Analog Devices Inc. AD7824CQ

Overview

AD7824CQ 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, ±1/2 LSB total unadjusted error, and 2.5 µs per-channel conversion time. It digitizes 0 V to 5 V analog inputs at up to 100 kHz per channel and is used in multichannel data acquisition systems for industrial process monitoring.

For engineers reviewing the AD7824CQ datasheet, AD7824CQ pinout, AD7824CQ application, or AD7824CQ equivalent, key selection factors include its industrial temperature range (–40°C to +85°C), Q-24 ceramic DIP package, no external clock requirement, microprocessor-compatible RD/CS interface, and guaranteed no missing codes over full 8-bit resolution.

Technical Context

The AD7824CQ employs a half-flash architecture using two 4-bit flash ADCs-one for MSBs and one for LSBs-combined with an internal 4-bit DAC to reconstruct and subtract the MSB analog approximation. This eliminates need for external clocking and enables deterministic 2.5 µs conversion time per selected channel.

It features a fully differential reference input (VREF(+) and VREF(–)) enabling ratiometric operation and programmable input span, while its analog input structure inherently provides 1 µs track-and-hold capability with 157 mV/µs slew rate support-sufficient for 10 kHz full-scale sinusoidal signals without external sample-hold circuitry.

Key Specifications

Pinout & Package

AD7824CQ is housed in a 24-lead hermetic ceramic dual-in-line package (Q-24), 0.3" wide, with 0.1" lead pitch and flat leads. Pin 1 identifier located at top-left corner when viewed from top with notch or dot oriented left.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7824LN and MAX1244ACPP+, the AD7824CQ uniquely combines industrial temperature rating, parallel microprocessor interface, no-clock operation, and guaranteed ±1/2 LSB error in a single Q-24 package-making it optimal for ruggedized embedded data acquisition where deterministic timing and thermal reliability are essential.

Availability

AD7824CQ is available at Aetrix Electronics and suitable for industrial process monitoring, motor control feedback, and test & measurement equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7824CQ 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 AD7824CQ belongs to Analog Devices' legacy LC2MOS precision data acquisition product line, designed specifically for cost-sensitive, microprocessor-based multichannel systems needing fast, reliable 8-bit conversion without external timing or support circuitry.

FAQ

What is the operating temperature range of the AD7824CQ?

The AD7824CQ is rated for industrial operation from –40°C to +85°C. This specification is confirmed in the Ordering Guide section of the AD7824/AD7828 datasheet Rev. F, where "C" grade denotes the –40°C to +85°C range and "Q" package indicates the 24-lead ceramic DIP. The device maintains all specified performance parameters-including ±1/2 LSB total unadjusted error and 2.5 µs conversion time-across this full range.

Does the AD7824CQ require an external clock signal to operate?

No, the AD7824CQ does not require an external clock signal. Its half-flash conversion architecture uses internal timing control driven solely by the RD and CS strobes. As stated in the General Description: "The half-flash conversion technique means that there is no need to generate a clock signal for the ADC." This eliminates clock distribution noise and simplifies interface design with microprocessors like the Z80 or MC68000.

How many analog input channels does the AD7824CQ support?

The AD7824CQ supports exactly four single-ended analog input channels: AIN1 through AIN4. This is explicitly defined in the Functional Block Diagram ("*AD7824 – 4-CHANNEL MUX"), Pin Configurations diagram (showing AIN1–AIN4 on pins 1–4), and Ordering Guide (model prefix AD7824, distinct from AD7828 for eight channels). Addressing is performed via A0 and A1 pins.

What package type is used for the AD7824CQ?

The AD7824CQ is supplied in a 24-lead hermetic ceramic dual-in-line package designated Q-24. Per the Ordering Guide, "CQ" suffix indicates the C-grade temperature range and Q-24 package. Outline dimensions are provided in the datasheet Rev. F on page 11, confirming 0.3" body width, 0.1" lead pitch, and flat-lead construction compliant with JEDEC MO-095AG.

Can the AD7824CQ interface directly with a Z80 microprocessor?

Yes, the AD7824CQ interfaces directly with the Z80 microprocessor in Mode 0 operation. As shown in Figure 16 of the datasheet, the RDY output connects to the Z80 WAIT input, and CS/RD are tied to MREQ and RD lines. A memory-read instruction (e.g., LD B, (C000)) initiates conversion and reads result automatically-no glue logic or timing adjustments needed beyond a 5 kΩ pull-up on RDY.