Analog Devices Inc. AD9221AR

Overview

AD9221AR from Analog Devices is a monolithic 12-bit analog-to-digital converter with 1.5 MSPS sampling rate, ±0.4 LSB typical integral nonlinearity, and 70 dB SINAD, operating on a single 5 V analog supply and 3–5 V digital supply. It integrates a sample-and-hold amplifier and programmable voltage reference, and is used in precision data acquisition systems requiring low-power, high-linearity digitization of dc-coupled or ac-coupled analog signals.

For engineers reviewing the AD9221AR datasheet, AD9221AR pinout, AD9221AR application, or AD9221AR equivalent, key selection considerations include its 1.5 MSPS throughput, 59 mW typical power consumption, 28-lead SOIC package, and compatibility with both single-ended and differential input configurations across imaging, medical, and communications signal chains.

Technical Context

The AD9221AR employs a four-stage differential pipelined architecture with digital error correction logic to guarantee no missing codes over temperature and deliver true 12-bit DC linearity. Its sample-and-hold amplifier supports flexible input spans (2 V or 5 V p-p) and common-mode levels (1 V or 2.5 V), enabling direct interface with multiplexed sensor arrays or IF-sampled RF receivers.

Internal timing uses the rising edge of CLK for sampling; pipeline latency is fixed at three clock cycles. The device accepts external references or uses its internal 1 V/2.5 V reference, with SENSE pin selecting mode, and features an out-of-range (OTR) flag synchronized to the MSB for overflow detection in real-time control loops.

Key Specifications

Pinout & Package

AD9221AR is housed in a 28-lead Small Outline Integrated Circuit (SOIC) package with standard JEDEC MS-013AC footprint (17.9 mm × 7.5 mm, 1.27 mm pitch). Thermal resistance θ_JA = 71.4°C/W enables operation up to +85°C ambient without forced airflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD9221AR, AD9223AR offers double the sampling rate at higher power, while ADS7822U trades speed and integrated features for ultra-low power and simplicity-making AD9221AR optimal for cost-sensitive, medium-speed industrial digitization where internal reference and SOIC compatibility are prioritized.

Availability

AD9221AR is available at Aetrix Electronics and suitable for medical instrumentation, industrial data acquisition, and communications test equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AD9221AR 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 AD9221AR belongs to the AD922x family of monolithic 12-bit pipeline ADCs designed for precision, low-power digitization in space-constrained, thermally demanding applications across industrial, medical, and test equipment markets.

FAQ

What is the maximum sampling rate supported by the AD9221AR?

The AD9221AR supports a maximum conversion rate of 1.5 MSPS, as specified in its datasheet under all operating conditions from –40°C to +85°C. This rate is guaranteed with proper decoupling, stable 5 V AVDD, and compliant clock timing (minimum 667 ns period, 300 ns high/low pulsewidth). Exceeding this rate degrades AC performance and may cause missing codes.

Does the AD9221AR require an external voltage reference?

No, the AD9221AR does not require an external voltage reference. It integrates a programmable internal reference providing either 1 V or 2.5 V output, selected via the SENSE pin. External reference operation is optional and supported through the VREF pin when higher initial accuracy or lower temperature drift is needed beyond the internal reference's ±35 mV tolerance at 2.5 V mode.

How is the out-of-range (OTR) signal used in the AD9221AR?

The OTR signal in the AD9221AR is an active-high, synchronous flag that asserts when the absolute value of the differential input (|VINA – VINB|) exceeds the selected reference voltage (VREF), indicating analog input overflow. It is timed to align with BIT 1 (MSB) and can be used in real-time systems to trigger automatic gain control, saturating alarm logging, or input range reconfiguration without CPU intervention.

Can the AD9221AR operate with a 3.3 V digital supply?

Yes, the AD9221AR supports DVDD from 2.7 V to 5.25 V, including 3.3 V operation. Its digital outputs are fully compatible with 3.3 V logic families: VOH is ≥2.95 V (IOH = 50 µA) and VOL is ≤0.4 V (IOL = 1.6 mA) at 3.3 V DVDD. This allows direct interfacing with 3.3 V FPGAs or microcontrollers without level shifters.

What is the significance of the CAPT and CAPB pins on the AD9221AR?

The CAPT and CAPB pins on the AD9221AR are dedicated noise reduction terminals for the internal voltage reference circuit. They must be connected to 0.1 µF ceramic capacitors tied to AVSS to stabilize the reference and minimize output noise. Omitting these capacitors increases input-referred noise from 0.09 LSB to 0.23 LSB (at 2.5 V reference), directly degrading SINAD and ENOB in precision measurement applications.