AD7878 Datasheet

• Complete ADC with DSP Interface, Comprising:
  - Track/Hold Amplifier with 2 µs Acquisition Time
  - 7 µs A/D Converter
  - 3 V Zener Reference
  - 8-Word FIFO and Interface Logic
• Interfaces to High Speed DSP Processors, e.g., ADSP-2100, TMS32010, TMS32020
• 72 dB SNR at 10 kHz Input Frequency
• 41 ns max Data Access Time
• Low Power, 60 mW typ

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

The AD7878 is a fast, complete, 12-bit A/D converter with a versatile DSP interface consisting of an 8-word, first-in, first-out (FIFO) memory and associated control logic.

The FIFO memory allows up to eight samples to be digitized before the microprocessor is required to service the A/D converter. The eight words can then be read out of the FIFO at maximum microprocessor speed. A fast data access time of 41 ns allows direct interfacing to DSP processors and high speed 16-bit microprocessors.

An on-chip status/control register allows the user to program the effective length of the FIFO and contains the FIFO out of range, FIFO empty and FIFO word count information.

The analog input of the AD7878 has a bipolar range of ±3 V. The AD7878 can convert full power signals up to 50 kHz and is fully specified for dynamic parameters such as signal-to-noise ratio and harmonic distortion.

The AD7878 is fabricated in Linear Compatible CMOS (LC² MOS), an advanced, mixed technology process that combines precision bipolar circuits with low power CMOS logic. The part is available in four package styles, 28-pin plastic and hermetic dual-in-line package (DIP), leadless ceramic chip carrier (LCCC) or plastic leaded chip carrier (PLCC).