Analog Devices Inc. AD7871JN

Overview

AD7871JN from Analog Devices is a complete monolithic 14-bit LC2MOS sampling analog-to-digital converter with integrated track-and-hold amplifier, 3 V buried Zener reference, and self-contained laser-trimmed internal clock. It delivers 80 dB SNR at 10 kHz, 57 ns data access time, and 83 kSPS throughput while operating from ±5 V supplies with ±3 V bipolar analog input range. It is used in high-speed DSP servo control and spectrum analysis systems requiring precise timing and low-noise conversion.

For engineers reviewing the AD7871JN datasheet, AD7871JN pinout, AD7871JN application, or AD7871JN equivalent, this page provides verified technical context, real-world interface configurations (parallel/byte/serial), dynamic performance metrics, package-specific pin functions, and validated alternative options for signal acquisition designs demanding 14-bit resolution and sub-2 μs acquisition.

Technical Context

The AD7871JN implements a successive approximation register (SAR) architecture with a voltage-output DAC and high-speed comparator, enabling full 14-bit conversion in ≤10.5 μs using its internal 2 MHz clock. Its track-and-hold amplifier achieves 14-bit settling in under 2 μs and supports input frequencies up to 41.5 kHz with 500 kHz small-signal bandwidth.

It features twos-complement coding, three configurable output formats (14-bit parallel, two 8-bit bytes, or 14-bit serial), and flexible digital interface logic controlled by the 14/8/CLK pin. The on-chip 3 V reference exhibits ±40 ppm/°C tempco and supports up to 500 μA external load via REFOUT, with CREF requiring a mandatory 10 nF AGND decoupling capacitor.

Key Specifications

Pinout & Package

AD7871JN is supplied in a 28-pin plastic DIP (PDIP) package with 0.6-inch width and through-hole mounting. Pin spacing is 0.1 inch, and the package meets JEDEC MS-001 standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 14-bit sampling ADC applications.

Compared with AD7871JN, AD7872JN sacrifices parallel interface flexibility for smaller footprint, while ADS8320U trades monolithic integration for higher resolution and external reference control-neither offers identical feature parity, making AD7871JN optimal for balanced speed, precision, and interface versatility in DSP-adjacent systems.

Availability

AD7871JN is available at Aetrix Electronics and suitable for digital signal processing, high-speed modems, and spectrum analysis applications requiring stable component supply, long-term obsolescence management, and traceable sourcing for industrial and defense programs.

Supply support for AD7871JN 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide and ISO 9001-certified manufacturing.

The AD7871JN belongs to Analog Devices' legacy high-speed precision ADC product line, engineered specifically for real-time data acquisition in DSP-centric systems where integration, dynamic performance, and flexible digital interfacing are essential.

FAQ

What is the operating temperature range for the AD7871JN?

The AD7871JN is rated for commercial operation from 0°C to +70°C. This J-grade version is intended for indoor, non-extended-environment applications such as test equipment, communications infrastructure, and industrial control panels where ambient thermal conditions remain within this band. Its specifications-including 80 dB SNR and ±1 LSB INL-are guaranteed across this full range.

Does the AD7871JN require an external clock to operate?

No, the AD7871JN does not require an external clock. It includes a self-contained, laser-trimmed internal oscillator nominally set to 2 MHz, which is enabled by tying the CLK pin to VSS. An external TTL-compatible clock may be applied to CLK only if precise synchronization with a system master clock is needed-otherwise, the internal clock eliminates timing component count and layout sensitivity.

How is the analog input configured for unipolar operation on the AD7871JN?

Unipolar operation on the AD7871JN is achieved by offsetting the VIN input with the internal 3 V REFOUT voltage, typically using a resistive summing network as shown in Figure 14 of the datasheet. This shifts the ±3 V bipolar range to 0 V–6 V, and the output code can be converted to straight binary by inverting the MSB. No hardware modification of the AD7871JN itself is required-only external passive components.

What decoupling is required on the CREF pin of the AD7871JN?

A 10 nF capacitor must be placed between the CREF pin and AGND for stable operation of the AD7871JN. This capacitor minimizes reference noise and prevents oscillation in the buried Zener reference circuit. The datasheet explicitly states this value is mandatory-not optional-and specifies it is sample-tested at +25°C to ensure compliance with dynamic performance specs like SNR and THD.

Can the AD7871JN interface directly with an 8-bit microprocessor bus?

Yes, the AD7871JN supports direct 8-bit microprocessor interfacing via its byte-mode output. When the 14/8/CLK pin is set to 0 V, the device outputs two 8-bit bytes (upper and lower) controlled by the HBEN pin (Pin 6). With HBEN high, DB7–DB0 carries bits DB13–DB6; with HBEN low, they carry DB5–DB0-enabling full 14-bit data transfer over an 8-bit data bus without external latches or glue logic.