Analog Devices Inc. AD7872JN

Overview

AD7872JN 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. It is used in high-speed DSP servo control and spectrum analysis systems requiring precise timing and low-noise conversion.

For engineers reviewing the AD7872JN datasheet, AD7872JN pinout, AD7872JN application, or AD7872JN equivalent, key selection considerations include its serial-only output architecture, ±5 V dual-supply requirement, 16-pin PDIP/CERDIP/SOIC package compatibility, and guaranteed 14-bit no-missing-codes performance across 0°C to +70°C.

Technical Context

The AD7872JN implements a self-contained LC2MOS SAR architecture with laser-trimmed internal 2 MHz clock, eliminating external timing components. Its track-and-hold acquires signals to 14-bit accuracy in ≤2 μs, and conversion time is fixed at 10.5 μs (internal clock) or 10 μs (external clock).

All dynamic specifications-including 80 dB SNR, −86 dB THD, and −86 dB IMD-are fully characterized at 10 kHz input frequency and 83 kSPS sampling rate. The on-chip 3 V reference exhibits ±40 ppm/°C tempco and supports up to 500 μA load, with CREF requiring a mandatory 10 nF decoupling capacitor to AGND.

Key Specifications

Pinout & Package

AD7872JN is packaged in a 16-pin plastic DIP (PDIP) with standard through-hole mounting. Pin assignments are validated per Analog Devices Rev. F datasheet Figure 8 and Table 6.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7872KN, AD7872JN offers lower cost and sufficient thermal margin for office/lab equipment; compared with ADS8320U, AD7872JN provides simpler system integration via on-chip reference and true bipolar input, albeit at 14-bit resolution.

Availability

AD7872JN is available at Aetrix Electronics and suitable for digital signal processing, high-speed modems, and DSP servo control applications requiring stable component supply over extended production lifecycles.

Supply support for AD7872JN 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.

The AD787x family was designed specifically for high-speed, high-accuracy data acquisition in real-time DSP systems-emphasizing integrated functionality, low power, and robust dynamic performance in ±5 V systems.

FAQ

What is the maximum sampling rate supported by the AD7872JN?

The AD7872JN supports a maximum throughput rate of 83 kSPS, achieved using its internal 2 MHz clock. This rate is guaranteed across the full 0°C to +70°C operating temperature range and is limited by the 10.5 μs conversion time plus track-and-hold acquisition. External clocking at 2 MHz yields identical performance, with timing parameters fully specified in Table 2 of the Rev. F datasheet.

Does the AD7872JN require external components to operate?

The AD7872JN requires only three external components for basic operation: a 10 nF capacitor between CREF and AGND, a 4.7 kΩ pull-up resistor on SSTRB, and a 2 kΩ pull-up resistor on SCLK. SDATA also requires a 4.7 kΩ pull-up. No external reference, DAC, or clock source is needed-the AD7872JN integrates a laser-trimmed 2 MHz oscillator and 3 V buried Zener reference.

Can the AD7872JN interface directly with a microcontroller using SPI?

The AD7872JN does not implement a standard SPI protocol. Its serial interface uses three dedicated lines-SSTRB (frame strobe), SCLK (gated clock), and SDATA (MSB-first twos-complement data)-with timing defined by t10–t14 in the datasheet. While functionally similar, it requires custom GPIO bit-banging or timer-driven firmware, not hardware SPI peripheral configuration.

What is the analog input impedance of the AD7872JN?

The AD7872JN analog input exhibits a typical impedance of 15 kΩ, as specified in the "Analog Input" section of the Rev. F datasheet. This value is consistent across the ±3 V input range and is independent of sampling state. For optimal linearity and settling, driving sources should have output impedance significantly below 15 kΩ, and anti-alias filtering must account for this loading effect.

How is the reference voltage stabilized on the AD7872JN?

The AD7872JN stabilizes its internal 3 V buried Zener reference via the CREF pin, which must be decoupled to AGND with a 10 nF capacitor. This capacitor minimizes high-frequency noise and ensures stable reference operation during conversion cycles. REFOUT provides the buffered 3 V output, rated for up to 500 μA load, with a maximum recommended capacitance of 50 pF on the REFOUT pin itself.