Analog Devices Inc. AD7878KPZ

Overview

AD7878KPZ from Analog Devices is a complete 12-bit, 100 kHz sampling analog-to-digital converter with integrated track/hold amplifier, on-chip 3 V Zener reference, and 8-word FIFO for DSP interfacing. It delivers 72 dB SNR at 10 kHz input, 41 ns data access time, and ±3 V bipolar analog input range - designed for high-speed digitization in real-time signal processing systems.

For engineers reviewing the AD7878KPZ datasheet, AD7878KPZ pinout, AD7878KPZ application, or AD7878KPZ equivalent, this page provides verified technical context, pin-level design meaning, FIFO-controlled throughput behavior, dynamic performance boundaries, and validated alternative options for DSP-adjacent ADC selection.

Technical Context

The AD7878KPZ implements a successive approximation register (SAR) ADC core with asynchronous CONVST triggering and internal clock division (÷4) for bit-trial timing. Its 8-word FIFO operates as a first-in, first-out buffer with programmable almost-full threshold (1–8 words) and status/control register accessible via ADD0-high reads/writes.

It features dual-ground architecture (AGND/DGND), triple-supply operation (+5 V VDD/VCC, –5 V VSS), and TTL-compatible digital I/O with 41 ns data access time - enabling direct interface to ADSP-2100, TMS32010, and other high-speed 16-bit DSPs without glue logic.

Key Specifications

Pinout & Package

AD7878KPZ is supplied in a 28-pin plastic leaded chip carrier (PLCC) package with gull-wing leads, RoHS-compliant finish, and 11.43 mm × 11.43 mm body size. Thermal resistance θ_JA = 50°C/W (typical).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit DSP-interfaced ADC applications.

Compared with AD7878KPZ, AD7874KPZ omits FIFO and degrades timing (100 ns vs. 41 ns), increasing DSP interrupt load; ADS8320U trades parallel bus simplicity for 16-bit resolution but introduces SPI protocol overhead and eliminates direct memory-mapped access - making AD7878KPZ uniquely balanced for deterministic, high-throughput DSP acquisition.

Availability

AD7878KPZ is available at Aetrix Electronics and suitable for digital signal processing, speech recognition systems, and spectrum analysis equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7878KPZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide.

The AD7878KPZ belongs to Analog Devices' LC2MOS precision ADC family, engineered specifically for real-time DSP integration - emphasizing FIFO-assisted throughput, asynchronous sampling integrity, and guaranteed dynamic performance in embedded signal acquisition.

FAQ

What is the guaranteed SNR performance of the AD7878KPZ at 10 kHz input frequency?

The AD7878KPZ guarantees a minimum 72 dB signal-to-noise ratio at 10 kHz input frequency under specified conditions (VDD/VCC = +5 V ±5%, VSS = –5 V ±5%, fCLK = 8 MHz, T = 0°C to +70°C). This value is measured with a full-scale sine wave and includes all noise and distortion components - confirming its suitability for high-fidelity speech and audio digitization where effective resolution exceeds 11.6 bits.

Does the AD7878KPZ require an external reference voltage?

No, the AD7878KPZ integrates a precision 3 V Zener reference output (REF OUT) with ±10 mV error at 25°C and ±15 mV over its full operating temperature range. The reference supports up to 500 µA load current and is internally used for ADC conversion - eliminating the need for external reference ICs unless higher accuracy or lower drift is required beyond the AD7878KPZ's specification.

How does the FIFO in the AD7878KPZ reduce software overhead in DSP applications?

The AD7878KPZ's 8-word FIFO allows up to eight consecutive conversions to be stored before the DSP must read data - reducing interrupt frequency by up to 8× compared to single-sample-per-interrupt architectures. Combined with the ALFL (almost-full) flag and programmable threshold (1–8 words), it enables deterministic, low-latency servicing that aligns with DSP instruction cycles - critical for real-time servo control and FFT-based processing.

What is the function of the BUSY signal on the AD7878KPZ, and how should it be used?

The BUSY signal on the AD7878KPZ goes low upon assertion of CONVST and remains low until the track/hold enters hold mode - indicating active conversion. It can be used to gate CS for extended read/write operations or to disable outputs (via DB5 in status register) during critical sampling intervals. This prevents bus transients from corrupting the held analog value - ensuring sampling integrity in high-jitter-sensitive applications like spectrum analysis.

Is the AD7878KPZ compatible with modern 16-bit microprocessors such as the MC68000?

Yes, the AD7878KPZ is explicitly designed for compatibility with 16-bit microprocessors including the MC68000. Its 41 ns data access time, TTL-compatible inputs/outputs, and control signal mapping (DMWR ≡ R/W, DMRD ≡ DEN) allow direct memory-mapped connection without wait-state insertion or level translation. The device's timing specifications are fully tested across temperature, ensuring robust operation in industrial embedded systems using such processors.