AD7878LP

Overview

The AD7878LP 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 a bipolar analog input range of ±3 V. The device provides a typical signal-to-noise ratio of 72 dB at a 10 kHz input frequency and supports sampling rates up to 100 kHz. Key timing parameters include a maximum data access time of 41 ns and a conversion time of 7 μs. The part is housed in a 28-pin Plastic Leaded Chip Carrier (PLCC) package and functions within an operating temperature range of 0 °C to +70 °C.

Feature Summary

• Integrates an 8-word first-in, first-out memory to reduce software overhead for digital signal processors.
• Includes an on-chip track/hold amplifier, 3 V zener reference, and 12-bit successive approximation ADC.
• Features a versatile DSP interface with fast data access times compatible with high-speed microprocessors.

Applications

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

Procurement Notes

Verify the specific grade suffix against the ordering guide to confirm performance characteristics such as SNR and access time. Ensure the package type matches the design requirements, as the LP suffix denotes a plastic leaded chip carrier. Confirm that the supply voltage rails and clock frequencies align with the absolute maximum ratings to prevent device damage.

Selection Notes

Select this component when interfacing directly with DSPs requiring minimal software intervention for data acquisition. The internal FIFO allows buffering multiple samples before processor servicing. Verify that the required dynamic performance metrics, such as SNR and THD, meet the application specifications within the specified temperature range.

Part Context

The AD7878 belongs to Analog Devices' family of complete ADCs designed for direct DSP interfacing. It utilizes LC2MOS technology to combine precision bipolar circuits with low-power CMOS logic. This architecture enables high-speed conversion while maintaining low power dissipation, making it suitable for battery-operated or thermally constrained systems.

Replacement Considerations

The AD7878LN offers identical electrical specifications and package options but features a faster maximum data access time of 41 ns compared to the standard 57 ns found in other variants like the AD7878JN. Both parts share the same pinout and functional compatibility.