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Analog Devices Inc. ADM1028ARQ-REEL7
- Part No.:
- ADM1028ARQ-REEL7
- Manufacturer:
- Analog Devices Inc.
- Category:
- Thermal Management
- Package:
- -
- Datasheet:
-
ADM1028ARQ-REEL7.pdf
- Description:
- IC SENSOR TEMP/FAN CTRL 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:11,000
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Product details
Overview
ADM1028ARQ-REEL7 from Analog Devices is a remote thermal diode monitor and linear fan controller IC for microprocessor-based systems. It integrates on-chip and remote diode temperature sensing (±3°C internal, ±5°C remote accuracy), an 8-bit DAC for 0–2.5 V analog fan speed control, SMBus-compatible serial interface, hardware overtemperature trip, and open-drain interrupt outputs. It is used in PC motherboard thermal management to regulate CPU cooling fans based on real-time processor die temperature.
For engineers reviewing the ADM1028ARQ-REEL7 datasheet, ADM1028ARQ-REEL7 pinout, ADM1028ARQ-REEL7 application, or ADM1028ARQ-REEL7 equivalent, key selection criteria include remote diode measurement accuracy, DAC output linearity and sourcing capability, SMBus timing compliance (100 kHz), fault-tolerant fan ramp rate control, and dual THERM output drive capability with integrated pull-up.
Technical Context
The ADM1028ARQ-REEL7 implements a switched-current delta-VBE measurement architecture for remote diode sensing, with 65 kHz low-pass filtering and chopper-stabilized amplification. Its 8-bit DAC drives the FAN_SPD/NTEST_IN pin with 0–2.5 V full-scale output and ±3% total unadjusted error at 2 mA load.
It features dual independent THERM outputs (THERMA/NTEST_OUT with integrated VCC3AUX pull-up, THERMB open-drain), programmable interrupt masking via SMBus registers, and hardware-initiated fan full-speed override when any temperature limit is exceeded - all operating across a 3.0–5.5 V supply range with typical 3.2 mA active current.
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 from 60°C to 100°C) - enables reliable ambient system temperature monitoring for thermal throttling decisions. |
| Remote Diode Accuracy | ±5°C (±3°C from 60°C to 100°C) - sufficient for CPU core temperature tracking in single-processor PCs and servers. |
| DAC Output Range | 0 V to 2.5 V - directly interfaces with standard op-amp fan driver circuits (e.g., AD8541, AD8519) for linear PWM-equivalent control. |
| SMBus Clock Frequency | 100 kHz - compliant with standard System Management Bus timing, enabling interoperability with Intel 810/ICH and compatible host controllers. |
| Fan Ramp Counter Freq | 1 Hz or 16 Hz (±50%) - selectable rate controls fan speed transition smoothness to reduce acoustic noise and mechanical stress. |
| THERMA Pull-Up | 9–14 kΩ to VCC3AUX - eliminates need for external pull-up resistor on primary thermal alert output. |
Pinout & Package
ADM1028ARQ-REEL7 is housed in a 16-lead Shrink Small Outline Package (QSOP, RQ-16), 3.9 mm × 4.9 mm body, 1.0 mm max height, 0.635 mm lead pitch. Thermal resistance: θJA = 105°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FAN_OFF | Digital output (open drain) | Independent fan shutdown signal - asserts low to disable fan regardless of FAN_SPD value; used for emergency power-down or BIOS-initiated halt. |
| GPI | Digital input (12 V tolerant) | General-purpose interrupt input - configurable as active-high/low; voltage >2.2 V = logic "1", floating = logic "0" - supports chassis intrusion or power-good monitoring. |
| AUXRST | Digital input | Local reset trigger - driven low to perform internal register reset without affecting SMBus address or configuration state. |
| VCC3AUX | Power & monitor input | 3.3 V auxiliary supply rail - powers internal bandgap reference and enables power-on reset detection; also serves as pull-up source for THERMA. |
| RST | Digital input | Main system power-loss indicator - pulled low by host to shut down FAN_SPD and reset R_OFF, ensuring fan stop during AC removal. |
| R_RST | Digital output (open drain) | Remote reset pulse - driven low via SMBus command to initiate system-level reset sequence; requires external pull-up. |
| FAN_SPD/NTEST_IN | Analog output / test input | Primary fan control DAC output (0–2.5 V); doubles as NAND board-level test input when enabled - supports manufacturing test without additional pins. |
| D– / D+ | Remote diode inputs | Dedicated current-sink (D–) and current-source (D+) terminals - measure ΔVBE of external diode/transistor; biasing prevents ground noise coupling. |
| THERMA/NTEST_OUT | Digital output (open drain + internal pull-up) | Primary thermal alert - asserts low on overtemperature; integrated ~12 kΩ pull-up to VCC3AUX removes external component. |
| THERMB | Digital output (open drain) | Secondary thermal alert - open-drain only; allows independent pull-up to different rail (e.g., 5 V or 12 V) for multi-rail system monitoring. |
| R_OFF | Digital output (open drain + internal pull-up) | Remote power-down signal - driven high via SMBus to request system shutdown; latched until RST assertion. |
| INT | Digital output (open drain) | Configurable interrupt - asserts low on software-defined limit violations (high/low temp); maskable per source in INT Mask Register. |
| SCL / SDA | SMBus clock/data | Standard bidirectional SMBus interface - 100 kHz operation, 4.7 ms bus free time, compatible with Intel PIIX4/ICH and AMD SB600 host controllers. |
Key Features
| Feature | Design Value |
|---|---|
| Fault-tolerant fan control | Hardware-implemented full-speed override on overtemperature - operates independently of SMBus communication or software state. |
| Linear fan speed ramping | Selectable 1 Hz or 16 Hz DAC update rate - reduces audible fan "clicking" and extends motor life by limiting dV/dt of speed transitions. |
| Dual THERM outputs | THERMA with integrated VCC3AUX pull-up + THERMB with flexible external pull-up - enables redundant thermal alerts across different voltage domains. |
| LDCM support | Logic-driven chip management compatibility - allows integration into legacy platform firmware using standard SMBus command sets. |
| Standby mode | Typical 1.77 mA at 3.3 V, 100 kHz SCLK - reduces thermal contribution and power draw during idle periods without disabling monitoring. |
Applications
| Server CPU Thermal Monitoring | Desktop PC Fan Control |
|---|---|
Use Scenario: Real-time monitoring of Intel Pentium III or AMD Athlon processor die temperature via on-die diode sensor. IC Role / Device Role / Timing Role: Remote diode temperature measurement and closed-loop fan speed regulation using 8-bit DAC output. Use Value: Maintains CPU junction temperature below 100°C under load while minimizing acoustic noise through controlled ramp rates. | Use Scenario: Ambient and CPU temperature tracking on ATX motherboard with dual-fan cooling solution. IC Role / Device Role / Timing Role: Concurrent reading of on-chip sensor and remote diode; generation of independent THERMA and THERMB alerts. Use Value: Enables BIOS-triggered fan speed scaling and graceful shutdown before thermal throttling occurs. |
| Test Equipment Thermal Safety | Office Equipment Power Management |
Use Scenario: Overtemperature protection in benchtop oscilloscopes or spectrum analyzers with high-power analog front-ends. IC Role / Device Role / Timing Role: Hardware trip point enforcement via R_OFF output to disable HV supplies when ambient exceeds 85°C. Use Value: Prevents component degradation and ensures calibration stability by halting operation before critical thermal limits are breached. | Use Scenario: Thermal supervision in multifunction printers with laser engine and fuser assembly. IC Role / Device Role / Timing Role: GPI input monitors fuser ready status; FAN_SPD regulates cooling fan based on measured fuser temperature. Use Value: Extends consumable life and avoids paper jams by maintaining optimal fuser temperature window (180–220°C). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar remote thermal diode monitoring and fan control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM95231CIMMX-2/NOPB | 2-channel remote diode sensing, 12-bit resolution, no integrated DAC; uses PWM fan output instead of analog voltage. | Lacks linear analog fan drive - requires external PWM-to-voltage converter for analog fan compatibility. | Choose when higher remote sensing resolution is required and fan interface is PWM-native. |
| MAX6657ASA+ | Single remote diode channel, 11-bit ADC, 0–2.5 V DAC output, but no R_OFF or R_RST outputs; SMBus address fixed at 0x4C. | No remote power-down/reset functionality - limits use in systems requiring coordinated shutdown sequences. | Choose for cost-sensitive embedded designs where only basic thermal monitoring and fan control are needed. |
Compared with LM95231CIMMX-2/NOPB and MAX6657ASA+, the ADM1028ARQ-REEL7 uniquely combines analog fan drive, dual THERM outputs with integrated pull-up, and remote reset/power-down signaling - making it suitable for PC/server platforms requiring full hardware-managed thermal safety.
Availability
ADM1028ARQ-REEL7 is available at Aetrix Electronics and suitable for server motherboard design, desktop PC thermal management, and test equipment safety-critical monitoring requiring stable component supply and long-term industrial availability.
Supply support for ADM1028ARQ-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, Inc. is a global semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies.
The ADM1028ARQ-REEL7 belongs to Analog Devices' hardware monitoring IC product line, designed specifically for thermal management and fan control in x86-based computing platforms including PCs, servers, and embedded office equipment.
FAQ
What is the function of the FAN_SPD/NTEST_IN pin on the ADM1028ARQ-REEL7?
The FAN_SPD/NTEST_IN pin on the ADM1028ARQ-REEL7 serves a dual role: as an analog output (0–2.5 V) from its 8-bit DAC for linear fan speed control, and as a test input for NAND board-level connectivity verification. When NAND test mode is disabled, it functions exclusively as the primary fan control voltage output, interfacing directly with op-amp-based fan driver circuits like those shown in Figures 5a–5e of the ADM1028ARQ-REEL7 datasheet.
Does the ADM1028ARQ-REEL7 support both on-chip and remote temperature sensing?
Yes, the ADM1028ARQ-REEL7 supports concurrent on-chip and remote temperature sensing. Its internal bandgap sensor measures ambient system temperature with ±3°C accuracy, while dedicated D+ and D– pins enable remote diode measurement (e.g., CPU die sensor) with ±5°C accuracy. Both values are digitized to 8-bit two's complement format and accessible via SMBus registers - allowing simultaneous monitoring of chassis and processor thermal conditions in a single IC.
How does the hardware overtemperature trip work in the ADM1028ARQ-REEL7?
The ADM1028ARQ-REEL7 implements a dedicated hardware overtemperature trip that operates independently of SMBus communication or software configuration. When any monitored temperature (internal or remote) exceeds its programmed limit for three consecutive conversions, the device immediately drives THERMA/NTEST_OUT low and forces FAN_SPD to full-scale (2.5 V), overriding any DAC ramping or software-set value. This fault-tolerant behavior ensures fan response even if host firmware hangs or SMBus is nonfunctional.
What is the purpose of the R_OFF and R_RST pins on the ADM1028ARQ-REEL7?
The R_OFF and R_RST pins on the ADM1028ARQ-REEL7 provide remote system-level control: R_OFF is an open-drain output with integrated VCC3AUX pull-up that goes high upon receipt of an SMBus "remote off" command, signaling host power management logic to initiate safe shutdown; R_RST is an open-drain output that pulses low on receipt of an SMBus "remote reset" command, triggering a hardware reset sequence. Both remain asserted until cleared by asserting the RST input pin low.
Can the ADM1028ARQ-REEL7 operate from a 3.3 V supply?
Yes, the ADM1028ARQ-REEL7 operates from a 3.0 V to 5.5 V supply, making 3.3 V fully supported. Its VCC3AUX pin is specifically intended for connection to a 3.3 V auxiliary rail, powering the internal bandgap reference and serving as the pull-up source for THERMA/NTEST_OUT. At 3.3 V, typical supply current is 3.2 mA with ADC active and interface inactive, and standby current drops to ~1.77 mA - confirming robust low-voltage operation suitable for modern energy-efficient platforms.
ADM1028ARQ-REEL7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- -
- 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:
- -
- Supplier Device Package:
- -
ADM1028ARQ-REEL7 FAQ
1.How can I place an order for ADM1028ARQ-REEL7 through Aetrix?
Please submit a Request for Quotation (RFQ) for ADM1028ARQ-REEL7 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-REEL7 reliable?
The price and inventory of ADM1028ARQ-REEL7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADM1028ARQ-REEL7 is usually 5 days.
3.What payment methods are accepted for ADM1028ARQ-REEL7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADM1028ARQ-REEL7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADM1028ARQ-REEL7?
ADM1028ARQ-REEL7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADM1028ARQ-REEL7 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-REEL7?
For technical support, including ADM1028ARQ-REEL7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADM1028ARQ-REEL7 requirements.
6.How does Aetrix verify that ADM1028ARQ-REEL7 is sourced from the original manufacturer or authorized distributors?
All ADM1028ARQ-REEL7 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-REEL7 meets industry standards.
7.What is the process for return or replacement of ADM1028ARQ-REEL7?
All ADM1028ARQ-REEL7 units undergo pre-shipment inspection (PSI). If there is an issue with ADM1028ARQ-REEL7, 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-REEL7 part is unused and in its original packaging.
Return procedure for ADM1028ARQ-REEL7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ADM1028ARQ-REEL7 Tags
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EMC2101-ACZL-TR
Microchip Technology
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MCP9844T-BE/MNY
Microchip Technology
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EMC2101-R-ACZL-TR
Microchip Technology
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TC670ECHTR
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SE98ATP,547
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AMC6821SDBQR
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MAX6604AATA+T
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onsemi
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