Analog Devices Inc. AD7777ANZ

Overview

AD7777ANZ from Analog Devices is a 10-bit, 4-channel, successive-approximation ADC with parallel digital interface, ±1 LSB relative accuracy, 380.95 kSPS maximum sampling rate, and integrated 2.0 V reference output - designed for high-speed data acquisition in DSP-based voice recognition, echo cancellation, and adaptive filtering systems.

For engineers reviewing the AD7777ANZ datasheet, AD7777ANZ pinout, AD7777ANZ application, or AD7777ANZ equivalent, this page delivers verified electrical specs, channel-to-channel isolation (–90 dB), timing constraints (tCLKIN = 125–500 ns), power-down mode behavior (1.5 mA), and microprocessor interface compatibility with TMS320 and ADSP-21xx families.

Technical Context

The AD7777ANZ implements a track-and-hold architecture supporting up to 189 kHz input sine wave bandwidth at full throughput, with dual-conversion capability (CR6 = 1) enabling simultaneous sampling across two selected channels. Its 10-bit SAR core uses two's complement coding and operates with external clock (CLKIN) ranging from 2 MHz to 8 MHz.

Control is managed via a 10-bit write-only register (CR0–CR9) defining channel selection (AIN1–AIN4), single/dual conversion mode, half-scale test, power-down (CR8), and BUSY/INT flag polarity (CR9). Reference is derived internally from REFIN (1.9–2.1 V) or REFOUT (2.0 V nominal), setting VBIAS = REFIN and VSWING = REFIN/2.

Key Specifications

Pinout & Package

AD7777ANZ is packaged in a 28-pin plastic DIP (PDIP) with 0.6-inch width, compliant with JEDEC MS-001. Pin functions are electrically identical to the SOIC variant (AD7777AR), differing only in lead form and thermal characteristics (θJA = 75°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit multichannel ADC applications.

Compared with AD7777ANZ, AD7777AR offers identical electrical performance in a surface-mount package ideal for volume production, while ADS8325IPW trades channel count and parallel interface for higher resolution and serial simplicity-neither is pin-compatible, but both serve overlapping data acquisition roles with distinct trade-offs.

Availability

AD7777ANZ is available at Aetrix Electronics and suitable for voice recognition front-ends, echo cancellation systems, and industrial sensor data loggers requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for AD7777ANZ 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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and real-time control.

The AD7776/AD7777/AD7778 family was engineered for DSP-centric data acquisition where speed, channel count, and interface simplicity outweigh ultra-high resolution - targeting voice, audio, and real-time control applications.

FAQ

What is the maximum sampling rate supported by the AD7777ANZ?

The AD7777ANZ achieves a maximum sampling rate of 380.95 kSPS when CLKIN = 8 MHz. This corresponds to a single-conversion time of 14 tCLKIN (1.75 µs), enabling accurate digitization of analog signals up to 189 kHz (Nyquist frequency). The AD7777ANZ maintains this rate across all four channels in sequential mode, and supports simultaneous sampling of two channels with automatic double-conversion sequencing.

Does the AD7777ANZ require an external reference voltage?

No - the AD7777ANZ includes an internal 2.0 V reference buffer accessible via REFOUT, which can directly drive the REFIN pin to set VBIAS and VSWING. However, an external 1.9–2.1 V reference may be applied to REFIN for improved stability or noise performance. The AD7777ANZ does not generate its own reference; it either buffers REFOUT or follows the external REFIN voltage.

How does the power-down mode function in the AD7777ANZ?

Writing CR8 = 1 places the AD7777ANZ in power-down mode, reducing ICC to 1.5 mA by disabling all linear circuitry. REFOUT is weakly pulled to AGND (5 kΩ), and ongoing conversions halt immediately. Control inputs (CS, RD, WR, CLKIN) remain functional, allowing wake-up via CR8 = 0. Valid ADC register contents are retained during power-down and readable until overwritten by the next conversion.

Can the AD7777ANZ interface directly with the TMS320C25 DSP?

Yes - the AD7777ANZ is explicitly characterized for interfacing with the TMS320C25 at 40 MHz, requiring one wait state. Timing parameters t1–t11 are fully specified for this configuration, and Figure 8 in the datasheet shows the complete interface schematic including READY signal synchronization. The parallel 10-bit bus (DB0–DB9), along with CS, RD, and WR, aligns with the C25's external memory interface protocol.

What is the purpose of the CREFIN capacitor in the AD7777ANZ circuit?

A 10 nF capacitor must be connected from CREFIN to AGND to stabilize the internal reference decoupling node. This capacitor suppresses high-frequency noise on the reference path and ensures consistent track-and-hold settling during conversion. Omitting or undersizing CREFIN causes increased code transition noise, reduced S/(N+D), and potential conversion errors - the AD7777ANZ will not meet datasheet specifications without this capacitor.