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Analog Devices Inc./Maxim Integrated MAX6685AU75H
- Part No.:
- MAX6685AU75H
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Thermostats - Solid State
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX6685AU75H.pdf
- Description:
- DUAL TEMPERATURE SWITCH
- Quantity:
- Payment:
- Shipping:
Inventory:3,631
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Product details
Overview
MAX6685AU75H from Maxim Integrated is a dual-output remote-junction temperature switch using an external diode-connected transistor for precision CPU die temperature monitoring. It features factory-programmed +125°C upper trip threshold, pin-selectable lower threshold range of +75°C to +115°C (in 5°C steps), ±1.5°C accuracy, and CMOS push-pull active-high TLOW output - deployed in thermal shutdown and fan control circuits for high-performance computing systems.
For engineers reviewing the MAX6685AU75H datasheet, MAX6685AU75H pinout, MAX6685AU75H application, or MAX6685AU75H equivalent, this device supports precise dual-threshold thermal management with low 200µA supply current, 8-pin µMAX package compatibility, and noise-immune remote-sensing architecture optimized for FPGA and multichip module environments.
Technical Context
The MAX6685AU75H integrates a BiCMOS remote-junction sensor front-end with two independent comparators: one fixed at +125°C (THIGH, open-drain active-low), and one programmable across +75°C–+115°C (TLOW, CMOS push-pull active-high). Threshold selection is set at power-up via S1/S2 logic levels, with hysteresis of 5°C preventing output chatter near trip points.
It sources 8–12µA bias current into the external sensing diode (DXP/DXN), employs oversampling and integrated filtering (2200pF recommended), and maintains ±2.0°C total threshold error over -40°C to +125°C ambient while operating from 3.0V–5.5V. Conversion time is 110ms typical with 450ms sample period.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Upper Trip Threshold | +125°C factory preset - triggers THIGH for critical thermal shutdown |
| Lower Trip Range | +75°C to +115°C in 5°C increments - selected by S1/S2 pins for staged thermal response |
| Temperature Accuracy | ±1.5°C typical, ±2.0°C max - ensures reliable trip point margin in CPU/FPGA thermal protection |
| Supply Current | 200µA average - enables low-power thermal monitoring without burdening system power budget |
| Output Type (TLOW) | CMOS push-pull, active-high - drives logic inputs directly without pull-up resistor |
| Hysteresis | 5°C typical - prevents oscillation during slow temperature transitions near thresholds |
| Operating Voltage | 3.0V to 5.5V - compatible with 3.3V and 5V system rails |
| Package | 8-pin µMAX (3mm × 3mm) - space-constrained PCB layout for dense compute modules |
Pinout & Package
MAX6685AU75H is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), thermally enhanced with exposed pad (not electrically connected). Pin 1 = VDD; Pin 2 = GND; Pin 3 = DXP (sensing diode anode drive); Pin 4 = DXN (sensing diode cathode return); Pin 5 = THIGH (open-drain active-low alarm); Pin 6 = TLOW (CMOS push-pull active-high alarm); Pins 7–8 = S1/S2 (lower threshold select inputs).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD (Pin 1) | Power supply input | 3.0V–5.5V rail; requires 0.1µF bypass capacitor to GND for stable operation |
| GND (Pin 2) | Ground reference | Common return for all internal circuitry and DXP/DXN sensing path |
| DXP (Pin 3) | Diode anode drive | Sources 8–12µA bias current into external PNP base-emitter junction |
| DXN (Pin 4) | Diode cathode return | Sinks bias current; must be shorted to GND with minimal trace length |
| THIGH (Pin 5) | Upper threshold alarm | Open-drain, active-low output - requires external pull-up to logic rail up to 5.5V |
| TLOW (Pin 6) | Lower threshold alarm | CMOS push-pull, active-high - directly interfaces with enable/shutdown logic |
| S1 (Pin 7) | Threshold select bit 0 | Logic level (GND/VDD/floating) sets lower trip point with S2 per Table 1 |
| S2 (Pin 8) | Threshold select bit 1 | Paired with S1 to configure +75°C–+115°C lower threshold in 5°C steps |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent trip outputs | THIGH for hard shutdown (+125°C), TLOW for early warning/fan ramp (+75°C–+115°C) |
| Pin-programmable lower threshold | No configuration register or I²C needed - S1/S2 logic states define trip point at power-on |
| Remote diode sensing accuracy | ±1.5°C typical error enables tight thermal guardbanding in CPU/FPGA thermal design |
| Low quiescent current | 200µA average draw allows continuous monitoring in always-on thermal safety circuits |
| Noise-immune sensing interface | Oversampled DXP/DXN with 2200pF filtering supports reliable operation near switching regulators |
| BiCMOS process integration | Combines precision analog sensing with robust digital output drivers in single 3×3mm package |
Applications
| CPU Temperature Protection | Fan Control |
|---|---|
|
Use Scenario: Monitors die temperature of x86 or ARM-based processors using on-chip PNP sensing diodes. IC Role / Device Role / Timing Role: Remote-junction temperature switch providing two-stage thermal response: TLOW initiates fan speed increase; THIGH forces immediate system shutdown. Use Value: Prevents thermal runaway with ±1.5°C accuracy and 5°C hysteresis - avoids false trips during transient load spikes. |
Use Scenario: Regulates cooling fan speed based on real-time junction temperature of GPU or ASIC. IC Role / Device Role / Timing Role: Generates active-high TLOW signal to enable PWM fan controller when temperature exceeds user-set lower threshold. Use Value: Enables staged thermal response - fan activates before critical temperature is reached, reducing acoustic noise and power consumption. |
| Multichip Modules | FPGA Temperature Protection |
|
Use Scenario: Tracks hot-spot temperature across stacked memory and processor dies in 2.5D/3D packages. IC Role / Device Role / Timing Role: Uses discrete diode-connected transistors placed near thermal hotspots to feed DXP/DXN inputs. Use Value: Dual outputs allow independent thermal throttling of logic and memory domains within same MCM substrate. |
Use Scenario: Protects high-density FPGA fabric from overheating during reconfiguration or high-clock-rate operation. IC Role / Device Role / Timing Role: Triggers partial reconfiguration or clock gating via TLOW, and full reset via THIGH if temperature exceeds +125°C. Use Value: Maintains FPGA reliability under variable workloads with no software overhead - fully hardware autonomous. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output remote-junction temperature switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6685AU75L | Same package and pinout; identical lower threshold range (+75°C–+115°C) but +120°C upper trip instead of +125°C | Used where less aggressive critical shutdown threshold is acceptable (e.g., industrial controllers with wider thermal margins) | Select MAX6685AU75L if system thermal design targets +120°C maximum safe junction temperature |
| MAX6686AU75H | Same package and thresholds, but TLOW is open-drain active-low (vs. CMOS push-pull active-high in MAX6685AU75H) | Requires external pull-up resistor and inverted logic handling; suited for legacy systems with open-drain bus architectures | Choose MAX6686AU75H only when interfacing with existing open-drain alarm buses or shared interrupt lines |
Compared with MAX6685AU75L and MAX6686AU75H, the MAX6685AU75H uniquely delivers +125°C critical trip with direct-drive active-high TLOW - eliminating pull-up components and simplifying interface to modern microcontroller GPIOs requiring asserted-high enable signals.
Availability
MAX6685AU75H is available at Aetrix Electronics and suitable for CPU thermal protection, FPGA safety monitoring, multichip module thermal management, and fan control systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX6685AU75H 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 and mixed-signal ICs for demanding industrial, computing, and communications applications - emphasizing performance, integration, and reliability.
The MAX6685/MAX6686 family was developed specifically for hardware-based thermal safety in high-performance digital systems, delivering dual-threshold remote-junction sensing without microcontroller dependency or firmware overhead.
FAQ
What is the upper temperature trip threshold of the MAX6685AU75H?
The MAX6685AU75H has a factory-programmed upper temperature trip threshold of +125°C. This value is fixed and cannot be adjusted. When the remote-sensed junction temperature exceeds +125°C, the THIGH output asserts low (open-drain, active-low). The MAX6685AU75H does not support field reprogramming of this threshold - it is laser-trimmed during manufacturing and verified per datasheet specifications.
How is the lower temperature trip threshold configured on the MAX6685AU75H?
The lower temperature trip threshold of the MAX6685AU75H is set using the S1 and S2 pins, which must be configured before VDD power is applied. For the AU75H variant, these pins select values from +75°C to +115°C in 5°C increments (e.g., S1=GND, S2=VDD yields +85°C). Configuration after power-up has no effect - the device latches the state present at power-on reset.
What type of output does the TLOW pin provide on the MAX6685AU75H?
The TLOW pin on the MAX6685AU75H is a CMOS push-pull, active-high output. It drives HIGH when the remote temperature exceeds the programmed lower threshold and LOW otherwise. Unlike open-drain variants, it requires no external pull-up resistor and can directly drive standard logic inputs, simplifying interface design in systems such as FPGA thermal management or microcontroller-based fan control.
Which external sensing element is required for the MAX6685AU75H?
The MAX6685AU75H requires an external diode-connected transistor - not a discrete diode - as its remote temperature sensing element. Recommended devices include ON Semiconductor 2N3904, Central Semiconductor CMPT3904, or Rohm SST3904, wired with base shorted to collector (diode-connected NPN) or emitter shorted to base (diode-connected PNP). The DXP/DXN pins source and sink bias current into this junction to measure VBE temperature dependence.
What is the supply voltage range and typical current draw of the MAX6685AU75H?
The MAX6685AU75H operates from 3.0V to 5.5V DC and draws 200µA typical average supply current. During conversion, current rises to 400–800µA for ~110ms. This low quiescent current enables continuous thermal monitoring in power-sensitive applications like portable computing or always-on embedded controllers without impacting system efficiency.
MAX6685AU75H 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:
- Cold, Hot
- Switching Temperature:
- 75°C
- Accuracy:
- ±1.5°C
- Current - Output (Max):
- 20mA
- Output Type:
- Push-Pull
- Output:
- Active High
- Output Function:
- /OverTemp
- Selectable Hysteresis:
- No
- Features:
- Selectable Trip Point
- Voltage - Supply:
- 3 V ~ 5.5 V
- Current - Supply:
- 200µA
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-µMAX
MAX6685AU75H FAQ
1.How can I place an order for MAX6685AU75H through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6685AU75H 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 MAX6685AU75H reliable?
The price and inventory of MAX6685AU75H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6685AU75H is usually 5 days.
3.What payment methods are accepted for MAX6685AU75H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6685AU75H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6685AU75H?
MAX6685AU75H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6685AU75H 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 MAX6685AU75H?
For technical support, including MAX6685AU75H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6685AU75H requirements.
6.How does Aetrix verify that MAX6685AU75H is sourced from the original manufacturer or authorized distributors?
All MAX6685AU75H 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 MAX6685AU75H meets industry standards.
7.What is the process for return or replacement of MAX6685AU75H?
All MAX6685AU75H units undergo pre-shipment inspection (PSI). If there is an issue with MAX6685AU75H, 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 MAX6685AU75H part is unused and in its original packaging.
Return procedure for MAX6685AU75H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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