AD7878JNZ

Overview

The AD7878JNZ 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 achieves a sampling rate of 100 kS/s with a typical power dissipation of 60 mW. Key performance metrics include a Signal-to-Noise Ratio (SNR) of 70 dB at a 10 kHz input frequency and a maximum data access time of 57 ns. The component utilizes a successive approximation architecture and includes an internal 3 V reference.

Feature Summary

• Integrated 8-word first-in, first-out (FIFO) memory reduces software overhead for servicing interrupts in digital signal processors.
• Versatile DSP interface logic allows direct connection to high-speed processors such as the ADSP-2100 and TMS320 series.
• On-chip track/hold amplifier and 3 V zener reference eliminate the need for external precision components.
• Status/control register provides real-time monitoring of FIFO occupancy, overrun conditions, and sample validity.

Applications

• Digital Signal Processing systems requiring fast data acquisition.
• Speech recognition and synthesis hardware.
• Real-time spectrum analysis equipment.
• High-speed modem implementations.
• DSP-based servo control loops.

Procurement Notes

Verify the specific suffix JNZ corresponds to the plastic DIP package variant with the 0°C to +70°C operating temperature range. Confirm that the SNR specification aligns with the 70 dB minimum requirement for this grade. Ensure supply voltages match the required ±5 V nominal rails with ±5% tolerance for specified performance.

Selection Notes

Select this model when interfacing directly with DSPs requiring a dedicated FIFO buffer to manage data throughput without excessive CPU intervention. Choose this part over standard ADCs if the application demands a built-in reference and track/hold stage to simplify the analog front-end design. Verify that the 57 ns access time meets the timing constraints of the target microprocessor bus.

Part Context

The AD7878 belongs to Analog Devices' LC2MOS family of complete A/D converters. This technology combines precision bipolar circuits with low-power CMOS logic to achieve high speed and low power consumption. The device is designed specifically to bridge the gap between analog signal conditioning and digital processing, reducing system complexity in high-performance data acquisition applications.

Replacement Considerations

The AD7878LN offers a faster 41 ns data access time while maintaining similar functionality. For military specifications, the AD7878SE4 provides extended temperature range capabilities. Direct pin-compatible alternatives within the same family should be evaluated based on required access speed and environmental operating limits.