Analog Devices Inc. AD7872BR

Overview

AD7872BR from Analog Devices is a complete monolithic 14-bit successive approximation analog-to-digital converter (ADC) with integrated track-and-hold amplifier, 3 V buried Zener reference, and serial-only digital interface. It operates from ±5 V supplies, accepts bipolar ±3 V analog inputs, delivers 83 kSPS throughput, achieves 80 dB SNR at 10 kHz, and features 57 ns data access time - enabling high-fidelity signal acquisition in DSP-based instrumentation and communications systems.

For engineers reviewing the AD7872BR datasheet, AD7872BR pinout, AD7872BR application, or AD7872BR equivalent, key selection considerations include its serial-only output architecture (SCLK/SSTRB/SDATA), internal 2 MHz clock option, ±3 V bipolar input range, 16-pin SOIC package, and compatibility with microprocessor- and standalone timing-critical sampling systems.

Technical Context

The AD7872BR implements a self-contained LC2MOS SAR architecture with laser-trimmed internal clock, eliminating external timing components. Its track-and-hold acquires to 14-bit accuracy in ≤2 μs, and conversion completes in ≤11 μs using the internal oscillator.

All dynamic performance - including 80 dB SNR, −86 dB THD, and −86 dB IMD - is specified across temperature for ±3 V full-scale sine-wave inputs up to 41.5 kHz, with dc accuracy guaranteed by ±1 LSB integral nonlinearity and ±12 LSB gain/zero error.

Key Specifications

Pinout & Package

AD7872BR is housed in a 16-pin small-outline integrated circuit (SOIC) package with gull-wing leads, 1.27 mm pitch, and JEDEC MS-012AC footprint. Pin 1 is marked with a dot or bevel; pins are numbered counterclockwise from pin 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7871BR and ADS8320U, the AD7872BR uniquely combines monolithic bipolar ±3 V input handling, integrated 3 V reference, and dedicated serial interface in a compact 16-pin SOIC - reducing component count and layout effort for cost-sensitive, space-constrained DSP acquisition systems.

Availability

AD7872BR is available at Aetrix Electronics and suitable for high-speed modem design, DSP servo control, spectrum analysis instrumentation, and speech recognition preprocessing requiring stable component supply and long-term production continuity.

Supply support for AD7872BR 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.

The AD7872BR belongs to Analog Devices' legacy high-speed precision ADC product line, engineered specifically for demanding digital signal processing applications where monolithic integration, dynamic performance, and bipolar input capability are essential.

FAQ

What is the maximum analog input frequency supported by the AD7872BR?

The AD7872BR supports full-power analog input signals up to 41.5 kHz while maintaining specified dynamic performance, including 80 dB SNR and −86 dB THD. This limit arises from the Nyquist criterion applied to its 83 kSPS throughput rate, making it suitable for audio-band and baseband communication signal digitization. The track-and-hold amplifier's 500 kHz 0.1 dB bandwidth ensures faithful capture of these frequencies without slew-induced distortion.

Does the AD7872BR require external clock components for operation?

No, the AD7872BR does not require external clock components. It features an internal laser-trimmed 2 MHz oscillator activated by tying the CLK pin to VSS. This self-contained timing eliminates crystals, oscillators, or RC networks, reducing bill-of-materials cost and board space. An external TTL-compatible clock may be applied to CLK if system-level synchronization is needed, but it is optional - the internal clock meets all datasheet timing specifications.

How is the serial interface of the AD7872BR configured and timed?

The AD7872BR uses a three-wire serial interface: SSTRB (active-low frame strobe), SCLK (gated or continuous clock output), and SDATA (serial data output). Data is valid on the falling edge of SCLK when SSTRB is low. The CONTROL pin selects SCLK behavior: 0 V enables gated operation (SCLK active only during transmission), while −5 V enables continuous SCLK. External 4.7 kΩ pull-ups on SSTRB/SDATA and a 2 kΩ pull-up on SCLK are mandatory for proper logic levels.

Can the AD7872BR operate with unipolar input signals?

Yes, the AD7872BR supports unipolar operation via external circuitry. Its REFOUT pin provides a stable 3.00 V reference that can offset the analog input stage - for example, using a resistive divider and op-amp to shift a 0 V to +5 V input into the ADC's ±3 V range. Figure 14 in the AD7872BR datasheet shows a verified unipolar interface circuit. The output remains twos-complement; unipolar data requires MSB inversion in firmware to yield straight binary format.

What are the grounding and decoupling requirements for optimal AD7872BR performance?

Optimal AD7872BR performance requires strict separation of AGND and DGND, joined only at a single-point star ground near the device. AGND handles analog core and reference return; DGND serves digital I/O. A 10 nF capacitor must connect CREF to AGND to stabilize the internal reference. Each supply (VDD, VSS) requires local 0.1 μF ceramic + 10 μF tantalum decoupling. REFOUT loads must be ≤50 pF; external buffering is needed for larger capacitive loads to prevent reference instability.