Analog Devices Inc. AD7944BCPZ

Overview

AD7944BCPZ from Analog Devices is a 14-bit, 2.5 MSPS successive approximation ADC (SAR ADC) with pseudo-differential analog input, on-chip 4.096 V reference, and SPI/QSPI/MICROWIRE-compatible serial interface. It delivers ±0.25 LSB typical INL, 84.5 dB SNR with external reference, and operates from −40°C to +85°C in battery-powered data acquisition systems.

For engineers reviewing the AD7944BCPZ datasheet, AD7944BCPZ pinout, AD7944BCPZ application, or AD7944BCPZ equivalent, key selection criteria include turbo/normal mode throughput scaling, 1.8 V–2.7 V logic interface compatibility, internal vs. external reference power trade-offs (15.5 mW vs. 28 mW at 2.5 MSPS), and pin-for-pin compatibility with AD7985/AD7986 for multi-bit resolution upgrades.

Technical Context

The AD7944BCPZ uses a charge redistribution capacitive DAC architecture with integrated track-and-hold, delivering zero pipeline delay and 100 ns transient response to full-scale steps. Its conversion is initiated by CNV rising edge, with timing fully controlled by on-chip clock - SCK is used only for data readout, not conversion execution.

Two operational modes are supported: TURBO high enables 2.5 MSPS continuous sampling without inter-conversion power-down, while TURBO low reduces throughput to 2.0 MSPS and powers down between conversions for lower average current. The serial interface supports CS mode (3- or 4-wire) and daisy-chain mode with busy indicator, all compatible with 1.8 V/2.5 V/2.7 V VIO supplies.

Key Specifications

Pinout & Package

AD7944BCPZ is housed in a 20-lead, 4 mm × 4 mm LFCSP (QFN) package with exposed pad recommended for soldering to system ground plane. Pin functions are validated per Analog Devices Rev. C datasheet Figure 4 and Table 6.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed SAR ADC applications.

Compared with AD7944BCPZ, AD7985BCPZ offers +2 bits resolution at identical speed and package, while AD7986BCPZ adds +4 bits but requires tighter noise control; both retain full software and layout compatibility, enabling scalable precision without redesign.

Availability

AD7944BCPZ is available at Aetrix Electronics and suitable for battery-powered equipment, medical instruments, and automated test equipment requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for AD7944BCPZ 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 AD7944BCPZ belongs to the PulSAR® family of precision SAR ADCs designed for applications demanding high speed, low power, and exceptional dc/ac accuracy - especially where zero latency and reference integration are critical.

FAQ

What is the maximum sampling rate of the AD7944BCPZ and under what conditions?

The AD7944BCPZ achieves a maximum sampling rate of 2.5 MSPS in TURBO high mode, which requires the TURBO pin to be held high and the CNV input to be driven at ≤400 ns minimum cycle time. This mode disables inter-conversion power-down, ensuring continuous high-speed operation. The first conversion in turbo mode contains meaningless data and must be discarded.

Does the AD7944BCPZ require an external reference, or does it include an internal one?

The AD7944BCPZ includes a factory-trimmed 4.096 V internal reference with ±10 ppm/°C temperature drift, accessible on the REF pin when PDREF is low. An external reference (2.4 V to 5.1 V) may be used by pulling PDREF high and connecting to REF, enabling optimized SNR or custom full-scale ranges. Both configurations are fully supported in the AD7944BCPZ datasheet.

Can multiple AD7944BCPZ devices be connected to a single microcontroller SPI bus?

Yes - the AD7944BCPZ supports daisy-chain mode: when SDI is low at the CNV rising edge, multiple AD7944BCPZ units can share one SDO line, with each device shifting its 14-bit result onto the bus sequentially. The busy indicator feature remains available, and no additional chip-select lines are needed, reducing host resource usage and PCB routing complexity.

What is the analog input structure of the AD7944BCPZ, and how should IN− be connected?

The AD7944BCPZ features a pseudo-differential analog input structure where IN+ is the signal input and IN− serves as a ground sense reference. IN− must be connected to the analog ground plane or to a remote ground point near the signal source to reject common-mode noise. The voltage difference (IN+ − IN−) must remain within 0 V to VREF, and absolute voltages on both pins must stay within −0.1 V to VREF + 0.1 V.

How does the power consumption of the AD7944BCPZ vary between internal and external reference configurations?

At 2.5 MSPS, the AD7944BCPZ consumes 28 mW with the internal reference enabled (PDREF = low) and 15.5 mW with an external reference (PDREF = high). This 12.5 mW reduction reflects elimination of the on-chip reference buffer's quiescent current. The internal reference option trades power for system simplicity; the external option optimizes for ultra-low-power portable designs where reference ICs are already present.