Analog Devices Inc. AD7824BQ

Overview

AD7824BQ 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 process monitoring.

For engineers reviewing the AD7824BQ datasheet, AD7824BQ pinout, AD7824BQ application, or AD7824BQ equivalent, key selection considerations include its industrial temperature range (–40°C to +85°C), Q-24 ceramic DIP package, half-flash architecture eliminating external clock requirements, and microprocessor-compatible parallel interface with RD/CS control.

Technical Context

The AD7824BQ employs 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 enables full 8-bit resolution without external timing clocks and supports Mode 0 (WAIT-state) and Mode 1 (non-WAIT) microprocessor interfacing.

Its analog input structure inherently performs sample-and-hold over ~1 µs, allowing accurate digitization of 10 kHz signals (157 mV/µs slew rate) across all four channels without external circuitry. Input leakage is ±3 µA max, and reference inputs are fully differential (VREF(+) and VREF(–)), enabling ratiometric or offset-adjusted operation.

Key Specifications

Pinout & Package

AD7824BQ is supplied 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 facing up.

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 MAX1136, the AD7824BQ provides optimal balance of industrial temperature rating, parallel microprocessor compatibility, integrated track-and-hold, and cost-making it ideal for legacy and new industrial DAQ designs where timing simplicity and proven reliability are prioritized.

Availability

AD7824BQ 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 AD7824BQ 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, founded in 1965 and headquartered in Wilmington, MA.

The AD7824BQ belongs to Analog Devices' LC2MOS high-speed data acquisition product line, designed specifically for cost-sensitive, multichannel industrial systems requiring integrated track-and-hold, simple microprocessor interfacing, and robust operation from –40°C to +85°C.

FAQ

What is the operating temperature range of the AD7824BQ?

The AD7824BQ is rated for industrial operation from –40°C to +85°C. This specification is confirmed in the Ordering Guide section of the official datasheet (REV. F), where "B" denotes the industrial temperature grade and "Q" specifies the 24-lead ceramic DIP package. The device maintains full performance-including ±1 LSB total unadjusted error and 2.5 µs conversion time-across this entire range without derating.

Does the AD7824BQ require an external clock signal?

No, the AD7824BQ does not require an external clock signal. Its half-flash conversion architecture uses internal timing generated by the CS and RD control signals. 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," enabling simpler system timing and reduced external component count compared to SAR or sigma-delta converters.

Can the AD7824BQ perform bipolar input conversions?

Yes, the AD7824BQ supports bipolar operation via external signal conditioning. Its fully differential reference inputs (VREF(+) and VREF(–)) allow offsetting the input range-for example, using an AD544 op amp as shown in Figure 12 of the datasheet to convert ±4 V inputs into the 0 V to 5 V range accepted by the ADC. The output code becomes complementary offset binary, preserving full 8-bit resolution.

What is the function of the RDY and INT pins on the AD7824BQ?

RDY is an open-drain status output that goes low when CS falls and returns to high-impedance when conversion completes-used to assert a microprocessor WAIT state. INT is an interrupt output that goes low upon conversion completion and returns high on the rising edge of CS or RD. Both signals are documented in the Functional Block Diagram and Timing Characteristics tables (REV. F), with RDY requiring an external pull-up resistor.

Is the AD7824BQ pin-compatible with other members of the AD7824/AD7828 family?

Yes, the AD7824BQ shares identical pinout and package (Q-24) with all other AD7824 variants (e.g., AD7824CQ, AD7824TQ). However, it is not pin-compatible with AD7828 variants, which use 28-pin packages (Q-28, N-28, etc.) and include A2 and additional analog inputs. Pin compatibility is confirmed in the Pin Configurations section and Ordering Guide of the datasheet (REV. F).