Analog Devices Inc. AD7703BR

Overview

AD7703BR from Analog Devices is a monolithic 20-bit sigma-delta analog-to-digital converter with on-chip 6-pole Gaussian digital filtering, self-calibration circuitry, and flexible serial interface. It delivers ±0.0003% integral nonlinearity (C grade), 0.1 Hz to 10 Hz programmable filter corner frequency, and 4 kSPS output data rate. It is designed for high-accuracy, low-frequency measurement in industrial process control and portable instrumentation.

For engineers reviewing the AD7703BR datasheet, AD7703BR pinout, AD7703BR application, or AD7703BR equivalent, key selection considerations include its unipolar/bipolar input range selection (0 V to +2.5 V or ±2.5 V), ultralow 10 µW standby power, LC2MOS process architecture, and system-level calibration capability for offset and gain error correction in sensor front-ends.

Technical Context

The AD7703BR employs a second-order sigma-delta modulator followed by a six-pole Gaussian digital low-pass filter, enabling 20-bit resolution with no missing codes and inherent linearity. Its conversion architecture continuously samples the analog input at f_CLKIN/256, updating the 20-bit output register at f_CLKIN/1024 - up to 4 kHz with a 4.096 MHz master clock.

Calibration is performed via an on-chip microcontroller and SRAM, supporting both internal zero/full-scale self-calibration and external system calibration modes using SC1/SC2 pins. The device supports two serial interface modes (SSC and SEC), with SCLK configurable as input or output depending on MODE pin state, and DRDY signaling data readiness.

Key Specifications

Pinout & Package

AD7703BR is available in a 20-pin plastic DIP package (dual in-line package) with 0.3-inch body width and standard through-hole mounting. Pin spacing is 0.1 inch, compatible with industry-standard PCB footprints and socketing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-accuracy, low-frequency ADC applications.

Compared with AD7714BRZ and LTC2440CGN#PBF, the AD7703BR uniquely combines 20-bit no-missing-codes performance, 4 kSPS output rate, bipolar/unipolar input flexibility, and dedicated system calibration control - making it the only option among the three supporting full signal-chain calibration in industrial-grade dual-supply systems.

Availability

AD7703BR is available at Aetrix Electronics and suitable for industrial process control, precision weigh scales, and portable instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7703BR 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, founded in 1965 and headquartered in Wilmington, MA.

The AD7703BR belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for high-resolution, low-frequency measurement in harsh industrial and portable environments where accuracy, stability, and low power are critical.

FAQ

What is the maximum master clock frequency supported by the AD7703BR?

The AD7703BR supports a maximum master clock frequency of 5 MHz for both internal oscillator (crystal between CLKIN/CLKOUT) and external clock configurations. At 4.096 MHz, it achieves 10 Hz filter corner frequency and 4 kSPS output data rate. Operation down to 200 kHz is guaranteed, enabling ultra-low-power configurations with reduced throughput.

Does the AD7703BR require external components for basic operation?

Yes - the AD7703BR requires a 1 nF ceramic capacitor from AIN to AGND to stabilize the analog input, and decoupling capacitors (0.1 µF and 10 µF) on each supply rail (AVDD, DVDD, AVSS, DVSS). A crystal or external clock source is also needed unless using the internal gate oscillator with appropriate loading capacitors per Table II in the datasheet.

How does the AD7703BR handle input overvoltage conditions?

The AD7703BR provides ±100 mV of analog input overrange headroom beyond ±VREF (i.e., ±2.6 V with 2.5 V reference), preventing saturation of the sigma-delta modulator and digital filter during noise peaks. Exceeding this range risks invalid conversions; external RC filtering or input attenuation is recommended for larger transient voltages.

Can the AD7703BR perform system-level calibration of external circuitry?

Yes - the AD7703BR supports system calibration via SC1 and SC2 pins. When CAL is asserted, specific combinations of SC1/SC2 states allow calibration of offset and gain errors introduced by external signal conditioning stages (e.g., op-amp buffers, sensor excitation circuits), storing correction coefficients in on-chip SRAM.

What is the settling time of the AD7703BR after a full-scale step input?

The worst-case settling time to ±0.0007% of final value is 125 ms when using a 4.096 MHz master clock. This corresponds to the 6-pole Gaussian filter's step response and must be observed before reading valid data after channel switching or large input transients - limiting suitability for fast multiplexed applications.