AD1555AP

Overview

The AD1555AP is a fourth-order sigma-delta modulator with an integrated programmable gain amplifier (PGA), designed for low-frequency, high-dynamic-range measurement applications. It operates from dual ±5 V analog supplies and a +5 V digital supply. The device features five PGA gain settings (1, 2.5, 8.5, 34, 128) and supports a sampling rate of 256 kSPS. It delivers a typical dynamic range of 120 dB at a 1 kHz output word rate and exhibits low input noise of 80 nV rms at 4 ms with a gain of 34,128. The continuous-time architecture eliminates the need for external antialias filters.

Feature Summary

• Fourth-order sigma-delta modulator with integrated PGA offering gains of 1, 2.5, 8.5, 34, and 128.
• Typical dynamic range of 120 dB at 1 kHz output word rate; minimum 116 dB guaranteed.
• Low input noise performance: 80 nV rms at 4 ms integration time with Gain of 34.
• Robust analog inputs with ±2.25 V full-scale range and high common-mode rejection.

Applications

• Seismic data acquisition systems
• Chromatography instrumentation
• Automatic test equipment

Procurement Notes

Verify component authenticity through authorized channels due to potential availability constraints. Confirm that the specific suffix 'AP' corresponds to the 0°C to 85°C operating temperature range as defined in the ordering guide. Ensure compatibility with the companion AD1556 digital filter/decimator for complete ADC functionality.

Selection Notes

Select the AD1555AP when an industrial temperature range of 0°C to 85°C is sufficient. For wider environmental tolerance, consider the AD1555BP variant specified for –55°C to +85°C. This component requires pairing with the AD1556 FIR digital filter/decimator to realize a complete 24-bit ADC solution.

Part Context

The AD1555 is part of the AD1555/AD1556 chipset family fabricated on Analog Devices’ BiCMOS process. It serves as the analog front-end modulator, while the AD1556 provides the digital filtering and decimation. Together, they form a high-performance system for precision measurements without requiring external antialiasing filters.

Replacement Considerations

The AD1555BP is the direct functional equivalent within the same package, differing only in the extended temperature range specification (–55°C to +85°C vs. 0°C to 85°C). No other cross-model replacements are documented in the provided datasheet.