Analog Devices Inc. AD7825BRUZ-REEL

Overview

AD7825BRUZ-REEL from Analog Devices is a 4-channel, 8-bit, 2 MSPS parallel-output analog-to-digital converter with on-chip 2.5 V reference, 420 ns conversion time, and automatic power-down triggered by CONVST logic level at EOC assertion. It operates from single 3 V ±10% or 5 V ±10% supply and targets high-speed data acquisition in DSP front ends and mobile communication subsampling systems.

For engineers reviewing the AD7825BRUZ-REEL datasheet, AD7825BRUZ-REEL pinout, AD7825BRUZ-REEL application, or AD7825BRUZ-REEL equivalent, key selection considerations include its 4-channel multiplexed analog input architecture, VMID-adjustable input span (0 V to 2.5 V p-p at 5 V, 0 V to 2 V p-p at 3 V), track-and-hold acquisition time of 200 ns, channel-to-channel isolation of −70 dB typ, and EOC-synchronized parallel interface for microprocessor/DSP interfacing without external timing control.

Technical Context

The AD7825BRUZ-REEL implements an 8-bit half-flash ADC architecture with two-stage conversion: a 4-bit coarse flash stage followed by a 4-bit fine flash stage, delivering full 8-bit resolution in ≤420 ns. Its track-and-hold amplifier supports full-power bandwidth up to 10 MHz and acquisition time of 200 ns after channel change or input step.

Channel selection is performed via dedicated A0/A1 address inputs, independent of data bus activity; conversion initiation and power-down control share the CONVST pin, while PD provides separate power-down control. The device integrates on-chip 2.5 V reference (±50 mV error, 50 ppm/°C TC) and supports external reference via VREF IN/OUT pin.

Key Specifications

Pinout & Package

AD7825BRUZ-REEL is housed in a 24-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, optimized for high-density PCB layouts and thermal performance (θ_JA = 128°C/W). The package is RoHS-compliant and moisture-sensitive level 3 (MSL3).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel, 8-bit, high-speed ADC applications.

Compared with AD7822BRUZ-REEL and AD7829BRUZ-REEL, the AD7825BRUZ-REEL delivers optimal channel count for mid-density DAQ systems: it avoids the underutilization penalty of the 8-channel part while eliminating the need for multiple single-channel devices and associated interconnect overhead.

Availability

AD7825BRUZ-REEL is available at Aetrix Electronics and suitable for disk drive servo control, mobile communication subsampling, and industrial data acquisition requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7825BRUZ-REEL 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 AD7822/AD7825/AD7829 family was designed specifically for high-speed, low-latency data acquisition in resource-constrained embedded systems - emphasizing minimal external components, flexible supply operation, and seamless microprocessor interfacing.

FAQ

What is the maximum sampling rate supported by the AD7825BRUZ-REEL?

The AD7825BRUZ-REEL supports a maximum throughput of 2 MSPS, corresponding to a maximum conversion time of 420 ns. This rate is achievable across the full industrial temperature range (−40°C to +85°C) and 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. The AD7825BRUZ-REEL maintains this rate without performance degradation due to its half-flash architecture and integrated track-and-hold.

Does the AD7825BRUZ-REEL require an external reference voltage?

No, the AD7825BRUZ-REEL includes an on-chip 2.5 V reference with ±2% initial tolerance and 50 ppm/°C temperature coefficient, accessible via the VREF IN/OUT pin. External reference is optional and used only when higher accuracy or lower drift is required. When using the internal reference, VREF IN/OUT may be left unconnected or decoupled to AGND with a 0.1 µF capacitor. The AD7825BRUZ-REEL functions fully with internal reference enabled.

How does channel selection work on the AD7825BRUZ-REEL?

Channel selection on the AD7825BRUZ-REEL is performed using the A0 and A1 address inputs, which directly select VIN1 through VIN4 without requiring register writes or serial configuration. The selected channel is sampled on the falling edge of CONVST. A0 and A1 must be stable before RD goes low to ensure correct data alignment. This hardware-based addressing simplifies interface design with microcontrollers and FPGAs, eliminating software overhead for channel switching.

What is the purpose of the VMID pin on the AD7825BRUZ-REEL?

The VMID pin on the AD7825BRUZ-REEL sets the center voltage of the analog input span, allowing the 2.5 V (5 V supply) or 2 V (3 V supply) input range to be positioned anywhere between AGND and VDD. With VMID unconnected, the default center is 1.25 V (5 V) or 1.0 V (3 V). Connecting VMID to an external voltage (e.g., from a precision divider) enables offset compensation for single-supply op amps or correction of system-level DC offsets - a key feature for sensor signal chains.

Can the AD7825BRUZ-REEL operate from a 3.3 V supply?

Yes, the AD7825BRUZ-REEL is specified for operation from 3 V ±10%, i.e., 2.7 V to 3.3 V. At 3.3 V, all electrical specifications - including conversion time (420 ns), SNR (48 dB min), INL/DNL (±0.75 LSB), and power consumption (12 mA max normal, 5 µA max power-down) - remain valid across −40°C to +85°C. Input voltage span automatically configures to 0 V–2 V p-p, and logic thresholds adjust accordingly (VINH ≥ 2.0 V, VINL ≤ 0.4 V).