Analog Devices Inc. AD7278BRMZ

Overview

AD7278BRMZ from Analog Devices is an 8-bit, 4 MSPS successive approximation analog-to-digital converter (ADC) in a 6-lead TSOT package, operating from 2.35 V to 3.6 V supply. It delivers 49 dB SINAD at 1 MHz input, 74 MHz full-power bandwidth, and 0.2 LSB integral nonlinearity - optimized for high-speed sensor interface and portable instrumentation where low power and small footprint are critical.

For engineers reviewing the AD7278BRMZ datasheet, AD7278BRMZ pinout, AD7278BRMZ application, or AD7278BRMZ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and two confirmed alternative parts with documented functional and packaging differences.

Technical Context

The AD7278BRMZ uses a track-and-hold amplifier with 60 ns acquisition time and no pipeline delay, enabling precise sampling control via CS falling edge. Conversion is clocked entirely by SCLK, requiring exactly 10 cycles at 48 MHz for full throughput - eliminating latency uncertainty in real-time control loops.

Its internal VDD-referenced architecture fixes the analog input range to 0 V to VDD, simplifying signal conditioning. The SPI-compatible serial interface outputs two leading zeros followed by 8 data bits and six trailing zeros (MSB first), ensuring deterministic timing for microcontroller firmware integration.

Key Specifications

Pinout & Package

AD7278BRMZ is housed in a 6-lead TSOT (Thin Small Outline Transistor) package, 2.9 mm × 1.6 mm × 0.8 mm, with exposed pad for thermal enhancement and standard surface-mount reflow compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7278BRMZ, AD7277BRMZ offers 2 extra bits at nearly identical speed and footprint - ideal for resolution upgrades without redesign. ADS7822U trades speed and integration for cost and simplicity, but requires external reference and cannot support >200 kSPS sampling.

Availability

AD7278BRMZ is available at Aetrix Electronics and suitable for motor control, portable test equipment, industrial sensor interfaces, and battery-powered condition monitoring requiring stable component supply and long-term production continuity.

Supply support for AD7278BRMZ 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, with design centers worldwide and deep expertise in precision data conversion.

The AD727x family was designed specifically for space- and power-constrained applications needing high-speed, low-latency SAR ADCs - targeting industrial automation, medical instrumentation, and portable electronics where small size and deterministic timing are critical.

FAQ

What is the maximum sampling rate supported by the AD7278BRMZ?

The AD7278BRMZ achieves a maximum throughput rate of 4 MSPS when operated with a 48 MHz SCLK. This is enabled by its 10-cycle conversion architecture - each sample completes in 208 ns. At lower SCLK frequencies, the rate scales linearly; for example, 24 MHz yields 2 MSPS. The device maintains specified AC performance (e.g., 49 dB SINAD) across the full 3–4 MSPS range per datasheet Table 4.

Does the AD7278BRMZ require an external voltage reference?

No, the AD7278BRMZ uses an internal reference derived from the VDD supply, establishing a 0 V to VDD analog input range. This eliminates the need for external reference components, simplifies PCB layout, and reduces BOM count. However, it means analog input full-scale accuracy tracks VDD tolerance - a ±2% VDD variation introduces ±2% gain error, which must be calibrated out in high-accuracy systems.

How does the AD7278BRMZ handle power management in low-duty-cycle applications?

The AD7278BRMZ supports three power states: normal operation (10.5 mW typ), partial power-down (102 μW typ), and full power-down (7.2 μW max). In full power-down mode, it draws just 0.1 μA typical, enabling ultra-low quiescent current between sampling bursts. Recovery time from full power-down is 1 μs, allowing rapid wake-up for event-triggered acquisition in battery-powered nodes.

Is the AD7278BRMZ pin-compatible with other devices in the AD727x family?

Yes - the AD7278BRMZ shares identical 6-lead TSOT pinout and signal mapping with AD7276BRMZ and AD7277BRMZ. All three use VDD, GND, VIN, SCLK, SDATA, and CS on the same pins, with identical electrical characteristics and timing. This allows direct substitution within the same hardware design when resolution or speed requirements change, provided firmware handles the differing data frame length (8 vs. 10 vs. 12 bits).

What is the significance of the "two leading zeros" in the AD7278BRMZ serial data format?

The AD7278BRMZ outputs a fixed 10-bit frame: two leading zeros, followed by 8 data bits (MSB first), then six trailing zeros. The leading zeros synchronize the data stream to a consistent bit boundary, enabling reliable framing by host processors regardless of SCLK phase alignment. This structure ensures that the first data bit (DB7) always appears on the third SCLK falling edge after CS assertion - simplifying firmware bit-shift logic and reducing timing margin risk.