Analog Devices Inc. AD7828LN

Overview

AD7828LN from Analog Devices is an 8-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, 2.5 µs per-channel conversion time, and 0 V to 5 V unipolar input range. It serves as a multichannel data acquisition front-end in real-time signal monitoring systems requiring simultaneous sampling of up to eight analog sensors.

For engineers reviewing the AD7828LN datasheet, AD7828LN pinout, AD7828LN application, or AD7828LN equivalent, key selection criteria include channel count (8), conversion speed (2.5 µs/channel), accuracy grade (±1/2 LSB), interface compatibility with Z80/MC68000/TMS32010 microprocessors, and DIP-28 package availability for through-hole prototyping and industrial control boards.

Technical Context

The AD7828LN 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 approximation, enabling full 8-bit resolution without external clocking. Its analog input structure inherently performs sample-and-hold over ~1 µs, supporting 10 kHz full-scale sinusoidal inputs (157 mV/µs slew rate) across all channels.

Digital control uses CS and RD signals to initiate conversions and read data via three-state DB0–DB7 outputs; status is signaled via open-drain RDY (for WAIT-state microprocessors) and active-low INT outputs. Addressing is performed via A0–A2 inputs, selecting among eight analog inputs (AIN1–AIN8) in binary order.

Key Specifications

Pinout & Package

AD7828LN is supplied in a 28-pin plastic dual-in-line package (PDIP, N-28), 0.6" wide, with 0.1" lead pitch and through-hole mounting. Pin 1 identifier is marked by notch or dot; pin 14 is GND, pin 15 is VREF(–), pin 16 is VREF(+), pin 28 is CS, and pin 27 is RD.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7828KN, AD7828LN offers tighter accuracy (±1/2 LSB) at identical speed and package, while MAX195BCPP trades channel count and integration for resolution-making AD7828LN optimal for cost-sensitive, space-constrained 8-channel 8-bit acquisition where ±1/2 LSB linearity is required.

Availability

AD7828LN is available at Aetrix Electronics and suitable for industrial data loggers, medical instrumentation, speech analysis systems, and test & measurement equipment requiring stable component supply and long-term obsolescence management.

Supply support for AD7828LN 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, communications, automotive, and healthcare markets since 1965.

The AD7828LN belongs to the AD7824/AD7828 family of LC2MOS high-speed multichannel ADCs, designed specifically for microprocessor-based data acquisition systems needing integrated track-and-hold, simple digital interfacing, and low-power 8-bit conversion in compact DIP packages.

FAQ

What is the maximum input signal frequency the AD7828LN can accurately digitize without external sample-and-hold?

The AD7828LN can accurately digitize full-scale sinusoidal inputs up to 10 kHz (157 mV/µs slew rate) across all eight channels without external sample-and-hold, thanks to its inherent track-and-hold function that stabilizes the input for ~1 µs after conversion start. This capability is confirmed in the datasheet's "INHERENT SAMPLE-HOLD" section and validated by TPC 3 (SNR vs. Input Frequency).

Does the AD7828LN require an external clock signal to operate?

No, the AD7828LN does not require an external clock signal. Its half-flash conversion architecture self-times the process using internal timing circuitry; only CS and RD control signals are needed to initiate conversion and read data. This eliminates clock distribution challenges and reduces system-level timing constraints, as explicitly stated in the "GENERAL DESCRIPTION" and "PRODUCT HIGHLIGHTS" sections.

What are the operating temperature limits and accuracy specification for the AD7828LN?

The AD7828LN is rated for commercial operation from 0°C to 70°C and guarantees ±1/2 LSB total unadjusted error across this range. This specification includes offset, full-scale, and linearity errors, and is confirmed in the "SPECIFICATIONS" table under "L Version" column. The device also supports extended temperature grades (e.g., AD7828CQ) but AD7828LN itself is strictly 0°C to 70°C.

Can the AD7828LN interface directly with a Z80 microprocessor, and how is timing managed?

Yes, the AD7828LN interfaces directly with the Z80 microprocessor in Mode 0 using its RDY output to assert the WAIT input, extending instruction cycles until conversion completes. As shown in Figure 16 and described in "MICROPROCESSOR INTERFACING", the Z80 executes LD B,(C000) to trigger conversion and read result, with RDY automatically managing timing synchronization-no additional wait-state logic is required for AD7828LN operation.

What package type and pin count does the AD7828LN use, and is it RoHS-compliant?

The AD7828LN uses a 28-pin plastic dual-in-line package (PDIP, N-28) with 0.6" body width and 0.1" lead pitch. While the original datasheet predates RoHS legislation, current production lots of AD7828LN are manufactured as RoHS-compliant per Analog Devices' product change notifications; legacy non-RoHS versions are obsolete and not distributed by Aetrix Electronics.