Analog Devices Inc. AD7828KNZ

Overview

AD7828KNZ 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 LSB total unadjusted error, and 2.5 µs per-channel conversion time. It digitizes 0 V to 5 V analog inputs across eight multiplexed channels and is used in real-time speech analysis, multichannel data acquisition, and industrial sensor monitoring systems.

For engineers reviewing the AD7828KNZ datasheet, AD7828KNZ pinout, AD7828KNZ application, or AD7828KNZ equivalent, this page delivers verified technical context, package-specific pin functions, confirmed timing behavior in Mode 0/1, exact channel selection logic (A2/A1/A0), and validated alternative parts for legacy system upgrades and supply continuity planning.

Technical Context

The AD7828KNZ implements 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. This eliminates need for external clock generation and enables deterministic 2.5 µs conversion time per selected channel.

It supports two microprocessor interface modes: Mode 0 uses RDY/INT to assert WAIT/DTACK, while Mode 1 latches address on RD rising edge and returns prior conversion result. Channel selection is controlled by A2/A1/A0 (000–111) for AIN1–AIN8, with no internal pull-ups on address lines.

Key Specifications

Pinout & Package

AD7828KNZ is packaged in a 28-lead plastic DIP (N-28), 0.6" wide, with 0.1" lead pitch and through-hole mounting. Pin 1 identifier is located at top-left corner when notch faces upward.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7828LNZ, AD7828KNZ trades 0.5 LSB accuracy for lower cost and broader availability; compared with MAX195BCPP, it delivers plug-and-play 8-channel operation without clock management or external S/H, making it optimal for legacy microprocessor-based designs requiring deterministic timing and minimal footprint.

Availability

AD7828KNZ is available at Aetrix Electronics and suitable for industrial PLC I/O modules, medical patient monitors, speech analysis systems, and test & measurement equipment requiring stable component supply and long-term obsolescence management.

Supply support for AD7828KNZ 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 AD7828KNZ belongs to Analog Devices' legacy LC2MOS precision data acquisition family, designed specifically for cost-sensitive, microprocessor-centric industrial and instrumentation systems requiring multichannel 8-bit conversion without external timing or hold circuitry.

FAQ

What is the maximum analog input frequency supported by the AD7828KNZ without external sample-and-hold?

The AD7828KNZ supports full-scale sinusoidal inputs up to 10 kHz across all eight channels without external sample-and-hold circuitry. This is enabled by its inherent track-and-hold function, which stabilizes the input for ~1 µs after conversion start. The 157 mV/µs slew rate specification ensures 1/2 LSB stability during that window, meeting rated accuracy for signals within this bandwidth.

Does the AD7828KNZ require an external clock signal to operate?

No, the AD7828KNZ does not require an external clock signal. Its half-flash conversion architecture uses internal timing circuitry to complete each 8-bit conversion in 2.5 µs deterministically. Only standard microprocessor control signals - CS and RD - are needed to initiate conversion and read data, simplifying system-level timing design.

How does the AD7828KNZ handle channel selection and address latching?

The AD7828KNZ uses three address inputs - A2, A1, and A0 - to select among its eight analog inputs (AIN1–AIN8). In Mode 0, addresses must remain stable while CS and RD are low; in Mode 1, the address is latched on the rising edge of RD. The truth table in the datasheet confirms binary mapping: A2A1A0 = 000 selects AIN1, 001 selects AIN2, up to 111 for AIN8.

What are the voltage ranges allowed on the VREF(+) and VREF(–) pins of the AD7828KNZ?

VREF(+) accepts 0 V to VDD + 0.3 V (i.e., up to 5.3 V), and VREF(–) accepts 0 V to VREF(+) - meaning the differential reference span can be set from near-zero up to 5 V. For example, setting VREF(+) = 2.5 V and VREF(–) = 0 V yields a 2.5 V full-scale range and 9.8 mV/LSB resolution, enabling ratiometric or offset-adjusted measurements.

Can the AD7828KNZ operate in bipolar input mode, and how is it configured?

Yes, the AD7828KNZ supports bipolar operation via external op-amp conditioning - such as the AD544 shown in Figure 12 - which shifts and scales the input to fit the 0 V to 5 V unipolar input range. With ±4 V input and appropriate resistor network, the device delivers complementary offset binary output with 31.25 mV/LSB resolution, preserving its native 8-bit accuracy and timing behavior.