Analog Devices Inc. AD7822BN

Overview

AD7822BN from Analog Devices is a high-speed, single-channel, 8-bit analog-to-digital converter (ADC) with 420 ns conversion time, 2 MSPS throughput, on-chip 2.5 V reference, and track-and-hold amplifier. It operates from 3 V ±10% or 5 V ±10% supply and supports standalone operation via EOC pulse for data acquisition in DSP front ends and mobile communication systems.

For engineers reviewing the AD7822BN datasheet, AD7822BN pinout, AD7822BN application, or AD7822BN equivalent, key selection considerations include its 1-channel configuration, automatic power-down triggered by CONVST logic level at EOC, VMID-adjustable input span (0 V to 2 V @ 3 V, 0 V to 2.5 V @ 5 V), and compatibility with microprocessor parallel interfaces requiring minimal address decoding.

Technical Context

The AD7822BN implements an 8-bit half-flash architecture: a 4-bit flash ADC generates MSBs, followed by a second flash stage for LSBs-achieving full conversion within 420 ns. Its track-and-hold acquires input in ≤200 ns and supports full-power bandwidth up to 10 MHz, enabling subsampling of RF/IF signals.

It integrates a 2.5 V ±2% on-chip reference, flexible analog input scaling via VMID (adjustable centering from AGND to VDD), and dual power-down control-automatic (via CONVST sampling at EOC high) and explicit (via dedicated PD pin). Logic interface complies with 3 V/5 V TTL levels and features high-impedance outputs with bus relinquish timing independent of external load capacitance.

Key Specifications

Pinout & Package

AD7822BN is housed in a 20-lead, 0.3" wide plastic dual in-line package (PDIP), with pin 1 identified by notch or dot. All pins are electrically defined per Analog Devices Rev. C datasheet; no NC (no-connect) pins present.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit, high-speed ADC applications.

Compared with AD7825BN and MAX1186BCPP+, the AD7822BN uniquely delivers single-channel simplicity, VMID-based input offset tuning, and true parallel bus autonomy - making it optimal for cost-sensitive, low-pin-count, high-throughput embedded acquisition where channel count is fixed and analog conditioning is minimal.

Availability

AD7822BN is available at Aetrix Electronics and suitable for high-speed data acquisition systems, disk drive servo control, and mobile communication subsampling applications requiring stable component supply and long-term industrial availability.

Supply support for AD7822BN 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 AD7822BN belongs to the AD782x family of high-speed, microprocessor-compatible sampling ADCs designed specifically for real-time signal acquisition in DSP front ends, disk drives, and portable communications equipment.

FAQ

What is the maximum sampling rate supported by the AD7822BN?

The AD7822BN supports a maximum throughput of 2 MSPS, enabled by its 420 ns maximum conversion time. This rate is achievable across the full industrial temperature range (−40°C to +85°C) and under both 3 V and 5 V supply conditions, provided timing constraints (e.g., t2 ≥20 ns CONVST pulse width, t3 ≥30 ns RD-to-CONVST spacing) are met per the Rev. C datasheet.

Does the AD7822BN require an external reference voltage?

No, the AD7822BN does not require an external reference voltage. It integrates a 2.5 V ±2% on-chip reference accessible at the VREF IN/OUT pin. The internal reference can be used directly - the pin may be left unconnected or decoupled to AGND with a 0.1 µF capacitor. An external reference may be applied only if higher accuracy or different voltage is needed.

How does the automatic power-down function work on the AD7822BN?

The AD7822BN enters automatic power-down when the CONVST pin is sampled low at the moment the EOC signal goes high (end of conversion). This feature eliminates the need for separate power-control logic. The device remains powered down until the next falling edge on CONVST initiates a new conversion, reducing average current to ≤0.2 µA in idle periods.

Can the AD7822BN interface directly with a 3.3 V microcontroller?

Yes, the AD7822BN supports 3 V ±10% operation and specifies logic input thresholds compatible with 3.3 V systems: VINH ≥2.0 V and VINL ≤0.4 V. Its DB0–DB7 outputs drive ≥2.4 V high and ≤0.2 V low at 200 µA load, meeting 3.3 V CMOS input requirements. No level-shifting circuitry is needed when interfacing with 3.3 V microcontrollers.

What is the purpose of the VMID pin on the AD7822BN?

The VMID pin sets the center voltage of the AD7822BN's analog input range. With VDD = 3 V, default span is 0 V to 2 V (centered at 1.0 V); with VDD = 5 V, it is 0 V to 2.5 V (centered at 1.25 V). Connecting VMID to a precise voltage shifts this center point anywhere between AGND and VDD - enabling offset correction for single-supply sensor interfaces without external op amps.