Analog Devices Inc. AD7817SR

Overview

AD7817SR from Analog Devices is a 10-bit, 4-channel successive-approximation ADC with integrated temperature sensor, 9 μs conversion time for analog inputs, on-chip 2.5 V reference (±1%), and overtemperature indicator output. It operates from 2.7 V to 5.5 V and delivers ±1 LSB relative accuracy across four single-ended input channels - used in industrial process control systems requiring ambient temperature-aware data acquisition.

For engineers reviewing the AD7817SR datasheet, AD7817SR pinout, AD7817SR application, or AD7817SR equivalent, key selection considerations include its 4-channel multiplexed architecture, channel-to-channel isolation of −80 dB at 20 kHz, automatic power-down mode (4 μW at 10 SPS), and compatibility with Intel 8051, SPI, QSPI, and MICROWIRE serial protocols.

Technical Context

The AD7817SR implements a capacitor-based successive-approximation DAC core with inherent track-and-hold functionality and an internal clock oscillator. Its 4-channel analog multiplexer selects VIN1–VIN4 or the on-chip temperature sensor (Channel 0), with conversion initiated by a falling edge on CONVST and BUSY asserted high during conversion.

It supports flexible serial communication via CS, RD/WR, SCLK, DIN, and DOUT pins, enabling read/write access to address and overtemperature registers. The OTI pin provides asynchronous overtemperature alerting based on comparison between Channel 0's ADC result and an 8-bit OTR register value.

Key Specifications

Pinout & Package

AD7817SR is housed in a narrow-body 16-lead SOIC package (width = 0.15 inch) with standard JEDEC MS-012AC footprint and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit multichannel ADC with temperature sensing applications.

Compared with AD7817SR, AD7818ARZ reduces channel count and package size while retaining identical temperature accuracy and serial protocol support, whereas MAX1240BCPA+ trades SPI compatibility and speed for I²C simplicity and lower quiescent power - making AD7817SR optimal for SPI-based 4-channel thermal-aware DAQ designs.

Availability

AD7817SR is available at Aetrix Electronics and suitable for industrial process control, battery management systems, and automotive cabin climate monitoring requiring stable component supply and long-term production continuity.

Supply support for AD7817SR 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 design centers worldwide and ISO 9001-certified manufacturing.

The AD7817SR belongs to Analog Devices' precision data acquisition product line, engineered for embedded systems needing integrated analog sensing, low-power operation, and robust serial interfacing in harsh environments.

FAQ

What is the maximum operating temperature range for the AD7817SR?

The AD7817SR operates from −55°C to +125°C, with temperature sensor accuracy specified as ±2°C from −40°C to +85°C when using the external 2.5 V reference. This extended range supports deployment in under-hood automotive and industrial environments where thermal extremes are common. The AD7817SR maintains functional integrity across this full range, though sensor error increases slightly outside the −40°C to +85°C band.

Does the AD7817SR require an external reference voltage?

No, the AD7817SR includes an on-chip 2.5 V ±1% reference that activates automatically when the REFIN pin is tied to AGND. An external 2.5 V reference can be applied to REFIN for improved accuracy, which disables the internal reference. The AD7817SR datasheet confirms internal reference operation is fully functional and eliminates external component requirements for most applications.

How does the overtemperature indicator (OTI) pin function on the AD7817SR?

The OTI pin on the AD7817SR asserts logic low when the ADC result from Channel 0 (temperature sensor) exceeds the value stored in the on-chip 8-bit overtemperature register (OTR). It resets automatically at the end of a serial read operation (rising edge of RD/WR with CS low). This hardware-level alert enables immediate thermal shutdown or warning without CPU polling, enhancing system safety in AD7817SR-based designs.

Can the AD7817SR interface directly with an STM32 microcontroller's SPI peripheral?

Yes, the AD7817SR supports SPI-compatible serial communication using CS, SCLK, DIN, DOUT, and RD/WR signals. Its timing aligns with standard SPI modes (CPOL = 0, CPHA = 0), and it accepts 8-bit control bytes for channel selection and register access. STM32 firmware can drive the AD7817SR using GPIO-controlled RD/WR and standard SPI hardware, confirmed by Analog Devices' AD7817 Serial Interface documentation.

What is the conversion time for the temperature sensor channel on the AD7817SR?

The AD7817SR requires 27 μs to complete a conversion on Channel 0 (temperature sensor), compared to 9 μs for VIN1–VIN4 analog inputs. This longer duration reflects additional internal settling and calibration steps specific to the on-die thermal sensor element. The 27 μs value is guaranteed across all versions (A/B/S) and operating conditions per the Rev. E datasheet Table 1.