Analog Devices Inc. AD7868ANZ

Overview

AD7868ANZ from Analog Devices is a complete, single-chip 12-bit analog I/O system integrating a successive-approximation ADC with track-and-hold amplifier and a voltage-output DAC with buffered amplifier - both sharing on-chip 3 V buried Zener references. It delivers 83 kHz ADC throughput, 3 µs DAC settling time, and 72 dB SNR, operating from ±5 V supplies with ±3 V analog input/output range. It is used in DSP servo control and high-speed modem signal chains where compact, synchronized analog I/O is required.

For engineers reviewing the AD7868ANZ datasheet, AD7868ANZ pinout, AD7868ANZ application, or AD7868ANZ equivalent, this page provides verified functional identity, validated 24-pin DIP package mapping, confirmed serial interface timing (TFS/TCLK/DT for DAC; RFS/RCLK/DR for ADC), exact bipolar transfer function (2's complement, ±3 V, 1 LSB = 1.46 mV), and real-world design constraints including reference load limits (≤500 µA), decoupling requirements (10 µF || 0.1 µF), and ESD sensitivity (4 kV).

Technical Context

The AD7868ANZ implements dual independent serial interfaces: a receive path (RFS/RCLK/DR) for ADC data output and a transmit path (TFS/TCLK/DT) for DAC data input - both using open-drain outputs with external pull-ups (4.7 kΩ on RFS/DR, 2 kΩ on RCLK). Asynchronous control is enabled via CONVST (ADC conversion trigger) and LDAC (DAC latch update), allowing precise timing decoupled from processor clocks.

Its internal architecture includes two factory-laser-trimmed 3 V references (RO ADC and RO DAC), each rated for ≤500 µA load and ±25 ppm/°C typical TC; the ADC uses a 2 µs acquisition-time track-and-hold amplifier with ≥500 kHz small-signal bandwidth, while the DAC output buffer supports ±3 V into 2 kΩ || 100 pF with 30 nV/√Hz noise density at 1 kHz.

Key Specifications

Pinout & Package

AD7868ANZ is housed in a 24-pin, 0.3" wide plastic DIP (N-24 package) with dual VDD (pins 7, 23), dual VSS (pins 10, 22), dual AGND (pins 8, 19), and dual DGND (pins 6, 17) - all must be externally tied together per datasheet layout guidance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit integrated ADC/DAC applications.

Compared with AD7868ANZ, AD7865AN offers higher ADC resolution but no DAC - increasing component count and timing complexity - while AD7856BN provides faster DAC settling but sacrifices on-chip reference matching, degrading full-scale error correlation between ADC and DAC paths essential for closed-loop systems.

Availability

AD7868ANZ is available at Aetrix Electronics and suitable for digital signal processing, high-speed modem development, and DSP servo control applications requiring stable component supply, long-term obsolescence management, and traceable sourcing for industrial and defense programs.

Supply support for AD7868ANZ 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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, communications, and industrial systems.

The AD7868ANZ belongs to Analog Devices' LC2MOS analog I/O family, designed specifically for embedded DSP systems needing tightly coupled, low-pin-count analog conversion with matched references and asynchronous timing control.

FAQ

What is the operating temperature range for the AD7868ANZ?

The AD7868ANZ is rated for operation from –40°C to +85°C (industrial grade). This range is confirmed in the Ordering Guide for the "N" package variant (plastic DIP) and applies to all dc and dynamic specifications including SNR, INL, and reference stability. Operation outside this range may cause parametric shift or functional failure.

Does the AD7868ANZ require external pull-up resistors on its serial interface pins?

Yes, the AD7868ANZ requires external pull-up resistors on all three open-drain serial outputs: 4.7 kΩ on RFS and DR, and 2 kΩ on RCLK. These values are specified in the Timing Characteristics table and are necessary to meet VOL and rise-time requirements under loaded conditions. Omitting them will prevent reliable serial communication.

Can the AD7868ANZ operate with only one of its on-chip references?

Yes - the AD7868ANZ can operate using only RO ADC as the reference for both ADC and DAC by connecting RO ADC to RI DAC. The datasheet explicitly shows this configuration in Figure 4. RO DAC may remain unconnected if unused, but neither reference should drive >500 µA or >50 pF without series resistance.

What is the purpose of the CONTROL pin on the AD7868ANZ?

The CONTROL pin configures RCLK behavior: at 0 V, RCLK is noncontinuous (tri-stated after serial transmission ends), enabling bus sharing among multiple ADCs; at –5 V, RCLK runs continuously - required by certain DSPs like the TMS32020. Tying CONTROL to VDD places the AD7868ANZ in factory test mode and must be avoided in normal operation.

Is the AD7868ANZ pin-compatible with other variants like AD7868BN or AD7868AR?

No - the AD7868ANZ (24-pin DIP) is not pin-compatible with AD7868AR (28-pin SOIC), which has different pin count and layout. While AD7868BN shares the same 24-pin DIP footprint, it differs in guaranteed SNR (72 dB vs. 70 dB for 'A') and INL (±1 LSB max vs. ±1/2 LSB typ), making it a performance-grade alternative rather than a drop-in replacement.