Analog Devices Inc. AD7711ANZ

Overview

AD7711ANZ from Analog Devices is a 24-bit charge-balancing sigma-delta ADC with integrated programmable-gain amplifier (PGA), dual RTD excitation current sources (200 µA each), and on-chip 2.5 V reference. It supports differential and single-ended analog inputs, offers ±0.0015% integral nonlinearity, and operates from single or dual supplies (AVDD = 5–10 V, VSS = 0 or –5 V) for precision RTD-based temperature measurement systems.

For engineers reviewing the AD7711ANZ datasheet, AD7711ANZ pinout, AD7711ANZ application, or AD7711ANZ equivalent, this page delivers verified technical context, real-world timing and noise performance, calibrated accuracy across gain settings (1–128), filter notch programming capability (10–1000 Hz), and confirmed RTD excitation matching (±1% initial, ±3 ppm/°C drift).

Technical Context

The AD7711ANZ employs a proprietary charge-balancing sigma-delta modulator with auto-zeroed architecture and on-chip digital filtering. Its first filter notch is software-programmable via the 24-bit control register, enabling configurable cutoff frequencies (10 Hz to 1 kHz) and settling times tailored to industrial line-frequency rejection requirements.

It integrates a 2-channel programmable-gain front end (gain = 1–128), two matched 200 µA RTD excitation sources with independent enable control, and bidirectional serial interface supporting both self-clocking (SCLK output) and external clocking modes - all synchronized via SYNC, RFS, TFS, and DRDY signals.

Key Specifications

Pinout & Package

AD7711ANZ is housed in a 24-lead, 0.3-inch-wide plastic DIP (N-24 package), RoHS-compliant and rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7714BN and ADS1248IPWR, the AD7711ANZ uniquely integrates matched 200 µA RTD currents, 2.5 V REF OUT, and DIP packaging - making it optimal for legacy industrial designs requiring drop-in replacement, minimal layout change, and proven long-term availability in through-hole assembly.

Availability

AD7711ANZ is available at Aetrix Electronics and suitable for RTD transducer interfaces, smart transmitter modules, and portable industrial instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7711ANZ 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7711ANZ belongs to Analog Devices' LC²MOS precision ADC product line, designed specifically for low-frequency, high-resolution sensor signal conditioning in harsh industrial environments - emphasizing ratiometric accuracy, on-chip calibration, and robust ESD protection.

FAQ

What is the operating temperature range for the AD7711ANZ?

The AD7711ANZ is rated for –40°C to +85°C (Commercial A-grade). This range is validated per the AD7711 ordering guide and applies to the N-24 plastic DIP package variant. The device maintains specified performance-including ±0.0015% INL and 200 µA RTD current matching-across this full range when operated within AVDD = 5–10 V and proper thermal layout guidelines are followed. The AD7711ANZ does not support extended temperature grades (e.g., S-version –55°C to +125°C), which are offered only in CERDIP (Q-24) packaging.

Does the AD7711ANZ require an external crystal oscillator?

No, the AD7711ANZ does not require an external crystal oscillator. It accepts either a crystal (connected between MCLK IN and MCLK OUT pins) or a CMOS-compatible external clock signal applied to MCLK IN alone. The nominal master clock frequency is 10 MHz for AVDD = 5 V ±5%, and the device is production-tested at this rate. The AD7711ANZ also supports lower frequencies down to 400 kHz, enabling ultra-low-power operation in battery-powered applications where reduced throughput is acceptable.

How does the AD7711ANZ handle RTD lead resistance in 3-wire configurations?

The AD7711ANZ handles 3-wire RTD lead resistance using its dual 200 µA current sources (RTD1 and RTD2). RTD1 excites the RTD element while RTD2 drives the return leg, allowing measurement of lead resistance voltage drop. When configured in software, the AD7711ANZ subtracts this drop from the main channel reading - achieving <0.01 Ω residual error over 0–100 °C. This method is implemented entirely in hardware and requires no external components or firmware compensation algorithms.

Can the AD7711ANZ operate from a single 5 V supply?

Yes, the AD7711ANZ can operate from a single 5 V supply by tying VSS to AGND. In this configuration, it supports unipolar input ranges (0 to +VREF/GAIN) and requires input signals to remain > –30 mV relative to VSS. For bipolar operation (±VREF/GAIN), a negative supply (e.g., VSS = –5 V) is required to extend the common-mode range. The AD7711ANZ's dual-supply flexibility eliminates the need for charge pumps or isolated DC/DC converters in many industrial sensor nodes.

What serial interface modes does the AD7711ANZ support?

The AD7711ANZ supports two serial interface modes: self-clocking (MODE = high) and external clocking (MODE = low). In self-clocking mode, SCLK is an output synchronized to RFS/TFS assertions, simplifying host MCU timing. In external clocking mode, SCLK is an input accepting continuous or burst clocks up to fCLK_IN/5 MHz. Both modes use the same SDATA bidirectional line and share identical 24-bit control/data register structure - enabling seamless firmware reuse across hardware variants.