Analog Devices Inc. AD7651ACPZ

Overview

AD7651ACPZ from Analog Devices is a 16-bit, 100 kSPS charge redistribution SAR analog-to-digital converter operating from a single 5 V supply, featuring an internal 2.5 V reference (±7 ppm/°C drift), no pipeline delay, and dual parallel/serial (SPI/QSPI/MICROWIRE/DSP-compatible) interfaces. It delivers 86 dB SNR and 98 dB SFDR at 45 kHz input, targeting precision data acquisition in instrumentation and medical instruments.

For engineers reviewing the AD7651ACPZ datasheet, AD7651ACPZ pinout, AD7651ACPZ application, or AD7651ACPZ equivalent, key selection criteria include unipolar 0 V to 2.5 V input range, 16 mW typical power at 100 kSPS without reference, 48-lead LQFP/LFCSP package compatibility, and support for both 3 V and 5 V logic interface levels.

Technical Context

The AD7651ACPZ implements a high-speed charge redistribution SAR architecture with integrated error correction circuitry, eliminating pipeline latency and enabling immediate data availability post-conversion. Its internal reference provides 2.48–2.52 V output at 25°C with ±7 ppm/°C temperature drift over –40°C to +85°C.

It supports three digital interface modes: parallel (16-bit bus with CS/RD/BUSY control), serial master (internal SCLK generation), and serial slave (external SCLK synchronization), all compatible with 3 V or 5 V OVDD. Conversion is initiated by CNVST falling edge, with aperture delay of 2 ns and acquisition time of 8.75 µs.

Key Specifications

Pinout & Package

AD7651ACPZ is available in two RoHS-compliant packages: 48-lead LQFP (ST-48) and 48-lead LFCSP (CP-48), both measuring 7 mm × 7 mm. Pin numbering follows standard top-view orientation with Pin 1 identifier.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with AD7652ASTZ and AD7660ARUZ, the AD7651ACPZ uniquely balances unipolar simplicity, ultra-low standby power, and integrated reference stability-making it the preferred choice for cost-sensitive, battery-aware, and space-constrained precision acquisition.

Availability

AD7651ACPZ is available at Aetrix Electronics and suitable for medical instrumentation, industrial process control, and portable test equipment requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for AD7651ACPZ 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, headquartered in Norwood, MA, with decades of expertise in precision data conversion and signal conditioning.

The AD7651ACPZ belongs to Analog Devices' PulSAR® family of precision SAR ADCs, designed specifically for applications demanding high resolution, low latency, and single-supply operation without sacrificing AC performance or thermal stability.

FAQ

What is the reference voltage specification for the AD7651ACPZ?

The AD7651ACPZ features an internal reference voltage of 2.48 V to 2.52 V at 25°C, with a typical temperature drift of ±7 ppm/°C over –40°C to +85°C. Full-scale error is ±0.12% of FSR when using the internal reference. The REF pin can also accept external references from 2.3 V to AVDD – 1.85 V, provided PDREF is held HIGH to disable the internal reference.

Does the AD7651ACPZ support both 3 V and 5 V digital interfaces?

Yes, the AD7651ACPZ supports dual-voltage digital interfacing via its OVDD supply pin, which accepts 2.7 V to 5.25 V. When OVDD = 3.3 V, all digital I/O (CS, RD, BUSY, DATA, etc.) operate at 3 V logic levels; at OVDD = 5 V, they comply with 5 V TTL/CMOS thresholds. This allows seamless integration with both modern low-voltage MCUs and legacy 5 V controllers.

How does the AD7651ACPZ handle power-down and low-power operation?

The AD7651ACPZ uses two dedicated control pins-PD (power-down) and PDREF/PDBUF-for granular power management. Asserting PD HIGH halts conversions and reduces current draw; setting PDREF and PDBUF HIGH disables the internal reference and buffer, cutting total power to 160 µW at 1 kSPS. This enables adaptive power scaling in battery-powered instruments without sacrificing startup time or accuracy.

Is the AD7651ACPZ pin-compatible with other PulSAR ADCs?

Yes, the AD7651ACPZ is explicitly stated as pin-to-pin compatible with other members of the PulSAR family, including the AD7650, AD7652, and AD7653. This allows drop-in replacement within the same 48-lead LQFP or LFCSP footprint when upgrading resolution, speed, or input configuration-provided interface mode (SER/PAR) and reference configuration (PDREF/PDBUF) are revalidated per design.

What is the significance of the BYTESWAP and OB/2C pins on the AD7651ACPZ?

BYTESWAP controls data byte ordering in parallel mode: LOW outputs LSB on D[7:0], MSB on D[15:8]; HIGH swaps them. OB/2C selects numeric format: HIGH yields straight binary (0x0000 = 0 V, 0xFFFF = 2.5 V); LOW inverts the MSB for twos complement (0x8000 = 0 V). These pins enable direct compatibility with diverse processor endianness and signed/unsigned arithmetic requirements without software bit manipulation.