Analog Devices Inc. AD7827BNZ

Overview

AD7827BNZ from Analog Devices is an 8-bit, 1 MSPS serial-output sampling ADC with on-chip track-and-hold and 2.5 V reference (±2% tolerance), operating from single 3 V ±10% or 5 V ±10% supply. It delivers 420 ns conversion time, 200 ns acquisition time, and supports 0 V–2 V input range at 3 V supply or 0 V–2.5 V at 5 V supply-used in real-time DSP data acquisition systems requiring low-latency analog capture.

For engineers reviewing the AD7827BNZ datasheet, AD7827BNZ pinout, AD7827BNZ application, or AD7827BNZ equivalent, key selection considerations include its dual-supply compatibility, automatic power-down via CONVST, 3-wire serial interface timing synchronization with RFS, and guaranteed 8-bit no-missing-codes performance across –40°C to +105°C.

Technical Context

The AD7827BNZ implements a half-flash architecture: a 4-bit flash ADC generates MSBs, followed by a second flash stage for LSBs-achieving full 8-bit resolution in ≤420 ns. Its track-and-hold acquires input within 200 ns and holds for 120 ns during conversion, enabling accurate subsampling of up to 10 MHz signals.

Conversion initiation and power-state control are unified on the CONVST pin: falling edge triggers hold mode and conversion start; logic level sampled ~530 ns after falling edge determines automatic power-down. The RFS output synchronizes serial readout to SCLK, supporting burst-mode interfacing with TMS320C5x, ADSP-21xx, and DSP560xx processors without glue logic.

Key Specifications

Pinout & Package

AD7827BNZ is housed in an 8-lead, 0.3" wide plastic DIP (N-8 package) with through-hole mounting and standard DIP thermal profile (θ_JA = 105°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit, serial-interface sampling ADC applications.

Compared with AD7827BNZ, AD7823BNZ removes integrated reference flexibility but retains identical speed and package; MAX11200BCPA+ trades speed for resolution and targets entirely different application domains-neither is pin-compatible or functionally substitutable without redesign.

Availability

AD7827BNZ is available at Aetrix Electronics and suitable for industrial motor control, portable data loggers, automated test equipment, and DSP-based signal analyzers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7827BNZ 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 AD7827BNZ belongs to Analog Devices' legacy high-speed sampling ADC product line, designed specifically for real-time embedded systems requiring low-latency, low-power, DSP-synchronous digitization with minimal external components.

FAQ

What is the maximum input frequency the AD7827BNZ can accurately sample?

The AD7827BNZ analog input structure supports input frequencies up to 10 MHz while maintaining >7 ENOB at 1 MSPS sampling rate, as verified by SNR vs. input frequency plots in the datasheet. This makes it suitable for subsampling applications where high-frequency signals are downconverted digitally. The on-chip track-and-hold's 200 ns acquisition time and 10 MHz small-signal bandwidth enable faithful capture of such signals. For optimal performance, ensure input drive capability meets the 310 Ω series resistance and 4 pF capacitance specified in the analog input equivalent circuit.

Does the AD7827BNZ require an external reference, or can it operate with its internal reference?

The AD7827BNZ can operate using either its internal 2.5 V ±2% reference or an external reference applied to the VREF pin. When left unconnected, the internal reference is automatically enabled. If higher accuracy is needed, an external 2.5 V source (e.g., AD780) may be used-but the VREF input voltage range remains fixed at 2.45 V to 2.55 V, so externally sourced references must meet this tolerance. The internal reference eliminates one component and simplifies layout, making AD7827BNZ ideal for cost- and space-constrained designs.

How does the automatic power-down feature work on the AD7827BNZ?

The AD7827BNZ implements automatic power-down by sampling the logic level on the CONVST pin approximately 530 ns after its falling edge-the same edge that initiates conversion. If CONVST remains low at that instant, the device powers down; a rising edge on CONVST later wakes it up. This eliminates the need for separate power-control lines and allows firmware to manage power state with a single GPIO. Power-down current drops to 1 µA max, reducing average consumption significantly in duty-cycled applications-verified in Figure 11 of the AD7827BNZ datasheet.

Is the AD7827BNZ compatible with microcontrollers lacking dedicated serial frame sync inputs?

Yes-the AD7827BNZ's RFS output is optional for basic operation. While RFS simplifies synchronization with DSPs like TMS320C5x, the part can be used with general-purpose microcontrollers by polling DOUT status or using software-timed SCLK sequences. The serial interface requires only SCLK and DOUT connections; CONVST controls conversion timing. However, omitting RFS requires careful timing alignment in firmware to avoid reading incomplete data, especially at maximum 1 MSPS throughput.

What package type is used for the AD7827BNZ, and what are its mounting characteristics?

The AD7827BNZ uses an 8-lead, 0.3" wide plastic dual-in-line package (DIP), designated N-8 in Analog Devices' ordering guide. It features through-hole leads compatible with wave soldering and manual assembly, with θ_JA = 105°C/W for thermal management. This package provides mechanical robustness and ease of prototyping-distinct from the SOIC variant (AD7827BR). Pin 1 is marked by a notch or dot; the top-view pinout places CONVST at position 1, VIN at 2, RFS at 3, GND at 4, VREF at 5, DOUT at 6, SCLK at 7, and VDD at 8.