AD7878LN

Overview

The AD7878LN is a complete 12-bit analog-to-digital converter featuring an integrated DSP interface with an 8-word FIFO memory. It operates on dual ±5 V supplies and supports a bipolar input range of ±3 V. The device achieves a signal-to-noise ratio of 72 dB at a 10 kHz input frequency with a 100 kHz sampling rate. Key performance metrics include a maximum data access time of 41 ns, a typical power dissipation of 60 mW, and a conversion time of 7 μs. The operating temperature range for this specific model is 0 °C to +70 °C.

Feature Summary

• Integrated 8-word first-in, first-out (FIFO) memory reduces software overhead by allowing multiple samples to be digitized before processor servicing.
• Versatile DSP interface with fast 41 ns data access time enables direct connection to high-speed digital signal processors and 16-bit microprocessors.
• On-chip track/hold amplifier with 2 μs acquisition time and internal 3 V zener reference simplify circuit design.
• Status/control register provides real-time monitoring of FIFO status, word count, and overrange conditions.

Applications

• Digital Signal Processing
• Speech Recognition and Synthesis
• Spectrum Analysis
• High Speed Modems
• DSP Servo Control

Procurement Notes

Verify the ordering suffix 'LN' corresponds to the plastic DIP package option and the specified 0 °C to +70 °C commercial temperature grade. Confirm that the 41 ns data access time requirement is met, as other variants in the family may offer different timing specifications. Ensure supply voltages match the required ±5 V nominal rails for proper operation.

Selection Notes

Select the AD7878LN when a 41 ns data access time is critical for interfacing with high-speed processors. This variant offers higher dynamic performance (72 dB SNR) compared to the standard J-grade parts. Consider the LCCC or PLCC packages if surface mount technology is preferred over the through-hole DIP format available in this part number.

Part Context

The AD7878 belongs to Analog Devices' LC2MOS family of complete ADCs, combining precision bipolar circuits with low-power CMOS logic. It is designed specifically for applications requiring fast data throughput and minimal processor intervention. The device integrates the track/hold, reference, and A/D converter into a single monolithic chip.

Replacement Considerations

The AD7878LP is a pin-compatible alternative offering the same 72 dB SNR and 41 ns access time but in a Plastic Leaded Chip Carrier package. For lower performance requirements, the AD7878KN provides 72 dB SNR with a 57 ns access time in a DIP package.