Analog Devices Inc. AD7171BCPZ-500RL7

Overview

AD7171BCPZ-500RL7 from Analog Devices is a 16-bit, low-power, sigma-delta analog-to-digital converter (ADC) with differential input, internal 64 kHz oscillator, and 2-wire serial interface. It delivers 125 Hz output data rate, 135 µA typical supply current at 5 V, and operates from 2.7 V to 5.25 V across −40°C to +105°C - ideal for battery-powered weigh scales and portable instrumentation.

For engineers reviewing the AD7171BCPZ-500RL7 datasheet, AD7171BCPZ-500RL7 pinout, AD7171BCPZ-500RL7 application, or AD7171BCPZ-500RL7 equivalent, key selection criteria include its unbuffered differential input architecture, 16-bit no-missing-codes performance, status-bit–appended read protocol, and LFCSP package compatibility with high-density sensor signal chains.

Technical Context

The AD7171BCPZ-500RL7 implements a sinc3 digital filter with fixed 125 Hz output data rate and 24 ms full settling time after reset. Its unbuffered analog input path requires careful source impedance management per Table 8 (e.g., ≤9 kΩ with 50 pF) to avoid 16-bit gain error.

It uses offset binary coding, supports ratiometric operation via REFIN(±), and features dual-function DOUT/RDY with built-in status bits (RDY, ERR, ID, PAT) for serial transfer validation. The PDRST pin provides synchronous power-down (5 µA) and hard reset, with 1 ms internal clock startup delay.

Key Specifications

Pinout & Package

AD7171BCPZ-500RL7 is housed in a 10-lead 3 mm × 3 mm LFCSP (CP-10-9) with exposed pad soldered to ground. Pin 1 index and coplanarity ≤0.08 mm ensure reliable reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7171BCPZ-500RL7, the AD7170BRMZ-REEL offers pin-compatible 12-bit reduction for lower-cost systems, while the ADS1115IDGSR trades fixed 125 Hz sampling and sigma-delta noise shaping for higher speed and integrated PGA - requiring redesign of timing and signal chain architecture.

Availability

AD7171BCPZ-500RL7 is available at Aetrix Electronics and suitable for weigh scales, pressure measurement systems, and portable instrumentation requiring stable component supply over extended production lifecycles.

Supply support for AD7171BCPZ-500RL7 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 Norwood, MA.

The AD7171BCPZ-500RL7 belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-power, high-resolution sensor digitization in industrial and portable measurement systems.

FAQ

What is the maximum allowed source impedance for the AIN(±) inputs of the AD7171BCPZ-500RL7 without degrading 16-bit accuracy?

The AD7171BCPZ-500RL7 unbuffered analog inputs require source impedances ≤9 kΩ when paired with ≤50 pF capacitance (per Table 8) to avoid gain error exceeding 1 LSB. Higher impedances introduce voltage division that corrupts the measured signal; external RC filters must follow this constraint to maintain full 16-bit linearity and noise performance.

Does the AD7171BCPZ-500RL7 support true bipolar input voltages referenced to ground?

No - the AD7171BCPZ-500RL7 accepts differential bipolar input ranges (e.g., ±5 V) but does not tolerate negative voltages relative to GND on AIN(+) or AIN(−). The absolute input voltage on each pin must remain between GND − 30 mV and VDD + 30 mV. Bipolar operation is achieved by setting AIN(−) to a mid-supply common-mode voltage (e.g., 2.5 V), allowing AIN(+) to swing 0 V to 5 V.

How does the status bit pattern (PAT2–PAT0) on the AD7171BCPZ-500RL7 verify correct serial communication?

The AD7171BCPZ-500RL7 appends eight status bits to every 16-bit conversion read, including PAT2–PAT0 set to '101' by default. When firmware reads the full 24-bit word, validating that these three bits equal '101' confirms the serial transfer completed without corruption - acting as a lightweight hardware checksum to detect clock glitches or timing violations during SCLK-driven reads.

Can the AD7171BCPZ-500RL7 operate with a 2.5 V external reference instead of VDD?

Yes - the AD7171BCPZ-500RL7 supports external REFIN voltages from 0.5 V to VDD. Using a precision 2.5 V reference (e.g., ADR391) improves noise performance versus VDD-referenced operation and enables ratiometric measurements when the same reference excites the sensor. However, REFIN source impedance must remain low (<100 Ω) to prevent gain error, and decoupling capacitors are only safe with such low-Z references.

What is the settling time behavior of the AD7171BCPZ-500RL7 after a power-on or PDRST reset?

After power-up or PDRST assertion, the AD7171BCPZ-500RL7 requires 24 ms for full analog/digital settling before the first valid conversion. Subsequent conversions occur every 8 ms (125 Hz), but any asynchronous analog input step change also demands 24 ms to resolve. The DOUT/RDY pin remains high until the first settled result is ready, then toggles low to indicate data availability.