Analog Devices Inc. AD7701ARS

Overview

AD7701ARS from Analog Devices is a monolithic 16-bit sigma-delta analog-to-digital converter with on-chip 6-pole Gaussian digital filtering, self-calibration circuitry, and flexible serial interface. It delivers 0.003% linearity error, 4 kSPS output data rate, and supports unipolar (0 V to +2.5 V) or bipolar (±2.5 V) input ranges. It is designed for precision low-frequency measurement in industrial process control systems.

For engineers reviewing the AD7701ARS datasheet, AD7701ARS pinout, AD7701ARS application, or AD7701ARS equivalent, this device requires attention to its dual-supply operation (±5 V), SLEEP mode power management (10 µW standby), MODE-selectable serial interface (AC/SEC/SSC), and system-level calibration capability via SC1/SC2/CAL pins.

Technical Context

The AD7701ARS employs a second-order sigma-delta modulator with continuous sampling and oversampling at up to 16 kHz, feeding a deterministic six-pole Gaussian digital filter that provides 55 dB rejection at 60 Hz when f_CLKIN = 4.096 MHz. Its output register updates at 4 kHz with guaranteed no missing codes across the full 16-bit range.

Calibration is performed by an on-chip microcontroller with SRAM storage, supporting zero- and full-scale self-calibration as well as system-level offset/gain correction when external signal conditioning is included in the calibration loop. The MODE pin configures three distinct serial protocols - asynchronous UART-compatible, synchronous external clocked, and synchronous self-clocked - each with defined timing constraints and data formatting.

Key Specifications

Pinout & Package

AD7701ARS is housed in a 28-lead SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch and exposed pad. Pin numbering follows standard SSOP top-view orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit sigma-delta ADC applications.

Compared with AD7701ARS, AD7703BRZ offers higher resolution at lower speed and simplified supply, while LTC2400CGN#PBF provides integrated reference and I²C in a smaller package - neither matches AD7701ARS's combination of 4 kSPS, dual-supply robustness, and MODE-configurable serial interface.

Availability

AD7701ARS is available at Aetrix Electronics and suitable for industrial process control, weigh scale instrumentation, and portable data loggers requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7701ARS 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Wilmington, MA.

The AD7701ARS belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for high-accuracy, low-frequency measurement in harsh industrial and portable environments.

FAQ

What is the maximum clock frequency supported by the AD7701ARS?

The AD7701ARS supports a master clock frequency (CLKIN) of up to 5 MHz, with production testing performed at 4.096 MHz. At this frequency, the digital filter corner is 10 Hz and the output data rate reaches 4 kSPS. Operation down to 200 kHz is guaranteed, enabling low-power or low-bandwidth configurations without sacrificing specification compliance.

Does the AD7701ARS require external components for basic operation?

Yes, the AD7701ARS requires external decoupling capacitors: 0.1 µF ceramic capacitors on AVDD, DVDD, AVSS, DVSS, and VREF pins, plus 10 µF bulk capacitors on AVDD and AVSS. A crystal (if using internal oscillator) must be connected between CLKIN and CLKOUT. No external op-amps or filters are required for basic functionality due to its integrated digital filtering and high-input-impedance AIN pin.

How does the SLEEP pin affect AD7701ARS operation and power consumption?

When the SLEEP pin is driven logic low, the AD7701ARS enters standby mode: CLKIN is disabled, conversion halts, and power drops to 10 µW typical. Upon returning SLEEP to logic high, the device resumes normal operation after internal reset and recalibration - no external reset is needed. This feature enables aggressive power cycling in battery-powered applications without loss of calibration state.

Can the AD7701ARS perform system-level calibration including external front-end errors?

Yes, the AD7701ARS supports system calibration via SC1 and SC2 pins. When CAL is asserted, specific combinations of SC1/SC2 states initiate offset or full-scale calibration routines that include the entire analog signal chain - such as sensor excitation, instrumentation amplifier, and RC filtering - thereby correcting gain and offset errors introduced before the AIN pin.

What are the voltage requirements for the AD7701ARS analog and digital supplies?

The AD7701ARS requires separate analog and digital supplies: AVDD and DVDD must each be +4.5 V to +5.5 V, while AVSS and DVSS must each be –4.5 V to –5.5 V. AGND and DGND must be tied together with ≤0.3 V difference. These dual-rail ±5 V supplies are mandatory to meet specified linearity, noise, and PSRR performance - operation outside these ranges invalidates all published specifications.