Analog Devices Inc. AD7703BNZ

Overview

AD7703BNZ 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 (typ), 4 kSPS output data rate, and 0.1 Hz to 10 Hz programmable low-pass filter corner frequency. It is designed for precision DC/low-frequency measurement in industrial process control and portable instrumentation.

For engineers reviewing the AD7703BNZ datasheet, AD7703BNZ pinout, AD7703BNZ application, or AD7703BNZ equivalent, key selection considerations include its unipolar/bipolar input range (0–2.5 V or ±2.5 V), ultralow standby power (10 µW), on-chip calibration support for system offset/gain error removal, and compatibility with UARTs or microcontroller serial ports via SSC/SEC modes.

Technical Context

The AD7703BNZ employs a second-order sigma-delta modulator with charge-balancing architecture, continuously sampling at 16 kHz (f_CLKIN/256) and feeding a six-pole Gaussian digital filter that outputs 20-bit words at 4 kHz (f_CLKIN/1024). Its filter provides 55 dB rejection at 60 Hz with 10 Hz cutoff and settles to ±0.0007% FS in 125 ms after full-scale step input.

Calibration is managed by an on-chip microcontroller with SRAM storage, supporting zero/full-scale self-calibration and extendable system-level calibration loops. The device operates from dual ±5 V supplies (AVDD/DVDD = +5 V, AVSS/DVSS = –5 V), features separate analog/digital grounds (AGND/DGND), and supports both crystal-based (CLKIN/CLKOUT) and external clocking.

Key Specifications

Pinout & Package

AD7703BNZ is supplied in a 20-pin plastic DIP package (0.3-inch width), RoHS-compliant, with through-hole mounting and industry-standard pin spacing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 20-bit sigma-delta ADC applications.

Compared with AD7714BNZ and LTC2400CGN#PBF, the AD7703BNZ uniquely combines 20-bit no-missing-codes performance, on-chip self-calibration, bipolar/unipolar configuration, and ultralow standby power in a through-hole DIP package-making it optimal for cost-sensitive, maintenance-free industrial and portable measurement systems.

Availability

AD7703BNZ is available at Aetrix Electronics and suitable for industrial process control, weigh scales, portable instrumentation, and remote data acquisition requiring stable component supply and long-term lifecycle support.

Supply support for AD7703BNZ 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 AD7703BNZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for high-accuracy, low-frequency measurement of chemical, physical, and biological sensor outputs in harsh industrial and portable environments.

FAQ

What is the maximum master clock frequency supported by the AD7703BNZ?

The AD7703BNZ supports a maximum master clock frequency of 5 MHz, with production testing performed at 4.096 MHz. At this frequency, the device achieves a 4 kSPS output data rate, 10 Hz filter corner, and 125 ms settling time. Operation down to 200 kHz is guaranteed, enabling ultra-low-power configurations where clock frequency is reduced to scale power consumption linearly.

Does the AD7703BNZ require external components for stable operation?

Yes - the AD7703BNZ requires a 1 nF ceramic capacitor from AIN to AGND to stabilize the high-impedance analog input, and source resistance must be ≤750 Ω. When using the internal oscillator, a crystal (e.g., 4.096 MHz) connects between CLKIN and CLKOUT; no loading capacitors are needed for this frequency. Decoupling capacitors (0.1 µF ceramic + 10 µF tantalum) are required on all supply pins (AVDD, DVDD, AVSS, DVSS) relative to their respective grounds.

How does the AD7703BNZ handle system-level calibration of external front-end circuitry?

The AD7703BNZ supports system calibration via SC1 and SC2 pins during CAL strobe events. By applying known zero- and full-scale voltages at the AIN pin (including contributions from external op-amps or filters), the on-chip calibration microcontroller measures and stores correction coefficients in SRAM. This process nulls both offset and gain errors introduced by the entire analog signal chain-not just the ADC itself-ensuring end-to-end accuracy.

Can the AD7703BNZ operate from a single supply?

No - the AD7703BNZ requires dual ±5 V supplies (AVDD = +5 V, AVSS = –5 V, DVDD = +5 V, DVSS = –5 V) to support its bipolar input range and internal charge-balancing architecture. Single-supply operation is not supported; attempting to tie AVSS/DVSS to ground will prevent proper analog modulator function and cause conversion failure. Isolated DC-DC converters or split-rail regulators are necessary for single-rail system integration.

What is the significance of the "BNZ" suffix in AD7703BNZ?

The "BNZ" suffix denotes a 20-pin plastic DIP package (B), lead-free (N), and RoHS-compliant (Z) variant of the AD7703. It specifies the through-hole, 0.3-inch wide, 0.1-inch pitch package with matte tin finish and no halogenated flame retardants. This variant is pin-compatible with the legacy AD7703BN but meets modern environmental compliance requirements for industrial and medical equipment.