Analog Devices Inc. AD7876BN

Overview

AD7876BN from Analog Devices is a complete monolithic 12-bit successive approximation analog-to-digital converter (ADC) with integrated track-and-hold amplifier, laser-trimmed internal clock, and on-chip 3 V buried Zener reference. It supports ±10 V bipolar input range, achieves 8 μs conversion time with external 2.5 MHz clock, and delivers 57 ns data access time for microprocessor interfacing in industrial data acquisition systems.

For engineers reviewing the AD7876BN datasheet, AD7876BN pinout, AD7876BN application, or AD7876BN equivalent, this page provides verified technical context, real-world interface timing constraints, confirmed SOIC-24 package mapping, and validated alternative options for ±10 V, 100 kHz sampling ADC designs requiring dc accuracy and standalone operation capability.

Technical Context

The AD7876BN implements a SAR architecture with internal 3 V reference used for both DAC scaling and bipolar offset biasing. Its track-and-hold amplifier acquires signals to 12-bit accuracy in ≤2 μs and supports full-power input frequencies up to 50 kHz.

It offers three configurable digital interfaces: 12-bit parallel (DB11–DB0), two-byte mode (HBEN-controlled), and serial (SCLK/SSTRB/SDATA), all synchronized to either internal laser-trimmed oscillator or external TTL clock applied at CLK pin. The 12/8/CLK pin selects between parallel-only (high), byte/serial (0 V), or continuous-clock serial (−5 V) modes.

Key Specifications

Pinout & Package

AD7876BN is housed in a 24-pin small outline integrated circuit (SOIC) package with 300 mil body width and standard gull-wing lead form. Pin 1 identifier is marked via notch or dot; pins are numbered counterclockwise from top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit, ±10 V input ADC applications.

Compared with AD7870BN and ADS7800U, AD7876BN uniquely combines ±10 V input support, internal reference, and laser-trimmed clock in one SOIC-24 package - reducing design risk, calibration effort, and total solution size for industrial data acquisition.

Availability

AD7876BN is available at Aetrix Electronics and suitable for industrial process monitoring, test & measurement equipment, motor drive current feedback, and power quality analyzers requiring stable component supply and long-term manufacturability.

Supply support for AD7876BN 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, headquartered in Norwood, MA, with design centers worldwide.

The AD7876BN belongs to the LC2MOS 12-bit sampling ADC product line, engineered for industrial and instrumentation applications demanding integrated precision, low power, and simplified system-level design without external timing or reference components.

FAQ

What is the maximum analog input frequency the AD7876BN can accurately digitize?

The AD7876BN supports full-power analog input signals up to 50 kHz while maintaining 12-bit accuracy. This is enabled by its track-and-hold amplifier, which has a 0.1 dB cutoff frequency of approximately 500 kHz and acquires input signals to 12-bit precision in ≤2 μs. For optimal SNR performance, input frequencies should remain below the Nyquist limit of half the sampling rate (i.e., ≤50 kHz at 100 kSPS). The AD7876BN datasheet confirms dynamic specifications including 70 dB SNR at 10 kHz input under 100 kHz sampling conditions.

Does the AD7876BN require external components to operate?

No, the AD7876BN is a complete monolithic ADC requiring only power supply decoupling capacitors for operation. It integrates a 3 V buried Zener reference, laser-trimmed internal clock oscillator, track-and-hold amplifier, and SAR core. External components are optional: a 200 Ω resistor plus 10 μF tantalum and 0.1 μF ceramic capacitors are recommended only if REF OUT is used externally; 4.7 kΩ pull-up resistors are needed for SSTRB and SDATA in serial mode; and standard 0.1 μF ceramic + 10 μF tantalum decoupling is required at VDD/VSS. No external op-amps, clocks, or references are necessary for basic ±10 V conversion.

How does the AD7876BN handle bipolar offset error in ±10 V mode?

The AD7876BN specifies bipolar zero error as ±6 LSB max (at +25°C) and ±2 LSB max over temperature for the C grade, directly referencing its internal 3 V Zener. This error arises from mismatches in the internal scaling network (2.1R/7R/3R) and comparator offset. The device does not include on-chip offset trim pins; however, system-level calibration can correct residual offset using the known twos-complement transfer function where 0 V maps to code 0x800 (2048 decimal). The AD7876BN datasheet provides full-scale and zero-error limits in Table 2 and confirms that adjustment procedures exist in the "Offset And Full-Scale Adjustment-AD7876" section.

Can the AD7876BN be used with an external clock, and what are the timing requirements?

Yes, the AD7876BN accepts an external TTL-compatible clock applied to the CLK pin. When 12/8/CLK is high, the device operates in 12-bit parallel mode with fCLK = 2.5 MHz, achieving 8 μs max conversion time. Timing parameters are fully specified: t1 (CONVST pulse width) ≥50 ns, t3 (RD pulse width) ≥60 ns, and t6 (data access time after RD) ≤57 ns. All timing specs are production-tested across temperature. The internal clock is disabled when CLK is driven; tying CLK to VSS enables the internal oscillator. External clock operation preserves all interface modes and timing guarantees documented in Table 3 of the AD7876BN datasheet.

What is the thermal performance of the AD7876BN over its operating temperature range?

The AD7876BN (B grade) operates from −40°C to +85°C with guaranteed performance. Key thermal specifications include reference tempco ≤±60 ppm/°C, full-scale TC ≤±60 ppm/°C, and integral nonlinearity maintained at ±1 LSB max over temperature. Power dissipation remains ≤95 mW across this range, with junction-to-ambient thermal resistance (θJA) of 110°C/W for the SOIC-24 package. The device meets industrial reliability standards and shows no degradation in conversion time, SNR, or THD when operated within these limits - confirmed by parametric testing in Tables 1 and 2 of the AD7876BN datasheet.