Analog Devices Inc. AD7703CRZ

Overview

AD7703CRZ 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% integral nonlinearity (C grade), 4 kSPS output data rate, and 0.1 Hz to 10 Hz programmable filter corner frequency. It is designed for high-precision DC/low-frequency measurement in industrial process control and portable instrumentation.

For engineers reviewing the AD7703CRZ datasheet, AD7703CRZ pinout, AD7703CRZ application, or AD7703CRZ equivalent, key selection considerations include its bipolar/unipolar input mode selection (BP/UP pin), sleep-mode power consumption (10 µW typical), system calibration capability via SC1/SC2 pins, and compatibility with both internal crystal oscillator (CLKIN/CLKOUT) and external clock sources.

Technical Context

The AD7703CRZ 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 low-pass filter that updates the 20-bit output register at 4 kHz (f_CLKIN/1024). Its filter provides 55 dB rejection at 60 Hz with 10 Hz cutoff, and settling time to ±0.0007% FS is 125 ms at 4.096 MHz master clock.

Calibration is performed by an on-chip microcontroller with SRAM storage, supporting zero/full-scale self-calibration and system-level offset/gain correction. The device operates from dual ±5 V analog supplies (AVDD/AVSS) and ±5 V digital supplies (DVDD/DVSS), with separate analog/digital ground pins (AGND/DGND) to maintain noise isolation.

Key Specifications

Pinout & Package

AD7703CRZ is housed in a 20-lead SOIC package (width 7.5 mm), RoHS-compliant, with gull-wing leads and standard JEDEC MS-013AC footprint. Pin numbering follows top-view orientation with notch or dot marking Pin 1 (MODE).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7703CRZ, AD7714BRUZ offers higher resolution at lower speed and simplified power architecture, while ADS1258IPWR trades calibration autonomy and bipolar operation for speed and channel density - neither provides identical combination of 20-bit guaranteed-no-missing-codes performance, on-chip calibration, and dual-supply noise robustness.

Availability

AD7703CRZ is available at Aetrix Electronics and suitable for industrial process control, weigh scale design, and portable instrumentation requiring stable component supply across extended temperature ranges (–40°C to +85°C) and long-term production continuity.

Supply support for AD7703CRZ 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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The AD7703CRZ belongs to Analog Devices' legacy precision sigma-delta ADC product line, engineered specifically for high-accuracy, low-power, low-frequency industrial and scientific measurement where stability, self-calibration, and noise immunity are critical.

FAQ

What is the maximum clock frequency supported by the AD7703CRZ for reliable operation?

The AD7703CRZ is production-tested at 4.096 MHz and guaranteed by characterization to operate up to 5 MHz for CLKIN. At 5 MHz, the output data rate becomes 4.88 kSPS and filter corner frequency rises to 12.2 Hz. Operation below 200 kHz is not recommended as it violates minimum clock specification and may impair calibration stability.

Does the AD7703CRZ require external passive components for stable operation?

Yes - the AD7703CRZ requires a 1 nF ceramic capacitor from AIN to AGND to stabilize the high-impedance analog input, and a 10 µF bulk capacitor on each supply rail (AVDD, DVDD, AVSS, DVSS). When using the internal crystal oscillator, CL1/CL2 loading capacitors must be selected per Table II in the datasheet (e.g., none required for 4.096 MHz crystal).

How does the AD7703CRZ handle input overvoltage conditions?

The AD7703CRZ provides ±100 mV analog overrange tolerance beyond its specified input range (e.g., up to +2.6 V in unipolar mode). Inputs exceeding this limit risk saturating the sigma-delta modulator or digital filter. Absolute maximum ratings allow AIN to swing from AVSS – 0.3 V to AVDD + 0.3 V, but operation outside ±(VREF + 0.1 V) yields undefined digital output (all 0s or all 1s).

Can the AD7703CRZ perform system-level calibration including external signal conditioning?

Yes - when SC2 is low and CAL is pulsed, the AD7703CRZ executes system calibration that includes the entire analog signal path. This allows removal of offset and gain errors from external amplifiers, filters, or sensor bridges connected to AIN, provided their output remains within the AD7703CRZ's input voltage and source impedance limits (≤750 Ω, ≤1 nA bias).

What is the significance of the BP/UP pin on the AD7703CRZ?

The BP/UP pin configures the AD7703CRZ's transfer function: logic low selects unipolar mode (0 V to VREF), while logic high selects bipolar mode (±VREF). This setting determines calibration behavior, output coding (straight binary vs. two's complement), and allowable input span - it must be set before calibration and cannot be changed dynamically during conversion.