/8 devices to share the same bus. This facilitates the design of multi-channel data acquisition systems without requiring extensive additional hardware. The interface also features a dedicated address pin and an alert function, which can be configured to signal when a conversion is complete or when an input signal exceeds a programmed threshold.

The device operates from a single supply voltage ranging from 2.7V to 5.5V and features extremely low current consumption, making it an excellent choice for battery-powered and portable instruments. Its combination of high resolution, integrated features, and low power consumption makes it ideal for a wide array of applications, including industrial process control, precision sensor measurement (e.g., strain gauges, thermocouples), portable medical devices, and test and equipment.

ICGOODFIND: The MCP3426A0-E/SN is a highly integrated and precise analog-to-digital converter that delivers exceptional performance for low-frequency measurement systems. Its combination of an 18-bit delta-sigma ADC, internal reference, PGA, and I2C interface in a small form factor provides an optimal balance of accuracy, simplicity, and cost-effectiveness for demanding design challenges.

Keywords: 18-Bit ADC, Delta-Sigma Modulator, I2C Interface, On-Board Voltage Reference, Programmable Gain Amplifier (PGA).