AD7878LPZ

Overview

The AD7878LPZ is a complete 12-bit analog-to-digital converter featuring an integrated DSP interface with an 8-word FIFO memory. It operates on ±5 V supplies and accepts bipolar analog inputs within a ±3 V range. The device utilizes LC2MOS technology to achieve a typical power dissipation of 60 mW. Key performance metrics include a signal-to-noise ratio of 72 dB at a 10 kHz input frequency, a maximum data access time of 41 ns, and a conversion time ranging from 7 μs to 9.125 μs depending on bus activity. The unit is housed in a 28-pin Plastic Leaded Chip Carrier (PLCC) package.

Feature Summary

• Integrated 8-word first-in, first-out memory reduces software overhead for servicing interrupts in digital signal processors.
• On-chip track-and-hold amplifier with 2 μs acquisition time ensures accurate sampling of high-frequency signals.
• Built-in 3 V zener reference eliminates the need for external voltage references.
• Status/control register provides real-time monitoring of FIFO occupancy, overrun conditions, and sample validity.

Applications

• Digital Signal Processing systems requiring direct interfacing with high-speed DSPs.
• Speech recognition and synthesis hardware.
• Spectrum analysis equipment.
• High-speed modem implementations.
• DSP-based servo control loops.

Procurement Notes

Verify the specific grade suffix corresponds to the required operating temperature range and dynamic performance specifications. Confirm that the PLCC package variant matches the target PCB footprint and soldering profile requirements. Ensure supply voltages align with the specified ±5 V nominal rails for optimal functionality.

Selection Notes

Select this component when a monolithic solution combining ADC, reference, and FIFO buffering is required for DSP architectures. Consider the 41 ns access time for compatibility with fast microprocessors. Evaluate the 72 dB SNR against system noise floor requirements. Verify that the ±3 V input range suits the application signal levels without additional attenuation.

Part Context

The AD7878 series comprises complete 12-bit sampling ADCs fabricated using Linear Compatible CMOS technology. Variants such as the AD7878JN and AD7878LN offer different trade-offs between speed and accuracy. The LPZ designation specifically denotes the plastic leaded chip carrier package option within the Analog Devices portfolio.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Cross-referencing requires matching the 12-bit resolution, 100 kHz sampling rate, and DSP-compatible interface logic.