Analog Devices Inc. AD7872JR

Overview

AD7872JR 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 AD7872JR datasheet, AD7872JR pinout, AD7872JR application, or AD7872JR equivalent, key selection considerations include its serial-only output architecture, internal 2 MHz clock option, ±3 V bipolar input range, 16-pin SOIC package compatibility, and suitability for embedded signal acquisition where board space and interface simplicity are critical.

Technical Context

The AD7872JR implements a self-contained LC2MOS SAR architecture with on-chip laser-trimmed oscillator, eliminating external timing components. Its track-and-hold acquires signals to 14-bit accuracy in ≤2 μs, and conversion completes in ≤11 μs using the internal clock.

It uses twos-complement coding, provides REF OUT at 3.00 V ±10 mV with ±40 ppm/°C tempco, and supports serial data transmission via open-drain SCLK and SDATA outputs synchronized by active-low SSTRB - all controlled solely through CONVST-triggered Mode 1 operation.

Key Specifications

Pinout & Package

AD7872JR is housed in a 16-pin small-outline integrated circuit (SOIC) package with standard 1.27 mm pitch, compatible with automated assembly and IPC-7351B footprint IPC7351SOIC16_390x190X127P.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7872JR, AD7872JN offers identical electrical performance in a through-hole package ideal for bench validation, while ADS8320U trades integrated reference and bipolar input for higher resolution and lower supply voltage - making AD7872JR optimal for space-constrained, ±5 V, self-contained 14-bit acquisition.

Availability

AD7872JR is available at Aetrix Electronics and suitable for high-speed modems, spectrum analyzers, DSP servo control systems, and digital signal processing equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7872JR 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 AD7872JR belongs to the AD7871/AD7872 family of fast, complete 14-bit sampling ADCs designed specifically for demanding real-time signal acquisition in digital signal processing, communications, and instrumentation applications.

FAQ

What is the maximum analog input frequency supported by the AD7872JR?

The AD7872JR can accurately convert full-power analog signals up to 41.5 kHz, as specified in the General Description. This is determined by its 83 kSPS throughput rate and Nyquist criterion. Performance metrics such as SNR and THD are guaranteed at 10 kHz input frequency, and the track-and-hold amplifier has a 0.1 dB cutoff typically at 500 kHz - ensuring faithful digitization well into the audio band. The AD7872JR maintains 14-bit linearity across this range when operated within its ±3 V input and ±5 V supply specifications.

Does the AD7872JR require an external clock source?

No, the AD7872JR does not require an external clock source. It features a built-in laser-trimmed internal oscillator nominally set to 2 MHz, which can be enabled by tying the CLK pin to VSS. This self-contained timing eliminates external crystal, oscillator, or clock generator components. An external TTL-compatible clock may be applied to CLK if system synchronization is needed, but it is optional - the AD7872JR functions fully with only ±5 V supplies, analog input, and serial interface connections.

How is the reference voltage generated and used in the AD7872JR?

The AD7872JR integrates a temperature-compensated buried Zener reference trimmed to 3.00 V ±10 mV at +25°C, with ±40 ppm/°C tempco over temperature. This reference serves dual purposes: it sets the full-scale range for the internal DAC and provides the dc bias for bipolar operation. The REF OUT pin delivers this voltage and can source up to 500 μA for external circuitry. For stability, a 10 nF capacitor must be placed between CREF and AGND. The AD7872JR does not require an external reference - the on-chip solution ensures consistent 14-bit accuracy without additional components.

What are the power supply requirements for the AD7872JR?

The AD7872JR requires two independent analog supply rails: +5 V ±5% on pins 9 and 16 (VDD), and −5 V ±5% on pin 15 (VSS). Digital ground (DGND, pin 8) and analog ground (AGND, pin 12) must be connected at a single point near the device. Total power dissipation is 50 mW typical (95 mW max), drawing 13 mA from VDD and 6 mA from VSS. Decoupling is mandatory: 0.1 μF ceramic capacitors per VDD/VSS pin, plus a 10 nF capacitor on CREF (pin 11) to AGND. No digital supply rail is needed - all logic interfaces operate from the analog VDD/VSS rails.

Can the AD7872JR operate in unipolar mode?

Yes, the AD7872JR supports unipolar operation via external circuitry. Its REF OUT pin (3.00 V) is used to offset the analog input, shifting the ±3 V bipolar range to a 0 V to 6 V unipolar range. A typical configuration uses resistive scaling (e.g., R3/R4 network per Figure 14 in the datasheet) to adjust input span to 0 V–5 V or 0 V–10 V. The output remains twos-complement; unipolar data is obtained by inverting the MSB. Offset and full-scale adjustments are supported using external trim pots (R5/R6). No internal register or pin configuration is required - unipolarity is achieved entirely through analog front-end design.