SBAS475A June   2009  – January 2023 AMC6821-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  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 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6 Pin Configuration and Functions

GUID-BC6CE4E4-795F-4E01-B27C-42A57378DA3F-low.gifFigure 6-1 DBQ Package16-Pin SSOPTop View
Table 6-1 Pin Functions
PINI/ODESCRIPTION
NAMENO.
PWM-OUT1

O

Digital output, open-drain. PWM output to control fan speed.
TACH2

I

Digital input. Fan tachometer input to measure the fan speed.
OVR3

O

Digital output, open-drain, active low. Goes low when temperature reaches the critical shutdown threshold or remote temperature sensor failed. (See the Interrupt section for details.)
NC4

-

Not connected. Reserved for manufacturer's testing.
GND5

_

System ground
VDD6

I

Power supply, 3 V to 5 V
THERM7

I/O

Digital input/output (open-drain). As an output, an active low output indicates the temperature over the THERM temperature limit. As an input, the pin provides an external fan control. When the pin is pulled low by external signal, the THERM-IN bit is set, and the fan is set to full-speed.
FAN-FAULT8

O

Digital open-drain output. Goes low when a fan failure is detected.
IN–9

I

Negative analog differential input. Connected to cathode of external temperature-sensing diode.
IN+10

I

Positive analog differential input. Connected to anode of external temperature-sensing diode Pentium-IV™ substrate transistor or general-purpose 2N3904 type transistor.
PWM-MODE11

I

PWM mode selection. When tied low (GND), the high PWM frequency range (1 kHz to 40 kHz) is selected. When tied to VDD or floated, the low PWM frequency range (10 Hz to 94 Hz) is selected. Checked only on power-up or reset.
A112

I

Device slave address selection pin (see the SMB Interface section for details). Checked only on power-up or reset.
A013

I

Device slave address selection pin (see the SMB Interface section for details). Checked only on power-up or reset.
SMBALERT14

O

Digital output, open-drain, SMBALERT, active low. Requires a pullup resistor (2.2 kΩ typical).
SDA15

I/O

Bidirectional digital I/O pin, SMBus data, open-drain. Requires a pullup resistor (2.2 kΩ typical).
SCLK16

I

Digital input, SMBus clock. Requires a pullup resistor (2.2 kΩ typical).