Analog Devices Inc. AD7478ART-500RL7

Overview

AD7478ART-500RL7 from Analog Devices is an 8-bit, 1 MSPS successive-approximation ADC in a 6-lead SOT-23 package, operating from 2.7 V to 5.25 V supply, delivering 49 dB SINAD at 100 kHz input, with 800 ns conversion time and 4.8 mW power dissipation at 3 V - used for compact, battery-powered data acquisition in portable medical sensors and optical monitoring systems.

For engineers reviewing the AD7478ART-500RL7 datasheet, AD7478ART-500RL7 pinout, AD7478ART-500RL7 application, or AD7478ART-500RL7 equivalent, this page delivers verified electrical specs, functional role in serial-conversion signal chains, real-world use-value metrics (e.g., 0–VDD input range, no pipeline delay), and validated alternative parts for low-power, space-constrained embedded sensing designs.

Technical Context

The AD7478ART-500RL7 implements a single-supply, track-and-hold–based successive-approximation architecture with internal VDD-referenced conversion, enabling full-scale analog input range from 0 V to VDD. It uses CS-controlled sampling on the falling edge and requires exactly 16 SCLK cycles per conversion, with no latency or pipelining.

Its SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface outputs 12-bit-aligned data (four leading zeros + eight data bits + four trailing zeros, MSB first) and supports flexible clock speeds up to 20 MHz. Standby current is limited to 1 μA maximum, and aperture jitter is specified at 30 ps typ.

Key Specifications

Pinout & Package

AD7478ART-500RL7 is housed in a Pb-free, RoHS-compliant 6-lead SOT-23 package (JEDEC MO-178AA), with 1.3 mm × 2.2 mm footprint and 0.95 mm height - optimized for high-density PCB layouts in handheld instrumentation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit SAR ADC applications.

Compared with ADS7822U and MAX11100ETT+, the AD7478ART-500RL7 uniquely balances 1 MSPS throughput, VDD-referenced simplicity, and ultra-small SOT-23 packaging - making it optimal for cost- and space-sensitive 8-bit acquisition where moderate SNR and deterministic timing are prioritized over extreme speed or ultra-low noise.

Availability

AD7478ART-500RL7 is available at Aetrix Electronics and suitable for battery-powered systems, portable medical instruments, optical sensors, and mobile communications requiring stable component supply and long-term production continuity.

Supply support for AD7478ART-500RL7 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7476/AD7477/AD7478 family was designed specifically for space-constrained, low-power embedded systems requiring fast, simple, single-supply analog-to-digital conversion - targeting portable instrumentation, sensor nodes, and energy-harvesting devices.

FAQ

What is the guaranteed resolution and missing-code performance of the AD7478ART-500RL7?

The AD7478ART-500RL7 is an 8-bit successive-approximation ADC with guaranteed no missing codes across its full operating temperature range (−40°C to +85°C). Its differential nonlinearity is specified at ±0.5 LSB max, ensuring monotonic transfer function behavior essential for closed-loop control and real-time waveform reconstruction. This specification is validated per Analog Devices' production test flow and documented in Rev. F datasheet Table 3.

Does the AD7478ART-500RL7 require an external reference voltage?

No, the AD7478ART-500RL7 uses an internal reference derived from the VDD supply, enabling a full-scale analog input range of 0 V to VDD. This eliminates the need for external reference components and simplifies layout in space-constrained designs. The device does not support external reference inputs - all conversions are inherently tied to VDD stability and noise performance.

What is the exact serial data format output by the AD7478ART-500RL7 on the SDATA pin?

The AD7478ART-500RL7 outputs a 12-bit-aligned serial frame on SDATA: four leading zeros, followed by the 8-bit conversion result (MSB first), followed by four trailing zeros. For example, a code of 0x80 appears as "0000 1000 0000" (12 bits total). Data is clocked out on the falling edge of SCLK, and the CS signal must remain low for the entire 12-bit transfer duration.

Can the AD7478ART-500RL7 operate from a 2.5 V supply?

No - the AD7478ART-500RL7 has a minimum VDD specification of 2.7 V, as confirmed in the Rev. F datasheet Section "AD7478 SPECIFICATIONS". Operation below 2.7 V is outside guaranteed specifications and may result in degraded INL, increased offset error, or failure to meet 1 MSPS timing. For 2.5 V systems, consider the AD7476A (12-bit) or AD7477A (10-bit), which specify operation down to 2.35 V.

How does the AD7478ART-500RL7 handle power-down mode, and what is the wake-up time?

The AD7478ART-500RL7 enters full power-down mode when CS is held high and SCLK is inactive, drawing ≤1 μA. Wake-up occurs on the first active-low CS pulse, with a typical power-up time of 1 μs (Table 4, tPOWER-UP). During this interval, the internal track-and-hold and reference circuits stabilize - no additional delay is required before initiating the first conversion after wake-up.