Analog Devices Inc. AD9221ARZ

Overview

AD9221ARZ from Analog Devices is a monolithic 12-bit analog-to-digital converter with 1.5 MSPS sampling rate, ±0.4 LSB typical integral nonlinearity, 70 dB SINAD, and on-chip sample-and-hold amplifier and voltage reference. It operates from a single 5 V analog supply and 2.7–5.25 V digital supply, delivering 59 mW typical power consumption for high-precision data acquisition in imaging and communications systems.

For engineers reviewing the AD9221ARZ datasheet, AD9221ARZ pinout, AD9221ARZ application, or AD9221ARZ equivalent, key selection criteria include its 12-bit resolution with no missing codes, straight binary output format, out-of-range (OTR) flag for overflow detection, and compatibility with both single-ended and differential analog input configurations across 0–5 V p-p spans.

Technical Context

The AD9221ARZ employs a four-stage differential pipelined architecture with digital error correction logic to guarantee 12-bit accuracy and no missing codes over –40°C to +85°C. Its sample-and-hold amplifier supports flexible input modes-single-ended or differential-with programmable common-mode level via CML pin and internal/external reference selection via SENSE and VREF pins.

Internal timing uses the rising edge of CLK for sampling; pipeline latency is fixed at three clock cycles. The device accepts a 5 V analog supply (AVDD) and 3–5 V digital supply (DVDD), with separate analog (AVSS) and digital (DVSS) grounds to minimize noise coupling between signal chains.

Key Specifications

Pinout & Package

AD9221ARZ is housed in a 28-lead SOIC package (R-28 option), with exposed pad not present and RoHS-compliant lead finish. Pin layout supports standard PCB assembly and thermal management per θ_JA = 71.4°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit ADC applications.

Compared with AD9223ARZ, AD9221ARZ trades 2× lower sampling rate for 41% lower power and identical dc linearity; compared with ADS7822U, it offers pipelined throughput and integrated reference at the cost of higher ac noise and pipeline latency.

Availability

AD9221ARZ is available at Aetrix Electronics and suitable for medical ultrasound imaging, industrial PLC analog input modules, and portable test equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD9221ARZ 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, headquartered in Norwood, MA.

The AD9221ARZ belongs to the AD922x family of monolithic 12-bit pipelined ADCs designed for cost-sensitive, low-power applications demanding true 12-bit linearity and robust ac performance in single-supply systems.

FAQ

What is the maximum sampling rate supported by the AD9221ARZ?

The AD9221ARZ supports a maximum conversion rate of 1.5 MSPS, as specified in its datasheet under "MAX CONVERSION RATE." This rate is guaranteed across the full industrial temperature range (–40°C to +85°C) with AVDD = 5 V, DVDD = 5 V, and VREF = 2.5 V. Clock period must be ≥667 ns, with minimum high/low pulse widths of 300 ns each. Exceeding this rate degrades AC performance metrics including SINAD and SFDR.

Does the AD9221ARZ require an external voltage reference?

No, the AD9221ARZ includes a programmable internal voltage reference that can be configured for either 1 V or 2.5 V output via the SENSE pin. When using the internal reference, VREF serves as the reference output and must be decoupled with CAPT and CAPB capacitors. An external reference may be applied to VREF if tighter initial accuracy or lower temperature drift is required, but the internal reference suffices for most general-purpose applications.

How does the OTR (Out-of-Range) signal function in the AD9221ARZ?

The OTR pin on the AD9221ARZ is an active-high digital output that asserts when the analog input exceeds the valid range defined by ±VREF. It works in conjunction with the MSB (BIT 1) to distinguish between high overflow (MSB = 1, OTR = 1) and low overflow (MSB = 0, OTR = 1). This enables real-time saturation detection without software polling or external comparators, simplifying firmware handling of clipped signals in data acquisition systems.

Can the AD9221ARZ operate with a 3.3 V digital supply?

Yes, the AD9221ARZ supports DVDD from 2.7 V to 5.25 V, making it compatible with 3.3 V logic families. Digital output levels meet VOH ≥ 2.80 V (IOH = 0.5 mA) and VOL ≤ 0.4 V (IOL = 1.6 mA) at DVDD = 3 V, ensuring reliable interfacing with FPGA or microcontroller GPIOs. However, AVDD must remain at 5 V ±5% to maintain analog performance specifications including INL, SNR, and full-power bandwidth.

What is the significance of the CML pin on the AD9221ARZ?

The CML (Common-Mode Level) pin on the AD9221ARZ sets the mid-supply bias voltage for the differential input stage. When tied to AVDD/2 (typically 2.5 V), it centers the input common-mode voltage, minimizing distortion caused by CMOS switch resistance modulation in the sample-and-hold amplifier. Operating with CML = 2.5 V and a 2 V p-p input span yields optimal THD performance, especially above 750 kHz, as confirmed in AD9221ARZ's typical performance curves.