Analog Devices Inc. AD7824KNZ

Overview

AD7824KNZ from Analog Devices is a 4-channel, 8-bit LC2MOS successive-approximation analog-to-digital converter with built-in track-and-hold, single 5 V supply operation, ±1 LSB total unadjusted error, and 2.5 µs per-channel conversion time. It digitizes 0 V to 5 V analog inputs across four multiplexed channels and is used in real-time data acquisition systems for industrial process monitoring.

For engineers reviewing the AD7824KNZ datasheet, AD7824KNZ pinout, AD7824KNZ application, or AD7824KNZ equivalent, key selection criteria include its 4-channel multiplexing capability, no-external-clock half-flash architecture, 10 kHz full-scale signal handling, 24-pin PDIP package compatibility, and direct interface with Z80 and MC68000 microprocessors without WAIT-state logic.

Technical Context

The AD7824KNZ implements a half-flash conversion architecture using two 4-bit flash ADCs - one for MSBs and one for LSBs - with an internal 4-bit DAC bridging them. This eliminates the need for an external conversion clock and enables deterministic 2.5 µs conversion timing per selected channel.

It features a fully differential reference input (VREF(+) and VREF(–)) enabling ratiometric operation and offset-adjustable unipolar or bipolar input ranges. Its analog input structure inherently provides sample-and-hold functionality, allowing stable digitization of signals with up to 157 mV/µs slew rate without external circuitry.

Key Specifications

Pinout & Package

AD7824KNZ is packaged in a 24-lead plastic dual-in-line package (PDIP, N-24), 0.3" wide, with 0.1" lead pitch and through-hole mounting. Pin 1 identifier is a notch on the top edge.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel, 8-bit ADC applications.

Compared with AD7824LNZ, AD7824KNZ trades 0.5 LSB accuracy for lower cost and broader commercial temperature tolerance; compared with MAX1136CPE+, it offers parallel interface simplicity and integrated track-and-hold but lacks SPI flexibility.

Availability

AD7824KNZ is available at Aetrix Electronics and suitable for industrial process monitoring, embedded data loggers, real-time speech analysis, and motor control feedback interfaces requiring stable component supply and long-term obsolescence management.

Supply support for AD7824KNZ 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7824KNZ belongs to Analog Devices' legacy LC2MOS precision data acquisition product line, designed specifically for cost-sensitive, microprocessor-integrated multichannel measurement systems requiring speed, simplicity, and reliability.

FAQ

What is the maximum analog input frequency supported by the AD7824KNZ without external sample-and-hold?

The AD7824KNZ supports full-scale analog input frequencies up to 10 kHz without external sample-and-hold circuitry due to its inherent track-and-hold function. This is validated by its 157 mV/µs slew rate specification and 2.5 µs conversion time. The AD7824KNZ achieves this by internally sampling the selected channel for ~1 µs after conversion start, capturing the instantaneous value for accurate 8-bit digitization - critical for real-time industrial monitoring where signal integrity must be preserved across all four channels.

Does the AD7824KNZ require an external clock signal for conversion?

No, the AD7824KNZ does not require an external clock signal. Its half-flash architecture uses two internal 4-bit flash ADCs and an integrated 4-bit DAC to complete each 8-bit conversion deterministically in 2.5 µs per channel. This eliminates clock routing, jitter concerns, and external timing components - a key advantage of the AD7824KNZ over SAR or sigma-delta ADCs in noise-sensitive or space-constrained designs.

What are the logic voltage levels compatible with the AD7824KNZ digital interface?

The AD7824KNZ accepts TTL/CMOS-compatible logic levels: VINH ≥ 2.4 V and VINL ≤ 0.8 V for inputs (CS, RD, A0, A1), and delivers VOH ≥ 4.0 V (at 360 µA source) and VOL ≤ 0.4 V (at 1.6 mA sink) on outputs (DB0–DB7, INT). These levels ensure robust interoperability with legacy 5 V microprocessors like Z80 and MC68000 - a defining feature of the AD7824KNZ's system integration advantage.

Can the AD7824KNZ operate with a reference voltage less than 5 V?

Yes, the AD7824KNZ supports fully differential reference inputs (VREF(+) and VREF(–)), enabling operation with any reference span from 1 V to 5 V. For example, using a 2.5 V reference yields 1 LSB = 9.77 mV, increasing resolution for low-amplitude signals. This flexibility - confirmed in the AD7824KNZ datasheet's "REFERENCE AND INPUT" section - allows ratiometric sensing and offset-adjusted unipolar/bipolar configurations without hardware changes.

What package type is used for the AD7824KNZ and is it RoHS-compliant?

The AD7824KNZ is supplied in a 24-lead plastic dual-in-line package (PDIP, N-24), 0.3" wide, with through-hole leads. While the original AD7824KNZ is a legacy part introduced before RoHS compliance mandates, Analog Devices confirms that the KNZ suffix denotes a Pb-free (RoHS-compliant) variant per manufacturer documentation - verified via Analog Devices' official product change notices and packaging specifications for the AD7824 family.