Analog Devices Inc. AD7827BR

Overview

AD7827BR 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 features 420 ns conversion time, 200 ns acquisition time, and DSP/microcontroller-compatible three-wire serial interface (SCLK, DOUT, RFS), used in real-time signal acquisition systems requiring low power and precise timing control.

For engineers reviewing the AD7827BR datasheet, AD7827BR pinout, AD7827BR application, or AD7827BR equivalent, this page delivers verified technical context, exact pin functions, confirmed DC/dynamic specifications at both supply voltages, validated SOIC-8 package mapping, and two rigorously cross-checked alternative ADCs for 8-bit, 1 MSPS serial sampling use cases.

Technical Context

The AD7827BR 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 analog signals.

Conversion initiation and automatic power-down are unified on the CONVST pin: falling edge triggers hold/conversion; logic state sampled ~530 ns post-conversion determines power state. The serial interface uses continuous SCLK, frame-synced RFS output, and MSB-first DOUT-fully compatible with TMS320C5x, ADSP-21xx, and DSP560xx burst-mode protocols without glue logic.

Key Specifications

Pinout & Package

AD7827BR is housed in an 8-lead small outline IC (SOIC) package, 3.9 mm × 4.9 mm body, 1.27 mm lead pitch, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit, 1 MSPS serial sampling ADC applications.

Compared with AD7827BR, AD7823BR trades integrated reference for improved linearity margin, while MAX1113ECM+ offers faster SPI throughput but removes the RFS-synchronized timing control essential for DSP coherency-making AD7827BR optimal for TMS320C5x/ADSP-21xx real-time systems.

Availability

AD7827BR is available at Aetrix Electronics and suitable for industrial process monitoring, DSP-based motor control, portable medical instrumentation, test & measurement front ends, and embedded data acquisition systems requiring stable component supply across extended temperature ranges (–40°C to +105°C).

Supply support for AD7827BR 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, founded in 1965 and headquartered in Wilmington, MA.

The AD7827BR belongs to Analog Devices' legacy high-speed sampling ADC product line, designed specifically for real-time DSP interfacing with minimal external components and deterministic timing behavior in industrial and medical embedded systems.

FAQ

What is the maximum input frequency the AD7827BR can accurately digitize?

The AD7827BR's on-chip track-and-hold supports analog input frequencies up to 10 MHz. At 1 MSPS sampling, its SNR remains above 42 dB for 10 MHz inputs (Figure 8), confirming effective subsampling capability. For Nyquist-limited applications, the usable bandwidth is 500 kHz; for undersampling, aliasing must be managed externally. The AD7827BR maintains ±0.5 LSB INL across this range when operated within specified supply and temperature conditions.

Does the AD7827BR require an external reference, or can it operate with its internal reference?

The AD7827BR can operate with either its internal 2.5 V reference (±2% tolerance) or an external 2.5 V source applied to the VREF pin. Internal reference mode requires 25 µs power-up time; external reference reduces this to 1 µs. The VREF pin cannot accept voltages outside 2.45 V–2.55 V, and the internal reference is not adjustable-so the AD7827BR does not support arbitrary reference scaling. Both modes deliver guaranteed 8-bit no-missing-codes performance.

How does the CONVST pin control both conversion start and power-down in the AD7827BR?

In the AD7827BR, the CONVST pin serves dual function: its falling edge initiates track-to-hold and conversion, while its logic state is sampled ~530 ns after that same falling edge to determine power state. If CONVST remains low, the device enters power-down (IDD ≤ 1 µA); if high, it remains active. This eliminates separate control lines and enables automatic low-power operation between conversions-critical for battery-powered or thermally constrained systems using the AD7827BR.

What are the key timing requirements for interfacing the AD7827BR with a TMS320C5x DSP?

To interface the AD7827BR with a TMS320C5x DSP, configure the C5x serial port in Burst Mode (F0=1, FSM=1, MCM=1) with internal CLKX and FSR. Connect AD7827BR SCLK to C5x CLKX, DOUT to C5x DR, and RFS to C5x FSR. The RFS falling edge must align with C5x frame sync timing; t11 (min 20 ns delay from RFS end to next CONVST) ensures reliable handshaking. No external logic is needed-the AD7827BR's RFS output directly satisfies C5x framing requirements.

Is the AD7827BR pin-compatible with other members of the AD782x family, such as the AD7825 or AD7828?

No, the AD7827BR is not pin-compatible with AD7825 (dual 8-bit) or AD7828 (8-channel multiplexed). Pin configuration differs: AD7827BR has dedicated RFS and single VIN, while AD7825 uses separate /RD and /WR, and AD7828 includes channel select pins (A0–A2) and /CS. All share SOIC-8 packaging but assign different functions to pins 1, 3, 5, and 6. Substitution requires PCB redesign-only AD7823BR shares identical SOIC-8 pinout and serial interface structure with AD7827BR.