ZHCSR80A June   2009  – January 2023 AMC6821-Q1

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 说明（续）
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Functional Block Diagram
    2. 8.2 Feature Description
      1. 8.2.1 ADC Converter
      2. 8.2.2 Temperature Sensor
        1. 8.2.2.1 Series Resistance Cancellation
        2. 8.2.2.2 Reading Temperature Data
        3. 8.2.2.3 Temperature Out-of-Range Detection
        4. 8.2.2.4 Remote Temperature Sensor Failure Detection
      3. 8.2.3 PWM Output
      4. 8.2.4 PWM Waveform Setting
      5. 8.2.5 Fan Speed Measurement
        1. 8.2.5.1 Tach-Data Register
          1. 8.2.5.1.1 Reading the Tach Data Register
          2. 8.2.5.1.2 RPM Measurement Rate
          3. 8.2.5.1.3 Select Number of Pulses/Revolution
          4. 8.2.5.1.4 Tach Mode Selection
          5. 8.2.5.1.5 Fan RPM Out-of-Range Detection
      6. 8.2.6 Fan Failure Detection
      7. 8.2.7 FAN-FAULT Pin
      8. 8.2.8 Fan Control
        1. 8.2.8.1 THERM Pin and External Hardware Control
          1. 8.2.8.1.1 THERM Pin as an Output
          2. 8.2.8.1.2 THERM Pin as an Input
        2. 8.2.8.2 Fan Spin-Up
        3. 8.2.8.3 Normal Fan Speed Control
          1. 8.2.8.3.1 Software DCY Control Mode
          2. 8.2.8.3.2 Software-RPM Control Mode (Fan Speed Regulator)
          3. 8.2.8.3.3 Auto Temperature Fan Mode
      9. 8.2.9 Interrupt
        1. 8.2.9.1 OVR Pin
        2. 8.2.9.2 SMBALERT Pin
        3. 8.2.9.3 SMBALERT Interrupt Behavior
        4. 8.2.9.4 Handling SMBALERT Interrupts
    3. 8.3 Device Functional Modes
    4. 8.4 Programming
      1. 8.4.1 SMBus Interface
        1. 8.4.1.1 Communication Protocols
      2. 8.4.2 SMBus Alert Response Address (ARA)
      3. 8.4.3 Power-On Reset and Start Operation
    5. 8.5 Register Map
      1. 8.5.1 Register Description
        1. 8.5.1.1 Device Configuration Registers
        2. 8.5.1.2 Device Status Registers
        3. 8.5.1.3 Fan Controller Registers
        4. 8.5.1.4 Temperature Data Registers
        5. 8.5.1.5 Temperature Limit Registers
          1. 8.5.1.5.1 Tach-Data Register
          2. 8.5.1.5.2 Tach Setting Register
          3. 8.5.1.5.3 Tach Low Limit Register
          4. 8.5.1.5.4 Tach High Limit Register
  9. 9 Application and Implementation
    1. 9.1 Power Supply Recommendations
  10. 10Device and Documentation Support
    1. 10.1 接收文档更新通知
    2. 10.2 支持资源
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 术语表
  11. 11Mechanical, Packaging, and Orderable Information

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8.2.6 Fan Failure Detection

When the TACH data are larger than the TACH low limit, the fan runs at a speed below the predefined minimum RPM. When this condition occurs, a spin-up process is applied to start the fan again when spin-up is enabled. Bits [STIME2:STIME0] of the Fan Characteristics Register define this time period. Figure 8-9 shows the function of the fan failure detection. Refer to the Fan Spin-Up section.

The fan speed is measured immediately after spin-up; the TACH-FAST bit of Configuration Register 4 determines the monitoring rate. If the fan does not return to a normal range after five consecutive spin-ups, a FAN-FAILURE occurs; the FAN-FAULT pin goes low when it is enabled (the FAN-FAULT-EN bit of Configuration Register 1 is set), and the spin-up process continues. If the fan returns to a normal speed range before the fifth spin-up, the FAN-FAULT pin does not go low even though the FANS bit is still set to '1'. No FANS (fan-slow) detections are performed during spin-up. After the FAN-FAULT pin goes low, spin-up is performed indefinitely until the RPM reading returns to within normal range or the spin-up is disabled.

GUID-F016031C-8C6F-4AC0-ABB1-34CEEC9AF29D-low.gifFigure 8-9 Fan Failure Detection and Spin-Up

The SMBALERT pin continues to generate interrupts after the assertion of the FAN-FAULT pin because the tach measurement continues even after a fan failure. Should the fan recover from the failure condition, the FAN-FAULT pin signal is negated and the fan returns to normal operating speed. Figure 8-10 shows the operation of a FANS interrupt.

GUID-D0977CAF-383D-437B-BC97-4DA1514DB04E-low.gif
INT is a Fan-Slow (FANS) Interrupt Through the SMBALERT Pin
Figure 8-10 Operation of the FAN-FAULT Pin With a Spin-Up Time = 2 Seconds