Analog Devices Inc. AD7715AN-3

Overview

AD7715AN-3 from Analog Devices is a 16-bit sigma-delta analog-to-digital converter optimized for low-frequency, high-accuracy measurement of transducer-level signals. It integrates a programmable-gain amplifier (gains 1/2/32/128), differential analog and reference inputs, on-chip digital filtering with programmable notch frequency, and a three-wire SPI-compatible serial interface. It operates from a single 3 V supply with 450 µA max current and supports unipolar (0–1.25 V) or bipolar (±1.25 V) input ranges - ideal for precision industrial sensor front ends.

For engineers reviewing the AD7715AN-3 datasheet, AD7715AN-3 pinout, AD7715AN-3 application, or AD7715AN-3 equivalent, key selection criteria include its guaranteed 16-bit no-missing-codes performance, ±0.0015% integral nonlinearity at 3 V, 90 dB common-mode rejection, 150 dB 50/60 Hz normal-mode rejection, and support for system/self-calibration to eliminate offset and gain drift.

Technical Context

The AD7715AN-3 employs a charge-balancing sigma-delta modulator architecture with an on-chip digital filter whose first notch frequency is software-programmable via register control - enabling precise adjustment of output update rate and line-frequency rejection (e.g., 25 Hz, 50 Hz, 60 Hz). Its analog front end includes a fully differential PGA and optional input buffer, allowing direct connection to low-output-impedance sensors like strain gauges without external signal conditioning.

It uses a three-wire serial interface (SCLK, CS, DIN/DOUT) compatible with SPI, QSPI, MICROWIRE, and DSP protocols. All configuration - gain, polarity, update rate, and calibration mode - is performed through on-chip registers accessible via the serial port. The device supports both internal and external master clock sources (1 MHz to 2.4576 MHz) and features power-down mode with 10 µA typical standby current.

Key Specifications

Pinout & Package

AD7715AN-3 is housed in a 16-lead plastic dual-in-line package (PDIP), 0.3 inch wide, with industry-standard lead pitch and thermal characteristics (θ_JA = 105°C/W, P_D = 450 mW).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar sigma-delta ADC applications.

Compared with AD7714BN and ADS1220IPWR, the AD7715AN-3 uniquely balances 16-bit precision, 3 V ultra-low-power operation, and proven industrial reliability in legacy designs - making it optimal for cost-sensitive, battery-backed, or retrofit instrumentation where pin compatibility and long-term supply continuity matter.

Availability

AD7715AN-3 is available at Aetrix Electronics and suitable for pressure measurement, temperature monitoring, smart transmitter design, and weigh scale electronics requiring stable component supply across extended product lifecycles.

Supply support for AD7715AN-3 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 AD7715 belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-frequency, high-accuracy industrial and instrumentation applications where noise immunity, calibration flexibility, and low-power operation are critical.

FAQ

What is the maximum operating temperature range for the AD7715AN-3?

The AD7715AN-3 is rated for operation from −40°C to +85°C (Commercial A version). This range is validated per the Absolute Maximum Ratings table and supported by full electrical specifications across temperature in the datasheet Rev. E. All static and dynamic performance parameters - including integral nonlinearity, offset drift, and 50/60 Hz rejection - are guaranteed within this range for the AD7715AN-3 variant.

Does the AD7715AN-3 support both unipolar and bipolar input configurations?

Yes, the AD7715AN-3 supports both unipolar (0 V to 1.25 V) and bipolar (±1.25 V) input ranges. Configuration is controlled by the B/U bit in the Setup Register: B/U = 1 selects unipolar mode with binary coding; B/U = 0 selects bipolar mode with offset binary coding. The input range scales inversely with PGA gain - e.g., at gain = 128, the differential input span is ±9.77 mV.

How does the AD7715AN-3 achieve 150 dB 50/60 Hz rejection?

The AD7715AN-3 achieves 150 dB common-mode 50/60 Hz rejection through its digital filter architecture - specifically, by placing the first notch of the on-chip sinc³ filter at 25 Hz or 20 Hz respectively. This is configured via the filter register (FS0/FS1 bits), and the rejection is guaranteed under specified conditions (e.g., REF IN = 1.25 V, fCLK IN = 2.4576 MHz). The analog front end contributes additional 90 dB CMR at dc.

Can the AD7715AN-3 operate with an external crystal oscillator?

Yes, the AD7715AN-3 supports external crystal or ceramic resonator operation. A crystal is connected between MCLK IN and MCLK OUT pins; the internal oscillator circuit drives it. The device is characterized for 1 MHz and 2.4576 MHz crystals. When using a crystal, DVDD current increases slightly versus external CMOS clock, and standby current remains ~10 µA typical due to oscillator shutdown in power-down mode.

What calibration modes are available on the AD7715AN-3?

The AD7715AN-3 provides two calibration modes: self-calibration (zero and full-scale) and system calibration (zero and full-scale). Self-calibration corrects internal offset and gain errors using on-chip references; system calibration uses external applied signals to remove errors introduced by the sensor and signal path. Both are initiated via the Communications Register and complete in under 100 ms.