Analog Devices Inc. AD7824KR

Overview

AD7824KR from Analog Devices is a 4-channel, 8-bit LC2MOS 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 at up to 100 kHz per channel and is used in multichannel data acquisition systems for industrial monitoring and real-time signal analysis.

For engineers reviewing the AD7824KR datasheet, AD7824KR pinout, AD7824KR application, or AD7824KR equivalent, key selection considerations include its 24-pin SOIC (R-24) package, Mode 0/Mode 1 microprocessor interface flexibility, 10 kHz full-scale sinusoidal input handling, and differential reference support enabling ratiometric or bipolar configurations without external sample-and-hold circuitry.

Technical Context

The AD7824KR employs a half-flash architecture using two 4-bit flash ADCs-one for MSBs and one for LSBs-with an internal 4-bit DAC bridging them. Its analog input structure inherently provides track-and-hold functionality for up to 1 µs after conversion start, eliminating need for external S/H in many applications.

Digital control uses Chip Select (CS) and Read (RD) signals only-no external clock required. It supports two timing modes: Mode 0 (WAIT-state microprocessors like Z80/MC68000) and Mode 1 (non-WAIT systems like TMS32010), with address latching on rising RD edge in Mode 1 and RDY/INT status outputs for synchronization.

Key Specifications

Pinout & Package

AD7824KR is packaged in a 24-lead SOIC (R-24) surface-mount package, 15.6 mm × 7.6 mm body size, 1.27 mm lead pitch, with gull-wing leads and standard JEDEC MS-013AD outline.

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 MAX1136, AD7824KR delivers optimal balance of cost, speed, and integrated functionality-its half-flash architecture eliminates clock dependency and built-in track-and-hold ensures accurate 10 kHz signal capture without additional components, making it ideal for compact, real-time embedded data loggers.

Availability

AD7824KR is available at Aetrix Electronics and suitable for industrial data acquisition, real-time speech analysis, embedded instrumentation, and motor control feedback requiring stable component supply and long-term design continuity.

Supply support for AD7824KR 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 AD7824KR belongs to the AD7824/AD7828 family of high-speed multichannel ADCs designed specifically for space-constrained, microprocessor-based data acquisition systems needing integrated track-and-hold and simple parallel interfacing.

FAQ

What is the operating temperature range of the AD7824KR?

The AD7824KR is rated for commercial temperature operation from 0°C to +70°C. This range is defined by its K-grade qualification and applies across all specified electrical parameters-including conversion time, total unadjusted error (±1 LSB), and power supply sensitivity-without derating. The device uses LC2MOS process technology optimized for stability within this ambient envelope.

Does the AD7824KR require an external clock signal to operate?

No, the AD7824KR does not require an external clock signal. Its half-flash conversion architecture generates internal timing for both the 4-bit MSB and LSB flash ADC stages. Conversion is initiated solely by asserting CS and RD low (Mode 0) or latching address on RD rising edge (Mode 1). This eliminates clock distribution, jitter concerns, and associated layout complexity in microprocessor systems.

Can the AD7824KR interface directly with a Z80 microprocessor?

Yes, the AD7824KR interfaces directly with the Z80 microprocessor in Mode 0. When mapped to a memory address (e.g., C000H), a LD instruction triggers CS and RD low, initiating conversion and placing the result in the target register upon completion. The RDY output connects to the Z80 WAIT input, extending the instruction cycle automatically until conversion finishes-no software polling or wait states required.

What is the maximum analog input source impedance supported by the AD7824KR?

The AD7824KR specifies a maximum recommended analog input source impedance of 100 Ω. This limit arises from its equivalent input RC network-31 pF of comparator capacitance charged through ~3–6 kΩ analog switch resistance-and ensures full 1/2 LSB accuracy during the ~1 µs tracking window. Exceeding 100 Ω increases settling error and degrades linearity, especially at full-scale 10 kHz inputs.

How does the AD7824KR handle bipolar input signals?

The AD7824KR supports bipolar operation via its fully differential reference inputs (VREF(+) and VREF(–)). By setting VREF(–) to 2.5 V and VREF(+) to 5 V, the input range becomes 2.5 V to 5 V, which maps to complementary offset binary codes representing ±4 V when conditioned by an external op amp (e.g., AD544). The device itself outputs natural binary; external signal conditioning establishes the bipolar transfer characteristic.