Analog Devices Inc. ADM1022ARQ-REEL7

Overview

ADM1022ARQ-REEL7 from Analog Devices is a low-cost PC temperature monitor and fan controller IC with dual remote diode sensing (D1+/D1–, D2+/D2–), on-chip bandgap temperature sensor, 8-bit DAC for analog fan speed control (FAN_SPD), dual supply voltage monitors (VCC, VMON), and SMBus-compatible serial interface. It delivers ±3°C internal sensor accuracy, ±5°C remote diode accuracy, and fault-tolerant fan control for microprocessor-based servers and office equipment.

For engineers reviewing the ADM1022ARQ-REEL7 datasheet, ADM1022ARQ-REEL7 pinout, ADM1022ARQ-REEL7 application, or ADM1022ARQ-REEL7 equivalent, key selection considerations include dual-diode thermal monitoring capability, SMBus address programmability via ADD/NTEST_OUT, open-drain interrupt/reset outputs (INT, RST1, RST2), and integrated brownout detection with 2.925 V reset threshold.

Technical Context

The ADM1022ARQ-REEL7 integrates two independent temperature measurement channels: one dedicated (D1+/D1–) and one configurable (D2+/D2– as diode input or THERM/GPI), both using switched-current ΔV_BE methodology with 1°C resolution and 16-cycle digital averaging. Its analog output uses an unsigned 8-bit DAC producing 0–2.5 V with ±5% total unadjusted error at 2 mA load.

It implements dual independent reset generators: RST1 triggered by VCC falling below 2.925 V (50 mV hysteresis), and RST2 responsive to VMON, MR assertion, or RST1 activity, with 140–560 ms active timeout. The SMBus interface supports 400 kHz clock, 7-bit address (A1/A0 set by ADD pin), and Read Byte/Write Byte protocols without mixed-mode transfers.

Key Specifications

Pinout & Package

ADM1022ARQ-REEL7 is housed in a 16-lead QSOP (RQ-16) package with 0.65 mm lead pitch, optimized for compact PCB layout near CPU sockets or VRMs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar temperature monitor and fan controller applications.

Compared with LM92CIMX-3/NOPB and MAX6657AESA+, the ADM1022ARQ-REEL7 uniquely combines dual-diode sensing, dual brownout monitors, and hardware fan disable-making it irreplaceable in dual-CPU server thermal management where fault tolerance and hardware-level overrides are mandatory.

Availability

ADM1022ARQ-REEL7 is available at Aetrix Electronics and suitable for server motherboard design, desktop PC power management, and office equipment thermal protection requiring stable component supply and long-term industrial availability.

Supply support for ADM1022ARQ-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 computing markets since 1965.

The ADM1022 belongs to Analog Devices' hardware monitoring IC product line, engineered specifically for cost-sensitive PC and embedded thermal management applications requiring integrated diode sensing, SMBus connectivity, and fail-safe reset generation.

FAQ

What is the function of the ADD/NTEST_OUT pin on the ADM1022ARQ-REEL7?

The ADD/NTEST_OUT pin on the ADM1022ARQ-REEL7 serves a dual role: during normal operation, it sets the two least-significant bits (A1/A0) of the 7-bit SMBus address (0x2C, 0x2D, or 0x2E) based on its logic state (GND, open, or VCC); during NAND board-level test mode, it functions as a test output. Its state is sampled only at power-up, so changes require a full power cycle to take effect. This enables multiple ADM1022ARQ-REEL7 devices on the same SMBus without address conflict.

Does the ADM1022ARQ-REEL7 support both NPN and PNP remote sensing transistors?

Yes, the ADM1022ARQ-REEL7 supports both NPN and PNP remote sensing transistors. For NPN, connect emitter to D– and base to D+; for PNP, connect base to D– and emitter to D+. The internal bias circuitry accommodates either configuration, and the ΔV_BE measurement technique remains valid. Layout guidelines recommend twisted-pair routing and ≤1000 pF capacitance between D+ and D– to maintain ±5°C accuracy with either transistor type.

How does the ADM1022ARQ-REEL7 handle fan control during a thermal fault?

During a thermal fault-such as exceeding a programmed temperature limit or detecting overtemperature on D2–/THERM-the ADM1022ARQ-REEL7 drives the FAN_SPD DAC to full-scale (2.5 V) and asserts FAN_OFF low only if explicitly commanded by external logic. Its fault-tolerant design ensures fan speed increases automatically without software intervention, while FAN_OFF remains under independent hardware control. This dual-path behavior prevents thermal runaway even if the host processor or SMBus communication fails.

What is the purpose of the D2–/THERM and D2+/GPI pins on the ADM1022ARQ-REEL7?

The D2–/THERM and D2+/GPI pins on the ADM1022ARQ-REEL7 are multifunctional: configured as a second remote diode input pair (enabling dual-processor monitoring), or repurposed as THERM (active-low overtemperature output) and GPI (general-purpose input with status bit). When used as THERM/GPI, pulling D2–/THERM low signals thermal overload and forces fan to full speed; D2+/GPI can be set as active-high or active-low to capture external events like lid-open detection or button press, with status latched until read.

Can the ADM1022ARQ-REEL7 operate with a 3.3 V supply while monitoring a 5 V VMON rail?

Yes, the ADM1022ARQ-REEL7 operates with a 3.3 V VCC supply while monitoring a 5 V VMON rail. Its VMON input accepts voltages up to VCC + 0.3 V (3.6 V typical), but the datasheet specifies VMON functionality for "second reset generator" with thresholds referenced to internal bandgap-meaning it monitors VMON relative to its own 2.925 V reset threshold, not VCC. Therefore, a 5 V VMON rail must be scaled via external resistor divider to fall within 0–3.6 V before connecting to the VMON pin to avoid damage and ensure correct brownout detection.