AD1555APZ

Overview

The AD1555APZ is a fourth-order sigma-delta modulator with an integrated programmable gain amplifier (PGA), packaged in a 28-lead PLCC. It operates from ±5 V analog supplies and a +5 V digital supply, dissipating 77 mW typically at 0°C to 85°C. The device features a continuous-time input architecture eliminating external antialias filters, supporting differential inputs up to ±2.25 V. Key electrical parameters include a typical dynamic range of 120 dB at 1 kHz output rate, 120 dB typical total harmonic distortion, and 122 dB intermodulation distortion. It provides five PGA gain settings (1, 2.5, 8.5, 34, 128) and outputs a ones-density bitstream for use with the companion AD1556 digital filter.

Feature Summary

• Fourth-order sigma-delta modulator with low noise PGA offering gains of 1, 2.5, 8.5, 34, and 128
• Continuous-time input architecture removes the need for external antialias filtering
• High dynamic range performance: 120 dB typical at 1 kHz output word rate
• Low power consumption of 77 mW typical with standby and power-down modes

Applications

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

Procurement Notes

Verify component authenticity through authorized Analog Devices distributors or direct channels. Confirm the specific AP suffix indicates the 0°C to 85°C operating temperature range. Check for RoHS compliance status and moisture sensitivity level requirements during storage and soldering. Ensure the package matches the 28-lead PLCC specification.

Selection Notes

Select the AD1555APZ when an operating temperature range of 0°C to 85°C is sufficient; use the BP variant for –55°C to +85°C operation. This component functions as a modulator and requires the AD1556 digital filter/decimator to form a complete 24-bit ADC system. Consider the required PGA gain settings and output data rates when designing the signal chain.

Part Context

The AD1555 is part of the AD1555/AD1556 chipset designed for high dynamic range, low-frequency measurement applications. It is fabricated on Analog Devices' BiCMOS process. The AP suffix denotes the commercial temperature grade (0°C to 85°C), while the BP suffix denotes the industrial grade (–55°C to +85°C). Both share identical electrical specifications but differ in environmental testing limits.

Replacement Considerations

The AD1555BP serves as the industrial temperature grade equivalent within the same family. No other direct cross-model replacements are documented in the provided datasheet.