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Melexis Technologies NV US91AEZE-AAA-000-RE
- Part No.:
- US91AEZE-AAA-000-RE
- Manufacturer:
- Melexis Technologies NV
- Category:
- Motor Drivers, Controllers
- Package:
- SOT-23-5 Flat Leads
- Datasheet:
-
US91AEZE-AAA-000-RE.pdf
- Description:
- IC MOTOR DRIVER 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,230
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Product details
Overview
US91AEZE-AAA-000-RE from Melexis is a Hall-effect-based two-coil brushless DC fan driver IC with integrated rotation detection (RD) output, no-VDD architecture, 500 mA peak output current, and SOT25 straight-leads package. It delivers locked-rotor protection with auto-restart and built-in clamping diodes for coil transient suppression in 12 V/24 V cooling systems.
For engineers reviewing the US91AEZE-AAA-000-RE datasheet, pinout, applications, or equivalent options, key selection considerations include RD alarm functionality, SOT25 thermal resistance (170 °C/W), no-VDD supply topology, and compatibility with two-coil BLDC fans requiring stall detection and automatic recovery.
Technical Context
The US91AEZE-AAA-000-RE implements a Hall-effect sensor with dynamic offset correction and dual low-side open-drain drivers (OUT1/OUT2) that switch based on magnetic pole polarity-North pole activates OUT1 high/OUT2 low, South pole reverses the state. Its no-VDD design eliminates the need for a dedicated power rail by deriving operating energy directly from the fan coil supply.
Locked-rotor protection triggers when rotational speed drops below 60 RPM (for 4-pole magnet), shutting off coil current for 210–350 ms (Ton) before attempting auto-restart every 1.5 seconds. The RD output is active-low during normal rotation and goes high upon stall detection, enabling direct interface with hardware monitoring or Super I/O ICs via pull-up resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Fan Supply Voltage | 4.7 V to 30 V - supports 12 V and 24 V two-coil BLDC fans; minimum VDD determined by RCOIL × IDD + 4.5 V |
| Peak Output Current | 500 mA - limits inrush current at startup without external current limiting |
| Continuous Output Current | 250 mA - sustains steady-state coil drive without thermal shutdown under typical airflow conditions |
| RD Output Clamp Voltage | 28 V - protects downstream monitoring circuitry from overvoltage during coil flyback |
| Operate / Release Points | BOP = 3–6 mT, BRP = 3–6 mT - ensures reliable commutation across temperature and magnetic tolerances |
| Thermal Resistance (Rθja) | 170 °C/W - measured on JEDEC single-layer board; defines maximum power dissipation before junction exceeds 125 °C |
| ESD HBM Rating | 4000 V - meets industrial-level ESD robustness requirements without additional board-level protection |
Pinout & Package
SOT25 package (straight leads), 5-pin outline with one NC terminal; compact surface-mount footprint optimized for automated assembly and space-constrained fan modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FG (RD) | Open-drain rotation detection output | Active-low signal indicates normal rotation; transitions high during stall - interfaces directly with Super I/O or GPIO with external pull-up |
| OUT1 | Low-side coil driver 1 | Switches fan coil 1 to GND; rated for 500 mA peak; includes internal clamp diode for flyback energy handling |
| OUT2 | Low-side coil driver 2 | Switches fan coil 2 to GND; complementary to OUT1 per Hall polarity; shares same protection features as OUT1 |
| GND | Power and signal reference ground | Common return path for coil current, Hall sensor, and RD output; must be low-impedance to ensure stable commutation |
| N.C. | No connection | Unused pin; must not be connected to any net - floating or grounded per EMC best practice (datasheet recommends grounding unused pins) |
Key Features
| Feature | Design Value |
|---|---|
| No-VDD architecture | Eliminates dedicated VDD pin and reverse-voltage protection diode - simplifies PCB layout and reduces BOM count while improving reverse-polarity survivability |
| Integrated RD alarm output | Provides immediate stall indication without external logic - enables real-time fan health monitoring in server, telecom, and industrial cooling systems |
| Locked-rotor protection with auto-restart | Reduces average stall current to 1/7 of nominal, preventing coil overheating and extending fan lifetime during mechanical blockage |
| Built-in output clamping diodes | Suppresses coil flyback transients up to 80 V - removes need for external zener diodes and improves system reliability |
| RoHS-compliant SOT25 package | Enables lead-free reflow assembly; 170 °C/W thermal resistance supports operation up to 125 °C junction temperature in enclosed enclosures |
Applications
| Server Rack Cooling | Industrial PLC Enclosures |
|---|---|
|
Use Scenario: Continuous forced-air cooling of high-density CPU/GPU modules in 19-inch rack servers where fan failure must trigger immediate alert. IC Role / Device Role / Timing Role: Two-coil BLDC fan driver with RD alarm output providing real-time stall detection to BMC or baseboard management controller. Use Value: Enables autonomous fan health monitoring without external comparators or microcontrollers - reduces system complexity and firmware overhead. |
Use Scenario: Fan-cooled programmable logic controllers deployed in factory-floor cabinets exposed to dust, vibration, and ambient temperatures up to 70 °C. IC Role / Device Role / Timing Role: Integrated Hall-sensor fan driver delivering locked-rotor protection and auto-restart to maintain thermal safety during mechanical obstruction. Use Value: Prevents thermal runaway during bearing seizure or debris ingress - extends field service intervals and avoids unplanned downtime. |
| Telecom Base Station Cabinets | Medical Diagnostic Equipment |
|
Use Scenario: Redundant cooling in outdoor telecom cabinets where fan reliability directly impacts radio uptime and remote maintenance cost. IC Role / Device Role / Timing Role: RD-output fan driver interfacing with system controller via open-drain signal to log stall events and initiate failover protocols. Use Value: Provides deterministic stall reporting with <350 ms detection latency - supports predictive maintenance and SLA compliance reporting. |
Use Scenario: Precision air-moving subsystems in MRI or CT scanner cabinets requiring silent, reliable cooling with zero risk of uncontrolled stall heating. IC Role / Device Role / Timing Role: No-VDD fan driver eliminating reverse-polarity damage risk during field servicing and reducing component count in safety-critical thermal paths. Use Value: Enhances functional safety by removing single-point failure modes associated with external VDD regulation and reverse-protection diodes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar two-coil BLDC fan driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| US91AVK-AAA-000-BU | Same die, TO-92 VK package (4-pin, bent leads); higher Rθja = 200 °C/W; bulk packaging | Designed for through-hole assembly and manual rework; less suitable for high-density SMT layouts | Select for legacy designs, prototyping, or low-volume production where hand-soldering or socketing is required |
| US91ADC-AAA-000-RX | Same die, SOIC-8 package (8-pin, narrow); Rθja = 150 °C/W; includes four NC pins | Offers superior thermal performance and compatibility with automated optical inspection (AOI) due to gull-wing leads | Select for high-power fan modules (>250 mA continuous) or designs requiring enhanced thermal margin and process traceability |
Compared with US91AVK-AAA-000-BU and US91ADC-AAA-000-RX, the US91AEZE-AAA-000-RE provides the smallest SMT footprint and fastest assembly throughput, trading moderate thermal resistance (170 °C/W) for board-space efficiency and compatibility with fine-pitch pick-and-place equipment.
Availability
US91AEZE-AAA-000-RE is available at Aetrix Electronics and suitable for server rack cooling, industrial PLC enclosures, and telecom base station cabinets requiring stable component supply, RoHS compliance, and long-term obsolescence management.
Supply support for US91AEZE-AAA-000-RE 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
Melexis is a Belgian semiconductor company specializing in sensor and driver ICs for automotive, industrial, and consumer applications, with ISO/TS 16949 and ISO 14001 certification.
The US91A belongs to Melexis' fan driver product line, engineered specifically for cost-sensitive, high-reliability two-coil BLDC cooling systems requiring integrated Hall sensing, stall detection, and no-VDD operation.
FAQ
What is the function of the RD output in US91AEZE-AAA-000-RE?
The RD (Rotation Detection) output in US91AEZE-AAA-000-RE is an open-drain signal that remains active-low during normal fan rotation and transitions high when rotational speed drops below 60 RPM - indicating a locked rotor condition. This enables direct connection to monitoring ICs or microcontrollers using a simple pull-up resistor, and is a core feature distinguishing US91AEZE-AAA-000-RE from the FG-output US90A variant.
Does US91AEZE-AAA-000-RE require an external VDD supply?
No, US91AEZE-AAA-000-RE operates without an external VDD supply - its no-VDD architecture derives operating power directly from the fan coil voltage. This eliminates the need for a dedicated power rail, reduces component count, and enhances reverse-voltage tolerance. The US91AEZE-AAA-000-RE uses the coil resistance to limit reverse current, making it inherently more robust against incorrect polarity connections than conventional fan drivers.
What is the maximum continuous current rating for US91AEZE-AAA-000-RE?
The maximum continuous output current for US91AEZE-AAA-000-RE is 250 mA per driver (OUT1 or OUT2), as specified in the datasheet's General Electrical Specifications table. This rating assumes proper thermal management - the device's 170 °C/W junction-to-ambient thermal resistance requires adequate copper area and airflow to sustain this current without exceeding the 125 °C maximum junction temperature.
How does locked-rotor protection work in US91AEZE-AAA-000-RE?
US91AEZE-AAA-000-RE detects locked rotor when rotational speed falls below 60 RPM (for a 4-pole magnet), triggering automatic coil current shutoff for 210–350 ms (Ton). After this interval, it attempts auto-restart every 1.5 seconds until rotation resumes. This cycling reduces average stall current to 1/7 of nominal, preventing thermal damage to both the US91AEZE-AAA-000-RE and the connected fan motor.
Which package type does US91AEZE-AAA-000-RE use, and what are its key mechanical properties?
US91AEZE-AAA-000-RE uses the ZE package: a SOT25 outline with straight leads, top-marked "US91A", and RoHS-compliant lead-free finish. Its mechanical dimensions conform to standard SOT25 footprints, supporting automated placement and reflow. Thermal resistance is 170 °C/W (junction-to-ambient, JEDEC board) and 20 °C/W (junction-to-case), enabling reliable operation in compact, sealed fan modules.
US91AEZE-AAA-000-RE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Melexis Technologies NV
- Series:
- -
- Package/Case:
- SOT-23-5 Flat Leads
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Not For New Designs
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushless DC (BLDC)
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- -
- Interface:
- On/Off
- Technology:
- -
- Step Resolution:
- -
- Applications:
- Fan Motor Driver
- Current - Output:
- 250mA
- Voltage - Supply:
- 4.7V ~ 30V
- Voltage - Load:
- 4.7V ~ 30V
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-25
US91AEZE-AAA-000-RE FAQ
1.How can I place an order for US91AEZE-AAA-000-RE through Aetrix?
Please submit a Request for Quotation (RFQ) for US91AEZE-AAA-000-RE 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 US91AEZE-AAA-000-RE reliable?
The price and inventory of US91AEZE-AAA-000-RE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for US91AEZE-AAA-000-RE is usually 5 days.
3.What payment methods are accepted for US91AEZE-AAA-000-RE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for US91AEZE-AAA-000-RE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for US91AEZE-AAA-000-RE?
US91AEZE-AAA-000-RE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your US91AEZE-AAA-000-RE 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 US91AEZE-AAA-000-RE?
For technical support, including US91AEZE-AAA-000-RE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your US91AEZE-AAA-000-RE requirements.
6.How does Aetrix verify that US91AEZE-AAA-000-RE is sourced from the original manufacturer or authorized distributors?
All US91AEZE-AAA-000-RE 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 US91AEZE-AAA-000-RE meets industry standards.
7.What is the process for return or replacement of US91AEZE-AAA-000-RE?
All US91AEZE-AAA-000-RE units undergo pre-shipment inspection (PSI). If there is an issue with US91AEZE-AAA-000-RE, 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 US91AEZE-AAA-000-RE part is unused and in its original packaging.
Return procedure for US91AEZE-AAA-000-RE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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