Analog Devices Inc. AD7940BRMZ-REEL7

Overview

AD7940BRMZ-REEL7 from Analog Devices is a 14-bit, single-supply successive approximation ADC in a 6-lead SOT-23 package, operating from 2.5 V to 5.5 V with 100 kSPS throughput, 81 dB SINAD at 10 kHz, and internal VDD-referenced input range (0 V to VDD). It serves as a compact, low-power analog-to-digital converter for space-constrained battery-powered measurement front-ends.

For engineers reviewing the AD7940BRMZ-REEL7 datasheet, AD7940BRMZ-REEL7 pinout, AD7940BRMZ-REEL7 application, or AD7940BRMZ-REEL7 equivalent, key selection criteria include its SOT-23 footprint, CS-controlled sampling with no pipeline delay, SPI-compatible serial interface, 0.5 µA shutdown current, and unipolar input architecture requiring no external reference.

Technical Context

The AD7940BRMZ-REEL7 implements a capacitive DAC-based successive approximation architecture with track-and-hold acquisition time of ≤500 ns (full-scale step) and aperture jitter of 30 ps typ. Its conversion is initiated on the falling edge of CS and clocked by SCLK, completing in exactly 16 cycles with no latency or pipelining.

It uses VDD as both supply and reference source, yielding an analog input range of 0 V to VDD and eliminating need for external reference circuitry. Digital I/O is compatible with 3 V or 5 V logic regardless of VDD, and power-down mode reduces supply current to 0.5 µA max at VDD = 5.5 V.

Key Specifications

Pinout & Package

AD7940BRMZ-REEL7 is housed in a RoHS-compliant, lead-free 6-lead SOT-23 package (JEDEC MO-178AA), measuring 2.9 mm × 1.6 mm × 1.1 mm, optimized for high-density PCB layouts and reflow assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar unipolar 14-bit SAR ADC applications.

Compared with AD7940BRMZ-REEL7, AD7942BRMZ offers higher speed and differential input at the cost of package size and signal-chain complexity, while ADS8860IDRCT delivers two extra bits of resolution in a larger footprint and with higher static current-making AD7940BRMZ-REEL7 optimal for space- and power-critical 14-bit unipolar applications.

Availability

AD7940BRMZ-REEL7 is available at Aetrix Electronics and suitable for battery-powered systems, portable medical instruments, and remote data acquisition systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for AD7940BRMZ-REEL7 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7940BRMZ-REEL7 belongs to Analog Devices' precision SAR ADC product line, engineered specifically for low-power, small-footprint data acquisition in portable and energy-sensitive applications where reference simplicity and timing determinism are critical.

FAQ

What is the absolute maximum analog input voltage for AD7940BRMZ-REEL7?

The absolute maximum analog input voltage for AD7940BRMZ-REEL7 is VDD + 0.3 V, per the Absolute Maximum Ratings table. Exceeding this risks forward-biasing internal ESD diodes and causing irreversible damage. For safe operation, the analog input must remain within 0 V to VDD under normal conditions, as specified in the Analog Input section. The device's 30 pF input capacitance and 25 Ω switch resistance further require careful attention to source impedance to maintain THD and SINAD performance.

Does AD7940BRMZ-REEL7 require an external voltage reference?

No, AD7940BRMZ-REEL7 does not require an external voltage reference. It derives its reference internally from the VDD supply, establishing a unipolar input range of 0 V to VDD. This eliminates the need for external reference ICs, decoupling networks, or trimming circuits-reducing BOM count and layout complexity. However, VDD must be well-decoupled (e.g., 100 nF ceramic + 10 µF tantalum) to maintain reference stability and achieve rated 81 dB SINAD performance.

How is power-down mode activated on AD7940BRMZ-REEL7?

Power-down mode on AD7940BRMZ-REEL7 is activated by pulling CS high between the 2nd and 10th falling edges of SCLK after the initial CS falling edge that starts conversion. This timing window ensures analog circuitry powers down cleanly, reducing supply current to 0.5 µA max. Bringing CS high outside this window-before the 2nd or after the 10th SCLK edge-keeps the device in normal mode. Exiting power-down requires a dummy conversion cycle before valid data is output.

Can AD7940BRMZ-REEL7 interface directly with 5 V logic microcontrollers?

Yes, AD7940BRMZ-REEL7 can interface directly with 5 V logic microcontrollers. Its digital inputs (CS and SCLK) tolerate voltages up to 7 V regardless of VDD, eliminating level-shifter requirements. However, the SDATA output logic levels are rail-to-rail with VDD-so when powered from 3 V, SDATA outputs 0 V/3 V signals. The microcontroller's input thresholds must accommodate this; most 5 V-tolerant GPIOs accept 0.7 × VDD as high-level minimum, satisfying compatibility at 3 V VDD.

What is the guaranteed integral nonlinearity (INL) specification for AD7940BRMZ-REEL7 across temperature?

The guaranteed integral nonlinearity for AD7940BRMZ-REEL7 is ±1 LSB maximum over the full operating temperature range (−40°C to +85°C) when VDD is 2.5 V to 4.096 V. At VDD > 4.096 V, the specification degrades to ±2 LSB max. This INL performance ensures monotonicity and predictable transfer function behavior in closed-loop control or calibrated measurement systems without requiring post-fabrication correction. Typical INL plots (Figure 9) show <±0.4 LSB deviation at 25°C and 3 V.