Analog Devices Inc. ADM1021AARQ-REEL7

Overview

ADM1021AARQ-REEL7 from Analog Devices is a dual-channel digital thermometer IC with on-chip and remote diode temperature sensing, ±1°C local accuracy and ±3°C remote accuracy, SMBus 2-wire interface, programmable over/undertemperature limits, and 3 V to 5.5 V operation - used for thermal monitoring in microprocessor-based systems including desktops and telecom equipment.

For engineers reviewing the ADM1021AARQ-REEL7 datasheet, ADM1021AARQ-REEL7 pinout, ADM1021AARQ-REEL7 application, or ADM1021AARQ-REEL7 equivalent, key selection criteria include remote sensor current (205 μA), conversion rate programmability (0.0625–8 Hz), ALERT interrupt behavior, standby current (1 μA), and QSOP-16 package compatibility with Pentium III–class thermal management subsystems.

Technical Context

The ADM1021AARQ-REEL7 implements a chopper-stabilized ΔV_BE measurement architecture that eliminates need for calibration by operating the remote PNP/NPN transistor at two current levels (I and N×I) and digitizing the resulting voltage difference. Its ADC delivers 8-bit two's complement temperature data with 1°C LSB resolution over 0°C to 127°C range.

It integrates dual comparators per channel (high/low limit), open-circuit detection on D−, status register flagging (BUSY, LHIGH, RLOW, OPEN), and SMBus-compliant timing (100 kHz max clock, t_SU:STA = 4.7 μs). Configuration is fully software-controlled via address pointer–based register map including conversion rate, offset, and mask bits.

Key Specifications

Pinout & Package

ADM1021AARQ-REEL7 is housed in a 16-lead QSOP package (5.3 mm × 10.2 mm, 0.65 mm pitch) with exposed pad not connected internally. Pin 1 is top-left corner (dot-marked), pin count increases left-to-right, top row then bottom row.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar temperature monitoring applications.

Compared with LM94022MF/NOPB and MAX6642AESA+, the ADM1021AARQ-REEL7 uniquely combines calibrated-free remote diode sensing, open-circuit fault detection, and SMBus alert signaling in QSOP-16 - making it optimal for PC-class thermal management where interrupt-driven reliability and minimal calibration overhead are critical.

Availability

ADM1021AARQ-REEL7 is available at Aetrix Electronics and suitable for desktop computers, telecom equipment, and industrial controllers requiring stable component supply with full lifecycle support and consistent parametric performance across production lots.

Supply support for ADM1021AARQ-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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The ADM1021A product line was designed specifically for cost-sensitive, SMBus-based thermal monitoring in x86 computing platforms - delivering calibrated-free remote diode sensing and interrupt-driven alarm capability in a small QSOP package.

FAQ

What is the remote temperature sensor compatibility of the ADM1021AARQ-REEL7?

The ADM1021AARQ-REEL7 supports both on-die PNP transistors (e.g., Pentium III) and discrete bipolar junction transistors such as the 2N3904 (NPN) or 2N3906 (PNP). It applies 205 μA bias current to the D+ pin and references D− at ~0.7 V above GND, enabling accurate ΔV_BE measurement without calibration. The device detects open-circuit conditions on the remote sensor via the OPEN1 status bit.

How does the ADM1021AARQ-REEL7 handle power-on initialization and default temperature values?

On power-up, the ADM1021AARQ-REEL7 defaults local and remote temperature value registers to −128°C (0x80). If STBY is high, it immediately performs conversions and updates registers with actual measurements before limit comparisons. If STBY is low, no conversions occur, causing both LLOW and RLOW flags to assert and drive ALERT low - cleared only after reading status or exiting standby with valid temperatures.

Can the ADM1021AARQ-REEL7 be used with 5 V SMBus systems?

Yes, the ADM1021AARQ-REEL7 supports VDD from 3.0 V to 5.5 V and meets SMBus logic thresholds across this range: VIH ≥ 2.2 V and VIL ≤ 0.8 V for SCLK, SDATA, and ALERT. Its SMBus interface operates up to 100 kHz and complies with timing parameters (t_SU:STA = 4.7 μs, t_LOW = 4.7 μs) at 5 V, enabling direct connection to 5 V masters without level shifters.

What is the function of the offset register (Address 0x11) in the ADM1021AARQ-REEL7?

The offset register (0x11) in the ADM1021AARQ-REEL7 stores an 8-bit two's complement value added to the raw remote temperature reading to correct systematic errors from PCB track resistance, common-mode noise, or layout asymmetry. It defaults to 0x00 (0°C offset) at power-up and supports compensation from −128°C to +127°C - improving effective accuracy in electrically noisy or thermally non-uniform environments.

Does the ADM1021AARQ-REEL7 support one-shot conversion mode?

Yes, writing any value to the one-shot register (address 0x0F) triggers a single conversion cycle - including remote and local temperature acquisition, limit comparison, and status update - even while the device is in standby mode. After completion, the ADM1021AARQ-REEL7 automatically returns to standby, preserving low-power operation while enabling on-demand thermal snapshots.