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Analog Devices Inc./Maxim Integrated MAX6668AUA40
- Part No.:
- MAX6668AUA40
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Thermostats - Solid State
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX6668AUA40.pdf
- Description:
- REMOTE TEMPERATURE SWITCH
- Quantity:
- Payment:
- Shipping:
Inventory:1,711
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Product details
Overview
MAX6668AUA40 from Maxim Integrated is a remote-junction thermal switch with integrated +12V/250mA fan driver, factory-programmed +40°C activation threshold, 8°C hysteresis, and automotive-grade operation from -40°C to +125°C. It directly controls cooling fans in PC power supplies and network switches using an external diode-connected transistor for remote temperature sensing.
For engineers reviewing the MAX6668AUA40 datasheet, MAX6668AUA40 pinout, MAX6668AUA40 application, or MAX6668AUA40 equivalent, this device delivers drop-in fan control without software, calibration, or external MOSFETs-ideal for thermal management in space-constrained embedded systems requiring stable trip-point accuracy and low quiescent current.
Technical Context
The MAX6668AUA40 implements a dedicated analog temperature comparator that monitors voltage across an external P-N junction (e.g., 2N3904) to infer die temperature. Its internal power MOSFET drives FANOUT as an open-drain sink up to 250mA at ≤1V saturation under load, with thermal shutdown protection at 170°C.
It operates from a +3V to +3.6V supply with 110µA typical supply current and samples temperature at 3.3Hz–4Hz. The device uses BiCMOS process technology and requires no configuration-threshold and hysteresis are factory-set and fixed for this variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Temperature Threshold | +40°C factory-programmed trip point for fan activation |
| Threshold Accuracy | ±2.2°C max over -40°C to +125°C ambient, enabling reliable thermal margining |
| Hysteresis | Fixed 8°C hysteresis prevents fan oscillation near trip point |
| FANOUT Drive Capability | +12V/250mA open-drain sink output with ≤1V VOL at full load |
| Supply Voltage Range | +3V to +3.6V-compatible with 3.3V system rails only |
| Quiescent Current | 110µA typical-minimizes standby power in always-on thermal monitoring |
| Operating Temperature | -40°C to +125°C automotive grade-validated for under-hood and industrial environments |
Pinout & Package
MAX6668AUA40 is housed in an 8-pin µMAX package (3.0mm × 3.0mm, 0.8mm height), pin-compatible with industry-standard uSOP-8 footprints and suitable for high-density PCB layouts.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | PGND | Power ground return for FANOUT MOSFET-must be routed separately from signal GND to avoid noise coupling |
| 2 | FORCEON | Active-low digital input to override thermal control and force FANOUT on regardless of temperature |
| 3 | DXP | Current-source positive terminal for remote diode-anode connection; requires 2200pF capacitor to DXN for noise immunity |
| 4 | DXN | Current-sink negative terminal for remote diode-cathode connection; internally biased to VBE |
| 5,7 | GND | Signal ground reference for internal circuitry and comparator inputs |
| 6 | VDD | +3V to +3.6V supply input-requires local 1µF bypass capacitor to GND |
| 8 | FANOUT | Open-drain power MOSFET output-sinks up to 250mA to drive +12V cooling fans directly |
Key Features
| Feature | Design Value |
|---|---|
| +12V/250mA integrated fan driver | Eliminates need for external MOSFET, gate driver, and current-sense resistor-reduces BOM count by ≥4 components |
| Factory-programmed +40°C threshold | Guarantees precise activation point without trimming or calibration-enables consistent thermal response across production units |
| 8°C fixed hysteresis | Prevents rapid fan cycling during marginal temperature conditions-extends fan lifetime and reduces acoustic noise |
| 110µA typical supply current | Enables continuous thermal monitoring in battery-backed or low-power standby systems without significant energy penalty |
| Automotive-grade (-40°C to +125°C) | Validated for under-dash, industrial control, and telecom equipment where ambient extremes demand robust operation |
Applications
| PC Power Supplies | Network Switches |
|---|---|
|
Use Scenario: Thermal regulation of +12V DC-DC converter stages in ATX PSUs. IC Role / Device Role / Timing Role: Remote-junction thermal switch triggering fan activation when MOSFET heatsink exceeds +40°C. Use Value: Prevents thermal runaway without firmware intervention-maintains PSU reliability across 0–100% load range. |
Use Scenario: Cooling management for multi-port Gigabit Ethernet switches with ASIC hotspots. IC Role / Device Role / Timing Role: Direct fan control based on remote diode attached to switch controller die. Use Value: Enables silent operation below threshold while ensuring airflow before critical junction temperatures are reached. |
| Notebook Motherboards | Laboratory Instruments |
|
Use Scenario: Compact thermal protection for CPU VRM modules in thin-and-light notebooks. IC Role / Device Role / Timing Role: On-board temperature switch driving small axial fan via FANOUT pin. Use Value: Occupies <3mm² PCB area-fits tight layout constraints while delivering ±2.2°C trip accuracy. |
Use Scenario: Overtemperature safeguard for precision analog front-ends in benchtop DMMs and oscilloscopes. IC Role / Device Role / Timing Role: Standalone thermal cutoff preventing measurement drift caused by self-heating. Use Value: No microcontroller dependency-ensures fail-safe behavior even during firmware reset or brownout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar remote-junction thermal switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6670AUB40 | 10-pin µMAX; adds WARN and OT outputs (+15°C/+30°C alerts); pin-selectable hysteresis (4°C/8°C/12°C) | Required when system-level warning and emergency shutdown signals are needed beyond basic fan control | Select MAX6670AUB40 if dual overtemperature alarms and configurable hysteresis justify extra pin count and cost |
| LM75BIMM-3/NOPB | I²C digital temperature sensor with programmable thresholds; no integrated fan driver; 8-pin VSSOP | Suitable only when microcontroller-based thermal management with adjustable logic and logging is available | Choose LM75BIMM-3/NOPB only when replacing MAX6668AUA40 requires software integration and fan drive is handled externally |
Compared with MAX6668AUA40, MAX6670AUB40 adds diagnostic outputs and hysteresis flexibility but increases footprint and complexity, while LM75BIMM-3/NOPB shifts responsibility for actuation to host firmware-neither offers the same plug-and-play fan control capability.
Availability
MAX6668AUA40 is available at Aetrix Electronics and suitable for PC power supplies, network switches, and laboratory instruments requiring stable component supply, guaranteed automotive temperature range compliance, and long-term obsolescence management.
Supply support for MAX6668AUA40 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
Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.
The MAX6668/MAX6670 product line delivers fully integrated thermal management solutions-eliminating software, calibration, and discrete power stages for reliable, low-cost fan control in thermally sensitive systems.
FAQ
What is the exact temperature threshold programmed into the MAX6668AUA40?
The MAX6668AUA40 has a factory-programmed temperature threshold of +40°C. This value is laser-trimmed during production and is not user-adjustable. The device activates its FANOUT driver when the remote P-N junction temperature exceeds +40°C, with ±2.2°C maximum error across the full -40°C to +125°C operating range. This fixed threshold ensures consistent thermal response without calibration overhead in the MAX6668AUA40 design.
Does the MAX6668AUA40 support hysteresis selection via external pins?
No, the MAX6668AUA40 features fixed 8°C hysteresis-unlike the MAX6670 family, it does not include a HYST pin or any mechanism for adjusting hysteresis. This simplifies layout and eliminates configuration risk but means the hysteresis cannot be tuned for specific thermal dynamics. The 8°C value is optimized to prevent fan chatter while allowing sufficient cooling time before deactivation, and it applies uniformly across all MAX6668AUA40 units.
Can the MAX6668AUA40 drive a 12V fan directly without external components?
Yes, the MAX6668AUA40 integrates a +12V/250mA open-drain power MOSFET on the FANOUT pin, enabling direct connection to standard 12V cooling fans. No external transistor, gate driver, or current-sense resistor is required. The device specifies ≤1V voltage drop at 250mA sink current, ensuring efficient fan operation. However, the fan's nominal supply must not exceed +12V (absolute maximum 15V), and PGND must be properly decoupled from signal GND to maintain stability.
What remote sensing components are compatible with the MAX6668AUA40?
The MAX6668AUA40 interfaces with standard diode-connected transistors such as the 2N3904, CMPT3904, SST3904, or KST3904-TF-devices with BF = 50–150, base resistance <100Ω, and forward voltage between 0.25V (at 10µA, high temp) and 0.95V (at 100µA, low temp). It also supports on-die thermal diodes in CPUs and ASICs. A 2200pF capacitor between DXP and DXN is mandatory for noise filtering in electrically noisy environments like motherboards.
Is the MAX6668AUA40 pin-compatible with other variants in the MAX6668 family?
Yes, all MAX6668 variants-including MAX6668AUA45, MAX6668AUA50, and MAX6668AUA75-share identical 8-pin µMAX packaging and pinout with the MAX6668AUA40. They differ only in factory-programmed temperature thresholds (+45°C, +50°C, etc.) and are fully interchangeable at the board level. No PCB changes are required when substituting within the MAX6668 series, provided the new threshold aligns with system thermal requirements.
MAX6668AUA40 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Trip Temperature Threshold:
- Hot
- Switching Temperature:
- 40°C
- Accuracy:
- ±2.2°C
- Current - Output (Max):
- 250mA
- Output Type:
- Open Drain
- Output:
- Active Low
- Output Function:
- /FanOut
- Selectable Hysteresis:
- Yes
- Features:
- -
- Voltage - Supply:
- 3 V ~ 3.6 V
- Current - Supply:
- 110µA
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-µMAX
MAX6668AUA40 FAQ
1.How can I place an order for MAX6668AUA40 through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6668AUA40 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 MAX6668AUA40 reliable?
The price and inventory of MAX6668AUA40 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6668AUA40 is usually 5 days.
3.What payment methods are accepted for MAX6668AUA40?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6668AUA40 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6668AUA40?
MAX6668AUA40 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6668AUA40 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 MAX6668AUA40?
For technical support, including MAX6668AUA40 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6668AUA40 requirements.
6.How does Aetrix verify that MAX6668AUA40 is sourced from the original manufacturer or authorized distributors?
All MAX6668AUA40 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 MAX6668AUA40 meets industry standards.
7.What is the process for return or replacement of MAX6668AUA40?
All MAX6668AUA40 units undergo pre-shipment inspection (PSI). If there is an issue with MAX6668AUA40, 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 MAX6668AUA40 part is unused and in its original packaging.
Return procedure for MAX6668AUA40:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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