Analog Devices Inc. AD7824TQ

Overview

AD7824TQ from Analog Devices is a 4-channel, 8-bit LC2MOS successive-approximation analog-to-digital converter with built-in track/hold, single 5 V supply operation, ±1 LSB total unadjusted error, and 2.5 µs per-channel conversion time. It digitizes full-scale 10 kHz signals (157 mV/µs slew rate) across all inputs and is qualified for extended temperature operation from –55°C to +125°C.

For engineers reviewing the AD7824TQ datasheet, AD7824TQ pinout, AD7824TQ application, or AD7824TQ equivalent, this page delivers verified technical context, package-specific pin functions, real-world use cases in harsh-environment data acquisition, and validated alternative options for military-grade embedded systems.

Technical Context

The AD7824TQ implements 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 approximation from the input, enabling 8-bit resolution without external clocking. Its analog input structure inherently performs sample-and-hold over ~1 µs after conversion start.

Digital interface relies solely on CS and RD control lines with no external clock required; Mode 0 supports WAIT-state microprocessors via open-drain RDY, while Mode 1 enables non-WAIT operation using INT for completion signaling. Address decoding uses A0/A1 for 4-channel selection, with no A2 pin present.

Key Specifications

Pinout & Package

AD7824TQ is supplied in a 24-lead Cerdip (Q-24) hermetic ceramic DIP package, 0.3" wide, with lead finish compliant with MIL-M-38510 requirements. Pin 1 is identified by dot or notch; leads are tin/lead plated or solder dipped.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7824CQ and AD7824BQ, the AD7824TQ uniquely provides guaranteed operation down to –55°C and is processed to /883B standards-making it the only option qualified for full-spectrum military environmental testing without derating.

Availability

AD7824TQ is available at Aetrix Electronics and suitable for avionics sensor acquisition, missile guidance conditioning, undersea sonar digitization, and nuclear reactor monitoring requiring stable component supply across extended temperature ranges and long lifecycle commitments.

Supply support for AD7824TQ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Wilmington, MA.

The AD7824TQ belongs to the AD7824/AD7828 family of LC2MOS high-speed multichannel ADCs, designed specifically for ruggedized embedded systems demanding integrated track/hold, single-supply operation, and extended temperature reliability.

FAQ

What is the maximum analog input frequency supported by the AD7824TQ without an external sample-and-hold?

The AD7824TQ supports full-scale analog input frequencies up to 10 kHz without external sample-and-hold circuitry. This capability stems from its inherent track/hold function, which stabilizes the selected input for ~1 µs after conversion initiation. At 157 mV/µs slew rate, the device maintains ±1/2 LSB accuracy across all four channels within this bandwidth, as confirmed in the AD7824/AD7828 datasheet TPC 3 and General Description section.

Does the AD7824TQ require an external clock signal to operate?

No, the AD7824TQ does not require an external clock signal. Its half-flash conversion architecture uses two internal 4-bit flash ADCs and an integrated 4-bit DAC to generate the full 8-bit result in 2.5 µs per channel. Timing is controlled entirely by the CS and RD digital inputs, with no clock pin or external oscillator needed-enabling simpler, more robust system designs.

What is the meaning of the "T" suffix in AD7824TQ, and how does it affect qualification?

The "T" suffix in AD7824TQ denotes the extended temperature grade (–55°C to +125°C), and the "Q" indicates the 24-lead Cerdip hermetic package. Per the Ordering Guide, AD7824TQ is available to MIL-STD-883B processing only, meaning it undergoes military-level screening including burn-in, temperature cycling, and hermeticity testing-unlike commercial (K/L) or industrial (B/C) variants.

Can the AD7824TQ perform bipolar input measurements?

Yes, the AD7824TQ supports bipolar operation through external signal conditioning. Its fully differential reference inputs (VREF(+) and VREF(–)) allow offsetting the zero-scale point-for example, using an AD544 op amp as shown in Figure 12 to accept ±4 V inputs. The resulting output uses complementary offset binary coding, with 1 LSB = 31.25 mV, enabling true bipolar digitization without modifying the AD7824TQ itself.

How does the RDY pin function in Mode 0 versus Mode 1 operation of the AD7824TQ?

In Mode 0, RDY is an open-drain status output that goes high-impedance at conversion completion, allowing it to drive a microprocessor WAIT input directly (e.g., Z80 or MC68000). In Mode 1, RDY provides no valid status and must be tied to GND, as conversion completion is signaled solely by the INT output. This distinction is critical for correct timing integration and is defined in Figures 14 and 15 of the AD7824/AD7828 datasheet.