Analog Devices Inc. AD7703CN

Overview

AD7703CN from Analog Devices is a monolithic 20-bit sigma-delta analog-to-digital converter with on-chip 6-pole Gaussian digital filtering, self-calibration microcontroller, and flexible serial interface. It delivers ±0.0003% typical integral nonlinearity, 4 kSPS output data rate, and 0.1 Hz to 10 Hz programmable filter corner frequency. It is designed for precision low-frequency measurement in industrial process control and portable instrumentation.

For engineers reviewing the AD7703CN datasheet, AD7703CN pinout, AD7703CN application, or AD7703CN equivalent, key selection considerations include its 20-bit no-missing-codes resolution, ultralow 10 µW standby power, bipolar/unipolar input range configuration (±2.5 V or 0–2.5 V), and system-level calibration capability for offset/gain error removal in sensor front-ends.

Technical Context

The AD7703CN employs a second-order sigma-delta modulator with charge-balancing architecture, continuously sampling at 16 kHz (f_CLKIN/256) and feeding a deterministic six-pole Gaussian digital filter that updates the 20-bit output register at 4 kHz (f_CLKIN/1024). Its internal calibration microcontroller executes zero- and full-scale self-calibration using on-chip SRAM storage.

It supports two serial interface modes: Synchronous Self-Clocking (SSC) with SCLK output at f_CLKIN/4, and Synchronous External Clocking (SEC) with SCLK input up to 5 MHz. Input range is selected via BP/UP pin (bipolar ±V_REF or unipolar 0–V_REF), and sleep mode reduces power to 10 µW via dedicated SLEEP pin control.

Key Specifications

Pinout & Package

AD7703CN is supplied in a 20-pin plastic DIP package (0.3-inch width), pin-compatible with industry-standard through-hole prototyping and industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7714BN and ADS1211U, the AD7703CN offers optimal balance of 20-bit no-missing-codes performance, 4 kSPS throughput, pin-selectable input range, and proven reliability in industrial temperature ranges (–40°C to +85°C), making it ideal for cost-sensitive, high-stability measurement systems where external gain and reference are already present.

Availability

AD7703CN is available at Aetrix Electronics and suitable for industrial process control, weigh scale instrumentation, portable test equipment, and remote environmental sensing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7703CN 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 Wilmington, MA.

The AD7703CN belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for high-accuracy, low-power, low-frequency measurement of physical, chemical, and biological signals in harsh industrial and portable environments.

FAQ

What is the maximum master clock frequency supported by the AD7703CN?

The AD7703CN supports a maximum master clock frequency of 5 MHz, whether supplied externally to CLKIN or generated internally via a crystal between CLKIN and CLKOUT. At 4.096 MHz, it achieves its specified 10 Hz filter corner frequency and 4 kSPS output rate. Operation down to 200 kHz is guaranteed, enabling ultra-low-power configurations with reduced throughput.

Does the AD7703CN require an external voltage reference?

Yes, the AD7703CN requires an external precision voltage reference applied to the VREF pin. It is designed for a 2.5 V nominal reference, which defines both the unipolar full-scale (0–2.5 V) and bipolar full-scale (±2.5 V) ranges. The device does not include an internal reference; using a stable, low-drift reference such as the REF02 or ADR3425 is essential to achieve ±0.0003% INL performance.

How does the AD7703CN handle system-level calibration of sensor front-end errors?

The AD7703CN supports system-level calibration via its SC1 and SC2 pins during CAL strobe events. By applying known zero and full-scale voltages at the AIN pin (including external op-amp offsets and gain errors), the device calibrates its entire input path - not just its internal circuitry. This allows removal of errors introduced by external signal conditioning stages, ensuring end-to-end accuracy without manual trimming.

Can the AD7703CN operate from a single 5 V supply?

No, the AD7703CN requires dual ±5 V analog supplies (AVDD = +5 V, AVSS = –5 V) and separate digital supplies (DVDD = +5 V, DVSS = –5 V). Its analog input range is centered around AGND, and the charge-balancing modulator architecture depends on symmetric rail-to-rail headroom. Single-supply operation is not supported; attempting it will result in incorrect conversion or damage.

What is the purpose of the BP/UP pin on the AD7703CN?

The BP/UP pin on the AD7703CN selects the analog input range mode: logic high configures bipolar operation (±VREF, e.g., ±2.5 V), while logic low configures unipolar operation (0 to VREF, e.g., 0–2.5 V). This pin directly controls the internal transfer function and determines how the 20-bit output code maps to input voltage - critical for applications requiring bidirectional measurement (e.g., force direction) versus unidirectional (e.g., tank level).