Analog Devices Inc. AD7654ASTZ

Overview

AD7654ASTZ from Analog Devices is a dual-channel, simultaneous-sampling, 16-bit SAR analog-to-digital converter with 500 kSPS throughput in normal mode and 444 kSPS in impulse mode. It features two independent track-and-hold amplifiers, ±3.5 LSB INL, 89 dB SNR at 100 kHz, and operates from a single 5 V supply. It is used in high-precision industrial data acquisition systems requiring synchronized voltage measurements across multiple phases.

For engineers reviewing the AD7654ASTZ datasheet, AD7654ASTZ pinout, AD7654ASTZ application, or AD7654ASTZ equivalent, key selection criteria include simultaneous sampling capability, dual 4-channel multiplexed analog input structure (INA1/INB1 or INA2/INB2), SPI/QSPI/MICROWIRE-compatible serial interface, parallel 16-bit output, and low-power impulse mode scaling with throughput.

Technical Context

The AD7654ASTZ implements a charge redistribution SAR architecture with internal error correction and no pipeline delay. Its dual T/H circuitry enables true simultaneous sampling of two analog channels per conversion cycle, with A0 pin selecting between input pairs INA1/INB1 or INA2/INB2.

It supports both parallel and 2-wire serial interfaces (SPI/QSPI/MICROWIRE/DSP compatible) with configurable logic levels (3 V or 5 V), and includes dedicated control pins for mode selection (IMPULSE, SER/PAR), channel readout (A/B, RD), and conversion timing (CNVST, BUSY, EOC). Power dissipation scales from 120 mW at 500 kSPS to 2.6 mW at 10 kSPS in impulse mode.

Key Specifications

Pinout & Package

The AD7654ASTZ is housed in a 48-lead LQFP (Low Profile Quad Flat Package) with exposed pad grounded for thermal performance. Pin 1 is marked by dot; EPAD connection to AGND is recommended but not required for specified performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel, simultaneous-sampling ADC applications.

Compared with AD7655ASTZ, the AD7654ASTZ trades resolution for speed-enabling faster control loop closure-while versus LTC2358ILX-16#PBF, it offers simpler power sequencing and integrated reference support, reducing BOM count in space-constrained designs.

Availability

AD7654ASTZ is available at Aetrix Electronics and suitable for AC motor control, 3-phase power monitoring, and industrial data acquisition requiring stable component supply and long-term production continuity.

Supply support for AD7654ASTZ 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 AD7654ASTZ belongs to the PulSAR® family of precision SAR ADCs designed specifically for industrial automation, energy metering, and motor control applications demanding simultaneous sampling, low latency, and robust noise immunity.

FAQ

What is the maximum sampling rate of the AD7654ASTZ in normal mode?

The AD7654ASTZ achieves a maximum throughput of 500 kSPS in normal mode, corresponding to a complete conversion cycle time of 2 μs. This specification is guaranteed over the full operating temperature range (−40°C to +85°C) and applies to both channels simultaneously. The AD7654ASTZ maintains this rate with 16-bit resolution and no missing codes, making it suitable for high-speed closed-loop control applications where timing determinism is critical.

Does the AD7654ASTZ support true differential input configurations?

The AD7654ASTZ does not implement true differential input architecture. It supports pseudo-differential operation via independent channel references (REFA/REFB) and ground-sense inputs (INAN/INBN), enabling rejection of common-mode noise on each channel. However, its analog inputs (INA1/INB1, etc.) are unipolar 0 V to 5 V, and differential voltage measurement requires external instrumentation amplifier front-end circuitry. The AD7654ASTZ datasheet explicitly categorizes it under "Multichannel/Simultaneous" in the PulSAR selection table-not "True Differential."

How does the IMPULSE pin affect power consumption in the AD7654ASTZ?

When the IMPULSE pin is driven high, the AD7654ASTZ enters reduced-power mode, scaling its power dissipation approximately linearly with throughput: 114 mW at 444 kSPS, 120 mW at 500 kSPS, and down to 2.6 mW at 10 kSPS. This mode retains full 16-bit performance and simultaneous sampling capability but adjusts internal clocking and bias currents dynamically. The AD7654ASTZ datasheet specifies all AC/DC accuracy parameters remain unchanged in impulse mode, ensuring no compromise in measurement fidelity at lower speeds.

Can the AD7654ASTZ interface directly with a 3.3 V microcontroller in serial mode?

Yes, the AD7654ASTZ supports direct 3.3 V logic interfacing in serial mode via its OVDD pin, which accepts 2.7 V to 5.25 V. When OVDD = 3.3 V, all serial interface outputs (SDOUT, SYNC, SCLK) swing between 0 V and 3.3 V, and inputs (SDIN, EXT/INT, INVSYNC, etc.) recognize 0.8 V/2.0 V thresholds compatible with 3.3 V CMOS levels. The AD7654ASTZ datasheet confirms SPI/QSPI/MICROWIRE compatibility at both 3 V and 5 V logic levels, eliminating need for level shifters in mixed-voltage systems.

What is the function of the A0 pin on the AD7654ASTZ?

The A0 pin on the AD7654ASTZ selects which pair of analog inputs is simultaneously sampled: when A0 is low, INA1 and INB1 are acquired; when A0 is high, INA2 and INB2 are acquired. This enables the AD7654ASTZ to serve as a 4-channel ADC with dual simultaneous sampling capability, supporting applications like three-phase voltage/current capture where phase-paired measurements must be time-aligned. The A0 control is sampled at CNVST falling edge and held throughout the conversion cycle, as verified in the AD7654ASTZ functional block diagram and timing specifications.