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Analog Devices Inc. ADM1028ARQ
- Part No.:
- ADM1028ARQ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Thermal Management
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
ADM1028ARQ.pdf
- Description:
- REMOTE THERMAL DIODE MONITOR W/L
- Quantity:
- Payment:
- Shipping:
Inventory:5,382
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Product details
Overview
ADM1028ARQ from Analog Devices is a remote thermal diode monitor and linear fan controller IC for microprocessor-based systems, featuring on-chip and external diode temperature sensing (±3°C internal, ±5°C remote accuracy), SMBus-compatible serial interface, 8-bit DAC analog output (0–2.5 V) for fan speed control, hardware over-temperature trip, and integrated ramp rate control to reduce fan acoustics - deployed in network servers and PC motherboard thermal management.
For engineers reviewing the ADM1028ARQ datasheet, ADM1028ARQ pinout, ADM1028ARQ application, or ADM1028ARQ equivalent, key selection considerations include its QSOP-16 package, dual-sensor architecture (internal + remote diode), fault-tolerant fan shutdown logic, SMBus address 0x5E, and support for LDCM-compliant system management.
Technical Context
The ADM1028ARQ implements a chopper-stabilized, 65 kHz low-pass filtered delta-VBE measurement circuit for remote diode sensing, with digital averaging across 16 conversion cycles to suppress noise. Its internal bandgap sensor feeds an 8-bit ADC producing two's complement temperature codes.
It integrates an unsigned 8-bit DAC driving FAN_SPD/NTEST_IN, controlled via a dedicated Fan Speed Ramp Register that governs slew rate (1–16 Hz counter frequency) to limit fan acceleration/deceleration - independent of THERMA assertion - while supporting NAND board-level test mode via shared pin functionality.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0 V to 5.5 V - supports direct connection to 3.3 V or 5 V system rails without level-shifting. |
| Internal Temp Accuracy | ±3°C (±2°C at 60–100°C) - enables reliable ambient monitoring for system-level thermal throttling decisions. |
| Remote Diode Accuracy | ±5°C (±3°C at 60–100°C) - sufficient for CPU die temperature tracking using standard substrate transistors. |
| DAC Output Range | 0 V to 2.5 V - provides full-scale analog drive for external op-amp/MOSFET fan interfaces per Figures 5a–5e. |
| SMBus Address | 0x5E (7-bit) - fixed default address enabling plug-and-play integration with Intel 810/ICH-class host controllers. |
| Operating Temp Range | 0°C to +100°C - qualified for server motherboard hot zones and industrial embedded enclosures. |
| Package | 16-lead QSOP (RQ-16) - surface-mount footprint compatible with automated PCB assembly and thermal pad-less layout. |
Pinout & Package
ADM1028ARQ is housed in a 16-lead Shrink Small Outline Package (QSOP, RQ-16), with 0.65 mm lead pitch and exposed pad not present. Pin functions are validated per Analog Devices REV. B datasheet (2003).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FAN_OFF | Digital Output (Open Drain) | Hardware fan disable signal - asserted low independently of DAC output to force immediate fan stop during critical thermal events. |
| GPI | Digital Input (12 V tolerant) | Configurable active-high/low general-purpose interrupt input - used to inject external fault signals into INT Status Register Bit 4. |
| AUXRST | Digital Input | Asynchronous reset pin - pulls device into known state when driven low, clearing registers and disabling outputs. |
| VCC3AUX | Power & Monitor Input | 3.3 V auxiliary supply rail - powers internal circuitry and serves as reference for power-on reset detection. |
| RST | Digital Input | System power-loss indicator - triggers FAN_SPD shutoff and R_OFF reset when pulled low by main PSU sequencing logic. |
| R_RST | Digital Output (Open Drain) | Remote reset pulse output - driven low for configurable duration upon receipt of SMBus "Reset" command (0x02). |
| FAN_SPD/NTEST_IN | Analog Output / Test Input | Dual-function pin: DAC-controlled fan drive (0–2.5 V) or NAND connectivity test input - mode selected via Configuration Register bit. |
| D− / D+ | Remote Diode Inputs | Dedicated current-source/sink pair for delta-VBE measurement - rejects common-mode noise and supports up to 1000 pF interconnect capacitance. |
| THERMA/NTEST_OUT | Digital Output (Open Drain w/ VCC3AUX pull-up) | Primary thermal alert - asserts low on hardware trip point violation; doubles as NAND tree output during test mode. |
| THERMB | Digital Output (Open Drain) | Secondary thermal alert - allows independent routing to alternate voltage domains (e.g., 5 V or 12 V logic) via external pull-up. |
| R_OFF | Digital Output (Open Drain w/ VCC3AUX pull-up) | Remote power-down signal - held high after SMBus "Power Down" command (0x01) until RST is asserted. |
| INT | Digital Output (Open Drain) | Configurable system interrupt - asserts low on software-defined limit violations (masked/unmasked per INT Mask Register). |
| SCL / SDA | SMBus Clock / Data | Standard 100 kHz SMBus interface - compliant with System Management Bus v1.1 timing (tBUF = 4.7 ms, tSU;DAT = 250 ns). |
Key Features
| Feature | Design Value |
|---|---|
| Fault-tolerant fan control | Hardware-enforced full-speed fan activation on over-temperature - operates independently of firmware or SMBus communication failure. |
| Linear fan speed ramping | Programmable slew rate (1–16 Hz counter) eliminates abrupt fan speed changes, reducing acoustic noise and mechanical stress on bearings. |
| LDCM support | Compliance with Legacy Device Compatibility Mode enables interoperability with older BIOS/system management firmware stacks. |
| Remote reset & power-down | Dedicated R_RST and R_OFF outputs allow host processor or BMC to initiate controlled system shutdown without local reset circuitry. |
| Standby mode | Typical 1.7 mA supply current at 3.3 V - minimizes quiescent power draw during idle or low-utilization states. |
Applications
| Server Thermal Monitoring | PC Motherboard Management |
|---|---|
Use Scenario: Real-time CPU die and ambient temperature tracking in dual-socket rack servers with redundant cooling. IC Role / Device Role / Timing Role: Remote diode sensor interface + DAC-driven 4-wire PWM fan controller + hardware thermal trip generator. Use Value: Enables automatic fan speed adjustment within 9.6 ms per remote measurement cycle while guaranteeing fail-safe full-speed operation if firmware hangs. | Use Scenario: Integrated hardware monitoring on ATX motherboards with Intel chipset-based SMBus hosts. IC Role / Device Role / Timing Role: Dual-sensor thermal supervisor with SMBus slave interface (address 0x5E), GPI for chassis intrusion detection, and R_OFF for legacy power sequencing. Use Value: Reduces BOM count by consolidating temperature sensing, fan control, and reset signaling into single QSOP-16 IC with no external passive calibration components. |
| Test Equipment Thermal Control | Office Equipment Power Management |
Use Scenario: Closed-loop temperature stabilization in benchtop oscilloscopes and spectrum analyzers with forced-air cooling. IC Role / Device Role / Timing Role: Precision ambient sensor + remote diode interface for FPGA/ASIC junction monitoring + analog fan drive with ramp smoothing. Use Value: Achieves ±3°C ambient and ±5°C remote accuracy over 0–100°C range, meeting Class II thermal specification requirements for calibrated instruments. | Use Scenario: Thermal-aware power-down in multifunction printers and network-attached storage enclosures. IC Role / Device Role / Timing Role: System-level thermal watchdog with AUXRST-triggered reset, R_OFF-initiated power rail disable, and THERMB-linked status LED driver. Use Value: Prevents thermal runaway during extended print jobs by coupling fan control with hardware-initiated 12 V rail shutdown - no host CPU involvement required. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar thermal monitoring and fan control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM92CIMX | Higher remote accuracy (±1.5°C), no integrated DAC or fan ramp logic - requires external PWM generator. | Best suited for precision sensor-only roles where fan control is handled by separate MCU or CPLD. | Select LM92CIMX when absolute remote diode accuracy > fan drive integration; avoid if linear analog fan control or hardware trip is required. |
| MAX6657ASA | Includes 10-bit DAC (0–VDD range), wider temp range (–55°C to +125°C), but lacks R_OFF/R_RST outputs and LDCM support. | Preferred for extended-temperature industrial environments where remote reset signaling is managed externally. | Select MAX6657ASA for harsh environments needing wider operating range and higher DAC resolution; retain ADM1028ARQ for SMBus-native server platforms requiring R_OFF/R_RST. |
Compared with LM92CIMX and MAX6657ASA, the ADM1028ARQ uniquely combines hardware thermal trip, programmable fan ramping, and dual remote reset/power-down outputs in a single SMBus slave - making it optimal for cost-sensitive, firmware-light server and PC thermal subsystems where deterministic fail-safe behavior is mandatory.
Availability
ADM1028ARQ is available at Aetrix Electronics and suitable for network servers, PC motherboards, and test equipment requiring stable component supply across extended product lifecycles.
Supply support for ADM1028ARQ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies.
The ADM1028ARQ belongs to Analog Devices' hardware monitoring IC product line, designed specifically for thermal supervision and intelligent fan control in x86-based computing platforms with SMBus infrastructure.
FAQ
What is the default SMBus address of the ADM1028ARQ?
The ADM1028ARQ uses a fixed 7-bit SMBus address of 0x5E (binary 0101110) at power-on. This address is not user-programmable and is hardwired into the silicon - ensuring predictable bus enumeration in multi-device systems like server motherboards where the ADM1028ARQ coexists with other SMBus slaves such as voltage monitors or EEPROMs.
Does the ADM1028ARQ support both NPN and PNP remote sensing transistors?
Yes, the ADM1028ARQ supports both configurations: for NPN, connect emitter to D− and base to D+; for PNP, connect base to D− and emitter to D+. The internal bias diode at D− ensures proper DC biasing regardless of transistor polarity, and the delta-VBE measurement technique remains valid - confirmed in the Functional Description section of the REV. B datasheet.
How does the ADM1028ARQ handle fan speed ramping during an over-temperature event?
During an over-temperature event, the ADM1028ARQ asserts THERMA low and drives FAN_SPD to full scale (2.5 V) immediately - bypassing the ramp rate register entirely. The ramp logic only governs transitions between non-trip temperature states; hardware trip response is deterministic and unimpeded by software-configured slew rates, ensuring rapid thermal mitigation in the ADM1028ARQ.
Can the ADM1028ARQ operate with a 3.3 V supply while interfacing to 5 V logic levels?
Yes - the ADM1028ARQ's digital inputs (SCL, SDA, GPI, etc.) accept VIH ≥ 2.1 V and VIL ≤ 0.8 V, making them fully compatible with 3.3 V CMOS logic even when VCC = 3.3 V. Its open-drain outputs (INT, THERMA, R_RST, etc.) can be pulled up to 5 V externally, enabling seamless interfacing with mixed-voltage SMBus buses without level shifters - verified in the Electrical Characteristics table.
What is the purpose of the FAN_OFF pin on the ADM1028ARQ?
The FAN_OFF pin on the ADM1028ARQ is an open-drain digital output that forces immediate fan shutdown independent of the FAN_SPD analog output value. When asserted low, it overrides all DAC-based speed control - providing a failsafe mechanism for critical thermal events, power faults, or emergency shutdown commands received over SMBus. Its function is explicitly defined in the Pin Function Descriptions section of the ADM1028ARQ datasheet.
ADM1028ARQ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Fan Control, Temp Monitor
- Sensor Type:
- Internal and External
- Sensing Temperature:
- 0°C ~ 100°C, External Sensor
- Accuracy:
- -
- Topology:
- ADC, Register Bank
- Output Type:
- SMBus
- Output Alarm:
- No
- Output Fan:
- Yes
- Voltage - Supply:
- 3V ~ 5.5V
- Operating Temperature:
- 0°C ~ 100°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QSOP
ADM1028ARQ FAQ
1.How can I place an order for ADM1028ARQ through Aetrix?
Please submit a Request for Quotation (RFQ) for ADM1028ARQ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ADM1028ARQ reliable?
The price and inventory of ADM1028ARQ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADM1028ARQ is usually 5 days.
3.What payment methods are accepted for ADM1028ARQ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADM1028ARQ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADM1028ARQ?
ADM1028ARQ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADM1028ARQ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ADM1028ARQ?
For technical support, including ADM1028ARQ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADM1028ARQ requirements.
6.How does Aetrix verify that ADM1028ARQ is sourced from the original manufacturer or authorized distributors?
All ADM1028ARQ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ADM1028ARQ meets industry standards.
7.What is the process for return or replacement of ADM1028ARQ?
All ADM1028ARQ units undergo pre-shipment inspection (PSI). If there is an issue with ADM1028ARQ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ADM1028ARQ part is unused and in its original packaging.
Return procedure for ADM1028ARQ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ADM1028ARQ Tags
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