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Analog Devices Inc./Maxim Integrated MAX31790ATI+T
- Part No.:
- MAX31790ATI+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Motor Drivers, Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
MAX31790ATI+T.pdf
- Description:
- IC MOTOR DRIVER 3V-5.5V 28TQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,078
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Product details
Overview
MAX31790ATI+T from Maxim Integrated is a 6-channel PWM-output fan RPM controller IC designed for precise, independent speed control and tachometer-based monitoring of up to six 4-wire fans in high-reliability thermal management systems. It features I²C interface (up to 400 kHz), ±1% RPM accuracy, programmable PWM duty-cycle slew rate, and operates from 3.0V to 5.5V over –40°C to +125°C.
For engineers reviewing the MAX31790ATI+T datasheet, MAX31790ATI+T pinout, MAX31790ATI+T application, or MAX31790ATI+T equivalent, key selection considerations include its dual-mode (PWM/RPM) fan control architecture, 12-tachometer-input capability via PWM pin reconfiguration, startup configuration pins (PWM_START0/1, FREQ_START), watchdog timer with I²C timeout, and TQFN-28 package compatibility with high-density server PCB layouts.
Technical Context
The MAX31790ATI+T implements a dual-loop fan control architecture: PWM mode directly sets duty cycle, while RPM mode dynamically adjusts duty cycle to match target tachometer counts derived from an internal 8192 Hz clock (fTOSC/4). Its tachometer measurement uses 11-bit resolution and supports selectable tach periods (1–32 pulses) per count window.
Startup behavior is hardware-configurable via five dedicated pins (PWM_START0/1, FREQ_START, SPIN_START, WD_START), enabling deterministic fan drive without host MCU initialization. The device integrates sequential fan activation (0–4 s inter-channel delay), FULL_SPEED override, and open-drain FAN_FAIL output with maskable fault reporting - all operating within the full industrial temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0 V to 5.5 V - supports direct connection to common system rails (3.3 V or 5 V) without level-shifting. |
| PWM Channels | 6 independent outputs - each drives 4-wire fan PWM input directly or modulates fan power via external transistor. |
| Tachometer Inputs | Up to 12 (6 dedicated + 6 reconfigurable PWMOUT pins) - enables monitoring of additional fans without extra ICs. |
| I²C Interface | Standard/fast-mode (400 kHz max) with timeout and watchdog - ensures robust communication in noisy server environments. |
| PWM Resolution | 9-bit (512 steps) - provides fine-grained speed control across full 0–100% duty cycle range. |
| RPM Accuracy | ±1% - achieved via precise 32.768 kHz internal oscillator (±7% over full temp/voltage range) or optional external crystal (±0.1%). |
| Operating Temp | –40°C to +125°C - qualified for under-hood telecom, base station, and enterprise server applications. |
Pinout & Package
MAX31790ATI+T is housed in a 28-pin, 4 mm × 4 mm, 0.5 mm pitch TQFN package with exposed pad (EP) for thermal dissipation. Pin functions are validated per Maxim's official datasheet Rev 3 (May 2020).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ_START, SPIN_START, WD_START, PWM_START0/1 | Power-up configuration inputs | Set default PWM frequency (30 Hz / 1.47 kHz / 25 kHz), spin-up duration (0.5 s / 1 s), watchdog enable, and initial duty cycle (0% / 25% / 50% / 100%) at POR - eliminates boot-time MCU dependency. |
| PWMOUT1–6 | Open-drain PWM outputs | Drive 4-wire fan PWM inputs directly; each can be reconfigured as tachometer input for expanded monitoring. |
| TACH1–6 | Dedicated tachometer inputs | Accept logic-level tach signals (2-pulse/rev typical); support locked-rotor detection for 2-/3-wire fan failure sensing. |
| SDA, SCL | I²C bidirectional data/clock | Open-drain, 5.5 V tolerant - compatible with mixed-voltage I²C buses; includes bus timeout and watchdog reset logic. |
| FULL_SPEED | Active-low override input | Forces all functional fans to 100% duty cycle - used with external thermal switches or cascaded FAN_FAIL signals across multiple MAX31790s. |
| FAN_FAIL | Open-drain fault indicator | Asserts low when ≥1 unmasked fan failure detected - enables system-level thermal shutdown or alert logging. |
| XTAL1/XTAL2 | Crystal oscillator terminals | Support optional 32.768 kHz crystal for enhanced tach accuracy (±0.1% vs. ±7% with internal oscillator). |
| CLKOUT | CMOS clock output | Provides 32.768 kHz reference - usable for system timing or calibration when crystal is absent or disabled. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable PWM slew rate | Adjustable 0–125 ms/LSB increment - reduces audible fan "click" during speed transitions in acoustic-sensitive environments. |
| Sequential fan activation | Configurable 0/250/500 ms/1/2/4 s inter-channel delay - prevents inrush current overload on shared 12 V power rails during cold start. |
| Dual-mode fan control | Hardware-selectable PWM or closed-loop RPM mode - balances simplicity (PWM) with precision (RPM) per fan channel. |
| Hardware-configurable POR | 5-pin strapping (ADD0/1, WD_START, SPIN_START, FREQ_START, PWM_START0/1) - ensures safe, predictable fan operation before firmware initialization. |
| 12-tachometer monitoring capability | 6 dedicated + 6 reconfigurable PWMOUT pins - supports mixed fan populations (e.g., 4× 4-wire + 2× 3-wire) on single IC without external muxing. |
Applications
| Server Rack Thermal Management | Telecom Base Station Cooling |
|---|---|
Use Scenario: Real-time adjustment of 6 redundant cooling fans across CPU, GPU, and ASIC zones in 1U/2U rack servers. IC Role / Device Role / Timing Role: Primary fan RPM controller with I²C telemetry, RPM feedback loop closure, and fail-safe FULL_SPEED override triggered by CPU thermal diode or BMC alarm. Use Value: Maintains sub-±2°C board temperature uniformity while reducing acoustic noise via controlled PWM ramping - critical for datacenter noise compliance. | Use Scenario: Coordinated cooling of RF power amplifiers, baseband processors, and power supplies in outdoor macrocell cabinets. IC Role / Device Role / Timing Role: Standalone thermal supervisor interfacing with 4-wire fans and analog temperature sensors; uses watchdog to detect host processor lockup. Use Value: Enables -40°C to +70°C ambient operation with ±1% RPM accuracy - ensures consistent airflow despite wide temperature swings and dust accumulation. |
| Network Switch Chassis Cooling | Industrial Edge Compute Gateway |
Use Scenario: Managing 6 high-static-pressure fans in modular L2/L3 switch chassis with hot-swap line cards and variable packet-processing loads. IC Role / Device Role / Timing Role: Fan controller with sequential startup (500 ms delay) and tach-based failure detection - reports faults via I²C to switch fabric controller. Use Value: Prevents 12 V rail collapse during simultaneous fan spin-up; detects bearing wear or obstruction via tach pulse dropout before thermal throttling occurs. | Use Scenario: Fan control in fanless-designed edge gateways upgraded with active cooling for extended temperature operation (-40°C to +85°C). IC Role / Device Role / Timing Role: Low-power thermal manager using internal 32.768 kHz oscillator and 3.3 V supply - interfaces with ARM Cortex-M host via I²C. Use Value: Delivers 1.5 mA quiescent current at 3.3 V - extends uptime in battery-backed or PoE-powered deployments without compromising RPM precision. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fan control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM75BIMM/NOPB | Temperature sensor only - no fan control, PWM, or tach monitoring capability. | Requires external MCU and driver circuitry to implement fan control logic. | Select only if discrete thermal sensing is needed alongside separate fan control solution. |
| ADT7470ARQZ | 5-channel fan controller with SMBus interface; lacks sequential startup, hardware POR strapping, and 12-tach input flexibility. | Designed for legacy PC platforms; limited industrial temp range (–40°C to +125°C not guaranteed). | Choose for cost-sensitive PC-compatible designs where I²C compatibility and extended temperature are not required. |
Compared with LM75BIMM/NOPB and ADT7470ARQZ, the MAX31790ATI+T uniquely integrates hardware-configurable power-on behavior, 12-tach monitoring scalability, and sequential fan activation - making it the only option that delivers full autonomous fan control without host intervention in harsh-temperature embedded systems.
Availability
MAX31790ATI+T is available at Aetrix Electronics and suitable for server rack thermal management, telecom base station cooling, and network switch chassis applications requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for MAX31790ATI+T 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.
The MAX31790ATI+T belongs to Maxim's thermal management product line, engineered specifically for autonomous, high-precision fan control in space-constrained, thermally demanding infrastructure equipment.
FAQ
What is the maximum number of fans the MAX31790ATI+T can monitor and control simultaneously?
The MAX31790ATI+T controls up to six fans via dedicated PWM outputs and monitors up to twelve fans using its six dedicated TACH inputs plus six reconfigurable PWMOUT pins as tachometer inputs. This 6+6 architecture allows flexible deployment - for example, controlling four 4-wire fans while monitoring two additional 3-wire fans using PWMOUT pins in TACH mode. All monitoring and control functions operate within the specified –40°C to +125°C temperature range.
Does the MAX31790ATI+T require an external crystal for accurate RPM measurement?
No, the MAX31790ATI+T includes an internal 32.768 kHz oscillator that enables ±7% tach accuracy over –40°C to +125°C and 3.0 V to 5.5 V. An external crystal (12 pF load, 50 kΩ ESR) may be connected to XTAL1/XTAL2 to improve accuracy to ±0.1%, but it is optional. The CLKOUT pin always provides a 32.768 kHz CMOS signal regardless of oscillator source, supporting system-level timing needs without added components.
How does the MAX31790ATI+T handle fan failure detection in RPM mode?
In RPM mode, the MAX31790ATI+T detects fan failure when any of three conditions occur: (1) tach count exceeds the TACH Target Count register value while PWM duty cycle is 100%; (2) tach count exceeds twice the target count while duty cycle is <100%; or (3) tach count reaches its maximum 11-bit value (0x7FF). Detection requires consecutive faults (1–6, user-selectable) before asserting the open-drain FAN_FAIL output. Failed fans can be configured to force 0% or 100% duty cycle, or continue normal operation.
Can the MAX31790ATI+T operate without I²C host intervention after power-up?
Yes, the MAX31790ATI+T supports fully autonomous operation via five hardware strapping pins: PWM_START0/1, FREQ_START, SPIN_START, and WD_START. These configure initial PWM duty cycle, frequency, spin-up behavior, and watchdog enable state at power-on reset - eliminating dependency on host firmware. Once configured, it maintains closed-loop RPM control, sequential fan startup, and fault reporting independently, making it ideal for systems with delayed or unreliable MCU boot sequences.
What is the purpose of the FULL_SPEED input on the MAX31790ATI+T?
The FULL_SPEED input on the MAX31790ATI+T is an active-low signal that forces all functional fans to 100% PWM duty cycle immediately, overriding all software-controlled settings. It remains active even in standby mode and is commonly used with external thermal switches or cascaded FAN_FAIL outputs from other MAX31790ATI+T devices to implement fail-safe overtemperature protection across multi-controller systems - ensuring continuous airflow during critical thermal events.
MAX31790ATI+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushless DC (BLDC)
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Low Side (6)
- Interface:
- I2C
- Technology:
- Power MOSFET
- Step Resolution:
- -
- Applications:
- Fan Motor Driver
- Current - Output:
- -
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TQFN (4x4)
MAX31790ATI+T FAQ
1.How can I place an order for MAX31790ATI+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX31790ATI+T 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 MAX31790ATI+T reliable?
The price and inventory of MAX31790ATI+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX31790ATI+T is usually 5 days.
3.What payment methods are accepted for MAX31790ATI+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX31790ATI+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX31790ATI+T?
MAX31790ATI+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX31790ATI+T 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 MAX31790ATI+T?
For technical support, including MAX31790ATI+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX31790ATI+T requirements.
6.How does Aetrix verify that MAX31790ATI+T is sourced from the original manufacturer or authorized distributors?
All MAX31790ATI+T 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 MAX31790ATI+T meets industry standards.
7.What is the process for return or replacement of MAX31790ATI+T?
All MAX31790ATI+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX31790ATI+T, 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 MAX31790ATI+T part is unused and in its original packaging.
Return procedure for MAX31790ATI+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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